New Build Heating

I'm doing a new build in NorthEast Tennessee.  My initial thought was to heat the place with radiant floor tubes and an outdoor wood boiler.

Wondering if anyone has experience with these outdoor wood furnaces and can help steer me in the right direction, the number of options are overwhelming to me and I'm struggling to distinguish which ones are quality and which are junk.

I suspect many will suggest I go the way of a rocket mass heater, i'm open to suggestion, but my wife has wanted radiant floor heating for 10+ years now, if we can make it work I'm open to ideas.

Thanks y'all!

Matt Walker has plans for a rocket boiler. I don't know what kind of heating capacity it has, but you can learn more at his site.

Walker Boiler

Radiant floor heating has been discussed quite a bit on the forums:

Here are some threads that you or others might find interesting:

https://permies.com/t/68051/Radiant-Heat-Rocket-Mass

https://permies.com/t/121160/Rocket-stove-driving-underfloor-heating

https://permies.com/t/154121/Uncle-Mud-Tiny-House-Rocket#1207030

https://permies.com/t/155232/RMH-Radiant-floor-heat-water

https://permies.com/t/178182/Rocket-wood-stove-Hydronic-radiant

Best wishes for you new build home.

I built my house with radiant floor heating (powered by a Polaris gas water heater), and it worked wonderfully. Fifteen years later I learned about the RMH and modified my plan for a custom wood stove in the living room into a bell style RMH, which has heated the main floor of my house for six winters now. I don't miss the floor heating, as the radiant mass warms everything. (The basement is still floor heated as the RMH can't affect downstairs.)

If you have a spread-out plan that would not be effectively heated by a single source, I would consider including a water reservoir in the mass (non-pressurized) that can supply a circulating floor loop in remote rooms. This would keep all of the heat source inside the house and avoid constant loss from boiler and pipes exposed to the outdoors.

Hi Geronimo,
To add to what Glenn suggested for an unpressurized hot water storage, I would suggest something like what American Solar Technics does. http://www.americansolartechnics.com/ They are currently have some supply chain issues (like everyone these days), but it is an unpressurized tank that can storage hundreds of gallons (depending on the size) of hot water. Through the use of heat exchangers you can hook it up to solar hot water, wood boiler, and other stuff.

As to the wood boiler, I would suggest sticking to companies based in cold climates and look at the warranty. If you do use the storage tank method, then you are going to care more about the efficiency and speed at which it can heat water. If you do not use that kind of storage, then the water storage on the boiler itself and the ability to slow down and start up again would be more important. I have not used one yet, but my wife's uncle had one for years. They loved that it kept the fire outside the house, and said that it heated the house without any issues. However during a winter storm, it was not fun to have to go out in it, to fill the boiler. They also found that they struggled to throw in the 4' logs that it took as they aged. So those are some things to consider. Placement and sizing.

Not sure what your building codes are like, but where i am, by code, i am required to have a "primary" heat source for the new residence.

For my new house build, i am planning on relocating an exsiting geothermal heat pump combined with radiant floor heating as the permit specified " primary" heat source, but i also have built a really nice working R.M.H for a few hundred dollars in the shop, that would keep my shop warm for 3 days - after it went out.
I also played with water heating to heat the main house 30 feet away or so...

https://permies.com/t/40107/hot-barrel

The main reason for the reply, is i have had a chance to see how outdoor furnaces work in person, and think it is a much better idea to go with a rocket stove in the house, then burn all the extra wood in an inefficient outdoor burner, while losing more heat pumping it to were you need it.

With the Rocket Stove, all the heat generated stays in the building, using a super efficient burner design when compared to an outdoor furnace set up...

Of course, i am facing the challenge of the same building codes telling me that i have to have my Rocket Stove W.E.T.T. certified or they will cancel my home insurance, but that depends on your area.

Outdoor boilers are nice in the fact the wood and ashes are outside.  But they are horribly inefficient at lower outputs.

I am going with a mini split heat pump as my primary heat. It is the cheapest way I can figure to meet code plus I do want an efficient dehumidifier for the worst of summer.