What size batteries and inverter do you use, nofossil? And what will it run? I'm thinking at minimum, you'd need enough capacity to run the blower on the boiler and at least one pump to get the hot water away from the boiler. I think in my house, if I was able to heat the gas boiler vessel, gravity would handle heating the house, at least at a minimum level. Since I live in town, I'm guessing I'd probably need hours--rather than days--of potential capacity. Can you charge a marine battery with a car or truck?