Carl Mathews

Glenn Herbert wrote:Can you take the top off the barrel to see how strong the basic feed tube, burn tunnel & riser are drafting?

You say 1.5" space around the sides of the heat riser & barrel, and "9 inches" of insulation. Are you saying the insulation is 9" thick around the riser? That seems like overkill, and if you only have 1.5" of space, you might be too tight for good flow there. Also, with only 1.5" of spae at the point where the manifold meets the horizontal duct, you would need a very wide duct to allow the gases to make the sharp turn. This is another potential major bottleneck.

Thanks Glen,

I cannot take the top of the barrel off. However, in my mock-up, the j-tube proportions were very rockety. The space at the manifold is significantly wider than 1.5 inches, closer to 3-4. The barrel is also slightly offset creating a larger gap towards the manifold.

Satamax Antone wrote:You need a chimney. that pipe going out of the wall with the H cowl is worth fcuk all!

Put two 10' lenghts of pipe on top, to raise it above the apex, and insulate it. Then you'll see what it's worth. Your transition area might be a smidge small too.

Also, what is your top gap? Side gap? Heat riser and burn tunel insulation.

Thanks for your input. The top gap is 2 inches, Sides are 1.5 inches. Heat riser is insulated 9 inches on all sides with vermiculite/clay. Burn chamber is insulated 4-5 inches on all sides with vermiculite/clay. I belled out the transition area as described in Ianto's book.

I will try your suggestion, and am certainly not dismissing it. However, I was under the impression that since the exit temperature was already quite low (barely warm to touch), that my problem was further upstream rather than at the exit.

I have an 8 inch system with a 29 inch riser, a burn chamber of 14 inches, and only about 20 feet horizontal capture. My exhaust is an "H" cowl atop about 4 feet of vertical stack. My RMH is dry. I have used only firebrick, cob, and granite around my ducting for the bench along with vermiculite insulation underneath. I burn only small pieces of well seasoned maple and oak. I also spent months making sure that all my internal measurements are the "ideal" proportions described in Ianto's book.

My Problems:

Even with the burn chamber just 2 inches below my barrel top, water boils VERY slowly. It takes hours.

With only 4 inches of cob and granite atop my ducting on the bench, the bench only gets warm within a foot of the barrel, and never really gets hot. I thought with only 4 inches I would be in danger of burning pillows and so forth. Nope.

The exhaust after only 20 feet of run is cool leaving the house, and produces thick dark wood smoke, the kind you would expect from a traditional wood stove.

Blow back. Even with the "H" cowl and placement on the lee side of our house, we are only able to run our RMH on the stillest of days.

?

Am I correct in assuming that the gasses are not mixing properly in order to re-burn?

Will shortening the burn chamber remedy my issues?

Are there any other solutions?

I live off grid, 5 miles from the nearest road or neighbor in northern Canada. If I don't get this fixed soon, it's gonna be a baaaad winter!









Thank you fire gurus for all your help.

Hello all,

I am brand new to this site, and am very excited to hear your advise. My wife and I bought a 50 acre patch of pristine old growth white pine forest in central Ontario last spring. We have built a tiny (320 sq.ft.) off-grid house next to a spring fed lake, and chose to heat it with a RMH. Although unfinished, we have had a few fires through it and are quite pleased with the results.

My issue is with the wind. I have the exhaust on the lee side of the house where it is most sheltered by the structure, I bodged together an impromptu wind baffle with a minnow trap capping the 2 ft vertical section of 8 inch duct, then place an upside down bucket over the whole works. All of that is under a very minimal hutch I built to support the snow load, right now we have 4+ feet. This works for all but the windiest of days, but now that I am out of the bush and can buy more materials, I'd like to return home with a better solution.

Does anyone have any experience with the "H" shaped baffle made from 3 T-joints that is depicted in Ianto's book?

How about a "vertical draft diverter", like to kind used to keep gas pilot lights from extinguishing?

Sorry I don't have any pics of my current baffle, but I do have some vids of the build.

Thank you for any suggestions!

http://youtu.be/PYuFyYiFZ9w

http://youtu.be/13cdTYkfbaE

http://youtu.be/LWKlPqsPIeo

http://youtu.be/wbgXePMZ7bs