Free cooling guide

01 | 2013

Free cooling guideC O O L I N G I N T E G R AT I O N I N LO W -E N E R G Y H O U S E S

Table of contents

1. Introduction to the concept of free cooling ...3

The need for cooling in low-energy houses .............4

Comfort and energy effi ciency – the best fi t

for low-energy houses ............................................4

Investing for the future – the design of a

low-energy house ...................................................5

2. Cooling loads in residential buildings .............6

Factors infl uencing the sensible cooling load ..........6

Factors infl uencing the latent cooling load .............7

The effect of shading ..............................................7

Room variation .......................................................8

Duration of the cooling load ..................................8

Required cooling capacity .......................................9

3. The ISO 7730 guidelines .................................10

Optimal temperature conditions ............................10

Draught rate .........................................................11

Radiant asymmetry ...............................................11

Surface temperatures ............................................12

Vertical air temperature difference ........................12

4. Capacity and limitations of radiant

emitter systems ..............................................13

Heat fl ux density ...................................................13

Thermal transfer coeffi cient ..................................13

Dew point limitations ............................................13

Theoretical capacities of embedded

radiant cooling ......................................................14

5. Ground heat exchangers .................................15

Ground conditions ................................................15

Ground heat exchangers .......................................16

Ground temperature profi le...................................17

Primary supply temperatures .................................17

Dimensioning of ground heat exchangers

for free cooling .....................................................17

6. Free cooling in combination with

different heat sources ....................................19

7. Choosing and dimensioning the radiant

emitter system ................................................20

Capacity of different radiant emitter systems ........20

Radiant fl oor constructions and capacity ..............22

Radiant ceiling constructions and capacity ...........24

Capacity diagrams .................................................24

Regulation and control..........................................26

The self-regulating effect in underfl oor heating ..27

Functional description of Uponor Control

System .................................................................27

Component overview ............................................29

8. Uponor Pump and exchanger group (EPG6)

for ground sourced free cooling .....................29

Dimensions ...........................................................30

Pump diagram .......................................................30

Control principle ...................................................31

Installation examples.............................................33

Operation of Uponor Climate Controller C-46 .......36

Operation mode of Uponor Climate

Controller C-46 .....................................................36

Dew point management parameters and

settings .................................................................37

Heating and cooling change-over:

external signal .......................................................38

Heating and cooling change-over:

Uponor Climate Controller C-46 ............................38

2 U P O N O R · F R E E C O O L I N G G U I D E

1. Introduction to the concept of free cooling

Free cooling is a term generally used when low external

temperatures are used for cooling purposes in buildings.

This guide presents a free cooling concept based on

a ground coupled heat exchanger combined with a

radiant heating and cooling system. A ground coupled

heat exchanger can for example be horizontal collectors,

vertical boreholes or energy cages. A radiant system

means that the fl oors, ceilings or walls have embedded

pipes in which water is circulated for heating and

cooling of the building. Under fl oor heating and cooling

is the most well know example of a radiant system.

A radiant system combined with a ground coupled heat

exchanger is highly energy effi cient and has several

advantages. In the summer period, the ground coupled

heat exchanger provides cooling temperatures that are

lower compared to the outside air. The radiant system

operates with large surfaces, which means it can utilize

the temperatures from the ground directly for cooling

purposes. The result is that free cooling can be provided

with only cost being the electricity required for running

the circulation pumps in the brine and water systems.

No heat pump is required.

In the heating season the system is operated using a

heat pump. As the ground temperature during winter

is higher compared to the outside air temperature,

the result is improved heat pump effi ciency (COP)

compared to an air based heat pump. In addition, the

radiant emitter a system (under fl oor heating) operates

at moderate water temperatures in large surfaces which

further improves the heat pump COP.

3U P O N O R · F R E E C O O L I N G G U I D E

The need for cooling in low-energy houses

Today, there is a high focus on saving energy and

utilising renewable energy sources in buildings.

The energy demand for space heating is reduced by

increased insulation and tightness of buildings.

However, increased insulation and tightness also

increase the cooling demand. The building becomes

more sensitive to solar radiation through windows and

becomes less able to remove heat in the summer. More

extreme weather conditions further contributes to the

cooling needs and together with an even more increased

consumer awareness of having the right indoor climate,

the need for cooling also in residential buildings will

become a requirement. Optimal architectural design

and shading will help to reduce the cooling need, but

simulations and practical experience show that such

measures alone will not eliminate the cooling need.

Space cooling is needed, not only in the summer, but

also in prolonged periods during spring and autumn

when the low angel of the sun gives high solar radiation

through windows. In order to meet the energy frame

requirements of the building regulations, space cooling

can be provided by utilising renewable energy sources

such as ground heat exchangers for cooling purposes in

conjunction with a radiant system with embedded pipes

in the fl oor, wall or ceiling.

Cooling needs will differ between rooms and are highly

infl uenced by direct solar radiation. Rooms with larger

window areas and facing the south will generally have

higher cooling requirements. In periods with high

cooling loads, active cooling is normally required during

both day and night time.

Comfort and energy effi ciency – the best fi t for low-energy houses

Using shading will help to reduce the cooling demand.

However, this forces occupants to actively pull down the

shades e.g. when leaving the house. Also, shading will

block daylight which increases electricity consumption

on artifi cial light, and shading will block the view which

may not be in the interest of the home occupant.

In fact many architects state that energy effi ciency

and comfort may confl ict when defi ning comfort in a

broader sense, such as the freedom to design window

sizes, spaciousness with increased ceiling height,

daylight requirements and the occupant’s tendency to

utilise open doors and windows. All such requirements

put increased demands on the HVAC applications.

Ground heat exchangers combined with radiant systems

is the only “all-in-one” solution, with the ability to

provide both heating and cooling. Such systems are

more cost effi cient and simpler to install than having

to deal with a separate heating and cooling systems.

Furthermore, radiant systems are able to heat at a

low supply temperature and cool at a high supply

temperature. This fi ts perfectly to the typical operating

temperatures of a ground coupled heat exchanger.

Furthermore, the connected heat pump will be able

to run more effi ciently and thereby consume less

electricity. In addition, a radiant system provides no

draught problems and provides an optimal temperature

distribution inside a room. Last but not least, radiant

systems provide complete freedom in terms of interior

design, as no physical space is occupied inside the room.

Even more important when looking at the lifetime and

property value of a house, such systems have very low

maintenance need and a lifetime that almost follows

the lifetime of the building itself. In today’s uncertain

environment of future energy prices, free cooling and

ground coupled heat pumps provides a high stability

on the future energy costs of the building in question.

It will most certainly meet today’s and future building

regulations even in a scenario where future property

taxation would be linked to energy effi ciency. Hence, it

is an investment that helps to maintain and differentiate

the future property value.


Investing for the future – the design of a low-energy house

A radiant system, e.g. underfl oor heating and cooling,

coupled to a ground source heat pump, provides

optimal comfort with high energy effi ciency both

summer and winter. In addition, due to the increased

tightness requirements in low-energy houses, a

ventilation system is necessary to maintain an

acceptable indoor air quality. In order to keep the

ventilation system energy effi cient, it should be coupled

to a heat recovery ventilation (HRV) unit to minimise

heat losses through the air exchange.

Energy sources for cooling

There are several alternative HVAC applications available

for cooling purposes. A district heating connection is an

energy effi cient option for space heating, but cannot

be used for cooling purposes. Alternative means of

cooling could be an air-to-water heat pump, but no

“free cooling” can be extracted from such a system,

hence cooling can only be provided with the heat

pump running causing a higher electricity consumption.

Purely air-based systems like split units can also act as

a cooling system but as can be seen from the picture

below, the effi ciency is considerably lower than for

water-based cooling systems.

European seasonal energy effi ciency ratio (ESEER) for different cooling systems. ESEER is defi ned by the Eurovent Certifi cation Company and calculated by combining full and part load operating conditions.

Correlation between average property m2 prices and energy class

The fi gure above shows the correlation between

property prices and the energy effi ciency level of the

property in Denmark. Properties with energy class A or

B are on average 6% more expensive than energy class

C and 17% more expensive than energy class D.

DKK/m2

Energy class

0

5

10

15

20

25

Air to air heat pump

Air to water heat pump

Brine to water heat pump

Freecooling


2. Cooling loads in residential buildings

The design cooling load (or heat gain) is the amount

of energy to be removed from a house by the

HVAC equipment, to maintain the house at indoor

design temperature when worst case outdoor design

temperature is being experienced. As can be seen

from the fi gure above, heat gains can come from

external sources, e.g. solar radiation and infi ltration

and from internal sources, e.g. occupants and electrical

equipment.

Two important factors when calculating the cooling load

of a house are:

• sensible cooling load

• latent cooling load

The sensible cooling load refers to the air temperature

of the building, and the latent cooling load refers to the

humidity in the building.

Factors infl uencing the sensible cooling load

• Windows or doors

• Direct and indirect sunshine through windows,

skylights or glass doors heating up the room

• Exterior walls

• Partitions (that separate spaces of different

temperatures)

• Ceilings under an attic

• Roofs

• Floors over an open crawl space

• Air infi ltration through cracks in the building, doors,

and windows

• People in the building

• Equipment and appliances operated in the summer

• Lights


The effect of shading

To reduce the cooling load from solar gains, the most

effi cient and sustainable way is to use passive measures.

From an architectural point of view, shading can be

created by building components and by using blinds.

Depending on the type of blinds used, the solar gain

can typically be reduced with up to 85% with external

shading. The fi gures below show a building simulation

example conducted on a low-energy single family

house, where using different shading factors have been

applied.

Without shading; cooling loads up to 60 W/m2.

Shading factor 50%; cooling loads up to 40 W/m2.

Shading factor 85%; cooling loads up to 25 W/m2.

As can be seen from the fi gures above, even with the

most effi cient shading factor, the cooling load still

amounts to 25 W/m2.

Exte

rnal

heat

gain

Inte

rnal

heat

gain

Transmission (Sensible)

Solar Radiation (Sensible)

Air

Ventilation

(Sensible)

(Latent)

(Sensible)

(Latent)

(Sensible)

(Sensible)

(Latent)

Lighting

Equipment

People

CO

ND

ITIO

NE

D

SP

AC

E

Total

sensible

Total

latent

Cooling

Load

2%5%

3%

10%

13%

15%

52%

Heat from air fl ows

Heat from occupants(incl. latent)

Heat from equipment

Heat from walls and fl oors (structure)

Heat from lighting

Heat from daylight(direct solar)

Heat from windows (including absorbed solar) and openings

Factors infl uencing the latent cooling load

Moisture is introduced into a room through:

• People

• Equipment and appliances

• Air infi ltration through cracks in the building, doors,

and windows

Internal gains in residential buildings are limited to the

people normally occupying the space and household

equipment. In national building regulations, the load

for internal gains in ordinary residential buildings is

often mentioned (3-5 W/m2). In residential buildings,

the cooling load primarily comes from external heat

gains, and mostly from solar gains through windows

and doors, transmission through wall and roof, and

infi ltration through the building envelope/ventilation.

The fi gure below shows that about 2/3 of the cooling

load comes from the solar radiation.


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No window opening, no HRV by-pass

Open windows, no HRV by-pass

Open windows, with HRV by-pass

UFH, no opening window

Room variation

There is a big variation in the cooling load from room

to room, caused by the architectural design of the

building. Large window areas facing the south and west

are needed for daylight requirements and winter heat

gains, but they also incudes high summer cooling loads.

As a result of large south facing window areas, the

cooling demand in south facing rooms are higher than

in the north facing rooms. In addition, the desired

temperature levels of each room may differ ranging

from the highest temperature requirements in the

bathroom, to the lowest temperature requirements in

the bedroom.

Duration of the cooling load

The fi gures below show the duration of over-tempera-

ture with different shading and ventilation strategies.

The data originates from a full year building simulation

of a low-energy single family house in Northern

European climatic conditions (Denmark).

Without shading; over-temperature up to 2 300 hours per year.

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Shading factor 50%; over-temperature up to 1 100 hours per year. Shading factor 85%; over-temperature up to 800 hours per year.

The simulations show that without active cooling

there will be a signifi cant amount of time with over-

temperature (assuming that the maximum temperature

allowed is 26 °C). All the cases also show that

with radiant fl oor cooling, it is possible to keep the

temperature below 26 °C all year round. National

building regulations across Europe have already started

to implement maximum duration periods of over-

temperature. In Denmark, the requirement in the 2015

standard is that a temperature above 26 °C is only

allowed for maximum 100 h during the year and above

27 °C for maximum 25 h during the year.


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Cooling

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Required cooling capacity

Based on the peak load calculations of the building, the

heating and cooling system can be designed. The HVAC

system should be designed to cover the worst case

(peak load). The fi gures below show an example of the

variation of the needed capacity to cover the heating

and cooling loads.

Required heating and cooling capacity

Low energy building, shading in-between windows.Window opening and HRV by-pass are used during cooling season

Low energy building, external shading.Window opening and HRV by-pass are used during cooling season

As can be seen, the cooling capacity peaks are actually

higher (up to 4 kW), than the heating capacity peaks

(up to 3.5 kW) under any shading conditions (excluding

domestic hot water). Although, the heating period

still remain longer than the total cooling period, it is

interesting to note that the cooling period extends into

early spring and late autumn.

Low energy building, no shading.Window opening and HRV by-pass are used during cooling season


In order to provide thermal comfort, it is necessary

to take into account local thermal discomfort caused

by temperature deviations, draught, vertical air

temperature difference, radiant temperature asymmetry,

and fl oor surface temperatures. These factors can

infl uence on the required capacity of the HVAC system.

Optimal temperature conditions

EN ISO 7730 is an international standard that can be

used as a guideline to meet an acceptable indoor and

thermal environment. These are typically measured in

terms of predicted percentage of dissatisfi ed (PPD)

and predicted mean vote (PMV). PMV/PPD basically

predicts the percentage of a large group of people

that are likely to feel “too warm” or “too cold” (the

EN ISO 7730 is not replacing national standards and

requirements, which always must be followed).

PMV and PPD

The PMV is an index that predicts the mean value of

the votes of a large group pf persons on a seven-point

thermal sensation scale (see table below), based on the

heat balance of the human body. Thermal balance is

obtained when the internal heat production in the body

is equal to the loss of heat to the environment.

PMV Predicted mean vote

PPD Predicted percentage dissatisfi ed [%]

+3 Hot

+2 Warm

+1 Slightly warm

0 Neutral

-1 Slightly cold

-2 Cool

-3 Cold

Seven-point thermal sensation scale

The PPD predics the number of thermally dissatisfi ed

persons among a large group of people. The rest of

the group will feel thermally neutral, slightly warm or

slightly cool.

The table below shows the desired operative tempera-

ture range during summer and winter, taking into con-

sideration normal clothing and activity level in order to

achieve different comfort classes.

Class

Comfort requirements Temperature range

PPD[%]

PMV[/]

Winter 1.0 clo 1.2 met

[°C]

Summer 0.5 clo1.2 met

[°C]

A < 6 - 0.2 < PMV < + 0.2 21-23 23.5-25.5

B < 10 - 0.5 < PMV < + 0.5 20-24 23.0-26.0

C < 15 - 0.7 < PMV < + 0.7 19-25 22.0-27.0

ISO 7730 basically recommends a target temperature

of 22 °C in the winter, and 24.5 °C in the summer. The

higher the deviation around these target temperatures,

the higher the percentage of dissatisfi ed. The reason

for the different target temperatures is because that the

two seasons apply different clothing conditions as can

be seen in below fi gure:

Operative temperature for winter and summer clothing

Dis

sati

sfi e

d [

%]

PP

D

PMV

Operative temperature [°C]

Basic clothing

insulation: 0.5

Pre

dic

ted

Perc

en

tag

e o

f

Dis

sati

sfi e

d [

%]

Basic clothing

insulation: 1.0

Metabolic rate:

1.2

3. The ISO 7730 guidelines

1 0 U P O N O R · F R E E C O O L I N G G U I D E

Radiant asymmetry

When designing a radiant ceiling or wall system, make

sure to stay within the limits of radiant asymmetry. As

can be seen in the fi gure below, the radiant asymmetry

differs depending on the location of the emitter system,

and whether it’s used for heating or cooling.

With the insulation levels typically used today, radiant

asymmetry does normally not cause any problems

due to the moderate heating and cooling load the

emitter has to perform. However, especially when using

ceiling heating, a calculation must be made for a given

reference room.

When designing radiant cooling systems, the dew point

is normally reached before radiant asymmetry problems

occur. Can be calculated according to ISO 7726.

Dis

sati

sfi e

d

Floor temperature

Local discomfort caused by warm and cool fl oors

0

0.4

0.05

0.2

0.15

0.25

0.35

0.2

0.3

0.5 41 1.5 2 2.5 3 3.5 4.5

3.0 K

4.0 K5.0 K6.0 K

7.0 K

8.0 K9.0 K

10.0 K

Maxim

um

air

velo

city

, 0.5

m f

rom

wall

[m

/s]

Recommended comfort limit for

sedentary persons

Height of cool wall [m]

Δt (wall-room)

Draught rate

Radiant systems are low convective systems and will

not create any problems with draught. However, down

draught from a cold wall can put a limitation to the

system. A cold wall can create draught as we know from

windows. When designing wall cooling, the velocity on

the air need to be within the recommendation (Class A

is 0.18 m/s).

1 1U P O N O R · F R E E C O O L I N G G U I D E

Surface temperatures

For many years, people have chosen underfl oor heating

systems as the preferred emitter system, because of the

perceived comfort of walking on a warm fl oor. Similarly,

the question is if the occupants complaint about discom-

fort when utilising the fl oor to remove heat (cooling).

According to ISO 7730, the lowest PPD (6%) is found

at a fl oor temperature of 24 °C. A typical fl oor cooling

system will have to operate with a minimum fl oor

temperature of 20 °C, where the expected PPD would

still be under 10%. As will be seen later, such fl oor

temperatures still provide a signifi cant cooling effect,

due to the large surface area being emitted.

Vertical air temperature difference

The comfort categories are divided into A, B and C

depending upon the difference between the air

temperature at fl oor level and at a height equivalent to

a seated person. As can be seen below, the temperature

difference must be under 2°C in order to reach

category A.

Category

Vertical air temperature difference a

°C

A < 2

B < 3

C < 4

a) 1,1 and 0,1 m above fl oor

A study done by Deli in 1995 shows the correlation

between the ΔT fl oor surface/room (difference between

the fl oor surface temperature and the dimensioned

room temperature) and the vertical air temperature

difference.

Vertical temperature profi le with different emitter systems

[°C]18 20 22 2624

Ideal heating Underfl oor heating

Radiant ceiling heating External wall radiator heating

Temperature profi le radiant cooling

[°C]18 20 22 2624

Radiant fl oor cooling

Radiant ceiling cooling

Radiant wall cooling

1

80

2

4

6

20

8

0 5 10 20 30 352515

0 9 18 36 54 634527

[°C]

[°F]

60

40

10

Dis

sati

sfi e

d [

%]

Radiant temperature asymmetry [°C]

Warm ceiling Cool wall

Cool ceiling Warm wallCorrelation between the temperature difference fl oor surface to room and the vertical air temperature difference (Deli, 1995).

The study concludes that up to a ΔT 8K, the comfort

category is still A. This would equal a fl oor temperature

of 20 °C and a dimensioned room temperature of

28 °C. The dimensioned room temperature must be

below 26 °C and similarly above a fl oor temperature

of 20 °C in order to reach comfort class B. Hence, the

vertical air temperature difference will in practice not

cause a indoor climate below category A.

As the pictures below show, different emitter systems

provide different temperature gradients in a room.

Clearly, a radiant heating system in the fl oor provides

a temperature gradient closest to the ideal. Similarly,

a radiant cooling system in the ceiling provides a

temperature gradient closest to the ideal.

0

0,5

1

1,5

2

2,5

3

2 4 6 8 10

A

B

ΔT fl oor surface room

Vert

ical

air

tem

pera

ture

dif

fere

nce

[K

]

0,1 - 1,1 m


Thermal transfer coeffi cient

The thermal transfer coeffi cient is an expression of how

large an effect per m2 the surface is able to transfer to

the room, per degree of the temperature difference

between the surface and the room. The fi gure below

shows the thermal transfer coeffi cient for different

surfaces for heating and cooling respectively.

Due to natural convection, the fl oor provides the

best thermal transfer coeffi cient for heating while the

ceiling provides the best thermal transfer coeffi cient for

cooling.

Dew point limitations

In order to secure that there is no condensation on the

surface of the emitter in the room the supply water

temperature should be controlled so that the surface

temperatures of the emitter always is above dew point.

In the diagram below, the dew point temperatures can

be found under different levels of relative humidity

(RH):

24

23

22

21

20

19

18

17

16

15

14

13

12

11

10

9

840 45 50 55 60 65 70 75 80

Dew

po

int

tem

pera

ture

[°

C]

Relative humidity RH [%]

Room temp. 26 °C

Room temp. 25 °C

Room temp. 24 °C

Room temp. 23 °C

All emitter systems, whether it is pure air-based,

radiators or pure radiant systems, are bounded by their

ability to transfer energy. The capacity of any radiant

emitter systems is limited by the heat fl ux density, which

differs depending on the location of the emitter, i.e.

fl oor, wall or ceiling. The heat fl ux density can be used

to calculate the capacity of the emitter, also known as

the thermal transfer coeffi cient. Specifi cally regarding

cooling, any radiant emitter will need to work within the

dew point limitations in order to avoid moisture on the

surface and within the construction.

Heat fl ux density

The ability of a surface to transfer heating or cooling

between the surface and the room, is expressed by the

heat fl ux density. According to EN 1264/EN 15377,

the values below can be used to express the heat fl ux

density.

Floor heating, ceiling cooling: q = 8.92 (θs,m

- θi)1.1

Wall heating, wall cooling: q = 8 (| θs,m

- θi |)

Ceiling heating: q = 6 (| θs,m

- θi |)

Floor cooling: q = 7 (| θs,m

- θi |)

Where

q is the heat fl ux density in W/m2

θs,m

is the average surface temperature (always limited

by dew point)

θi is the room design temperature (operative)

4. Capacity and limitations of radiant emitter systems

10

5

0

15

Surface heating and cooling

Floor Ceiling Wall

Heating

Cooling

[W/m2K]

Th

erm

al

tran

sfer

coeffi

cie

nt


Emitter surface and humidity

Design temperatures for cooling systems are specifi ed

according to the dew point. The dew point is defi ned by

the absolute humidity in the room and can be estimated

from the relative humidity RH and the air temperature.

The cooling capacity of the system is defi ned by the

difference between the room temperature and the mean

water temperature.

Often standard design parameters for cooling systems

are an indoor temperature of 26 °C and a relative

humidity of 50%. At the dew point, condensation

will occur on the emitter surface. In order to avoid

condensation, the emitter surface temperature has to be

above the dew point temperature.

For radiant fl oor cooling a minimum surface temperature

of 20 °C is required, which means that only when the

relative humidity exceeds 70% in the room, the risk

of condensation occurs, because that corresponds to

a relative humidity of 100% at the emitter surface.

Radiant cooling from the ceiling is limited by the radiant

asymmetry between the surface of the emitter and the

room temperature recommendation is that it should not

exceed more than 14 K. For standard conditions (26 ºC,

50% RH) the surface of the emitter usually reaches the

dew point before the radiant asymmetry limit.

Distribution pipes and manifolds

In any cooling system where you have distribution pipes

or manifolds you have to be aware of that these parts

of the system also have a risk of condensation because

they sometime operates below the dew point. Insulation

of distribution system is often necessary in order to

avoid condensation.

Design temperature

The design supply water temperature of the system

depends on the type of surface used, the design indoor

conditions (temperature and relative humidity) and the

cooling loads to be removed. It should be calculated to

obtain the maximum cooling effect possible from the

system.

The capacity and mean water temperature for radiant

fl oor cooling depends on the fl oor construction, pipe

pitch and surface material. To have the highest possible

capacity of the system you should design your fl oor

construction so the surface temperature is equal to the

minimum temperature of 20 °C.

The capacity and mean water temperature for radiant

cooling from the ceiling is calculated, or can be read

directly, in the capacity diagram of the cooling panels.

To have the highest possible capacity of the system you

should design as close to the dew point as possible.

Theoretical capacities of embedded radiant cooling

Taking both ISO 7730 (surface temperatures, radiant

asymmetry, and down draught) and the dew point

limitations into account, the following surface

temperature limitations exist.

Surface temperature limitations

With these surface temperature limitations in mind, the

maximum capacities of different radiant emitter systems

can be calculated. The results are shown in the fi gure

below.

Maximum heating a cooling capacities

In theory, the highest heating capacity can be achieved

from the wall. Since space is limited due to windows

and other things hanging on the wall, the real heating

capacity from walls is signifi cantly reduced. Hence, the

biggest capacity can be achieved by heating from the

fl oor, and cooling from the ceiling. In practice, either

a fl oor system or a ceiling system is installed and used

for both heating and cooling. A fl oor system should

be chosen if the heating demand is dominant and a

ceiling system should be chosen if the cooling demand

is dominant.

35

25

15

45

30

20

40

Floor Ceiling Wall

Heating

Cooling

Parimeter

Tem

pera

ture

[°

C]

80

40

0

120

60

20

100

140

180

160

200

Floor Ceiling Wall

Heating

Cooling

Parimeter

Heati

ng

an

d C

oo

lin

g C

ap

aci

ty [

W/m

2]


5. Ground heat exchangers

Ground conditions

When planning the use of ground heat exchangers,

the ground conditions are of fundamental importance.

Determining the ground properties, with respect to

the water content, the soil characteristics (i.e. thermal

conductivity), density, specifi c and latent thermal

capacity as well as evaluating the different heat and

substance transport processes, are basic pre-requisites

to determine and defi ne the capacity of a ground heat

exchanger. The dimensioning has a signifi cant impact

on the energy effi ciency of the heat pump system.

Heat pumps with a high capacity have unnecessary

high power consumption when combined with a poorly

dimensioned heat source.

With a higher water concentration in the ground, you

get a better system capacity. Horisontal collectors are

hence depending on the ground’s ability to prevent rain

water from mitigating downwards due to gravitation.

The smaller the corn size in the soil, the better the

ground can prevent rain water from gravitation. Hence

clay will provide a better performing ground heat

exchanger than sand. Vertical collectors are depending

on being in contact with ground water. Hence the depth

of ground water levels has an important impact on the

performance of a vertical ground heat exchanger.

In addition to the water concentration, different ground

types have different thermal conductivity. For example

rock has a higher thermal conductivity than soil, so

ground conditions with granite or limestone will give a

better performing ground heat exchanger than sand or

clay.

Soil type

Thermal conductivity

(W/m K)

Clay/silt, dry 0.5

Clay/silt, waterlogged 1.8

Sand, dry 0.4

Sand, moist 1.4

Sand, waterlogged 2.4

Limestone 2.7

Granite 3.2

Source: VDI 4640


Ground heat exchangers

With ground heat exchangers, a distinction is made

between horisontal and vertical collectors. These can be

further classifi ed as follows:

Horisontal:

• Horisontal or surface collectors

• Energy cages

Vertical:

• Boreholes

• Energy piles and walls

The suitability of the different collectors depends on the

environment (soil properties and climatic conditions),

the performance data, the operating mode, building

type (commercial or private), the space available and

the legal regulations.

Horisontal collectors

Collectors installed horisontally or diagonally in the

upper fi ve meters of the ground (surface collector).

These are individual pipe circuits or parallel pipe

registers which are usually installed next to the building

and in more rare cases under the building foundation.

Energy cages

Collectors installed vertically in the ground. Here, the

collector is arranged in a spiral or a screw shape. Energy

cages are a special form of horisontal collectors.

Boreholes

Collectors installed vertically or diagonally in the

ground. Here one (single U-probe) or two (double

U-probe) pipe runs are inserted in a borehole in

U-shape or concentrically as inner and outer tubes.

Energy piles

Collectors build into the pile foundations that are

used in construction projects with insuffi cient load

capacity in the ground. Individual or several pipe runs

are installed in foundation piles in a U-shape, spiral or

meander shape. This can be done with pre-fabricated

foundation piles or directly on the construction site,

where the pipe runs are placed in prepared boreholes

that are then fi lled with concrete. Most often energy

piles are used for larger commercial buildings.


Ground temperature profi le

The fi gure below shows a generic temperature profi le in

the ground for each season during the year.

The closer to the ground surface, the higher the

infl uence from the outside temperature and solar

radiation. Hence not surprisingly, the highest

temperatures are found in late summer and the

lowest temperatures in late winter. The reason for the

temperatures being higher in late autumn than late

spring, has to do with the ground’s ability to store

energy. After a warm summer period, the ground

remains relatively warm during the autumn. Ground

temperatures stabilize below 10-15 m. It is clear from

these ground temperature profi les that the cooling

capacity is higher below 15 m. Hence vertical collector

systems provides a better cooling capacity than

horisontal collector systems.

Primary supply temperatures

The temperatures mentioned in the previous section

are often referred to as the undisturbed ground

temperature. Depending on the thermal resistance

between the collector and the surrounding ground, the

temperature of the fl uid in the collector will be higher

than the surrounding ground.

0 2020

0

15

10

5

0 2010 155

10 155

1. February

1. May

1. November

1. August

Temperature (earth’s surface) [°C]

Dep

th i

n s

oil

[m

]

Temperature (depth) [°C]

Dimensioning of ground heat exchangers for free cooling

The fi rst thing to decide is whether the ground heat

exchanger shall be used for heating only or for both

heating and cooling. As demonstrated in this guide,

new built low energy houses will often have substantial

cooling loads. It is therefore highly recommendable to

use the ground heat exchanger for free cooling in the

summer period. A combined use for heating and cooling

also balances of the ground temperature during the

year and leaves the ground environment undisturbed.

Existing guidelines for dimensioning ground heat

exchangers are typically based on the peak load for the

heating demand. But in order to ensure that adequate

cooling capacity is available in the summer season, it

is recommend doing a design check for the maximum

cooling load as well.

Dimensioning for the heat load should be done based

on the peak load for space heating plus the domestic

hot water need. As a heat pump is used for covering

the heat load, the COP of the heat pump on the

coldest day (design day) should be applied in the

design calculation. In addition to this, the specifi c

characteristic of the chosen heat exchanger and the

thermal conditions in the ground must be taken into

account.

Dimensioning for the cooling load should be done

based on valid information of the maximum cooling

load in the building. Free cooling operates without a

heat pump. It is therefore vital that the thermal capacity

of the ground heat exchanger is able to fully cover the

max cooling load (no COP is included). In residential

buildings in Northern Europe the cooling need will

normally be covered with the capacity derived from

the heating requirements. But a design check is always

recommended.

In special cases in residential buildings and typically in

offi ce buildings, the cooling need will be dominant and

thus the design driver. In such case vertical collectors

are normally recommended as the deeper ground

temperatures are suffi ciently stable and independent of

surface temperature and solar radiation. If a horizontal

system is chosen, the space requirements can be a

capacity limitation. Designing for inadequate cooling

capacity on the warmest summer days may then

be necessary compromise, but should be evaluated

carefully.


Dimensioning examples

In order to dimension ground heat exchangers cer-

tain information has to be considered. First of all an

estimation of the physical properties of the ground is

needed. Normally its possible to obtain local ground

data (thermal conductivity etc.) from local databases

or authorities. The fi gures below show the capacity for

different collectors.

Horisontal collectors Energy cage Vertical collectors

Pipe size 25, 32 and 40 mm Normal 32 mm XL 32 mm 40 mm

Capacity cooling 7-28 W/m2 800-1120 W 1000-1500 W 30-70 W/m

Dimensioning temperature, supply/return

17-20 °C 14-17 °C 10-13 °C 10-13 °C

*) Energy cage; normal height is 2.0 m, and XL height 2.6. Required depth is 4 m.

Flow and pressure drop in the collector

When the cooling need is defi ned, the fl ow can be

calculated. When using ground collectors, the water

used has to be mixed with anti-frost liquid. Hence,

the specifi c heat capacity and density in the brine is

Cooling need

[kW]

Ethanol Monoethylenglyciol Propylenglycol

Flow [kg/s] Flow [l/s] Flow [kg/s] Flow [l/s] Flow [kg/s] Flow [l/s]

2 0.16 0.15 0.18 0.19 0.17 0.18

3 0.24 0.23 0.27 0.28 0.26 0.27

4 0.32 0.31 0.36 0.38 0.34 0.36

5 0.40 0.38 0.45 0.47 0.43 0.45

6 0.48 0.46 0.54 0.56 0.51 0.54

different from the physical properties of pure water.

The table below shows the required fl ow of often used

brines for providing different cooling capacity.

When calculation the pressure loss in the collector the

fl ow is divided equally up in the number of loops. For

vertical collectors the total pressure loss is normally

very low hence the pressure is equalized and it is only

the pressure loss in the feeding pipe has an infl uence.

For horisontal collectors and partly energy cages

the pressure loss has to be calculated in order to be

sure that the pump will be able to circulate the water

through the collector and the cooling exchanger

including manifolds and valves.

Example: 4 kW installations

Horisontal collector extraction

power

15 W/m2

Liquid Monoethylenglycol

Total fl ow 0.38 l/s, 1.37 m3/h

Diameter of collector Ø 32 mm

In the diagram below, the pressure loss in the

ground collector should be maximum 34 kPa at the

dimensioning conditions, and the ground collector

should be dimensioned so that the pressure loss in each

loop is less than 34 kPa.

Pump diagram

Available pressure for the primary circuit.

CP1

CP2

0 0.5 1 1.5 2 2.5 3

50

40

30

20

10

0

Pressure loss [kPa]

Rate of fl ow [m3/h]


6. Free cooling in combination with diff erent heat sources

Heating mode, the free cooling is deactivated Cooling mode, the free cooling is activated

The illustrations below shows a ground heat exchanger

combined with a radiant system in heating mode and

cooling mode. In this example a ground sourced heat

pump is providing heating to domestic hot water

(DHW), space heating, and for heating up the incoming

ventilation air. This could of course be utilized with

other heat sources such as boilers or district heating.

Free cooling is provided through a special pump and

exchanger group (see chapter 8) that supplies cold

water/brine from the ground heat exchanger directly to

the radiant emitter system and possibly the incoming

ventilation air. In cooling mode, the heat pump will only

be active for domestic hot water generation.

As one can see from the grey connection lines the pump

and exchanger group is not active in heating mode.

Similarly, the connection lines from the heat pump (or

any other heat source) to the emitter systems are in-

active in cooling mode.

If a boiler or district heating system is used as heating

source, the ground heat exchanger will only work during

cooling (also known as a bivalent system). If a ground

source heat pump is used as heat source, the ground

ground heat exchanger will work both during heating

and during cooling (also known as a monovalent

system).


Embedded emitters are the key to any radiant system.

In order to have an energy effi cient and comfortable

solution, the emitter system has to be designed to

the construction but also to the task it has to solve.

There are many types of constructions for fl oor, wall

and ceilings. Uponor offers emitters that can meet the

requirements of all types of installations. All emitters

are able to provide heating and cooling. However, some

emitters are more effi ciently than others. The most

effi cient cooling system is placed in the ceiling, but the

heating effi ciency is lower whereas an emitter system in

Capacity of different radiant emitter systems

In order to calculate the capacity of the radiant emitter,

it is important to know the construction in which the

embedded emitter is integrated, including the surface

material on top of the construction. In general, there are

three factors that infl uence on the capacity of a radiant

emitter system:

• Thermal resistance in the surface construction RB

• Pipe pitch, i.e. the distance between the pipes T

• Thermal conductivity in the construction material

In practice, this means that when designing the fl oor

construction, the performance of the radiant system can

be optimised by choosing the right construction, pipe

layout and surface material.

Floor installation Wall installation Ceiling installation

the fl oor has the highest heating effi ciency, but with a

lower cooling effi ciency.

Another important factor is the supply water

temperature. Radiant emitter systems operate on a

relatively low temperature for heating, and a relatively

high temperature for cooling. A radiant system should

be designed for the lowest possible temperature for

heating and the highest possible temperature for

cooling. This secures a heating/cooling system with

high energy effi ciency and optimal conditions for the

heating and cooling supply.

Example: fl oor construction

7. Choosing and dimensioning the radiant emitter system


Pipe pitch, i.e. distance between the pipes

The pipe pitch, i.e. the distance between the pipes in

the embedded construction, not only has an infl uence

on the capacity, but also on how equal the surface

temperature is. This is especially important from a

comfort perspective.

The diagram shows the capacity of a concrete fl oor

construction with =1.8 W/(mK), and with different

kinds of surface material. The diagram illustrates the

variation of the capacity depending on the pipe pitch.

A short distance between the pipes, gives a higher

capacity and vice versa. For a combined heating and

cooling system, it is recommended to use a relatively

small distance 300 mm between the pipes, in order

to utilise free cooling and maintain an even surface

temperature.

Thermal conductivity in the construction

The thermal conductivity in the construction has an

effect on the system’s ability to distribute heating and

cooling in the thermal mass. A construction with a low

thermal conductivity requires a smaller pipe pitch, in

order to obtain an equal surface temperature variation.

RλB

= 0

RλB

= 0.05

RλB

= 0.10

RλB

= 0.15qCN

(RλB

= 0.15)

qCN

(RλB

= 0)

ΔθCN

Y = Specifi c thermal output qc [W/m2]

X = Temperature difference between room and cooling medium [θ

c K]

45

40

35

30

25

20

15

10

0.1 0.15 0.2 0.3 0.4 0.50.25 0.35 0.45

Th

erm

al o

utp

ut

q [

W/m

2 ]

Pipe spacing T [m]

θm 15.5 °C,

14 mm parquet

θm 15.5 °C,

7 mm parquet

θm 15.5 °C,

10 mm tiles

θm 18.5 °C,

14 mm parquet

θm 18.5 °C,

7 mm parquet

θm 18.5 °C,

10 mm tiles

Floor surface temperature limit 20 °C

Thermal resistance in the surface construction

The thermal resistance in the surface construction has a

big infl uence on the performance of the emitter. In the

diagram, an example of a cooling curve where different

thermal resistance values from 0.00 to 0.15 m2K/W are

shown. The curve shows that higher resistance gives a

lower capacity. All constructions with embedded radiant

emitter systems will have a surface resistance that has to

be considered. In order to get the highest effi ciency, the

resistance value has to be as low as possible.

Field of characteristic curves of a cooling system

For dry constructions, high performance material like

heat distribution plates in aluminium or similar are used

to ensure optimal heating and cooling distribution.


Surface material

Tiles 10 mm, = 1.0 W/mK

Surface material

Wood 14 mm parquet, = 0.014 W/mK

Installation principle

Cooling effect q [W/m2]θ

m 15.5 °C


m 18.5 °C


m 15.5 °C


m 18.5 °C

Wet fl oor

installation42 40 33 24

Installation

integrated in

construction

42 40 33 24

Installation on the

joists28 20 27 19

Dry fl oor

installation28 20 27 19

Installation

between the joists24 17 18 14

Floor installation

Radiant fl oor constructions and capacity

Radiant fl oor systems are far more common than

ceiling or wall systems, and can be used for cooling and

heating. A radiant fl oor system can be installed in wet

constructions using concrete and screed, and in dry

constructions with heat emissions plates.

A radiant fl oor has a cooling capacity of up to 42 W/m2

limited by a surface temperature of 20 °C. The most

effi cient installation is in a wet construction with con-

crete or screed, because of its high heat conductivity,

using a relatively short distance between the pipes, and

a surface material with a low thermal resistance.

In the fi gure below, an overview of the capacity in

the most common fl oor installations is shown with

mean water temperatures of 15.5 °C and 18.5 °C

corresponding to supply temperatures of 14 °C and

17 °C with a T of 3 K over the emitter loops. Figures

are based on a room temperature of 26 °C and a surface

temperature of 20 °C.


Wallinstallation



m 15.5 °C


m 18.5 °C


m 15.5 °C


m 18.5 °C


m 15.5 °C


m 18.5 °C

Dry wall

installation45 32

Wet wall

installation60 45

Stud wall

installation42 34

Radiant wall constructions and capacity

Radiant wall systems are typically used as a supplement

to fl oor and ceiling emitter systems for rooms

with a higher need for cooling/heating. Instead of

dimensioning the fl oor or ceiling system according to

the room with the highest peak load, it can be designed

according to the average and the peak room(s) can be

supplemented with a wall emitter.

A radiant wall system will be limited by the architecture

and by the furnishing. Radiant wall systems have a

cooling capacity of up to 60 W/m2 (active area) limited

Surface material

Plaster 10 mm, = 0.7 W/mKSurface material

Plaster 11 mm, = 0.24 W/mK

Surface material


by a surface temperature of 17 °C, in order to be within

the limits of radiant asymmetry and to prevent draught.

In the fi gure below, an overview of the capacity of the

most common wall systems is shown with mean water

temperatures of 15.5 °C and 18.5 °C corresponding

to supply temperatures of 14 °C and 17 °C with a T

of 3 K over the emitter system. Figures are based on a

room temperature of 26 °C and a surface temperature

of 20 °C .




m 15.5 °C


m 18.5 °C


m 15.5 °C


m 18.5 °C


m 15.5 °C


m 18.5 °C

Wet ceiling

installation75 55

Dry ceiling

installation59 42

Suspended

ceiling

installation

97 67

Ceilinginstallation

Radiant ceiling constructions and capacity

Radiant ceiling systems are the most effi cient systems

for cooling, but can also be used for heating. Ceiling

systems have originally been developed for offi ce

environments, but are also available for residential

constructions using wet plaster or dry gypsum panels.

Radiant ceiling systems have a cooling capacity of up

to 97 W/m2. It is important to note that especially for

ceiling cooling, the surface temperature of the system

is in peak often very close to the dew point. Special

attention has to be taken for adequate dew point

control.

In the fi gure below, an overview of the capacity in

the most common ceiling systems is shown, with

mean water temperatures of 15.5 °C and 18.5 °C

corresponding to supply temperatures of 14 °C and

17 °C with a T of 3 K over the emitter system. Figures

are based on a room temperature of 26 °C and a surface

temperature of 16 °C.

Capacity diagrams

Uponor offers a wide range of embedded emitter

systems adapted to different kinds of constructions in

the fl oor, wall or ceiling. Whenever the choice of system

has been selected, detailed diagrams can be used in

order to make the planning of the capacity. The diagram

and example on next page shows a fl oor construction

with the cooling and heating output of the emitter

system.

Dimensioning diagram for cooling

Analogue to dimensioning for heating, the following

parameters must be considered:

1. Cooling effect of the radiant area qc [W/m2]

2. Thermal resistance in the surface construction RB

[m2 K/W]

3. Pipe pitch, i.e. centre distance between the pipes T

[cm]

4. Difference between room temperature and mean

water temperature θc. = θ

i - θ

c [K]

5. Recommended minimum surface temperature

(20 °C)

6. Difference between room temperature and surface

temperature θv - θ

r, m [K]

If three of the parameters above are known, the

remaining parameters can be calculated using the

diagram to the right.

Surface material


Surface material


Surface material



0,15

0,05

0,10

T qH ΔθH,N

cm W/m2 K

10 98,6 15,915 96,3 18,120 93,0 20,325 87,3 22,030 81,3 23,6

0

0,05

0,10

20

100

40

60

80

0,15

T qC ΔθC,N

cm W/m2 K

10 34,8 815 39,8 820 27,5 825 24,5 8

0

20

40

60

80

0

Δθ H = θ H

Ðθ i = 15 K

T 15

T 25

T 30

T 20

T 10T 15T 20

T 25

T 10T 15

T 20T 2

5

Heating

Cooling

T 30

ΔθC = θi

ÐθC = 4 K

10 K

8 K

6 K

Dimensioning example for cooling

Estimating the dimensioned supply water temperature θV, Ausl.

Given: qc = 29 W/m²

θi = 26 °C

RB = 0.05 m² K/W

Chosen pipe pitch = Vz 15

T: θv - θ

H = 2 K

Read from the diagram: θc = 12 K

θr, m

- θi = 3.9 K

Calculated: θr, m

= i - 4.3 K

θr, m

= 21.7 °C

(O.K., as this is above the recommended

minimum surface temperature (20 °C)

θV, calc.

= θi - θ

c - (θ

v- θ

R)/2

θV, calc.

= 26 - 9 - 2/2

θV, calc.

= 16 °C

Th

erm

al

ou

tpu

t h

eati

ng

qH [

W/m

2]

Th

erm

al

resi

stan

ce R

B [

m2 K

/W

]

Th

erm

al

ou

tpu

t co

oli

ng

qc [W

/ m

2]

Note: The required cooling effect can only be achieved

if the median surface temperature and the dimensioned

supply temperature are above the dew-point. In order

to avoid condensation, a supply water controller such as

Uponor Climate Controller C-46 is needed.


The purpose of a control systems is to keep one

or more climate parameters within specifi ed limits

without a manual interference. Heating and cooling

systems require a control system in order to regulate

room temperatures during shifting internal loads and

outdoor temperatures. Good control systems adapt

to the desired comfort temperatures while minimising

unnecessary energy use.

In residential buildings two different types of controls

principles are common; zone control and individual

room control.

In a zone control system, the temperature is

controlled in a common zone consisting of several

rooms and heating and cooling is supplied evenly to

the full zone. Not all national building codes allow

zone control systems as they have major shortfalls with

comfort as well as energy consumption.

In low-energy buildings there will in particular be high

variations in the individual room heating and cooling

loads (see fi gure 5.2). This means that lack of individual

room control causes the room with the highest demand

to determine the heating or cooling supply to a full

zone, resulting in over temperatures and unnecessary

high energy consumption.

An individual room control system is much

preferable in order to meet room specifi c load variations

and individual comfort requirements. Due to high

variations in the individual room loads in low-energy

buildings, an individual room control system is also

required to minimise the energy consumption.

The basic principle in an individual room control system

is that a sensor measures the room temperature and

regulates the heating or cooling supplied to the space

controlled in order to meet a user defi ned temperature

set point. The most well-know examples are radiators

with thermostatic valves and underfl oor heating systems

with room thermostats.

In addition, room by room regulation provides the

possibility to shut down cooling in a specifi c room, such

as a bathroom or a room without cooling loads.

21°C

21°C

21°C18°C

18°C

22°C22°C 20°C21°C

Typical desired temperature (set points) in a single family house. Typical variation between individual room heat demands in a low-energy house.

Regulation and control

Living room KitchenRoom 1

Bedroom Bath 1 Room 3 Entrance Bath 2

Room 2


The self-regulating effect in underfl oor heating

Radiant fl oor heating and cooling benefi ts from a

signifi cant effect called ”self control” or “self regulating

effect”. The self regulating effect occurs because the

heat exchange from the emitting fl oor is proportional

to the temperature difference between the fl oor and

the room. This means that when room temperature

drifts away from the set point, the heat exchange will

automatically increase.

The self regulating effect depends partly on the

temperature difference between room and fl oor surface

and partly on the difference between room and the

average temperature in the layer, where the pipes are

embedded. It means that a fast change of the operative

temperature will equally change the heat exchange.

Due to the high impact the fast varying heat gains

(sunshine through windows) may have on the room

temperature, it is necessary that the heating system can

compensate for that, i.e. reduce or increase the heat

output.

Low-energy houses will largely benefi t from the self

regulating effect, because the temperature difference

between fl oor and room will be very small. A typical

low-energy house has on average for the heating

season a heat load of 10 to 20 W/m² and for this size of

heat load, the self regulating effect will be in the range

of 30 - 90%.

Self-regulating effect. UFH/C outputs for different temperatures between room and fl oor surface.

Functional description of Uponor Control System

Individual room control with traditional on/off functionality

For a radiant fl oor heating and cooling system, the

control is normally split up in a central control and

individual room controls. The central control unit is

placed at the heat source. It controls the supply water

temperature according to the outside temperature

based on an adjustable heat curve. The individual room

control units (room thermostats) are placed in each

room and controls the water fl ow in the individual

underfl oor heating circuit by ON/OFF control with a

variable duty cycle. Its done according to the set-point

by opening and closing an actuator placed at the central

manifold.

Individual room control with DEM technology

Uponor’s Dynamic Energy Management control

principle is an advanced individual room system based

on innovative technology and an advanced self learning

algorithm. Instead of a simple ON/OFF control, the

actuators on the manifold supplies the energy to each

room in short pulses determined based on feedback

from the individual room thermostats.

Uponor Control System DEM is self learning and will

remember the thermal behavior of each room. This

ensures an adequate and very accurate supply of

energy, which means better temperature control and

energy savings.

Typical behaviour in a heavy fl oor construction, where Uponor DEM technology ensures that a minimum of energy is lost to the construction. Compared with traditional on/off regulation, saving fi gures between 3-8% can be obtained.

19

20

21

22

23

24

25

26

27

°C

c

b

a

= Floor surface temperature

= Room temperature

a heating = 19.1 W/m2

b heating = 13.9 W/m2

c cooling = -10.5 W/m2

Time

Uponor DEM

technology

Saved energy when

using Uponor DEM technology Actuator on/off

Lost energy when

using Uponor DEM technology

Higher temperature

+

-Lower temperature

Thermostat set point 20 °C

Time


Zone control

When using zone control for a radiant fl oor heating

and cooling system, the central controller is normally

placed at the heat source. It controls the supply water

temperature according to the outside temperature

based on an adjustable heat curve. The manifold system

Simple zone control, the central controller provides a regulated supply temperature based on the outdoor/indoor temperature.

M

C-46

230 V AC

230 V AC

24 V DC

M

C-56C-56

C-56

I-76

H-56

T-75

T-55T-54

has no actuators and normally the system works at a

constant fl ow with temperature regulation based on

a reference thermostat is placed in one of the main

rooms.

Individual room control, the central controller provides a regulated supply water temperature based on the outdoor/indoor temperature and the room thermostat controls the room temperature by using actuators.

C-46

M

230 V AC


The Uponor Pump and exchanger group, EPG6,

is designed for a separate cooling supply and

temperature control for ground source free

cooling. The EPG6 is pre-mounted and ready

to install in the installations. Together with

the Uponor ground collectors it is ready

to provide free cooling for radiant emitter

systems.

The EPG6 can be integrated in HVAC

installations for applications a separate supply

of cooling needs to be provided through a

heat exchanger (e.g. from a ground collector).

The EPG 6 is controlled by Uponor Climate

Controller C-46, which is able to adjust the

secondary temperature supplied to the emitter

8. Uponor Pump and exchanger group (EPG6) for ground sourced free cooling

system and interact with the Uponor Control

System used to control the emitter system.

Uponor Climate Controller C-46 is also able to

control the temperature according to the dew

point, in order to prevent condensation.

The primary side of the system is driven by

a circulation pump, to circulate the fl uid

in the brine circuit and a 3-way mixing

valve for controlling the primary fl ow, in

order to maintain the correct temperature

on the secondary side. The exchanger that

exchanges the brine from the ground circuit

with the water in the emitter system is

designed for a capacity up to 6 kW.

1

2

34

5

6

7

8

9

1

2

3

4

5

6

7

8

9

10

10

11

11

Secondary circlet,to emitter system

Primary side, ground collector or other cooling supply

Component overview

Primary side

The primary side of the system (ground collector) is

connected to the EPG6 and will work as the heat sink.

The mixing valve (1) will adjust the fl ow of the primary

side and is controlled by the Uponor Climate Controller

C-46 (10), which opens and closes the valve to the

adjusted supply temperature on the secondary side

measured by the supply sensor (7). The primary pump

(2) will circulate the fl uid in the brine circuit through

the exchanger (4) and will shut down when there is no

request from the secondary control system. The fi lling

and air valve (3) is used to fi ll up the primary system

with brine. Connection to an expansion tank and safety

valves can be done on the connection valve (9).

Secondary side

The secondary ball valves (5 and 6) are shutting down

the secondary side of the system, and have a ball

valve (5) including a check valve to prevent backfl ow

in the system. The blind piece (8) can be replaced

by a circulation pump, if no other pump is used for

the secondary side. The secondary pump has to be

connected to the Uponor Climate Controller C-46 (10).

3 way mixing valve Kvs 7 m3/h

Primary circulation pump Grundfos Alpha 2L 26-60

Filling and air valve G ¾”

Heat exchanger 6 kW SWEP ESTH x 40/1P-SC-S 4 x ¾”

Ball valve with integrated check valve and thermometer Rp 1”

Ball valve with integrated thermometer Rp 1”

Sensor pocket (supply)

Blind piece 180 mm G 1¼” for secondary circulation pump

Filling valve G ¾”

Uponor Climate Controller C-46

Primary connection Rp 1¼”


Dimensions

Pump diagram

Available pressure for the primary circuit

Rp 1¼

360

580

Rp 1 Rp 1

125

230

80

Rp 1¼

CP1

CP2

0 0.5 1 1.5 2 2.5 3

50

40

30

20

10

0

Pre

ssu

re l

oss

[kP

a]

Flow rate [m3/h]


Control principle

Controls is required for the primary system as well as the

secondary system.

Since the primary control of the heating mode is

separated from the primary control of the cooling mode,

the change-over between heating and cooling must

be defi ned. This can be done either automatically if a

communication interface can be setup between the

Uponor Climate Controller C-46 and the heat source or

through a manual switch if it is not possible to setup a

communication interface.

Because a radiant emitter system can act for both

heating and cooling, the secondary system can be

controlled by one system as described below.

Secondary control – heating and cooling

For the secondary control of the emitter system,

Uponor recommends to apply individual room control,

in order to provide energy effi ciency and comfort. The

individual control system also secures that cooling can

be deactivated in single rooms/zones, e.g. in bathrooms

where cooling might not be required. The Uponor

Control System offers a long range of benefi ts for the

user and can be integrated with the primary controller

for cooling, Uponor Climate Controller C-46.

Primary control – cooling

The primary control of the cooling system is provided by

the EPG6 which includes the Uponor Climate Controller

C-46 that manages:

• the supply temperature of the system

• pump management of primary and secondary

pumps

• change-over between heating and cooling

• dew point management with up to six wireless dew

point sensors (Uponor Relative Humidity Sensor

H-56)

In order to eliminate the

risk of condensation on the

emitter surface, dew point

management is an essential

part of the cooling system.

The relative humidity sensors

measure the relative humidity

and the temperature in the

room, and Uponor Climate

Controller C-46 uses the data

to calculate the dew point.

Thereby, it is able to secure

that the supply water temperature never gets too low,

and that no condensation will occur on the emitter

surface.

C-56 I-76

T-75H-56 T-54 T-55


Hydraulic change-over between heating and cooling

Uponor recommends using a diverting valve in the

secondary heating/cooling distribution system, which

opens and closes when changing between heating and

cooling. The diverting valve is controlled by the Uponor

Climate Controller C-46 either directly through a 24 V

actuator or through a relay for a 230 V actuator. The

diverting valve is activated by the change-over signal

between the heating and cooling modes.

Heating mode

In heating mode, the free cooling system is deactivated.

Hence, no pumps are running and the diverting valve is

closed (the fl ow goes straight through).

Cooling mode

In cooling mode, the free cooling system is activated.

Hence, pumps are running and the diverting valve is

open. An internal circuit is secured for the heat source

for producing domestic hot water.


TW

M

6

4

3

1

2

3

4

5

6

7

8

7

9

5

8

1

2

9

Installation examples

Brine to water heat pump with Uponor EPG6

The system diagram illustrates a Uponor free cooling

installation using a ground collector and Uponor EPG6

in combination with a brine to water heat pump for

space heating and domestic hot water.

The EPG6 (3) is connected to a Uponor ground collector

(1) on the primary side of the free cooling installation. If

more than one ground loop is installed, a manifold can

be used to connect the ground loops.

The secondary side of the EPG6 is connected to the

heating pipe system before the manifold of the radiant

system (4).

A diverting valve (7) is used to switch the fl ow direction

in the hydraulic system between heating and cooling

(diverting valve to open when cooling is activated).

When switching between heating and cooling, the heat

pump must be in a position where it only produces

domestic hot water (typically “summer mode” can be

used).

The Uponor Climate Controller C-46 can send an

external signal to the heat pump when switching

between heating and cooling or it can be done

manually with a relay switch. Contact the heat pump

manufacturer in order to check the possibilities.

Ground collector

Brine to water heat pump

Uponor EPG6 with Uponor Climate Controller C-46

Radiant emitter system

Buffer tank

Domestic hot water tank

Diverting valve

Non return valve

Secondary circulation pump


M

6

2

5

8

7

4

1

3

1

2

3

4

5

6

7

8

Condensing boiler with Uponor EPG6



in combination with a gas/oil boiler for space heating

and domestic hot water.

The EPG6 (3) is connected to a Uponor ground

collector (1) on the primary side of the free cooling

installation. If more than one ground loop is installed, a

manifold can be used to connect the ground loops.



system (4).

A diverting valve (7) is used to switch the fl ow direction

in the hydraulic system between heating and cooling

(diverting valve to open when cooling is activated).

When switching between heating and cooling, the boiler

must be in a position where it only produces domestic

hot water (typically “summer mode” can be used).

The Uponor Climate Controller C-46 can send an

external signal to the boiler when switching between

heating and cooling or it can be done manually with a

relay switch. Contact the boiler manufacturer in order to

check the possibilities.

In the example below, a solar collector is supporting the

boiler for space heating and domestic hot water but is

not interacting with the cooling system.

Ground collector

Condensing boiler



Solar tank

Solar panel

Diverting valve

Secondary circulation pump


M

1

2

3

1

2

3

Free cooling with Uponor EPG6



as a stand-alone system.

The EPG6 (3) is connected to a Uponor ground

collector (1) on the primary side of the free cooling

installation using the same supply line as to the heat

pump. If more than one ground loop is installed, a

manifold can be used to connect the ground loops.



system (4).

Please note that a circulation pump (180 mm) has to be

added to the EPG6 in order to circulate the secondary

circuit. There is a blind piece on the EPG6 that can be

replaced with a pump.

The activation of the EPG6 cooling module can be

done automatically through the Uponor Climate

Controller C-46 included in the EPG6 or through

another external signal through the climate controller.

Ground collector (or bore hole)




Operation mode of Uponor Climate Controller C-46

Two possible operation modes for cooling are described

below. The most typical operation mode of Uponor

Climate Controller C-46 is heating and cooling mode

when the controlled radiant system is used for both

heating and cooling emitter. In the case where a radiant

ceiling or wall system is installed purely for cooling

purposes, the operation mode is set to cooling mode.

This could apply to an example where cooling is needed

in an energy renovated house with radiators.

Operation mode heating and cooling of Uponor Climate Controller C-46

When having a combined heating and cooling system

where you change between heating and cooling, the

climate controller always have to be in heating and

cooling mode, even though the climate controller is not

used as the primary controller for heating.

Uponor > Main menu > Control settings > Advanced control > Operation mode. Note that the startup wizard will start when changing mode.

Heating min./max. supply Uponor Climate Controller C-46

In the case of combined heating and cooling system,

where you can change between heating and cooling,

the climate controller C-46 must always be set to

Heating and cooling mode, even when the climate

controller is not used as primary controller for heating.

In this case the heating setting in the climate controller

must be neutralized as follows:

Uponor > Main menu > Control settings > Heating > Min./max supply OK, also covered in startup wizard.

Operation of Uponor Climate Controller C-46

Uponor EPG6 is delivered integrated with Uponor

Climate Controller C-46. It is important that the settings

and parameters are programmed to fi t the designed

system. A detailed user manual describes all settings

and parameters.

Wizard – great installation guide

When Uponor Climate Controller C-46 is started for

the very fi rst time, it guides the installer to make the

necessary primary settings of the system. Wizard helps

you step by step through the installation process. On

the display, the installer can read all about the set-up

and what to do next. The installation wizard is also

started after changing or resetting the operation mode.

Quick menu – gives easy access to basic settings

Made for end-users: The quick menu consists of a series

of screens easily accessible from the Uponor screen.

These screens display readings for daily use. If the

Uponor Climate Controller C-46 is set to installer access

level, it is also possible to modify some parameters.

Main menu – all informations and settings on the

whole

The main menu and all its sub-menus are used for

displaying any accessible information, parameter

settings, and selecting operating modes that are

accessible in the system.

Operating mode

Heating

Heating and cooling Cooling

Min./max supply

Min

5.0 °C

Max

8.0 °C


Uponor > Main menu > Control settings > Cooling > Dew point

The functions require Uponor Relative Humidity

Sensor H-56 and can handle up to six sensors, placed

in different rooms/zones. The sensor mode function

allows to decide which value to use in the dew point

calculation. It can be set as an average or maximum

value of the sensor. For cooling application, it is always

recommended to use the maximum sensor mode.

Uponor > Main menu > Control settings > Cooling > Sensor mode

Resulting supply water temperatures

The dew point control is activated if the cooling supply

setpoint is below the calculated dew point. The function

overrules the cooling supply setpoint, and automatically

adapts the temperature according to calculated dew

point based on the measured room temperature and

humidity of the room/zone. The resulting supply water

temperature is the calculated dew point + the dew point

margin.

Uponor Climate Controller C-46 calculates the dew

point using data from Uponor Relative Humidity Sensor

H-56, i.e. relative humidity and temperature. It is

displayed in the quick menu.

Cooling mode only

If the system works as a stand alone cooling system

without any change over between heating and cooling,

cooling mode is chosen:

Uponor > Main menu > Control settings > Advanced control > Operation mode. Note that the startup wizard will start when changing mode.

Dew point management parameters and settings

In the operation mode cooling, indoor compensated

supply with dew point control will help you to prevent

condensation problems if the actual condition in the

room/zone is different from the design criteria.

The supply water set point is referring to the design

supply temperature of the system, and is the absolute

minimum temperature that the Uponor Climate

Controller C-46 will provide. The supply temperature

should be set according to the design of the emitter

system, taking into account the limitations factors, such

as surface temperature and dew point.

Uponor > Main menu > Control settings > Cooling

The function also allows using a dew point margin as

an extra safety to compensate for having the variation

in room conditions, occupation of the room, etc. The

dew point margin can be adapted to the installation.

A smaller margin will improve the cooling power, while

a larger margin will reduce the risk of condensation.

The installation needs to be checked after startup and

re-confi guration. If condensation occurs, the dew point

margin must be increased.

Sensor mode

Average

Maximum

Calculated dew point

18.3 °C

Dew point margin

1

Operating mode

Heating

Heating and cooling Cooling

Supply setpoint

14.0 °C


Uponor > Main menu > Control settings > H/C switchover > Bus master

Uponor > Main menu > General settings > General purpose output > Mode

Heating and cooling change-over: Uponor Climate Controller C-46

Change-over between heating and cooling can also

be handled by Uponor Climate Controller C-46, either

automatically using the indoor-outdoor temperature

controlled switch-over, or a manual command. When

the change over from the climate controller is activated,

the hydraulic change-over with the diverting valve is

managed by the general purpose output (11 and 12)

that sends out a potential free signal. At the same time,

the same signal can be used through a relay to send a

signal to the heat source. The automatic change-over

indoor, outdoor and trigger parameters have to be

selected in the climate controller, as well as the function

of the general purpose output.

The heat source must be able to receive potential free signal, i e sense a dry contact closure. The supplier of the heat source will be able to give guidelines of which signal is available

Heating and cooling change-over: external signal

When having a combined emitter system for heating

and cooling, the change-over between heating and

cooling system can be managed by Uponor Climate

Controller C-46 or through it. The climate controller

has several options for how to switch between heating

and cooling. The most common is to use the general

purpose input (5 and 6) in the climate controller, to

control that the system should switch from heating to

cooling. The general propose input is a contact sensing

input that can be connected to a relay in the heat

source or a manual switch. The heating and cooling

change-over behavior needs to be confi gured in Uponor

Climate Controller C-46. The hydraulic change-over with

the diverting valve is managed by the general purpose

output (11 and 12) that sends out a free signal using a

dry contact output.

Contact closing output from the best source or from manual switch. The supplier of the heat source will be able to give guidelines of which signal is available.

Activating the general purpose output needs to be

confi gured in Uponor Climate Controller C-46.

Uponor > Main menu > Control settings > H/C switchover

H/C switchover

Bus master Bus slave

No bus

Bus master

Indoor and outdoor

Supply water temp.

General purpose input

General purpose output

Inactive

H+C commands Fault signalling

V ~ 50 Hz

N L 0-10V

-

NL

+ 230 V ~

50 Hz

μ 2 A

230 V ~

G H I J K L

230 V

μ 2A 24VAC/DC

1 2 3 4 5 6 7 8 9 10 11 12

5 6

C-5

6

Reset

24 V

230 V

1

2

3

4

5

1

2

3

4

5

Heat pump

Pump

Diverting valve

Actuator 24 V

Relay (e.g. Uponor 1000517)

1

2

3

4

5

V ~ 50 Hz

N L 0-10V

-

NL

+ 230 V ~

50 Hz

μ 2 A

230 V ~

G H I J K L

230 V

μ 2A 24VAC/DC

1 2 3 4 5 6 7 8 9 10 11 12

5 6

C-5

6

Reset

24 V

1

23

4

5

Heat pump

Pump

Diverting valve

Actuator 24 V

Relay (e.g. Uponor 1000517)


Uponor > Main menu > Control settings > H/C switchover

Uponor > Main menu > Control settings > H/C switchover > Bus master

Uponor > Main menu > General settings > General purpose output > Mode

Pump management EPG6

The EPG6 is equipped with a Grundfoss circulation

pump Alpha 2L 25-60 for circulation of the primary

brine circuit. The pump is powered up through the

Uponor Climate Controller C-46 and prepared for pump

management. The actuator for the three-way mixing

valve is also powered by the climate controller and

connected to the control signal. The signal adjusts the

valve and secures the correct supply temperature using

the supply sensor which is also pre-installed in the

EPG 6.

In order to get the correct operation of the mixing

valve, motorised valves have to be selected in Uponor

Climate Controller C-46. The pump management also

has to be selected in the climate controller and in order

to get optimal control, “bus control” is selected. The bus

control will react on the secondary control system and

the pump will stop if there is no demand to the zones.

The secondary pump can also be connected through

the Uponor Climate Controller C-46, but the pump relay

has a limit of 100 W for the primary and the secondary

pump. The primary pump has a maximum consumption

of 45 W. Hence, 55 W is left for the secondary pump.

An alternative is to connect the secondary pump to the

secondary controller, i.e. Uponor Controller C-56.

Uponor > Main menu > Control settings > Advanced control > Pump management

Pump management

Internal control

Bus control

Always on

230 V

μ 2A 24VAC/DC

1 2 3 4 5 6 7 8 9 10 11 12

C-5

6

Reset

DEM

6 5

Bus master

Indoor and outdoor

Supply water temp.

General purpose input

General purpose output

Inactive

H+C commands Fault signalling

H/C switchover

Bus master Bus slave

No bus


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Uponor Corporation www.uponor.com

Uponor reserves the right to make changes, without prior notifi cation, to the specifi cation of

incorporated components in line with its policy of continuous improvement and development.

Free cooling guide

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