gac15a

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

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.

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.

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.

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.

INTRODUCTION

Hot Water Distribution and Sustainability

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


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.


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.

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

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.



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.



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.

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

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

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.

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?

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

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

HOT WATER DISTRIBUTION

METHODS

Evolution and Performance

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.

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.

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?

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

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

• 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

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.

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

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.

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.

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

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

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.

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.

• 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

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

How Is It Activated?

• Hardwired push button

• Motion sensor

• Remote push button

OPTIONS

Residential and Commercial

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.

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

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.

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.

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

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.

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.

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

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%

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.

RESEARCH AND CASE STUDIES

Proven Efficiency of Demand Control Systems

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

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

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.

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.

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.

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.

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.

COURSE SUMMARY

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.

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.

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

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

gac15a

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