Small recirculation pump for heating?

Discussion in 'HVAC Heating & Cooling' started by leejosepho, Nov 6, 2007.

  1. leejosepho

    leejosepho DIY scratch-pad engineer

    I have purchased a small hydronic heater to install in the kickspace under a kitchen cabinet, and now I need a potable-water recirculation pump to pull water through it. The heater only needs 1 gpm @ 140*, and I plan to draw its water from the supply line to the kitchen sink (the tee will go to the sink) and to then send the water back to the bottom of the water heater through a separate recirculation line with the pump and a check valve. I have searched through past discussions here about hydronic heat and recirculation lines and have found various pumps mentioned, but I do not know which might be best in this application. A line-voltage thermostat on the wall will control the pump, and the heater has an internal control that turns its blower on at 110*.

    Any suggestions for a pump?

    Thank you.
  2. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Any small pump like a grundfos UP15 or a Taco 007 would probably do the trick. Get a model with intergral check valve, else you will need to install one. Since you are on an open system you must use a bronze or stainless steel pump. you cannot use a cast iron.

    At 1 GPM, you will exhause a 50 gallon water heater in 35 minutes, and the temperature at the 35 minute point will be down to about 110. Are you sure this system will work?
  3. leejosepho

    leejosepho DIY scratch-pad engineer

    Understood.

    No, but it is not going to cost too terribly much to find out! Also, the kickspace heater has a low-temp (110*) cutout I might be able to interlock with the pump or thermostat to keep from depleting the water heater.
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