We have an opportunity to buy a larger (7000 sf) older (1930s) home with an old natural gas boiler (Burnham K-5010 circa 1977 install). The boiler has not been used in a few if not many years by the previous homeowner as they chose to go with forced air solution. We have never had radiant heat source before but have heard it is much better. The house has fin-tube type radiators all about the main two floors with the steam boiler centrally located in the basement. We had a technician come to fire the boiler to test it but a gas regulator valve and a safety valve were defective and he was unable. He suggested pressurizing the radiator lines/pipes with nitrogen to see if they were leaking anywhere upstairs and if not it would be reasonable to buy the new parts to get the boiler working. If the boiler was not functional we would have to buy a replacement boiler. The house has had no major renovation, still with original windows and insulation. I have several questions that I wanted to put out there for those with experience using/maintaining/installing boilers.
1. In a large old/inefficient home is radiant heat the best heating system (here natural gas is much cheaper than electricity or oil)
2. Is a boiler from 1977 at the end of its life so that it is not worth spending a $ on parts to revive it.
3. If we change to a new boiler it will be approx 6x cost of parts to get old one running, should we keep exact specs and shop for different brands (e.g. buderus, peerless) or replace it with the identical burnham spec unit since we are not renovating windows, insulation, etc.
Thanks in advance for you time/expertise