Anthony Carlson

1 1/2 inches is my top gap

Cold my mass temp is 30s after burning all weekend the parts close to the barrel are 120-140s but by the flue is 50-60s and still very wet and steamy,  all over steamy but mostly by the flue

No, I'm getting actual smoke out my flue with wood smells and all. I haven't taken temps at the top of the stack, I live on a hill and it's snowed and there's ice on the roof and of course the garage it at the edge of the hill
The flue inside (double walled) is getting around 70

And yes after reading the book a core rebuild may be necessary
I used all fire clay and sand cob in the build (1 clay to 3 sand) with concrete walls and stone in between them with the cob on top
Thank you again

TY Thomas,

the summer, I was told it will also cool the cob in the summer with enough draw

I'm running 15ish Feet straight 5" black stove pipe then 11ish Feet straight out the roof doubled wall stove pipe, I did not double through the cob

It is in cob imgur link https://imgur.com/a/762If

The Jtube is 5x5 square stock (yes it's metal and before I found permies) with a 12" feed tube x 24" burn chamber x 36" riser in cased in a 10" (I think) pipe with perlite and fire clay insulated, I do have pics of it but not in that imgur link

There are 2 doors wielded on the top and a clean out on the front

But yes the top of the barrel is getting just over 400 and only if I'm feeding it as much as it can burn as quickly as possible. If not and just feeding it every 15 to 20 mins then between 280 and 320.
I did use a laser heat gun to check and it was with 3 to 9 degrees of the one at work so I think its fairly accurate and the one in the pics seemed to be under but fairly close to each other also

Simply asking if the draw can be too great while burning. Even when at 40 degrees and hasn't been burned in all week the draw is incredibly strong.  Don't get me wrong during the summer it will be great, but am I losing heating time and could it be cooling the system or incomplete burns. I ask because the top of my barrel is barely getting to 400 degrees during an intense burn and just burning its about 280 degrees normally but even with the door wide open or almost closed the draft is VERY strong. I did finally order the book off Amazon will be here Friday, any suggestions

Insulated heat riser was actually my first problem I didn't let it dry for more then a week and didn't realize perlite would expand that much. It completely chocked off the fire when it rose to the top of the barrel, but after cutting the excess off I haven't had one problem

I used clay and perlite in the riser and its just the straight run of 15ish feet, its also only 5" pipe the jtube is 5" square stock (which actually turned out to be more money then the firebrick would of been) and before I found permies. I did understand that I would loose a bit of heat retained in the mass and it is still very wet and in MN atm very cold in the garage so may not even dry all the way this winter but between the blue flame propane heater and the rmh i can get it over 70 and the insulation I did this summer keeps it above 60 for hours after everything is shut off I also did the straight run for both space saving and I wanted the chimney at the back part of the roof, it's only a 2 and a 1/2 car garage and wanted a cheaper way to help heat it and plenty of junk pallets at work

I built a rocket mass heater using a metal jtube construction it draws great but im getting more smoke out of it then some people seem to be getting. Im wondering if its just because of its length or if i really need to be concerned with creosote build up. Its not complete and still very wet. I will link pics through imgur below. Any help or criticism  (because it's metal) will be appreciated

My rocket mass heater 2nd update https://imgur.com/gallery/Ik00S