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Fundamentals of Hydronic Design

Radiant Based HVAC Systems



This educational material is copy written © 2006 by Robert Bean, R.E.T., All Rights Reserved.

Information is provided for not for profit purposes.

If you wish to use this presentation for non commercial or for profit purposes, please contact [email protected] for details and restrictions.

Portions of this presentation are copy written by others including materials copy written © 2005, by the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.

(www.ashrae.org). Reprinted with permission from ASHRAE Handbooks.

This material may not be copied nor distributed in either paper or digital form without permission from Robert Bean, ASHRAE or other copyright holders.

Some slides contained animations in the original .ppt format which have been eliminated in the conversions to Adobe�s .pdf format.



Radiant Cooling & Heating


Fundamentals of Hydronic DesignEverything You

Needed to Know About Radiant You Discovered

Before Kindergarten



Ondol in Russia

Hypocaust in UK/Rome

Ondol in Korea


Fundamentals of Hydronic Design� Radiant Principles

� Thermography



� Thermography

Image Source: Bob �Hot Rod� Rohr



� Schlieren and Shadowgraph: Dr. G. Settles



� FEA Software Modeling: Dr. M. deCarli


Fundamentals of Hydronic Design� Heat & Moisture

Wet Dry

Earth

Conduction

Fire

Radiation

Air

Convection

Water

Evaporation

Hot

Cold



Emit

Absorb

Reflect

Reradiated

Transmitted

Long Wave Energy


Fundamentals of Hydronic Design� Emittances & Absorptances

© 2005, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Reprinted with permission from ASHRAE Applications Handbook. This article may not be copied nor distributed in either paper or digital form without ASHRAE�s permission.



�...physiologists have discovered that living human skin has extraordinarily high

absorptivity and emissivity (0.97), greater than almost any other known substance.�

Dr. Andrew Marsh


Fundamentals of Hydronic Design@1 met, 60% of The Bodies Sensible Heat

Transfer Is Via RADIANTCredit: JOHN BAVOSISCIENCE PHOTO LIBRARY

Credit: MEHAU KULYK/SCIENCE PHOTO LIBRARY



Image Credit: TONY MCCONNELL/SCIENCE PHOTO LIBRARY Image Credit: DR. ARTHUR TUCKER/SCIENCE PHOTO LIABRARY


Fundamentals of Hydronic Design� Thermal Comfort

� Dr. Fanger� ANSI/ASHRAE � Standard 55-2004� 80% Satisfaction

� +5 to 10%� Specific Metrics


Fundamentals of Hydronic Design�The purpose of this standard is

to specify the combinations of

indoor thermal environmental

factors and personal factors that

will produce thermal

environmental conditions

acceptable to a MAJORITY of

the occupants within the space.�© 2005, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Reprinted with permission from ASHRAE Standards.



� Demonstration of:� ASHRAE Thermal

Comfort Program V.1.0, by C. Huizenga, M.Sc., Berkley University, Dr. Fountain, Environmental Analytics

� Thermal Comfort Calculator by Dr. Marsh, Welsh School of Architecture at Cardiff University

Thermal Comfort Test Facilities, Circa 1970, Lingby, Denmark Danish Technical University



ASHRAE Comfort ProgramASHRAE Comfort Program


Fundamentals of Hydronic DesignRetiring boomers like conditioned floor temperatures

Predicted

Percent D

issatisfied

60

30

10

40

80

66 °F 84 °F

4

6

41 50 59 68 77 86 95 104

Floor Surface Temperature, °F

Design

Range


Fundamentals of Hydronic DesignPred

icted Percen

t Dissatisfied

60

20

10

46

40

80

0 9 18 27 36 45 54 63

Radiant Temperature Asymmetry, °F

War

m C

eilin

g

Cool

Cei

ling

Warm Wall

Retiring boomers don�t like whacked out temperatures

Cool

Wal

l

Design

Range

© 2005, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Reprinted with permission from ASHRAE Standards.


Fundamentals of Hydronic DesignRetiring boomers don�t want wrinkles, colds or viruses

Dew

Point T

emperatu

re, °F

70

50 55 60 65 70 75 80 85 90 95 100

65

60

55

50

454035

10

908070605040302010

Rel

ativ

e H

um

idity,

%

Operative Temperature, °F (is the Mean Radiant Temperature plus Dry Bulb Temperature / 2)

Summer Design Range

20% RH

60%

RH

Winter Design Range

Winter Summer

Chemical Interactions Allergic & Asthma Mites Fungi Viruses Bacteria

Ozone Production

Respiratory Infections1 Allergic & Asthma

Viruses

Bacteria

�or dry eyes, flaking skin, dandruff, cracked lips etc.

Based on:Met Rate = 1.0Clo = 0.5ANSI/ASHRAE Std. 55


Fundamentals of Hydronic DesignRetiring boomers like temperature consistency

0 4 11 14 187

60

20

10

2

6

40

80 Pred

icted Percen

t Dissatisfied

8

Design Range

Air Temperature Difference Between Head and Feet, °F


Fundamentals of Hydronic Design� Thermal Comfort� Five Factors To Consider

� Activity� Clothing� �Operative� Temperature� Humidity� Air Speed



Operative Temperature is a combination of the air and surface temperatures in the space.



Radiant conditioned spaces have higher operative temperatures.



Humans like consistent temperatures between their ankles and head�< 5°F ∆t



Humans like floor temperatures above 66 °F when cooling and below 84 °F when heating.



Humans prefer drafts below 3 fps in heating and humidity between 30% and 70% rh.


Fundamentals of Hydronic Design� Radiant System Performance� What happens from start up to steady state?

� What happens to thermal comfort performance when the architecture changes?

� How much heat we can deliver from a floor?



� Thermal Lag at Start Up

� With Radiant Systems�

� The air is only warm because the surfaces are warm!

Temperature of Room Mass

Air Temp



� Thermal Lag at Start� Thermal Recovery Is Fast� Think �Light�� Radiant Transfer occurs as soon as there is

a difference in temperatures.



Think Thermal Battery




� Soil Conductivity and Slab Insulation

When it comes to specifying insulation types, the obligations of a professional designer are based on liability exposures. �What is the

standard of care expected from a design professional when specifying insulation?� Are you below, at or above the benchmark in your decision?

Sand Silt ClayLow, <4% 0.17 0.08 0.08Medium, 4 to 20% 1.08 0.75 0.58High, > 20% 1.25 1.25 1.25

Thermal Conductivity, Btu/h.ft.°FSoil Moisture Content(by mass)

Table 3, Soil Thermal Conductivities, 2000 ASHRAE, Systems and Equipment, pg 11.9



As you go through the next slides imagine you are in the space and it is heated with air.



As you go through the next slides imagine you are in the space and it is heated with radiant.



1) Radiant energy travels from a heated surfaces to cooler surfaces

2) As cooler surfaces are warmed they reradiate to other cooler surfaces.



By raising the temperature of all the

surfaces we can counteract the effects of

adding windows.



Floor Coverings Make Good Radiators



How much heat can we release or absorb with a radiant surface?


Fundamentals of Hydronic Design� Radiant Systems Performance

� Output Examples - Typical

111.961.1Ceiling

81.481.4Wall

71.2111.9Floor

W/m2 · ºKBtu/h ·ft2 ·°FW/m2 · ºKBtu/h ·ft2 ·°FSurface

CoolingHeatingMode

Total Heat Exchange Coefficient




Example For Radiant Heated Floors

(85oF � 72oF) x 2.0 Btu /sf / oF

= 26 Btu/sf floor output


Fundamentals of Hydronic DesignTotal Heat Exchange Coefficient

Radiant + ConvectiveBtu/h ·ft2 ·°F1.91.1

1.41.4

1.21.9


Fundamentals of Hydronic Design� Typical High Mass Poured Floor System

Image Source: Uponor


Fundamentals of Hydronic Design� Typical Low Mass Channel Sub Floor System

Image Source: Uponor

MHRC

DP

RH

T H

HT

RH

DP

DP

RH

T HH

RH

DP

TM

M

rh%

HRV/ERV

Chilled Water

Heated Water

Economizer

M

Heat/Cool Water

IAQHTG CLG/rh% IAQ

IEQ =

Conditioning the BodyICQ

Conditioning the AirIAQ




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This material is presented as an educational service and is supported by downloading the Guide to Indoor Comfort Quality and the Architectural Guide to


Files... · 2007-03-24 · Ł Radiant Systems Performance Ł Output Examples - Typical Ceiling 1.1...

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