One of these days I'd like to convert my home to hydronic heat with a gasification boiler as the primary unit and a fossil fuel backup that would be rarely used since I'd be incorporating storage into the system as well. We don't generally go away during the heating season so as long as my storage allows me to skip a day/day and a half between burns the backup would not be used much. I'd also be incorporating a home built flat plate solar collector which should provide plenty of DHW outside of the heating season, and should supplement the boiler during it. Right now I have forced air oil heat so I have a 275 gallon tank in good condition in my basement, so that's one factor steering me toward an oil boiler. I also have a good relationship with my oil supplier (even though I don't buy much oil ) who is local, family owned, etc... For these reasons I was thinking of going with the cheapest oil boiler I could find since I'm not to worried about efficiency considering I'm going to try to use it as little as possible. Then there are the other dinosaur based fuel options. Natural gas is out because there is no gas available where we live (bummer, since it's so cheap), but of course there's always propane. Propane is not the most attractive since it's more expensive, but it does have the added advantage of allowing me to have a gas stove (we have an electric range which we hate), plus I could hook up the grill to the big tank instead of paying through the nose to fill 15 pound tanks. What would you do in my case?