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Cast iron radiator question.

bob eck
bob eck Member Posts: 930
I am closing in my patio and making it a four season room.
I have a Triangle Tube PE110 nat gas boiler and I have it piped P/S and the patio room will be on its own zone.
I will be using a Grundfos UPS 1558FC circulator and running 3/4" radiant Pex tubing out to the cast iron radiators.
I will be installing three cast iron radiators on one wall. Total of all three CI radiators is about 22,000 BTU and this will be enough to heat the room.
The patio room is a concrete slab so I will be running through one radiator then through the second and then through the third and then back to the boiler.
The room will have its own thermostat.
Will the three radiators work together as one large radiator?
Thanks for your input.


  • Harvey Ramer
    Harvey Ramer Member Posts: 2,239
    The way you described it they won't. They'll be in series.

    Now if you bring the supply into the top of the first rad, do both a top and bottom (2pipe) connection between the rads and take the return out of the bottom of the last rad; they will be as one.