Added water heater to the mix

Discussion in 'Boiler Forum' started by velcrobots, Dec 9, 2009.

  1. velcrobots

    velcrobots New Member

    Messages:
    3
    Location:
    nj
    OK, so I have an oil-fired Weil McLain boiler for both baseboard heat and hot water. The coil was starting to go, and was very unpredictable, so we decided to add a gas hot water heater.

    We just cut the in/out to the coil and re-routed to the new water heater. My question is this - what about the control mounted on the coil? Do we need to disconnect it?
  2. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    You need to disconnect every thing that ties the two systems togeather....
    Last edited: Dec 9, 2009
  3. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    You no longer need to maintain boiler temperature so you should either turn the low limit all the way down or by-pass it.
  4. velcrobots

    velcrobots New Member

    Messages:
    3
    Location:
    nj
    I set the aquastat to HI 180 LO 160, diff set to 20. That should be good, no?

    Attached Files:

    Last edited: Dec 10, 2009
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,806
    Location:
    New England
    when you have an in-boiler, domestic water heater coil, the boiler is always kepts between the set points so you have instant hot water capability. If you are no longer using that, unless you disable that portion, the boiler will stay hot all year thinking it is making your hot water. You don't want to pay for that. You might save money by making a new zone and using your boiler to heat an indirect WH rather than a totally separate gas WH. Essentially, you want your boiler to be able to shut itself off when it is not needed, rather than staying hot all year round. How easy that is to do will depend on what controls you have.
    Essentually, you want the boiler to come on when there is a call for heating, and not maintain itself at the ready all year long.
  6. velcrobots

    velcrobots New Member

    Messages:
    3
    Location:
    nj
    I have honeywell control, not sure of the model number but it's in the image above. Is it just a matter of disconnecting some wires?
  7. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    Its a Honneywell L8124. Turn the low limit down as far as it will go, leave the diff at 10
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