RMH Radiant floor heat without water or exhaust

hey Y'all,   As usual please let me know where I'm being stupid, please and thank you.  I love getting back into rocket stove stuff!  I got thinking this weekend that maybe I could steal the radiant heat from a RMH barrel with a blower and run it through a gravel sub floor to heat a cob floor in a cabin i am designing in the northern USA.  

I was originally researching ways to heat water (maybe using the Walker boiler) and somehow run it in pex tubing through the cob floor.  Then I got the idea that maybe radiant air heated from the barrel could be blown with fans down into the gravel sub floor and vented back into the room (maybe another fan?) on the opposite side after helping heat the cob floor.  Maybe baffles would be needed in the floor for even-heating.  Was thinking I could simply build a thermal wall with bricks 1" or so away from the barrel to capture the radiant air around the barrel and then move it down with a fan into the gravel sub floor.  Does anyone have a good idea of IF this would work, or if it would be practical?  Has it been done before?   It would rely on a power source to run the fans.  

Brilliant or Boneheaded?  Odds are the later....Either way I'm having a blast designing these future projects!  Cheers      

What you're talking about has been (more or less) done in Korea for something like 7000 years.

https://en.wikipedia.org/wiki/Ondol

Worth doing a bit of research, but I'd say that it's totally possible to combine the concept of an ondol and a RMH

Nick - thanks for your link and quick response.

Does anyone have any experience or resources for using a RMH as an Ondol or hypocaust system with a cob floor?  It involves running exhaust beneath with the floor, essentially the cob floor would be the top of the exhaust bell.  Should I worry about monoxide poisoning from the exhaust leaking into our modern and somewhat airtight house (compared to the less airtight ancient structures these systems were designed for)?

That's what got me thinking about running the radiant air instead of the exhaust air.  

Hi Michael;   I'm thinking if you build a RMH in your cabin, that you will be so warm so will not want a heated floor.
The "Ondal" design has been around a very long time.  As I understand it , A constant fire is used to keep the floors & home toasty warm.

Trying to move warm air and store that warmth in a mass  is not easily accomplished.
Not to say that it wouldn't help keep the floor a bit warmer.
If it is easy, then give it a try.  If it is a big project then I don't think I would want to spend the time.

I appreciate your thoughts, Thomas.   Sounds like my idea might be experimental, I wonder if there have been documented attempts?  

I think Thomas is probably correct about a traditional RMH heating the cabin just fine, however its a tall structure (20') with only a small loft so lots of ceiling space.  I'm looking for a way to capture heat down low and would love additional help or resources to help me decide if my concept is experimental, or has been accomplished.  If this idea is experimental, I will probably choose to install a traditional RMH with the exhaust running through an 8" stove pipe or a bell in either a bench or a section of the floor.

       

Hi Michael,

Here may be an example of what you are looking for. The fellow used a RMH to heat his greenhouse and also a bit into the floor.

Rocket Mass Heater - On Steroids

This is also a form of passive solar heat. The warm air is passed over rubble that the floor is built over.

Michael Dimauro

There are many ways and reasons to heat a floor mass. I will be doing the same (heating the floor) with a RMH to provide a warm waking environment in the mornings provided by the 'time lag' for the heat moving upward to be released into the space - the idea of warm feet is very appealing. The local weather is typically above 45°F from around noon to early evening say around 4 during the winter with night temperatures averaging 20°F. The structure will be 200sf inside wall to wall, basically a survival structure used for sleeping and cooking to initiate building a farmstead on a very remote 36 acres. Its the first building that will be followed by a 200sf modified Trombe Wall bathhouse with passive (ducted) underfloor heating. Labor is needed to help with the farmstead, if individuals namely families can get clean each day mothers with kids will participate. The bathhouse will have a clothes washer.

Anyway heating the large floor mass may take a few days but after, only a SINGLE evening maintenance fire will be needed to provide morning warmth.

You could install a underfloor duct that runs up a wall to the ceiling being the air intake. The other end would pop up by the opposite wall where a heating source could be boxed it over the duct riser. The heat rising out of the box would draw on the duct sucking air from the ceiling down under the floor heating it.