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no boiler loop with old converted gavity system

maybemark Member Posts: 1,131
I had gotten a suggestion from someone on the site, make it simple, just go ahead and install my Lochinvar whn85 to a secondary loop only. Do not use a pump for the boiler, just one pump for both boiler and heat, then second pump for DHW.
I live in a 90+ year old house, no insulation on the walls, and an unheated basement. I have much too many radiators in my house. My house at the moment is being circulated by a taco cartrage pump. i think an 007.
I would very much like to hear your thoughts about what was suggested


  • maybemark
    maybemark Member Posts: 1,131
    I forgot to mention, it's a single zone system only 1 thermostat.
    I have 3" pipes down to 2" pipes for the horizontal runs.
    The pump that is on my old system now is a taco 007 f-3. For 35 years the system worked
  • JStar
    JStar Member Posts: 2,752
    The WHN should be a fire-tube boiler, so the resistence in the boiler does not require its own dedicated circulator. That boiler will LOVE being attached to an old gravity system. A 007 may be adequate. What is the heat-loss of the house?
  • maybemark
    maybemark Member Posts: 1,131
    thanks for getting back to me, I calculate about 73k heat loss using the slant fin calculator. I have no insulation on 3" of massonry walls. My house is about 2600 sq ft with an unheated basement, that i did not caculate in for the heat loss
    I had purchased a new15/58 for the circulation. I was told that would work, but keep it on the low setting. Do you agree?