Electric water heater with outdoor wood boiler

Discussion in 'Water Heater Forum, Tanks' started by clawbennett, Dec 16, 2019.

  1. clawbennett

    clawbennett New Member

    Joined:
    May 21, 2019
    Location:
    Stanwood, MI
    We have a Central Boiler outdoor wood boiler for heating the air and water for the home.

    The issue we are having is that we aren’t being supplied enough hot water for the house. The OWB is hooked up to the electric hot water heater via a sidearm. I have read this is not optimal for our household size and usage. After a shower and a chore (dishes or laundry) we are at lukewarm water at best. And it takes hours to rebuild the hot water back up.

    i have been told to turn the breaker off for the electric water heater when running the OWB during our winter months.

    My question is can I turn the electric water heater back on and use the OWB at the same time? I am hoping by using the OWB it will warm the water enough to still reduce the cost of the water heater usage.

    we use well water and crude testing of the cold water temp out of the faucet is approx. 50f. So to raise the temp from 50f to 120f is quite energy consuming!
     
  2. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    An electric fed from the wood-fired WH should be good and fairly efficient.

    If you take a lot of showers and the shower is not on the bottom floor, a heat exchanger that recovers heat would be good. Dana has posted nice info on that.
     
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  4. clawbennett

    clawbennett New Member

    Joined:
    May 21, 2019
    Location:
    Stanwood, MI
    Cool. I am assuming then that it is okay to turn the water heater back on while running the wood boiler?

    I ask bc I’m getting mixed answers. Some are suggesting it will “overheat”?
     
  5. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    I am not a plumber.

    The problem I see is that the electric WH will slow the arrival of the the wood-heated water. This would prevent you from getting hot water from the wood heater alone. Maybe a recirculation pump could get turned on once you are ready to switch to hybrid electric+wood.

    Maybe some valving could let you switch over, but you would want to make sure you don't power the electric unit if the water level drops there.
     
  6. clawbennett

    clawbennett New Member

    Joined:
    May 21, 2019
    Location:
    Stanwood, MI
    There is a recirculating pump on at the boiler outside. Would that be enough?
     
  7. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    Would it recirculate water through the electric WH too? If so, I would think yes.
     
  8. phog

    phog Active Member

    Joined:
    Jul 29, 2017
    Location:
    Rochester NY
    Maybe I'm missing something here, but what is the rationale behind leaving off the electric WH? The electric element is controlled by a thermostat and will only turn on as needed, to supplement the wood boiler. If the OWB provides sufficient heat output then the electric will barely switch on at all. Since the OWB alone is already proven to provide insufficient hot water (or at least inadequate recovery time) then you need the electric element to provide the rest. I am going to assume that the OWB circulation is functioning properly, and that this is a winter-only problem (ie. the electric WH works as intended when switched on during the summer months). If there are any equipment malfunctions then those should be addressed first of course.
     
    Tuttles Revenge likes this.
  9. clawbennett

    clawbennett New Member

    Joined:
    May 21, 2019
    Location:
    Stanwood, MI
    When we bought the house everything was here already. The previous owner said they never needed to keep the electric WH on in the winter months when the OWB was burning. So they flipped the breaker off. So last winter we didn’t notice much because we didn’t know better. However this year we’ve noticed how lacking the hot water really is.

    I have flipped the water heater back on this evening and we have hotter water and quicker recovery time. But we seem to still run out of “hot” water and it quickly goes down to about 105-110f out of the faucets.

    The first few minutes of full blast hot water will come out hot! 135f hot but it’s very short lived. Quickly returning to 110f or lower.
     
  10. phog

    phog Active Member

    Joined:
    Jul 29, 2017
    Location:
    Rochester NY
    You may want to check the electric tank system for proper basic function (or have a pro check it out).

    First check the resistance of the electric elements in the tank to make sure they're not burned out. Especially the lower element. They do go bad occasionally and they're cheap & not that difficult to replace.

    Second, if everything is ok there, check the electric tank thermostats for proper function. After a full hot water drawdown, observe the electric tank warming up. The upper element turns on first when starting from a tank of cold water. Then after the upper tank water is warm the upper element should turn off and the lower element should turn on to heat the lower water. When the tank reaches temperature then the lower element turns off as well. If you don't see this occur in that order then you could have a faulty thermostat. Those go bad less often than the heater elements but do occasionally go.

    Last, if the elements and thermostats are ok & you still don't get good results then this could mean a faulty dip tube in the tank or a cold to hot crossover somewhere.

    When you do get the system running optimally, what you should see is the wood boiler and electric elements supplementing each other. The electric will still run each time you draw on the hot water tank, but the heat from the wood loop will heat the water in tandem with the electric elements and the tank will reach the thermostat setting much more quickly than electric alone. Greatly reducing the amount of time the electric elements have to operate.
     
    Last edited: Dec 16, 2019
  11. WorthFlorida

    WorthFlorida The wife is still training me.

    Joined:
    Oct 28, 2009
    Occupation:
    Retired
    Location:
    Orlando, Florida
    Is there any inline thermometers at the wood burner? When going from all electric to wood burner, are any valves opened or closed to isolate the wood burner hot water loop from the electric heater during the summer months?
     
  12. Tuttles Revenge

    Tuttles Revenge In the Trades

    Joined:
    Oct 15, 2014
    Having hot water for a short time from a water heater often indicates that the dip tube that sends the incoming "cold" water to the bottom of the tank to be heated by the first element has failed and its sending water only to the top where its being maintained by the upper element.
     
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