RMH usability and design question for supplemental heat

Hello everyone!  I'm new to permies but I've been looking into RMH for about 2 years now.  I have a design question that I'd like some input on.

I want to put a RMH in my garage that we now use a a workout/exercise room.  On the other side of the garage wall is my living room.  After I'm done using the workout room I'd like to direct that heat into my house. What would be the best way to get heat from the RMH into my livingroom with as little disruption to the living room space as possible (it's a small room to begin with).  

I thought about putting duct work into the mass that would allow me to blow air from the livin groom through the mass and have it return to the living room.

I also thought about having the thermal mass directly against the studs of the wall in the garage and removing the insulation in the wall so the thermal mass on one side and the drywall on the other would create an air space/channel.  I could put vents at the bottom and top of the wall which would allow air to flow through the channel via normal convection so no electric would be needed.  This would circulate cold air from the floor of my living room up along the thermal mass and out the top vents.

Does anyone have any experience with this type of setup!

Thanks,

Pete

I've played around with doing just that but have found it to be ineffective. The thermal mass bench doesn't really get hot enough to warm fast moving air passing by, over, or even inside the bench. I.e. think of the bench being around 90 degrees F, and the fast moving fan driven air temperature being in the range of 50 to 60 degrees. That fast moving cool air will not be heated to anywhere near the 90 degree temperature of the bench. Hypothetically, if the fan driven air managed to warm to say 80 degrees, even an 80 degree "breeze" in the house will be felt as being cooling to most folks.

However, when being fired, the RMH barrel gets "wood stove" hot and can easily heat fan driven air.

Maybe put a larger barrel over the bell and cut two holes for ducting. One on side towards bottom another on top and connect a fan blowing in to barrel from side through to the top transporting the hot air to wherever you need it. It could even be a 12v fan run off of batteries or solar. Only problem is it might make it burn less efficient by stealing heat before the re-burn.

At least in most cases, I don't believe there is a reburn in the barrel after the heat riser, so stealing heat from there would not be an issue.

Your workout room will presumably want instant heat while the house will want long-term heat, so having any mass at all in the garage would be counterproductive. I might suggest a small barrel over the heat riser, as is standard, with the exhaust from that going through the wall to a masonry bell (a hollow brick box) in the house. This bell could be as small as 2' square by 5' tall more or less, and would give you a good amount of lasting gentle radiant heat. The exhaust duct out of the bottom of that could go back through the wall to a chimney in the garage, if the house is not conducive to an internal chimney. It would not have enough heat in the final exhaust to be hazardous, if the parts are sized appropriately.