Best way to heat an addition?

Hi James. One way is to run radiant heat off your existing boiler. You can install a zone valve and thermostat. There is a link for radiant, but I don't know it. If you decide on a seperate boiler, or vented space heater, fireplace, etc. you still will have to extend the gas line anyway. A furnace on the 2nd floor is also an option, but requires installation of ductwork.

Thanks for the info. on the zone valve and thermostat on an expansion of the current radiator system. I already considered just expanding the current system but a local (and reputable?) plumber recommended exploring other options because in their opinion, opening such an old system may invite leaks and other problems. (But the plumber didn’t mention the zone valve and thermostat options.) According to the son of the former and original owner (Yes, I bought it from the man who built it in the 1930s, what a find!) this is only the second boiler that was ever utilized and he cannot recall whether the system was ever opened other than to replace the boiler and bleed it.

Having said that, my questions are: 1) Do you think I am opening myself up to problems if I simply add to the current radiator system, and 2) in the alternative, what is your opinion of the system utilizing the hot water heater and a recirc. pump. (My perception is that the hot water heater option is easier since as a DIYer, I am more than capable of sweating copper but have no experience with traditional hot water radiator system).

Thanks again for the information, it is greatly appreciated.

I don't think you will have a problem adding additional radiators to the existing system. It entails draining down and cutting in tee's to the supply and return piping. However since your current boiler is 30 + years old, consider replacing with a 80% or higher AFUE. Do a heat calc. and add the additional square footage of the addition. This will enable you to "size" the boiler, and give you a proper BTU input. Crown makes a decent boiler with a good warranty on the heat exchanger. They are popular here in philly, because their manufactured here and the warehouse is close by. They are also competetive with other manufactures' such as Well McClain and priced moderately lower. As far as advantages of a hydronic system, It's clean, and flexible. You can heat an area below the level of the boiler. Also independent heating zones can be readily installed with a "zone valve". The hot water remains in the pipes after the boiler has ceased firing, creating more of an even temperature. The only disadvantage is in the event of a long power outage, the pipes could freeze and burst. If you want to save money on a new boiler, do some pricing yourself on materials. Then negotiate a price with your plumber. Tell him you will be supplying the material. Some plumber's charge an outrageous mark-up on material. You will then be only paying for the labor. Whatever you decide, I wish you the best of luck.