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condensing gas boilers and home run to each radiator

bob eck
bob eck Member Posts: 930
I have a Triangle Tube PE110 nat gas boiler in my house and I have large 2" mains in the basement going to cast iron radiators on the first and second floor.

Only one zone and the thermostat turns the boiler off with the first floor comfortable at 70*F but the second floor is always cooler.

Radiators on the second floor are big enough for the rooms but the water going from the large 2" main in the basement only goes by gravity. I have the PE110 boiler piped primary secondary and have a Grundfos circulator pumping up into the 2" main and then gravity out to all radiators.

I want to install a radiant manifold and run 1/2" Viega fostapex direct from the manifold to each radiator with the second floor coming of the manifold first and with the manifold I can control flow easy to each radiator.

Anyone doing this type of installation and what were your results?


  • Alan (California Radiant) Forbes
    I Like Gravity

    If the bedrooms are upstairs, cooler rooms can be preferable unless it's too cool.

    As far as re-piping, that's a lot of work.  If the pipes are in good condition, I'd leave it alone and try to figure out how to limit the downstairs radiators to let the upstairs catch up. 

    Being the hydronicist that you are and have to tinker, the manifold system will definately improve system performance, but you will have to abandon the gravity part and add a pump.  And since you only have one thermostat, it would be a good idea to install TRV's at each radiator.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • NYplumber
    NYplumber Member Posts: 503

    I am missing a part of this scenario. If there is a pump on the feed 2" line, how is it acting as gravity?
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