Hi - We are in the process of completing an addition on an old farm house (main house is 190yrs old) in central Massachusetts. The existing house is approx 1500sqft, somewhat drafty, with one zone of forced hot water baseboard heat supplemented by a wood cookstove. The extension is still in progress but will be approx 1200sqft, modern construction, with four zones of radiant floor heat (pex on plates under subfloor, not in concrete). I'm not thrilled with the baseboard heaters, but I'm not renovating the existing house right now.
The existing heat is on an oil boiler, marked as 112,000BTU/hr, with a domestic hot water coil, tankless. I think the baseboard heaters are hooked up wrong, because the domestic hot water coil only provides a decent level hot water (both temperature and quantity) so long as the baseboard heat is cranked up, and the baseboard heaters all get hot whenever the boiler is running all year round. Even in New England, in a drafty old house, our oil use in the summer isn't a whole lot less than the winter. Yeah, we have the wood cookstove going a lot in the winter, but that still seems off.
Are the tankless boilers like that just super inefficient for domestic hot water? Can we add a tank? Can we run both the baseboards and the radiant floor heat off of that, and actually be able to take a hot shower occasionally?
If I do need a new boiler, I'd really love to get a nice cordwood gassification boiler. Cordwood is nearly free for us, and besides I just like wood. But the boilers we've seen so far (Tarm, in New Hampshire) are not in the budget right now, especially with the recommended tank. Besides, I don't know if is it really reasonable to use a cordwood boiler for domestic hot water year round, even though I know some folks do.
Someone suggested that with a wood boiler, I'm better off using the existing boiler for domestic hot water and only firing up the wood boiler when we need heat. But the existing boiler is terrible for domestic hot water!
I've had trouble finding an HVAC guy out here who knows anything about radiant floor heat or the high-efficiency wood boilers, so any advice would be appreciated.