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Indirect plus electric

Dave Meers
Dave Meers Member Posts: 103
I have a Weil McLain 60 gallon indirect and am thinking of adding an electric DHW heater along with it for use in summer so I can shut the WM Ultra boiler down completely. I will be installing an expansion tank as well so how should they be piped so both tanks can use the expansion tank - in parallel or series. I also want to be able to isolate each of them when not in use unless there's a way to use one as a storage tank to increase the DHW capacity. Any suggestions from the Pro's?


  • Uni R_2
    Uni R_2 Member Posts: 589

    Why do you want to shut your boiler down in the summer? Here electric is twice the price per BTU of natural gas, and our gas rates are low!

    You could use an non-powered electric WH as a tempering tank... saves energy in the summer -- and favors a poorly insulated tank.
  • Andrew Hagen_2
    Andrew Hagen_2 Member Posts: 236

    As Uni said, there is no penalty for using your Ultra for DHW production in the summer. In fact, it's the most efficient way to make hot water.
  • Dave Meers
    Dave Meers Member Posts: 103
    More info

    Sorry, I should have mentioned that the boiler is running on propane and not NG. It just seems a little overkill to fire up a 155,000 BTU boiler to heat water for one shower every morning during the summer. I figured I would put the electric tank on a timer.

    So is there a suggested way of tying these two tanks together and yet being able to isolate them when only one is in use?
  • hr
    hr Member Posts: 6,106
    Why not just

    install the timer on the boiler and indirect you have? Without knowing your cost per KWH and LP cost nobody here could give you an answer to the operating costs difference.

    Unless your electric rates are below $.07, I doubt the electric tank would be less costly to operate. Plus the recovery is generally slower on electric tanks.

    Seems a small electric on demand heater would be a better match for a small one load, one time use? If you really want to get away from LP.

    Hate to see you spend the time and money to add another appliance and end up with higher operating costs.

    hot rod

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