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Advice needed: Twin Boiler Gravity Conversion Heating System W/indirect Water Heater
First of all; Thank you, Dan, for "Pumping away", "Primary and secondary Pumping", and your fabulous article online about gravity heating. My 1909 system originally used the dining room radiator as the expansion tank: It has two bleeds, one top, and one on the bottom so you could establish an air cushion in the radiator. And the room was over-radiated to make up for it... (a second large radiator). The system has been heated with coal, then fuel oil, and, since 1985 with natural gas. Sometime ago, I got a good price on two high mass boilers that essentially split the heat load, and I have the Danfoss balancing valves as well. My plans to use the exsisting gravity heating loop as the primary circuit, with the two boilers connected to it (the secondary circuit) with reverse return on the boilers. I will be following up with a circuit plan, but I have many questions first: Should I plumb the non-gas portion of this with copper or steel? What are the pros and cons? I'm basically equipped to do it with either material. I lack experience with threading and positioning unions. I've done lots of sweating...
(I'm sweating a little bit right now, Winter is getting closer... Hee Hee) Also, It seems like the contractors in the Minnesota area mostly have no clue about "Primary-Secondary" Is there someone near Minneapolis that might be able to advise me as well? Thank you, Dale.