So i was talking to one of my clients today!

I remember reading something about needing a pressure relief in the system. I'm an engineer and thought about doing something similar. You could use your water heater as a heat source too for your baseboard heat.

Hydronic underfloor heating is pretty common around here but I've never heard of using a wood stove as the heat source. Sounds like a fun project! I agree with the previous suggestion about needing a T&P relief valve in the system. You could maybe use one from a water heater...

I think I would consider better insulation first but it does sound like a fun project.

I think a heat sink wood actually be a pretty safe way to do this. Less chance of creating steam than how some do it by running tubes around the flue or firebox.... Just don't let those engineers make it too efficient or placed too close that there wood be a chance of steam. You'll also have to think of a safe place for the pressure release to go just in case (outside, safe area of the basement...).
My dad is a plumber/steamfitter & he distributes heat from the basement woodstove through the hydronic rad system & uses large rads to collect the heat from above, behind & upper sides of the stove. It works okay, but there is definitely a trade-off btwn a good safety factor in the water temp, and good heat output from the baseboard rads. You may want to look at adding rads in the bathroom or using a larger one since the water going to it will have to be cooler than from the gas boiler.

As for storing excess heat by pumping into hot water tank: If you mean the domestic hot water tank, then no that won't be easy & would require a heat exchanger...you can pump potable water through your rads or vice-versa As for storing it in a reservoir tank for the boiler/hydronic system, that would be cool, but I just don't see it being useful enough to bother. How much do you run the stove? Do you have to run stove & boiler at the same time to heat the house? If yes then I could see it helping a lot as a pre-heater system. Bottom line is a lot of work just to capture & store heat that would otherwise be going into your house anyway.

chumby said:

I think I would consider better insulation first but it does sound like a fun project.

Click to expand...

+1 on that. Insulation is almost always cost-effective & just plain effective when done right IMHO.

Brainstorm: You said your feet froze in the bathroom. Is the floor tile? How about making it a radiant floor using PEX from below? Radiant floor does much better than baseboard heaters with lower water temps. It would be oh-so-cozy.

+1 insulation
+ 2 radiant floor

You just got to find a way to make it and pump in over from the stove. have fun, keep us posted.

I have a good friend that has heated his house with a woodstove in Maine for 20 plus years as his majoir heating source. He used to just burn a woodstove in the basement of his ranch home and that heated the house. He only has one flue on his chimney (that we built when he bought the place), but at some point he did install an oil boiler for when he was gone. He has it set up so that he switches the flue pipe when needed. About 8 years ago after installing a big addition with a seperate basement, he took short pieces of hot water baseboard set them side by side and connected them in series so that the baseboard covered the top of his fisher wood stove. He has firebrick sitting on top of the baseboard. He then pumbed that into his oil boiler circuit. He also installed a couple of aquastats, one is a low limit that turns on the circulator pump and sends heat to the boiler, if the thermostats are calling for heat, the boiler works conventionally. He has a high limit aquastat that runs a circ pump to a dump zone that is equipped with radiators and a small fan forced unit heater. All the water is tied to the oil boier system so he used the boiler safety releif as his system releif. The final backup system is a set of valves and unions that allows him to swing the coils up and out of the way fo the stove, if the power is out and his circ pumps dont work he heats his house like he used to.

Even though he almost doubled the size of his house with the addition, he cut his wood usage by a third. I keep trying to get him to go with a more efficient stove to cut down on the amount of wood he uses but its a hard sell.

It works for him, but he does have a lot of service valves that could inadvertently be closed and potentially could isolate the heat exchanger area from oil boiler relief, if other people messed with it, I would install a dedicated relief valve right on the coil outlet without any intervening valves.