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Hot Water Re-CirculationNational Conference Center

Lansdowne, VA

March 25th & 26th, 2010

Thank you for attending the session on

Hot Water Re-Circulation.

Slide 2

AGENDA

• Water Waste Statistics

• Intro to Hot Water Recirculation

• Pump Fundamentals

• Sizing & Selection

• Troubleshooting

Slide 3

288,817,200,000

This is the average number of gallons that

are wasted in a year in the United States.

Do You Know...

• ASPE, the American Society of Plumbing Engineers, recommends

– A maximum wait of 10 seconds from the time a faucet is turned on until hot water reaches the faucet

– 11 – 30 seconds is marginally acceptable, depending on the application

This information is from ASPE’s “Domestic

Hot Water and Heating Manual.”

Slide 5 How much water are we wasting

• An average home over 2000 square feet (home sizes have grown from 1,440/sq in 1970 to over 2,200/sq in 2007. The distance between the hot water tank and the faucet

continues to increase) will have 125 feet of 3/4 inch pipe.

• A Type L copper 3/4 inch pipe 125 feet long holds 3.14 gallons of water.

• 10 draws per day will waste 31 gallons waiting for hot water.

• The waste of water in 1 year would be 11,461 gallons.

• If all the homes over 2000 square feet are waiting for hot water, they would waste 288,817,200,000 gallons.

Slide 6

Did you know…..

*****FACT*****

• An estimated 36 of 50 states are facing water shortage problems. The solution to the hot-water waste must offer a convenient product that is easy to use and has a short pay-back time

7

Slide 8 Hot Water Recirculation

How HWR Works?

Hot water recirculation helps you save

water by keeping hot water in the

recirculation line.

Slide 9 Hot Water Recirculation

UP Series - New Home

A Grundfos Comfort Pump can save more

energy and water by utilizing a timer.

Typical Installation

Note the correction position of the pump

is on the return.

Slide 11

• Volute: (pump body) encloses the impeller & the pumped fluid, & provides a channel to get it into the discharge piping

> Fundamentals: Pump Terms

• Impeller: adds energy to the fluid & moves it to wherever it is needed

• Motor: is the driver it spins the impeller

Volute

Impeller

Motor

Slide 12 Impeller Direction of Rotation

It is very important that the impeller turn in the right direction. The vanes need to “fling” the water, rather than “cup: it. Explain that as the impellers rotate, they hurl water outward and up out of the pump. This naturally creates a vacuum at the eye of the impeller, which allows in more water. Otherwise, the pump can only develop about 70% of its designed pressure. And it can damage the pump and motor

Centrifugal force

• Remember when you were a child and went to the playground and got on the spinning wheel

• When you were standing in the middle you could stand for ever and ever no matter how fast the wheel was turning YOU WERE KING

• But when you were at the end of the wheel and it began to spin you could only hold on for so long the faster the wheel spun theharder it was to hang on and is was not long that you were thrown off

• THAT’S Centrifugal force

Slide 14

Slide 15 How are you using the pump in the house?

Open system: the water is open to oxygen/outside air

Closed system: the water is contained and not open to outside air

One must determine if the project is to

heat the home or to provide hot water

recirculation.

Open or Closed?

• I have radiators that provide heat to my house. The heat source is a hot water boiler.

• I have a hot water recirculation line that circulates water from my water heater to my bathroom and back to my water heater.

The first situation is a closed system and

the second is an open system.

Slide 17 Impact to Pump Choice

• In closed system where there is no air coming in contact with the water, we can use Cast Iron.

• In open systems we must use a material that will not rust or corrode away, like Bronze or Stainless steel.

When choosing a pump, it is important to think about whether it is for a closed or open system. Pumps come in different materials: cast iron, bronze, and stainless steel. For a closed system where there is no oxygen to impact the pipes, cast iron can be used. In an open system where the system will be exposed to oxygen, bronze or stainless steel should be the choice. For hot water recirculation, we will have an open system.

Slide 18 Residential Product Selection

• UP/UPS Series Circulators in Bronze and Stainless Steel

UP Series Circulators in Bronze Bronze circulators are available with optional timer and aquastat controls to offer greater control of the HWR system. Bronze units can be ordered with flange, or sweat fittings. The bronze unit can also be ordered with a check valve integrated into a union tail piece. The piping connection is then sweat fitted to the system. UP Series Circulators in Stainless Steel Stainless steel circulators are available with optional timer and aquastat controls to offer greater control of the HWR system. Stainless steel units can be ordered with union or flange fittings.

Hot Water Recirculation

Comfort System – Retrofit

You can still improve the energy savings

and water savings in an existing home,

you just need a Comfort System for the

retrofit.

Slide 20 DirectionOfWaterflow

This is an example of a properly installed

pump for a retrofit.

Slide 21

Pg 15Thermal Bypass Valve

This is the Thermal Bypass Valve that

makes the system work.

Note that in some homes you may need to install rigid risers and cutting the valve into the risers with compression fittings.

Tankless water heaters

Cold In

Hot out

Comfort pump going on hot side to house

Small 2-4 gallon hot water tank

Valve

Cold water in

Hot water to valve

Tankless

A

Slide 23

Slide 24

Highlights of Hot Water Recirculation

Systems

• Convenient (not like low flow showers or low flush toilets)

• The Comfort of Instant Hot Water

• Water Conservation

• Distinguishes Home from Others

Slide 26 How to Select a Pump for Domestic Hot Water

Recirculation

This is our path to selecting the correct circulator. The first box is empty because it deals with calculating a heat load. It’s not relative to what we’re doing here so we begin with determining our flow.

Slide 27 How do you determine GPM?

• Determine the water volume of the hot water piping, desired time to purge the standing water from the pipe, and the flow rate needed to keep the velocity below 4 feet/sec

• Easy way is 10,000btu =1gallon (1 GPM can carry 10,000BTU’s)

• BTU load 8.3 x 60 (seconds) x 20 (Delta T) = flow rate

• 80,000 btu / 10,000 Factor= 8gpm

Note that this is the “best case” scenario, but as we move on we’ll give you a rule of thumb to use when sizing domestic HWR systems. (Rule of Thumb listed below) Why do we want the velocity less than 4 feet/second? When it gets above that there may be noise in the pipes, above 8 feet/second can cause pin-holes to develop in the elbows and joints of copper tubing.

Determine GPM

• Heat Loss chart for Copper Tube (Pg. 58 HVAC Tech Guide)• 100 ft of ¾ ” Supply + 100ft of ½ “ Return:• ¾ ” Pipe (120 deg.)= ? (17)

– 17 x 100= 1700 BTU+

• ½ ” Pipe (120 deg.) = ? (13)– 13 x 100 = 1300 BTU

• 1300 BTU + 1700 BTU = 3000 BTU– 3000 BTU / 10,000 BTU = .3 GPM

Slide 29 How do you select the proper sized pipe?

– Golden Rule of Pipe Selection

– Velocity through the pipe network should not exceed 4 feet/second

See page 39 in the Technical Book

Slide 30 Select Pipe

• Pg. 39 HVAC Tech Guide– How many GPM can you put thru:

• ½” Pipe

• ¾” Pipe

• 1” Pipe

– Velocity through the pipe network should not exceed 4 feet/second

• Smaller pipe saves $$ up front…..but….cost more $$ for pump and cost to run pump.

How do you determine head?

– Head is calculated by multiplying the length of the hot water main, the return line, and the fittings, by the friction loss values.

– Rule of thumb add 20% for fitting friction loss

– Length of pipe and fittings –The friction loss is small except for spring loaded check valves. As high as 9 ft head

Slide 32 Determine Head

• Determining Friction Loss (pg. 39 of HVAC Tech guide):– 100 ft of ¾ “ Supply (Copper Type L)

• Flow 1 GPM= .44

– 100 ft of ½ “ Return (Copper Type L)

• Flow 1 GPM = 2.45

– Total: 2.45 + .44 = 2.89 FL + .58 (20% Fittings) = 3.47 TDH

Slide 33 Friction Loss Example….

• System Parameters:– Main line:

• 3/4 type L copper• 20 std. 90’s

• 10 Std. T’s• 100 feet of pipe

– Return line:

• 1/2 “ type L copper• 10 std. 90’s

• 100 feet of pipe

Floor Plan: 55’6” x 25’ Hot Water Main: 50 feet of ¾” Type L Copper Return Line: 50 feet of ½” Type L Copper

Solution for Problem One – Main Line

Desc of Ftgs Qty of Ftgs Value Equiv of Pipe Ea Equiv LgthStd 90 Elbows X =

Std Tee X =

Ftgs Equiv Lgth Actual Pipe Lgth Total Equiv Lgth+ =

Total Equiv Lgth Friction Factor Total Friction LossX =

10 2.3 23

30 100 130

130/100 .44 0.572

5 1.4 7

Slide 35 Solution for Problem One – Return Line

Desc of Ftgs Qty of Ftgs Value Equiv of Pipe Ea Equiv LgthStd 90 Elbows X =Check Valve X =

Ftgs Equiv Lgth Actual Pipe Lgth Total Equiv Lgth+ =

Total Equiv Lgth Friction Factor Total Friction LossX =

10 1.6 16

16 100 116

116/100 2.45 2.842

Slide 36 Solution for Problem One

Main Line + Return LineTotal Head Loss of System

3.41

________________________________

___

Where do you find the pump curves to use in

selecting the pump? Picking the right pump save you $$$$$$$

Slide 38 The System Curve

Shut-off / Dead-head

Operating Point

Run-Out

Pg 7

Slide 39 Pick a Pump

• UP Product Guide

• Look at head first….

Review

Slide 41 Outline of Problem Two

• Objective:– Select the proper hot water recirculation pump for the given home

• Tools:– Product Information Guides (Pump Curves)– Technical Data Book (Friction Loss Tables)

• Information:– Information needed to solve problem located in System Parameters


Slide 42 Outline of Problem Two

• System Parameters:– Supply line:

• 3/4 type L copper• 200 feet of pipe

– Return line:• 1/2 “ type L copper

• 200 feet of pipeThe water heater is set on 120* FFriction Loss thru Fittings….

Solution for Problem Two

• Determine the required flow– ¾ ” Pipe-Supply:

• 17 x 200= 3400 BTU

– ½ ” Pipe-Return:

• 13 x 200= 2600 BTU

• Total: 6000 BTU

• 6,000/10,000 = .6 GPM

• 10,000 BTU = 1 GPM (reminder R.O.T)

– One GPM will ensure that the velocity remains below 4 feet/second

– One GPM allows you to select the smallest pump available for thejob

Slide 44 Solution for Problem Two

• Determining the Head Loss:

• ¾”=200 ft = head loss – .88 ft (.44 x 2)

• ½ =200 ft = head loss – 4.9 ft (2.45 x 2)

» Total:

» 5.78 ft

• Add 20% for fittings in the system » 1.16 ft

» TOTAL:

» 6.94ft

Slide 45 Step 4

Pick a Pump

• GPM is .6 or 1gpm- needed to overcome heat loss

• Head or friction is 7 ft

• PUMP ?????– UPS 15-55SFC

• What happens is we go from ½” return to ¾” return

Outline of Problem Three

• System Parameters:– Supply line:

• ¾ ” type L copper

• 200 feet of pipe

– Return line:

• ¾ “ type L copper• 200 feet of pipe

The water heater is set on 120* FFriction Loss thru Fittings….


Slide 47 Solution for Problem Three

• Determine the required flow– ¾ ” Pipe-Supply:

• 17 x 200= 3400 BTU

– ¾ ” Pipe-Return:

• 17 x 200= 3400 BTU

• Total: 6800 BTU

• 6,800/10,000 = .68 GPM

• 10,000 BTU = 1 GPM

– One GPM will ensure that the velocity remains below 4 feet/second

– One GPM allows you to select the smallest pump available for thejob

As a rule of thumb, always size domestic HWR systems for a flow of 1 gpm. As noted, one gpm will ensure that velocity is below 4 feet/sec.

Slide 48 Solution for Problem Three

• Determining the Head Loss:

• ¾ ”=200 ft = head loss – .88 ft (.44 x 2)

• ¾ =200 ft = head loss – .88 ft (.44 x 2)

» Total:

» 1.76 ft

• Add 20% for fittings in the system » .352 ft

» TOTAL:

» 2.11ft

Pick a Pump

• GPM is .6 or 1gpm- needed to overcome heat loss

• Head or friction is 2.11 ft

• PUMP ?????– UP10-16BU/ATLC

Slide 50 Residential Product Selection

• UP10-16

UP10-16 The UP10-16 is designed for domestic hot water recirculation systems. Units are available complete with timer, aquastat, line cord, check valve (on union mounted models), isolation valve (on union mounted models), or a combination of features. All wetted parts are non ferrous as noted below (see page 16 of the UP Series Circulation Pumps Product Guide for a complete listing of the materials of construction): Rotor/Impeller Unit Stainless steel, EPDM, PPO, PFTE, Graphite Pump Housing Brass MS 58

Slide 51 Trouble Shooting Tips

• Noise– Pump to large…velocity over 4 ft per second

– Air in system

• “Pin holes” in copper pipe…

• No Hot Water Recirculation– Air not purged

– Power to pump

– Pump installed incorrectly

Hot water supplyto house

CirculatorPump

Check ValveReturn line connected to

water heater drain

Dip Tube: forces cold waterto enter at the bottom of thewater heater

Ball Valve

ISO or BallValve

ISO or BallValve

(optional)

Hose Bib

Cold watersupply

Properly purging air from an HWR System:

Slide 53 Resources

• http://www.grundfos.com/

• Grundfos Technical Institute

• Your local Grundfos Distributor

• Grundfos Handbook….

Slide 54 Grundfos Hydronic+HWR Handbook

• Piping Strategies

• Pump Selection

• Installation Tips

• Troubleshooting

• References

• Etc…

• www.grundfos.us/handbook

Thank you for your attention

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