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Indirect heat exchanger to fit electric hot water heater?

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seo
seo Member Posts: 4
Hi,

I'm switching over from an old conventional Weil-McLain oil fired boiler with tankless hot water heater,to a Thermo Dynamic boiler that's set up to use an indirect domestic water heater.

I also have a 42 gallon electric hot water heater that is not being used, and my question is whether it can be used as an indirect hot water heater. I am sure that I have read somewhere that some company makes a heat exchanger that can bolt into the hole that one of the electric electrodes bolts into. Anyone heard of these? Know who makes them? Knows how well they work?

The hot water heater in question is a pretty good one, with insulation in good shape. It also has one of those insulated covers over it, so its heat loss is probably pretty low. I think that it has a plug that can be used for a control aquastat.

I'd appreciate any response.

SEO

Comments

  • billtwocase
    billtwocase Member Posts: 2,385
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    the only thing that would make sense

    would be to use a plate heat exchanger to heat that tank. There is no magic coil that will plug into the tank, only the heating elements that it now has. I would either keep it as a separate unit producing your hot water within, or invest in a good indirect. You may spend too much time and money on re-engineering the electric tank.
  • kcopp
    kcopp Member Posts: 4,443
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    Bill is correct....

    Which model Thermodynamics boiler are you planning on using? Im guessing a LM series.
  • Plumdog_2
    Plumdog_2 Member Posts: 873
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    Wiel-Mclain

    I think made something like that. A box containing a heat exchanger sat on the floor next to the water heater, and a specially-configured pump circulated thru the drain opening! A supply/return went back to the boiler in another room. We removed one recently. You can configure one with a flat-plate exchanger and a stainless or bronze pump on the domestic side. Accurately tracking the parts cost, you would soon approach the cost of a REAL indirect. 
  • seo
    seo Member Posts: 4
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    seo

    It is an LMD, which I bought from someone who's converting to Natural Gas. I got an 80 gallon Amtrol indirect heater at the same time, but that's a lot more hot water than I need. As I was reading about indirect heaters, I saw a comment on replacing the heater element of an electric heater with a flat plate heat exchanger.
  • seo
    seo Member Posts: 4
    edited December 2011
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    seo

  • Interceptor
    Interceptor Member Posts: 46
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    solar

    I have seen the heat exchangers that you're thinking of. They install in

    place of the electric element. I believe they are made for small solar

    conversions, I don't think they would support the flow and heat transfer

    requirements of a boiler indirect system.



    I can think of a few minor advantages to using an electric tank with an external heat exchanger vs an indirect. If either the tank or the heat exchanger fails, you only need to replace the failed part, which would be considerably less expensive than a whole new indirect tank. You can also still have hot water (electric back-up) if you ever want/need to shut the boiler down, such as warm weather shut down, boiler repairs, or run out of fuel.
  • seo
    seo Member Posts: 4
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    exchanger area?

    How big is the heat exchanger in a 40 gallon indirect? In square inches of surface area, or heat capacity.
  • Interceptor
    Interceptor Member Posts: 46
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    square feet, not inches!

    The WM 40 gallon has 16 square feet of heat exchange surface.
This discussion has been closed.