Rocket stove driving underfloor heating?

Satamax Antone wrote:  . . . If you are getting creosote build up, your combustion is incomplete.

Sorry for the misunderstanding. I quoted the video source. That isn't my water heater.  

https://www.milkwood.net/2011/10/28/rocket-stove-water-heater-redux/

Creosote is often a problem when you add water coils to wood burning chambers or flues because the water absorbs a crazy amount of heat and lowers the volatile gas temperatures until they won't combust. The smoke particulates fall out of the flow and build up on the sides of burn chambers and flues as un-burnt tar. That stuff can later be burnt off with a rapid blaze, but then you have problems with flue fires as that gunk burns off. So boiling water with wood needs a hotter flame all around. Still those folks did get 3 years of hot showers with a very simple set-up, and it's interesting to see how it looked when they deconstructed it.

Also, I totally understand the strong guidance against adding pressurized water boilers to rocket mass heaters.  These mass heaters are DIY earth-hacker designs and water-heater pressure-valve fiddling is almost always designated a professional plumber's domain. If you are going to influence the masses of people to make stuff like this in their homes, it is wise to spread caution about the differences in risks.  Putting a bunch of mud around a burn box is a lot less risky DIY project than plumbing a close-system boiler.

If a Walker cabin stove lacks the push to drive under floor stove pipe circuits, then what about a stratification chamber under the floor?  The ondol used a direct thermosiphon with the fire source below the floor level, and when used with coal briquettes when wood sources disappeared, was associated with significant deaths from carbon monoxide poisoning.  So, maybe you need to seal the floor with modern materials rather than clay, and tiles.

Travis Johnson wrote:I like pressurized systems because they are far more efficient. It is also easier to move heat because they are not subject to elevational changes (they do not have the negative effects of atmospheric pressure acting upon them).

My plan is to do thermosiphon based radiant floor heating using retired solar collectors from heated pools. I used to live in FL and used collectors are abundant there so I might have to take a trip down there sometime. We're building close to where the land drops off down a hill and can use that hill for the collectors. The frost line is one foot deep at most so the water lines could be buried. They might still try to freeze underneath the collectors with a string of cold cloudy days so I may end up having to add something as anti-freeze. If the thermosiphon didn't work out, though it should, I could always add a little pump. That might even negate having to use anti-freeze.

If I were to build a rocket mass heater sunken into the floor, the radiant floor line could run through it too.

hmmm

Run the rocket heater on cloudy days only.

John Pollard wrote:I used to live in FL and used collectors are abundant there so I might have to take a trip down there sometime.

Why is that? Don't they work anymore or have they been replaced by electrical heating?

Guys and gals,
    My RMH is a real water heater.  My lower heavy duty barrel also has the top removed. Resting on that is a regular 55gal barrel filled with water.  When the RMH burns the internal riser exhausts below the bottom of the upper water barrel.  The smaller bung at the top is loose to relieve any pressure. Facts:  this is a 6 inch cast refractory RMH that probably reaches 1500f-2000f BEFORE the riser reaches the bottom of the water barrel, and the heat differential between the riser temp and the water barrel surface supercharges the draft adding to the pump action of the RMH. All other RMH characteristics occur- low external temps, clear exhaust, good fuel efficiency etc. plus tapping into the 200f water on top to heat anything should be easy.  Also the burn chamber temp is 1500f-2000f  while the final exhaust temp as it leaves is never above 80f.(amazing btu recovery). This getup has survived a 7.2 earthquake.  I sent Erica a set of pics if you want to see...hope she got them. May the revolution continue! Mark H.

Can you post the pictures here? I'm sure we would all like to see them.

Mark S Heidbrink wrote:Guys and gals,
    My RMH is a real water heater.  My lower heavy duty barrel also has the top removed. Resting on that is a regular 55gal barrel filled with water.  When the RMH burns the internal riser exhausts below the bottom of the upper water barrel.  The smaller bung at the top is loose to relieve any pressure. Facts:  this is a 6 inch cast refractory RMH that probably reaches 1500f-2000f BEFORE the riser reaches the bottom of the water barrel, and the heat differential between the riser temp and the water barrel surface supercharges the draft adding to the pump action of the RMH. All other RMH characteristics occur- low external temps, clear exhaust, good fuel efficiency etc. plus tapping into the 200f water on top to heat anything should be easy.  Also the burn chamber temp is 1500f-2000f  while the final exhaust temp as it leaves is never above 80f.(amazing btu recovery). This getup has survived a 7.2 earthquake.  I sent Erica a set of pics if you want to see...hope she got them. May the revolution continue! Mark H.

New guy here. Great info thanks for posting, i was looking to do something almost exactly as you describe.

Graham Chiu wrote:

John Pollard wrote:I used to live in FL and used collectors are abundant there so I might have to take a trip down there sometime.

Why is that? Don't they work anymore or have they been replaced by electrical heating?

Florida is a major retirement state, and many retirees think the solar hot water heaters look like an eyesore.

I have been thinking about something similar, the idea is a sawdust stove with a  substantial steel stove grill above it supporting a copper immersion heater. The immersion heater would be filled with either sand or water.The copper coil inside the tank would be connected to a small blower. The intake for the blower would be a flexible hose much like a vacuum hose which would be extended under the suspended wooden floor and connected to one end of the copper coil. The exhaust hose from the other end of the copper coil would extend further under the suspended floor. The air would be warmed on its passage through the copper coil which in turn would be warmed by the sand/water. There would be no chance of fumes as the air would be drawn in away from the fire. The sawdust stove would be situated outside, the pipes would be lagged and the immersion heater insulated in a metal cover. Sawdust is cheap or free if you look for it. Woodchip or small sticks could also be used. Any suggestions. Phil.

Graham Chiu wrote:If a Walker cabin stove lacks the push to drive under floor stove pipe circuits, then what about a stratification chamber under the floor?  The ondol used a direct thermosiphon with the fire source below the floor level, and when used with coal briquettes when wood sources disappeared, was associated with significant deaths from carbon monoxide poisoning.  So, maybe you need to seal the floor with modern materials rather than clay, and tiles.

Hi Graham, I saw an ondol described in Fine Homebuilding archives. Built in USA, in CA I think, it was covered with 4 inches of concrete. While this might be the easiest wat to get it inspected, I worry that such a large thermal mass addition creats an enormous 'thermal flywheel', so that one might need to predict heating needs and fire it 9-12 hours ahead of when heat is needed. I haven't calculated how much heat or cold could be stored in that design. I do plan to only burn wood, and I am not sure that concrete bests clay for air sealing. What modern material did you have in mind?

Brian
-