Good thread started here. It gives me a chance to think about what I would have done over if I could start again. Some background – I moved into my new house a year ago after designing it and building it over a period of four years. I think I did a lot of things wrong.
First – if you have the wood supply (you already have an OWB) put one in. Either an indoor gasification boiler like Greenwood or EKO, or an outdoor boiler. My business partner has an EKO 40 that he installed in a lean-to off his house, it’s a self-contained room off his kitchen that stores three cords of wood and the boiler. I have a Central Boiler with a dual-fuel setup (propane and wood) and I would NOT do that again. I would still install an OWB, probably try to build some kind of pole building so that the OWB and a winter’s worth of firewood would be under cover. I would also try to have a separate buried, insulated tank (maybe surplus 500 or 1000 gallon propane tank) that would circulate continuously off a secondary port and give me between 700 and 1500 gallons of water (depending on the model of OWB and the size of the tank) as a water jacket. That would allow LONG burn times and less frequent feeding, I think.
I would not do the dual-fuel option. I have found that the propane part of the OWB is incredibly inefficient, and it’s also a pain to clean the firebox in the summer when the water temp is 180 degrees. I would spend the money to install an ultra-high-efficiency wall-mount propane boiler (or oil, if you prefer) in the basement, one of the ones that can vent through a PVC pipe.
As far as radiant heat, PEX in the basement slab is the way to go. I am heating my entire house right now with a loop under each of two second-floor bathroom tile floors, and the basement slab. There is no other heat in the house. If I were to do it over, I would have used something like Warmboard subfloor, or something that put the radiant tubing in or above the subfloor. Staple-up is OK but a pain to install. I don’t care much for the gypcrete PEX installations but you might be happy with that. Putting the PEX in gypcrete on the first and second floor allows you to have a large thermal mass, but it makes installing everything else difficult unless it’s very well planned out. There’s an unbelievable about of information out there on radiant in-floor heat, and it’s something I couldn’t ever imagine changing about the way I heat my house. I’ll be building a garage in the summer and I plan on heating it with another zone and loop from the OWB. The secondary storage tank that I didn’t think about the first time, might be installed in an insulated room in the garage, and I can use that ‘extra’ hot water to run a dry kiln for lumber.
Also give some thought to running your OWB systems off-grid, so that you are not without heat in a power outage.
