Water heater recirculating question

Discussion in 'Water Heater Forum, Tanks' started by Cass, May 22, 2009.

  1. Cass

    Cass Plumber

    Nov 12, 2005
    I have a customer who has a 50 gal. gas power vent and 80 gal. electric heater...the 80 gal. heater is not hooked up to electric because his panel is full... customer wants to use it (80) as a storage tank using the 50 gal. gas tank and a recirculating pump to keep the 80 gal. tank hot...

    Have any of you done this in the past and if not does any one think it will work...the pump would be pumping water from the 80s drain into the 50s drain and recirculate from the hot side on the 50 into the cold side on the 80...the house would feed from hot side of the 80...

    To me it seems like the 50 will be struggling to keep all that water hot...there is a lot more to this story but moot for this question...
    Last edited: May 22, 2009
  2. Master Plumber Mark

    Master Plumber Mark Master Plumber

    Feb 6, 2005
    Sensitivity trainer.. plumber of mens souls
    indianapolis indiana - land of the free, home of
    Cass it will work ...but..

    I would get a 10 year warranty on the power vent
    becasue it will probably burn out in 6 1/2 years...

    it will have to work a lot harder, and I would insualte both
    the tanks with waterheater blankets

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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    The recovery rate would be lousy, but it should work. On second thought, if the pump ran while you were using the water, you'd cool the water off of the whole system faster and lose the natural tendency of keeping the hot at the top to dispense. So, you may need a flow switch on the outlet outside of the recirculation loop to turn the pump off while drawing water from the system. While recovering, you could end up with it cooling off first, then gradulally warming up again. It would depend on planned usage schedule. If there were long gaps between needs, may not be a problem.
  5. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona

    Absolutely nothing unique about it. You are using the 80 gallon tank as a storage tank. It has absolutely no effect on the life of the heater, the recovery, or anything else. You can use the upper thermostat on the heater to operate the circulation pump. If it is set below the temperature of the gas heater it will cycle on and off as the temperature fluctuates. If it is set too high the pump will never turn off and all the water will be at the temperature of the gas heater.
  6. FloridaOrange

    FloridaOrange Plumbing Designer

    Dec 2, 2005
    Plumbing Designer
    SW Florida

    It seems to me that 80 gallons as a storage tank is a waste. That would only be benificial if your customer had needs of 130 gallons + whatever could be produced by the gas unit for the period of time. Say 175 gallons in an hour or so, but only for short durations of the day. This would be similar to a setup for a hotel where the water needs is huge for an hour or two and not so much for the rest of the day. The setup would work but would it be really benificial. To answer the question you/we would need to know the water needs of your customer.
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