discontinue use of tankless coil

Discussion in 'HVAC Heating & Cooling' started by Handyman Extraordinaire, Jan 11, 2008.

  1. Handyman Extraordinaire

    Handyman Extraordinaire Junior Member

    Jan 11, 2008
    I have an older weil-mclain boiler that has a tankless coil in the top of the boiler. I am going to discontinue using the tankless coil. Do I need to remove it or can I simply disconnect it and leave it in place?
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    To provide DHW, this type of boiler tends to maintain internal boiler water temperature higher and more consistent than those that do not have this feature. There may be a separate aquastat and possibly a flow sensor. You'd want to fool the boiler to think that the DHW requirements were met so it wouldn't fire in the summer or other times unnecessarily. Also, some of these have a flow restrictor in them to help ensure adequate heat output. You may need to address that if you do what is described in the next paragraph.

    You may want to still run the output of this coil to your tank as the cold input if you can't disable the controls. Someone with more understanding of the controls may be able to help decide the best route.

    Are you going with an indirect, or a separately fired WH?
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  4. Handyman Extraordinaire

    Handyman Extraordinaire Junior Member

    Jan 11, 2008
    We are going with a seperate unit. Thanks for the help
  5. Bob NH

    Bob NH In the Trades

    Oct 20, 2005
    New Hampshire
    I have a tankless coil and wanted to shut down the boiler in the summer because the fuel to keep it hot was so great.

    I connected the tankless coil to the input of an electric water heater. In the winter the oil-fired boiler heats water going to the water heater. In the summer the water heater takes over. The only management of the process is turning off the boiler when heating is not needed.

    I did install valves so the tankless can be isolated from the water heater and bypassed.

    If I were abandoning the tankless coil I would disconnect it, blow out the water with air, and plug both ends. That way, if it ever sprung a leak it would be contained.
  6. Handyman Extraordinaire

    Handyman Extraordinaire Junior Member

    Jan 11, 2008
    more opinions please

    anyone else have ideas on this?
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