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Hot Water Recirculation Pumps. Tim Pehl Outside Sales Rep For Dawson Company. Topics. Scenario. How a recirculation Pump works. History of recirculation Pumps. Latest technology. Scenario. We get up in the morning and we turn on the hot water to take a shower.
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Hot Water Recirculation Pumps. Tim Pehl Outside Sales Rep For Dawson Company.
Topics • Scenario. • How a recirculation Pump works. • History of recirculation Pumps. • Latest technology.
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 don’t have a recirculation pump!
Traditional non-recirculated system Traditional non-recirculated system Normal Hot Water Operation: Following morning at 7:00am 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: None – Existing water cools to 60°F DHW Pipe run: 100 feet ¾” Copper Pipe Water heater output: 130°F Hot Water DHW Pipe run: 100 feet ¾” Copper Pipe WH WH Scenario.Dead end piping
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. • How Much Water is 14,000 Gallons?
System with hot water recirculation Normal Hot Water Operation: Following morning at 7:00am • 60psi WH Scenario.Return line added with Circulator.
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.
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
10 8 Head (FT) 6 10 5 2 4 2 2 1 3 4 5 6 Flow (GPM) 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 40 Watts Duty Point 5 Watts 88% LESS ENERGY CONSUMPTION
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 Speed Control Variable Temperature Control NEED PIC
Options • Most pumps come standard with constant speed. • Power cords are sometimes optional. • Variable speed. • Temperature control. • Time clocks
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.
