Rick Stevenson

Allen, I discovered that HVAC pipe is not very good for the stack. The temperature inside the stack gets 700 - 1000 degrees and that type of pipe disintegrates under those temperatures. The better solution is to use firebrick that is rated for those temperatures. This can be purchased at stone and masonry dealers. Fire bricks are 9 X 4 inches and are either 3 or 2 1/2 thick. I was able to purchase the bricks for $1.90 if memory serves. Good luck.

Thanks for finding that for me Chris! I'll keep working at it.

Chirs, the manifold is a little over 6 in sq. I was going to insulate the riser when I brought it in the house. Does the uninsulated riser really make a difference in smoke back?

Ok I tried shortening the distance and I'm still getting smoke back. Here are some pics.

Craig thanks for the reply. I don't have a picture yet. I did some research and I believe that the space between my riser and the barrel is to large. I'm using a 6 in pipe. Turns out the proper distance should be 1.5 in. After a remeasure I have 2 in. Going to shorten that area and see if there is a difference.

I just started my first RMH. I set up everything out side to make sure it worked before bringing it in. I can give more info on how I built it if someone needs to know specifics, but basically I lit it up without the 55 gl drum in place and everything was working great! No smoke back, sounded rockety. Then I placed the drum over the vent tube and I began to get smoke back and finally the fire went out. The vent tube was 1 3/4 shorter than the top of the drum. Anyone have any idea why placing the drum would cut off the draw? Thanks