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Replacing a1958 270,000 BTU boiler
Need some advise from others. I've had 3 HVAC estimates and all have different ideas. I have a monoflow system throughout my tri-level home from 1958. Still has original boiler. There is only one zone/ pump (variable speed/manual only). The system has 1.25" supply that goes all the way around the house. The house is right about 2100 sq ft, well built, all new quality windows. One of the company's based their sizing estimate solely on the size of the existing 1.25" pipe. They estimated about 104,000 BTUs. I read a little about how pipe size works with GPM/BTUs/Delta-T, yada yada, but I'm a total layman about heating systems and am not sure about making a call based solely on pipe size? I do have an addition that was added to the system some time in the past and those 2 rooms do not heat well. The gentleman who based all on the 1.25" saw that the T-diverter that is feeding the addition was just a , normal T. So that was a plus for him, the other two missed that. The other 2 estimates both suggested 122,000'ish for the new boiler. These 2 both took size of the house into consideration, one measured base board fin footage and the other, based on his 4 + decades of experience came up with the same number base on approximate house size. Originally I also was looking at adding a zone for the addition mentioned early, it's a master suite, but perhaps just putting a diverter-T there instead of the normal T would fix that issue? Please give me any feedback you can on this. I will provide more numbers if someone needs them. Thanks