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Hot water heater configuration

rlakein Member Posts: 1
Hi there!

We are switching from steam to water and I am having my regular plumber install my new heater. He has done many of the old ones, but never a high efficiency that is going to both radiators and radiant.

My questions is if I can use the same manifold for both the radiant floors and the radiators, or do I need two systems as they need different temperatures, and how you would recommend setting it up.

4 floors. Basement and 3rd floors are radiant, 1st and 2nd are old radiators with 3/4 pex doing to the radiators, one line for each two radiators split with a t.


  • Jamie Hall
    Jamie Hall Member Posts: 23,275
    Why on earth are you switching from steam to hot water? That is NOT the right way to upgrade a heating system...

    There are ways to do both hot water heat and radiant off the same boiler. They aren't very efficient, most of them. There are also ways to do steam and radiant off the same boiler. They are at least as efficient.

    Oh dear...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Jamie Hall
    Jamie Hall Member Posts: 23,275
    And furthermore...

    If you do insist on changing from steam to hot water...

    Yes, there are ways to set up the manifolds and pumps and controls to get both radiant (low temperature, 24/7 pumping) and hot water (if you are using the old steam radiators, very high temperature) from the same boiler, but they are neither simple nor straightforward. I hope you have somebody who really knows what he or she is doing. This is assuredly not a job for a plumber, unless he or she is also a pretty brilliant and experienced heating man.

    Much easier and more efficient to set up the pumps and controls to get the radiant off a steam system...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • KC_Jones
    KC_Jones Member Posts: 5,736
    @Jamie Hall I think the steam has already been torn out since they mention everything is run in PEX already.
    To the OP if I was you I would have pause at this moment. If your plumber doesn't know the answer to these questions how will they know to install it properly?

    Did they do a full room by room heatloss on the entire building? Not only for boiler sizing, but also to make sure each room gets proper heat with flow, tube spacing (in the case of radiant). In addition were the steam radiators measure to make sure they could provide heat at the greatly reduced output on hot water? Are your radiators connected across the top so that they will work on hot water? Early steam rads were not and won't work on hot water.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
    delta T
  • delta T
    delta T Member Posts: 884
    Agree with all the above. It is not as easy as connecting the boiler. LOTS of design work needs to be done before the installation to ensure that it will work correctly. Steam to hot water conversions will not work correctly if you do not do the design up front. Find a heating pro from this site to help you using the link at the top.