Flue pipes embedded in floor

I'm wondering if anyone has embedded the heating flue pipes 4" below floor level. We are planning a very small build and putting the flue pipes in the floor would save space. I'm thinking that we would have to insulate well below the pipes (what with ?) so as to have most of the heat move up to the clay based floor above. I can see it saving a lot of space but I'm wondering if anyone has tried it and has pointers.

it has been done, and it's a great idea. there are some additional considerations that aren't an issue with bench systems, like placing clean-outs, but a radiant floor is a great way to heat a space. not great for instructional purposes, but I believe there's a video of an in-floor system before the floor was installed on paul's youtube channel.

Bryan, i'm thinking of doing the same for my workshop. With one twist, i want tu put the top of the feed tube flush with the floor, so i can brush shavings, dust, sawdust etx into the hole

Thanks for the info Tel, I checked and saw the video on Pauls you tube channel. I really like the idea and think it makes sense to heat a small space and not have the bench taking up space. I wonder how you would insulate under it and also I like the idea in the video that you could have a damper that gives more heat in the barrel for cooking and than send it down the flue pipe after the fire is going well. Do you know of anyone who actually has this in place,

insulating is could be a challenge. rigid foam insulation might work. a thick layer of perlite with just a bit of clay slip as binder might work. neither of those seem like really good weight-bearing materials, though. maybe a layer of wood between the insulation and floor might be necessary. I'm hoping to do an in-floor heater for an outdoor kitchen this summer, so I'm also very interested in solutions. I've got a fair amount of perlite laying around, so I'm hoping that will work.

Here is a heated floor: RMH for a Yurt With additional Pictures.

I have bee living in a 20' yurt heated with a RMS in the floor for two years now (second winter in Montana). It works great for capturing and storing heat but I am still tinkering with the draft. I used a fan the first winter to get it to pull through to a short four foot tall outside stack. This fall I went to a 12 foot insulated outside stack and eliminated the fan. It worked great but was inconsistent. I finally realized yesterday that the issue was wind. I was using a 12 inch elbow at the top of the stack to deflect wind and weather. I realized that the directional aspect caused wind to funnel down the stack if it blew into the elbow or created a vacuum that limited draft if it blew from the back side of the stack. Both situations smoked me out of the yurt. I pulled the big elbow off and installed a standard cap on the 6 inch flew pipe and pegged the thermometer on the barrel top by the time I got off the ladder and back into the yurt.

I have torn this stove down four times to improve efficiency and yesterday I dug up the floor to see if the underfloor pipes were clogged before I hit on the wind thing. I think it finally has taught me what I need to know.
Some suggestions:
Limit the length of your exhaust, especially in the floor.
If you have a turn around under the floor consider a plenum box instead of two 90 degree elbows. This limits the turbulence of air at the corners allowing a smoother exit.
Consider clean out locations at directional changes that gives you access to potential problem areas.
I use a shop van to clean the ash out but what if you are off grid? Designing straight shots that can be cleaned with a chimney brush would be a good idea.

Guys, regarding insulation and load bearing, or flue lengs, there's a solution.

I don't know what you call it in english exactly. In france, it's called hourdis et poutrelles.

Which is prestressed concrete beams and concrete blocks.

http://www.google.com/search?q=concrete+beams+and+blocks&hl=en&rlz=1R2ADFA_frFR472&site=webhp&tbm=isch&tbo=u&source=univ&sa=X&ei=fndkUeSEBbSU0QW91IGACg&ved=0CD8QsAQ&biw=1152&bih=638#hl=en&rlz=1R2ADFA_frFR472&site=webhp&tbm=isch&sa=1&q=concrete+beams+and+blocks+floor&oq=concrete+beams+and+blocks+floor&gs_l=img.3...34797.37234.0.39093.6.6.0.0.0.0.125.750.0j6.6.0...0.0...1c.1.8.img.tJ1P0o3N3OA&bav=on.2,or.&bvm=bv.44990110,d.d2k&fp=574ff30c26b0f0ed&biw=1152&bih=638

A layer of vermiculite underneath on the ground, concrete blocks or bricks on four sides, insulated with rockwool for example. Prestressed beams and blocks above, with a thin layer reinforced slab on top, something like 3 or 4 inch with rebar grid. This oughs to be airtight. And then you have a huge bell. With mass on top!

sounds like a hypocaust. not a bad idea.

I also have this option...
But... the draft!
But... how do you clean it?

About draft, we know the average and what we can do, but I am going to open a new post just for this topic.
(I would like to know how we can estimate and balance the different factor, when there is a weak factor such as pipes under the combustion chamber level)

About insulation, why not just use the same criterii as for insulating the heat riser?
Light and less conductive materials...

tel jetson wrote:sounds like a hypocaust. not a bad idea.

Exactly what this is!

Nicolas, draft of a bell, or hypocaust is usualy quite good. For cleaning, may be a door? But if you have a foot space underneath, may be you can last a lifetime without cleaning.

Max, I did not understand what is hypocaust and the use of what we call here viguetas y bobadillas! (3lingual forum!)

for the cleaning door, it is usually on the SIDE, and there are no sides for a floor... is it possible to have this access on top?

Nicolas, a door on top should be good! If airtight.