Installing a Condensing Modulating Boiler with an Indirect Hot Water Tank; still efficient w/ old plumbing and cast iron radiators?
Is installing a condensing modulating boiler w/ indirect hot water in an old home with cast iron radiators in Minneapolis still efficient if the house has old 2”+ dia. cast iron piping and cast iron radiators? I’ve read that if the water returning to the boiler isn’t under a certain temperature the heat exchanger won’t function efficiently. Also need to add an additional zone for a previously unconditioned space where we would like to use a wall hung radiant panel. My understanding is that old boilers w/ cast iron radiators typically operate with water temps at 180 degrees F, the wall hung radiant panel wants to run at 150 degrees F, and the hot water will be heated to about 120 degrees F. Is it a problem for a single modulating unit to supply different zones with different temperature demands?
This is for a frugal household – 2-3 people, 1 shower, 3 sinks, clothes washer, no dishwasher.
Any recommendations of manufacturer’s based on field installation experience would be appreciated.
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