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connecting HP water heater to heat indirect tank

jrv8984
jrv8984 Member Posts: 45
I just picked up a Rheem Proterra 50 gallon water heater. I will only be using it in the summer/shoulder months. The rest of the year I heat a Vaughn 70 gallon indirect tank with my coal boiler (AHS S260).

Is there a simple/creative way to plumb the 2 together so that the HP unit also heats the indirect tank. I obviously would have valves to separate the 2 units during the winter time, as I wouldn't need any more capacity than what the indirect gives me.

I'm open to using heat traps, zone valves, or a circulator if I have to, although the simpler the better.

Thoughts, schematics, am I missing something with this idea.
Thanks

Comments

  • ethicalpaul
    ethicalpaul Member Posts: 3,739
    What is your goal? Are you trying to increase your hot water capacity in the summer?
    1 pipe Peerless 63-03L in Cedar Grove, NJ, coal > oil > NG
  • jrv8984
    jrv8984 Member Posts: 45
    Yes, that is my goal
  • ethicalpaul
    ethicalpaul Member Posts: 3,739
    edited August 2021
    OK thanks. Set aside for a moment the complication of how to get the hot water to the indirect (there may be an easy way that I'm not picturing). My additional concern would be this: How do you prevent the Rheem from having to heat both units during recovery time, thereby lengthening the recovery time by possibly twice as much?

    But that first complication really has me scratching my head. The Rheem only has one input port and one output port. So let's say there is a use of water happening like a long shower that has started to cool the indirect (because of the fresh cold water entering it). How do you get hot water out of the rheem for the shower at the same time you might be trying to get hot water out of the rheem to circulate to the indirect to try to recover its temperature?

    It seems that you would actually be reducing the amount of usable hot water by the residents as compared to the Rheem being standalone.
    1 pipe Peerless 63-03L in Cedar Grove, NJ, coal > oil > NG
  • jrv8984
    jrv8984 Member Posts: 45
    The Vaughn has a standby heat loss of .45°f an hour, so extremely minimal.  The thought was, that if the Rheem unit has both tanks heated, you really shouldn't run out of hot water at any given time (120 gallons total capacity).  There are height restrictions, which is why I can't install an 80 gallon unit.



  • Larry Weingarten
    Larry Weingarten Member Posts: 2,544
    edited August 2021
    Hi @jrv8984 , You might be able to use a solar control, (differential control) to measure temps in both tanks for turning on a pump to move hot water from the HP to the indirect, basically making the HP a sidearm heater for the indirect tank. Probably cold in and hot out to fixtures should remain with the indirect. Just thinking out loud :p

    Yours, Larry

    ps. You could also just use the HP as a preheater for the indirect. And, it would be useful to know just how much hot water you need in an hour.
  • jrv8984
    jrv8984 Member Posts: 45
    I guess I'm leaning towards plumbing them separately, with valves to switch between the two.