Hot%20Water%20Recirculation%20Pumps.

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Hot Water Recirculation Pumps.

• Tim Pehl
• Outside Sales Rep For Dawson Company.

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Topics

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

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Scenario.

• We get up in the morning and we turn on the
• hot water to take a shower.
• we put our hand into the stream of water to
• check the temperature, and it is cold.
• We may wait for a full 60 seconds, or longer,
• before we can step in and take our
• shower.
• Why??
• We dont have a recirculation pump!

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Scenario.Dead end piping

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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

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Scenario.

• How Much Water is 14,000 Gallons?

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Scenario.Return line added with Circulator.
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How a pump works
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SYSTEM CURVE
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Recirculation pump with ECM technology
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Standard Induction Motors
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ECM ( Electrically Commutated Motor) Technology
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Induction Vs Permanent Magnet

• Permanent Magnet Motor
• Permanent magnet on rotor
• Eliminates the requirement for input power to
  magnetize rotor
• Stator coils generate a rotating field to induce
  the permanent magnet to rotate
• Motor 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.

• 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.

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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

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SYSTEM CURVE
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System Curve
System Curve
System Curve
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Recirculation pump with ECM technology
Variable speed option can reduce smallest pump
energy consumption even further..
e3-4
System Curve
System Curve
Flow (GPM)
Duty Point 5 Watts
Duty Point 40 Watts
88 LESS ENERGY CONSUMPTION
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One Switch - Two Options

• Every ECM circulator has a switch installed- you
  have the choice
• Variable Speed Control
• Variable Temperature Control(68 to 158 Deg.F.)

Variable Temperature Control
Variable Speed Control
NEED PIC
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Options

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

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What if I dont have a return line?Autocirc 14
watts
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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.

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Questions?