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![Page 1: gac15a](https://reader034.fdocuments.net/reader034/viewer/2022051218/5695d2411a28ab9b0299b2ce/html5/thumbnails/1.jpg)
Demand Controlled Pumping Systems
Hot Water On-Demand Course Number: gac15a
An AIA Continuing Education Program
Credit for this course is 1 AIA HSW/SD CE Hour
© GreenCE, Inc. 2011
ACT, Inc. Systems
3176 Pullman St., Suite 119
Costa Mesa, CA 92626
P: (800) 638-5863
www.gothotwater.com
Please note: you will need to complete
the conclusion quiz online at
GreenCE.com to receive credit
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An American Institute of Architects
(AIA) Continuing Education Program
Approved Promotional Statement:
• GreenCE, Inc. is a registered provider with The American Institute of
Architects Continuing Education System. Credit earned upon
completion of this program will be reported to CES Records for AIA
members. Certificates of Completion are available for all course
participants upon completion of the course conclusion quiz with +80%.
• This program is registered with the AIA/CES for continuing professional
education. As such, it does not include content that may be deemed
or construed to be an approval or endorsement by the AIA or GreenCE,
Inc. of any material of construction or any method or manner of
handling, using, distributing, or dealing in any material or product.
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An American Institute of Architects
(AIA) Continuing Education Program
• Course Format: This is a structured, web-based course with a
final exam.
• Course Credit: 1 AIA Health Safety & Welfare (HSW),
Sustainable Design (SD) CE Hour
• Completion Certificate: A copy is sent to you by email or you
can print one upon successful completion of a course. If you
have any difficulties printing or receiving by email please send
requests to [email protected]
• Design professionals, please remember to print or save your
certificate of completion after successfully completing a course
conclusion quiz. Email confirmations will be sent to the email
address you have provided in your GreenCE.com account.
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Course Description
Discover how the distribution of hot water impacts energy
and water consumption and waste. Learn how demand
recirculation pumps improve water and energy efficiency
and overall sustainability.
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Learning Objectives
By completing this course, the design professional will be able to:
• Explain the basics of hot water distribution in domestic systems
and its relation to water and energy efficiency.
• Compare and contrast the different options for designing a hot
water distribution system and the impact of such choices on
water and energy sustainability.
• List the water and energy efficiency advantages of on-demand
pump controls over other hot water distribution strategies.
• Describe residential and commercial/multifamily application of
on-demand pump technology.
• Discuss the water and energy savings generated by using an on-
demand circulation pump.
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INTRODUCTION
Hot Water Distribution and Sustainability
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Introduction to Hot Water
Distribution Sustainability This course reviews the delivery of hot water throughout a
building's network of pipes
and the effects on water
and energy efficiency in
terms of sustainability.
free-build-it-info.com
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Introduction to Hot Water
Distribution Sustainability • Q: What is a hot water distribution system and how does it
consume water or energy?
• A: A hot water distribution system is the means of moving hot
water from the point at which it is heated to the desired
fixture, whether it be a faucet, shower, or other location
where hot water is needed.
*An inefficient design leads to water waste while waiting to get
hot water, and energy waste by rapidly losing heat which needs to
be made up by the water heater.
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Introduction to Hot Water
Distribution Sustainability • Q: What is NOT hot water distribution?
• A: Distribution is NOT the process of heating the water. While
the water heater, tankless water heater, or boiler is the point
at which energy is consumed, an unsustainable distribution
design forces the heater to turn on more often.
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Water and Energy Consumption:
Importance for Sustainability • Three uses of resources impacted by hot water distribution
design:
– Water
– Energy used to heat the water (electric, natural gas, etc.)
– Electricity used for any pumps
• In order of costs:
– 1: Energy Used to heat the water – the heat losses are substantial
and hot water has 20x the embedded energy as cold water –
depending on the building this can be worth thousands of dollars
per year
– 2: Electricity to run the pump – This can be worth a few hundred
dollars a year
– 3: Water – This also can be worth a few hundred dollars per year
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How Do Hot Water Distribution Systems
Use Substantial Amounts of Resources?
Water:
• Slow distribution means users will waste water while waiting
for hot water to arrive.
• Poor design can cause premature deterioration of pipes
commonly known as pinhole leaks.
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How Do Hot Water Distribution Systems
Use Substantial Amounts of Resources?
Energy:
• Wasting water is wasting energy.
• All water has embedded energy, such as the electricity, used to
move water from the water utility to your home.
• Distribution methods often involve electrical equipment such as
pumps, which use electricity.
• Also, improper design creates
excessive heat losses, which is
another form of energy consumption.
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How Do Hot Water Distribution Systems
Use Substantial Amounts of Resources?
Material Costs:
• Piping systems that are not designed to sustainability standards
lead to extra material costs and wasted resources.
• Hot water systems that are continuous or controlled add more
unnecessary wear and tear to the pipes and water tank, thus
causing more repair costs and replacement materials to be
used.
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Energy Consumption
Water Heating
31%
AC45%
Lighting3%
Misc7%
Appliances14%
Energy End Use
At 31%, Water Heating is the 2nd largest energy user in a typical
home and a critical consideration for sustainable design.
US Dept. of Energy’s Lawrence Berkeley National Laboratory
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Water=Energy
• 10 gallons of water lost through normal hot water distribution
represents 1 kilowatt-hour of energy.
• As with inefficient distribution systems and inevitable water
waste, the embedded energy is also lost down the drain.
• According to the U.S. Environmental Protection Agency’s (EPA)
Green Lights program, production and consumption of
electricity is directly linked to air quality and carbon footprint.
• On average, every kilowatt-hour of electricity emits:
– 1.5 POUNDS OF CARBON DIOXDE
– 5.8 GRAMS OF SULFUR DIOXIDE
– 2.5 GRAMS OF NITROGEN OXIDES
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Impacts on Costs and Resources
• A little waste in one household leads to a lot of waste across
society.
• A little improvement makes a big impact to resource
sustainability.
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On Demand Pumps: A Viable
Solution for Sustainable Design How much money can be saved in California or the US by using
demand pumps in single family homes?
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Sustainable Design and Meeting
our Needs • Sometimes we don’t think about sustainability of our water
distribution, but oftentimes a more sustainable design
contributes to what we really want from hot water, which is:
• Advances in sustainable distribution design, such as demand
pump systems, have the double benefit of saving our resources
and meeting our needs conveniently!
• Clean clothes • Clean dishes
• Clean hands • Clean body
• Relaxation • Enjoyment
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Do Our Expectations of Hot
Water Align with Sustainability? What do we expect from hot water systems?
What demand controlled pump systems provide:
• Proper water temperature prevents energy waste and also
preserves our health and safety.
• Having more reliable systems means less maintenance and
repair costs.
• Convenience means we are waiting less for hot water and thus
saving water.
Safety • Not too hot • Not too cold • No harmful
bacteria or particulates
• Sanitation
Reliability • Little or no
maintenance • Last forever • Low cost
Convenience • Adjustable
temperature and flow
• Never run out • Quiet • Hot water now
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HOT WATER DISTRIBUTION
METHODS
Evolution and Performance
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The History of Recirculation Pumps
and their Sustainable Impact
• 1970 - Today
– Median US home increased from 1600 to 2400 square feet
– Distance to the furthest fixture from the hot water heater
increased from 30 to 80 feet
– Number of hot water fixtures increased from 6 to 12
• Result
– 18 times as long to get hot water
– Pipe area increased by 3x, velocity reduced by 3x
– Fixture flow rate reduced by 3, velocity reduced by 3
– Distance increased by at least 2, time increased by 2
As our houses became bigger and our flow rates became slower, the result meant
more water waste while waiting to get hot water. By adding a recirculation pump,
the water waste was diminished and the system became more convenient to use,
but heat losses and electrical consumption of the pump created higher energy
consumption. This is the sustainability dilemma for hot water distribution
systems.
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When Do You Not Need
Recirculation? • In buildings where the fixtures are close to the water heating
source and where there is a small volume water in the pipes
between the fixture and the water heater may not need a
pump to recirculate water.
• Not having recirculation is only possible when the volume of
water that needs to be drained is small because the amount of
time it takes to get hot water is dependent on the fixture flow
rate and the volume.
• For example if there is 3 gallons of water (volume) in the
piping, and the faucet has a 1 gallon per minute flow rate, it
will take the user 3 minutes to drain that water and thus get
hot water.
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Why You Need Recirculation
• No recirculation is only recommended if all the fixtures are
within 1 gallon of the water heater. In most cases this is not
possible.
• By not using recirculation the user will be foregoing getting hot
water quickly.
• This results in tremendous water waste. How much? In a typical
home, this can be roughly 12,000 gallons per year.
• In a commercial/multifamily building this can be hundreds of
thousands of gallons of water waste. In fact, recirculation is
required in large structures because the wait time without
recirculation can be 10 minutes or more and some tenants may
never even get hot water. So what are the options?
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Methods for Distributing Hot Water
and Effects on Water and Energy
Distribution Method Water Energy
Non-Recirculated Wasteful Efficient (if works)
Continuous Recirculation Efficient Wasteful
Timer Controlled Recirculation Wasteful/Efficient
Depending on the time
Wasteful/Efficient
Depending on the time
Temperature Controlled Recirculation Efficient Wasteful
Demand Controlled Recirculation Efficient Efficient
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The Long Wait for Hot Water!
Non-Recirculated Distribution
• No Return line
• No Recirculation Pump
• Water Pressure Release at the
point of use causes the water to
move
• Not effectively sustainable
because water is wasted while
waiting for the hot water to arrive
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• Recirculation pumps, again, reduce the
wait for hot water.
• They can be installed in both new and
existing construction, either at the
furthest fixture where the hot and cold
water pipes dead end or on a
dedicated return line.
• Many times, the recirculation pump is
left running continuously, so that hot
water is always at every tap without
any wait time whatsoever.
Recirculated Distribution
Retrofit Application
Dedicated Return Line
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Distribution with Continuous
Recirculation • Continuous recirculation solves the problem of having to drain
unacceptable amounts of water or waiting an unacceptable
time to get hot water.
• However, it has three major drawbacks:
– Uses energy - a pump is needed which consumes electricity
– Continuous movement of hot water will wear away at the pipes
and water heater
– It wastes tremendous water heating energy from heat losses in the
pipe.
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Continuous Recirculation Wastes
Energy • Think about it. In a home, there can be hundreds of feet of hot
pipe and in a multifamily/commercial building, thousands of
feet of hot pipe—convecting heat into the surrounding air at all
times.
• Heat losses in the distribution pipes account for more than 25%
of all the total energy used in central hot water systems. This
is due primarily to excessive pump run time.
• When does the pump NOT
need to run?
– If there is no user demand for
hot water AND
– If there is already hot water at
the point of use
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Continuous Recirculation Wastes
Heat Energy • A recent study conducted under California Energy Commission's
Public Interest Energy Research studied energy flow in
multifamily buildings. The results are depicted here:
• 70% of all energy input into the hot water distribution system is
lost from continuous recirculation.
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Distribution with Controlled
Recirculation • Because running the pump continuously is both unnecessary
and highly energy intensive, controls may be put on the pump
to automatically turn it off when it does not need to run.
• This is the most sustainable way to design the hot water
distribution system.
• However, some control methods are more efficient than
others.
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Timer Controlled Recirculation
• Turns on and off according to time schedule
• Will not work if user demands hot water during "off" period
• Often a guessing game; timers are often disconnected because
it’s hard to schedule the need for hot water
• Still wastes water and energy
• A non-sustainable solution, as it runs the pump too much when
its ‘on’ creating unnecessary heat losses and runs the pump too
little when it’s
‘off’ creating unnecessary
water waste
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Temperature Controlled
Recirculation • Automatically turns pump on and off based on temperature
(usually 120˚) via a sensor on the return line
• It is water sustainable as it keeps the wait for hot water to a
minimum, but is not very energy efficient
• Although the pump uses less electricity, it keeps the
distribution loop hot to maintain the 120˚ temperature even
when there is no demand,
creating the same heat losses as
a continuous pump
• Slightly more sustainable than
Time Clocks
Sensor
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Controlled Recirculation Options and
Their Influence on Sustainability • Time Clocks – A non-sustainable solution, as it runs the pump too much when
its ‘on’ creating unnecessary heat losses and runs the pump too little when it’s
‘off’ creating unnecessary water waste.
• Temp regulator – Turn the pump off when there is already hot water in the
pipes (will continue to run the pump during periods of no demand to keep the
pipes constantly hot). It is water sustainable as it keeps the wait for hot water
to a minimum, but not very energy sustainable. Although the pump uses less
electricity, it keeps the distribution hot creating the same heat losses as a
continuous pump. Better than Time Clocks but not the best.
• Time/Temp – Combination of time clock and temperature regulator (will run
the pump as needed to keep pipes hot only during the "on" period. Although
this is better than timers or temp regulators standalone, it still has the
combination of the same problems, making it only semi-sustainable.
Although these are not ideal methods for controlled recirculation, controlled
recirculation is always better than no recirculation or continuous recirculation.
Demand Control is the method that solves all these problems.
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Demand Controlled Recirculation
• This method controls recirculation of
hot water according to real-time user
demand within the building or home via
an activator.
• A demand system returns water in the
hot water pipe to the boiler or water
heater through the cold water line or
designated return line, reducing water
waste.
• The system uses a thermal sensor so the
fixture demanding hot water only
receives the water when a sensor is
activated, reducing energy waste.
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• What makes demand controlled recirculation the most
sustainable hot water delivery method?
– Demand Controls match user demand to the delivery of hot water
(the pump only runs when the user requires hot water).
– Get hot water quickly, when you want it
– Reduces energy use
– Conserves water
– Reduces wear and tear on entire water heating system
• The U.S. Department of Energy specifically recognizes the
efficiency of these systems as a “Hot Water Waste Prevention
System” and “a novel system that conserves water and
energy.”
Sustainable Benefits of Demand
Controls
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Demand Controlled Pumping
Systems Demand controlled pumping systems work with all hot water
heating systems (tank or tankless, gas or electric) and with either
Structured or Standard Plumbing.
Standard Structured
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How Is It Activated?
• Hardwired push button
• Motion sensor
• Remote push button
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OPTIONS
Residential and Commercial
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Residential Hot Water
Distribution Typical Distribution Layouts
• Most single family homes and single unit dwellings have pipes
that extend from the water heater to each of the fixtures and
which dead-end at the furthest fixture in the dwelling.
• Residential dwellings without any recirculation pump must rely
on city pressure to move the water from the water heater to
the fixture or fixtures that are demanding hot water. This is
the most common scenario and can result in excessive wait
times for hot water, depending on the length of the pipe runs.
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Traditional Plumbing Layout
Single Trunk, Branch and Twig: • Longer pipes increase the volume of water between the water
heater and the fixture. This water must be drained before the
user gets hot water, increasing wait time.
• Sustainable Design minimizes the length of Branch and Twig
pipes in order to reduce heat-energy loss and the wait time for
hot water.
Hot Water Piping
Water Heater
1 inch
¾ inch
½ inch
Hot Trunk
Twig
Branch
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Demand Controlled Pumps for
Commercial/Multifamily • As with residential, the demand controlled pumps for
commercial use employs the same sequence of operation; it
will only run when there is a simultaneous sensed demand for
hot water AND an indicator that water in the pipes is not
sufficiently heated—thus securing the most sustainable
delivery of hot water.
• Although many of the same concepts between a residential hot
water distribution system and a commercial distribution system
are consistent, there are some key differences primarily due to
the larger scale.
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Commercial/Multifamily Hot
Water Distribution Key Differences:
• There is more hot water to deliver; the pipes are larger and
hold a greater volume of water.
• Hot water must travel greater distances to reach the numerous
fixtures throughout a building.
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Commercial/Multifamily Hot
Water Distribution • Recirculation pumps are essential components to central hot
water systems in commercial structures
• Most commonly, the recirculation is running on a continuous
basis. This solves the problem of getting hot water quickly and
thus saves water, but creates another problem: Exorbitant Heat
Loss
• Recirculation pumps
are ONLY sustainable
if operated with on-
demand controls
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Sustainability : Central vs.
Individual Distributed • Multi-unit dwelling buildings, such as multifamily apartments, dorms,
hotels and motels, may have either individual water heaters
distributed in each unit or a centralized hot water system that can
service multiple units or an entire building.
• While a distributed system solves some of the heat loss issues, it
creates a bigger sustainability issue: exorbitant material waste.
Instead of one water heater used for 50 units, you have 50 water
heaters. That means you have:
– 50x the water heating materials that are manufactured and transported
– 50x the maintenance/labor and materials for repair
– 50x the possibility that it leaks and destroys other parts of the building
• For the purpose of distinguishing the major differences between
commercial and residential hot water distribution, we will heretofore
refer to "commercial" applications as those buildings that have central
domestic hot water systems, and not distributed.
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How it Works 1) City cold water supply
2) Is heated to Approximately 140℉
3) Hot water is continuously circulated throughout the building from the storage tank
4) Pipes lose significant heat into the surrounding environment as hot water is continuously circulating
5) When water returns, it is much cooler and these heat losses must be made up, resulting in excessive gas usage. This is occurring 24/7, whether or not anyone is actually using hot water
A demand controlled pump turns on and off based on
real-time feedback from two sensors.
A demand sensor which tells the pump, is there someone
using hot water in the building right now? How does it
know someone is using hot water?
Whenever there is a hot water tap open anywhere in the
building, water is exiting the hot water system. Since, hot
water system is pressurized, this means cold water must
be coming into the water heater simultaneously as the
hot water is flowing out of the fixture.
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Using Demand Controls at the End of
a Twig and on the Distribution Loop • Multiple demand units can be used in large buildings where the pipe branches
are so long that there is a significant wait for hot water, regardless of
recirculation on the trunk line.
• This combines the method used in a commercial building with the retrofit
application of demand controls in single family homes with no return line.
• This is the most sustainable retrofit method for large buildings with long
branches that won’t be served by the main recirculation loop or trunk.
Use Demand controls on
the existing recirculation
loop to increase
efficiency of the trunk
line
Use Demand controls at the
end of each twig to create
new vertical loops to reduce
the wait time for hot water
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How Much Energy Savings Can Be
Achieved? • 3rd party analysis shows consistent 10-30% reduction in natural
gas usage above baseline conditions
• Analysis also shows consistent 80-90% reduction in electricity
used for pumping
• Cost payback is typically between 1-3 years
GAS ELECTRICITY
10-30% 80-90%
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Save Energy by Reducing Heat Loss in
the Recirculation Loop
*Graphic Courtesy of Domestic Hot Water, Commercial and Residential Systems, Matt Tyler, PECI
A demand controlled pump is the only method that allows the pipes to cool
during down-time, which minimizes heat losses. This is why it is the most
efficient system to distribute hot water and the highest grade of sustainable
design.
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RESEARCH AND CASE STUDIES
Proven Efficiency of Demand Control Systems
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Research on Demand Controlled
Recirculation • Since 2005 the State of California has funded extensive
research into the energy savings potential of demand
controlled recirculation pumps in central domestic hot water
systems for multifamily buildings
• Dozens of buildings using demand controlled pumps have been
monitored for energy savings during this time period using a
refined methodology for showing decreased gas usage by the
water heater
• As a result of these successful studies, demand controlled
pumps will be added to the CA building energy codes as a
baseline requirement beginning in 2011
California Energy Commission
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DHW System Performance Under
Controls
Site #2 – SF, CA
59%
Gas Consumption Reduction normalized by gallon of water
Recirculation Loop Losses Reduction normalized by gallon of water
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Case Study – Welk Resort
• Background: Welk Resorts needed a solution to their high hot water
bills.
• A 2-month test was run employing a demand pump system at their
timeshare luxury resorts in Escondido, CA.
• Over the 2-month period, none of the guests were asked to alter their
normal water consumption behavior.
• During the test, the demand system was able to reduce water heater
electricity usage by
18% and reduce circulation pump
electricity usage by more than
97%.
• Projected savings of 7688 kWh
per year – without any interruption
or compromise of service to its
guests.
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Case Study – Marriott Resort
• In this instance, SoCal Gas Company wanted to run an independent
test of demand pumps in order to prove the range of energy savings.
• The test was conducted at the Marriot Resort in Palm Desert, CA over
the course of 12 months
• SoCal’s engineers determined that the demand pump saved Marriot
11.7% in gas usage and just under 4% in total water usage.
• The resort received zero
complaint of problems with hot
water service from any of the
guests, nor was any kind of
restriction imposed as to when
or how the guests could use
their hot water.
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Case Study Pinhole Leaks
• In 2009, master plumber Kevin Bennett began conducting research to
find a solution to a client’s pinhole leak problems. The client was the
owner of the Family Tree Apartment complexes in Santa Clara,
California.
• Bennett’s research identified that the problem was being caused by
the continuous operation of the domestic hot water pump combined
with hard mineral content of the water. Bennett's independent tests
revealed that the mineral content on the site was at a staggering 370
parts per million (ppm), which is almost four times more than the
average “acceptable” range of between 15 and 100 ppm.
• By upgrading the buildings to a demand
pump system, the damaging effects of
continuous hot water circulation were
significantly reduced, allowing the
owner substantial savings in plumbing
repairs.
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Case Study - ODE
• In 2008, a demand controlled pump provider collaborated with
Benningfield Group and SoCal Gas to test the efficiency of a demand
pump system in order to promote an On Demand Efficiency rebate
program.
• By monitoring hot water demand in a central heating system, the
pump is able to shut itself down when it is not in use, saving energy
and preventing unneeded waste. A total of 39 sites were tested and
the results showed a 10-30% reduction in gas usage by the water
heater. The pump ran an average of 2 hours per day as opposed to 24
hours of a continuous pump.
• Savings in electricity from this difference is over 1,300 kWh or an 84%
reduction. Total energy saved based on this study if extended to 300
units would be more than 450,000 therms of gas and 390,000 kWh of
electricity/yr.
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Case Study – Archstone
• Tracking equipment was installed into 2 multi-unit buildings at
Archstone Tunlaw Gardens in Washington, DC in order to evaluate the
effectiveness of a demand controlled pump on a central hot water
system.
• The data was collected over 2 months. Records from the study
showed there was 15% reduction in gas used by the water heater and a
98% savings in electricity used by the circulation pump. In billing
terms this translates into an annual savings of $1,083 per building or
more than $16,000 over the life of the pump.
• This amount does not include
materials and money saved by
reduced wear and tear on the pipes
and water tank. Most importantly,
these savings were achieved without
incurring any customer complaints.
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COURSE SUMMARY
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Key Points to On Demand
Sustainability
• Without recirculation, the wait for hot water is long and gallons
of water must be drained/wasted for hot water to reach the
tap.
• Demand recirculation pumps deliver hot water only by user
request.
• The more quickly hot water reaches the necessary fixture, the
less water is wasted waiting for it.
• Demand controlled recirculation is the most water and energy
efficient recirculation option available.
• The user of demand recirculation pumps saves water, energy,
and money by diminishing sewage costs in reducing the amount
of water running down the drain.
• These systems can contribute significantly toward making any
building or project more sustainable.
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Course Summary
Now, the design professional will be able to:
• Explain the basics of hot water distribution in domestic systems
and its relation to water and energy efficiency.
• Compare and contrast the different options for designing a hot
water distribution system and the impact of such choices on
water and energy sustainability.
• List the water and energy efficiency advantages of on-demand
controls over other hot water distribution strategies.
• Describe residential and commercial/multifamily application of
on-demand technology.
• Discuss the water and energy savings generated by using an on-
demand circulation pump.
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Demand Controlled Pumping Systems
Hot Water On-Demand Course Number: gac15a
An AIA Continuing Education Program
Credit for this course is 1 AIA HSW/SD CE Hour
© GreenCE, Inc. 2011
ACT, Inc. Systems
3176 Pullman St., Suite 119
Costa Mesa, CA 92626
P: (800) 638-5863
www.gothotwater.com
Please note: you will need to complete
the conclusion quiz online at
GreenCE.com to receive credit
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This course is sponsored by:
ACT, Inc. D’MAND Systems
www.gothotwater.com
3176 Pullman St
Suite 119
Cost Mesa, CA 92626
P: (714) 668-1200
F: (714) 668-1927