Hot Water Recirculation Pumps.Hot Water Recirculation Pumps.

Tim PehlTim Pehl Outside Sales Rep For Dawson Outside Sales Rep For Dawson

Company.Company.

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TopicsTopics

Scenario.Scenario. How a recirculation Pump works.How a recirculation Pump works. History of recirculation Pumps.History of recirculation Pumps. Latest technology.Latest technology.

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Scenario.Scenario.

We get up in the morning and we turn on theWe get up in the morning and we turn on the hot water to take a shower.hot water to take a shower. we put our hand into the stream of water to we put our hand into the stream of water to check the temperature, and it is cold.check the temperature, and it is cold. We may wait for a full 60 seconds, or longer,We may wait for a full 60 seconds, or longer, before we can step in and take ourbefore we can step in and take our shower. shower. Why??Why?? We don’t have a recirculation pump!We don’t have a recirculation pump!

Scenario.Scenario.Dead end pipingDead end piping

WH

Normal Hot Water Operation:

Last hot water use at night time around 11:00pm

Normal Hot Water Operation:

Last hot water use at night time around 11:00pm

Water heater output:

130°F Hot Water

DHW Pipe run:

100 feet ¾” Copper PipeWH

Normal Hot Water Operation:

Following morning at 7:00am

Water heater output:

None – Existing water cools to 60°F

DHW Pipe run:

100 feet ¾” Copper Pipe

Traditional non-recirculated system Traditional non-recirculated system

Scenario.Scenario. Residence is three bedroom with four occupants and two baths. Water heater is approximately 60’ from master bedroom Hot water supply line from water heater is un-insulated ¾” copper

pipe Assume the following volume of hot water wasted per day:

Master lavatory 1.5 gal fixture 2.625 gal wasted/day Second bathroom lavatory 1.5 gal fixture 7.5 gal wasted/day Master Shower 2.5 gal fixture 15 gal wasted/day Second bathroom shower 2.5 gal fixture 2.625 gal wasted/day Kitchen Sink 2.5 gal fixture 12.5 gal wasted/day

• Water consumption is based on the system operating 350 days per year• Total water wasted in a year is 14,087 gallons based on total water

wasted of 40.25 gallons per day

Scenario.Scenario. How Much Water is 14,000 Gallons?

Scenario.Scenario.Return line added with Circulator.Return line added with Circulator.

60psi

WH

Normal Hot Water Operation:

Following morning at 7:00am

System with hot water recirculation

How a pump works

SYSTEM CURVE

Recirculation pump with ECM technology

Standard Induction Motors

ECM ( Electrically Commutated Motor) Technology

Induction Vs Permanent Magnet Induction Motor No magnet on rotor

• Stator coils create magnetic field which induces current into rotor

• The rotor currents interact with the rotating magnetic field which causes a rotational motion on the rotor.

• Because the magnetic and electric fields are out of phase (slip), there are greater current requirements and current losses.

Permanent Magnet Motor Permanent magnet on rotor

Eliminates the requirement for input power to magnetize rotorStator coils generate a rotating field to induce the permanent magnet to rotateMotor is microprocessor controlled to keep the stator current in phase with the magnets of the rotor.The lower current requirement and no “slip” result in greater efficiency.

Comparison: Spherical Motor vs. Canned Motor

Key Advantages

• Simplicity – just one high precision part

• No shaft, no bearing bushings

• Self-aligning rotor

• Long term quiet and trouble free operation

• No start-up problems

SYSTEM CURVE

System Curve

System Curve

System Curve

Recirculation pump with ECM technology

Duty Point 5 Watts Duty Point 40 Watts

Flow (GPM)1 2 3 4 5 6

2

4

6

8

10

Flow (GPM)

Head

(FT)

System Curve

System Curve

88% LESS ENERGY CONSUMPTION

e3-4

Variable speed option can reduce smallest pump energy consumption even further..

10

5

2

One Switch - Two Options Every ECM circulator has a switch installed- you

have the choiceA. Variable Speed ControlB. Variable Temperature Control(68 to 158 Deg.F.)

Variable Temperature

Control

Variable Speed Control

NEED

PIC

Options

Most pumps come standard with constant speed. Power cords are sometimes optional. Variable speed. Temperature control. Time clocks

What if I don’t have a return line?Autocirc 14 watts

But I have a Tankless water heater

Sizing a pump for Tankless water heaters is the same as a tank type. However, a larger pump will be needed as the Tankless units have a heat exchanger inside that produces a higher pressure drop.

Questions?