Hello. I'm getting ready to scrap the old heating system in my 1900 Philadelphia house. It consists of an oil-burning converted coal furnace with an added B&G pump feeding through 2-inch and 2 1/2-inch cast-iron mains and returns to 1 inch for cast-iron radiators and 3/4-inch copper for one room of baseboard radiators. I plan to repipe the mains with 1-inch and/or 3/4-inch copper, with appropriate tees and a couple of zone valves. I've got a Viessmann mid-efficiency gas boiler ready to go.
Now my question (but if anyone wants to throw in any other advice, that's fine). Is there any way to remove the old cast-iron pipe without demolishing it? I thought I might be able to loosen the threaded fittings once I removed some copper ends, but no dice so far. Propane heat on the joints appears to make no difference. I've got a metal cutting blade for my circular saw and a 4-inch angle grinder with metal-cutting wheels, so that's my fall-back option. But I figure someone might want this pipe, so if I can leave it usable, that's my preference.
Thanks,
Josh Schneider Philly