Smoke exiting thermal break

[mrchipster]

*** Help needed ***

Getting a few wiffs of smoke out the front when the wind blows but as you can see from the smoke pattern on the brick not much comes out the front. I have a 10 inch I.D. - 12 O.D. double wall Stainless Flue. and my thermal break between the inner arch and the flue arch smokes a little into the oven cavity. I think I will need to do some sort of sealing there.

Does anyone have any ideas as to what I can put there the gap was intended to be direct contact but at some points is less than 1/16 of an inch wide and a little irregular as there are spots where the mortar filled in the gap. It does not seem to smoke when the flue is exhausting just when the door is closed forcing smoke directly into the gap area.

The inside of the thermal break is filled with vermicrete and a nearby layer of creamic blanket is no longer easily accessible. Smoke seems to come from around the edges of the vermicrete and through the ceramic blanket. I will be adding more blanket and loose vermiculite over affected area but am concerned about smoke tar buildup outside the oven in the insulating layers.

The temporary door is not built well and is leaking some air -- thus smoke.

Thanks Chip

[GianniFocaccia]

Hey Chip,

Thanks for the heads up on the thermal break 'leak'. My only thoughts are to squeeze high-temp silicone behind the offending gaps but this would be difficult now that your oven is built. Since my plans incorporate a thermal break much like yours I will be facing the same dilemma if I can't get uniform contact between inner and entryway arches. Have you thought of pointing some refractory repair mortar into the gaps?

[Tscarborough]

Glass rope if the gap is big enough, silicone if it isn't (although it will probably burn out at the top).

[mrchipster]

Originally Posted by GianniFocaccia

Have you thought of pointing some refractory repair mortar into the gaps?

I did but I am also concerned about firming up the joint and causing cracking issues in either arch.

When I built the dome the first time I did not have the issue, I believe because I had better contact building the flue arch outside of the dome and I was sealing the flue arch bricks directly against the stainless ring providing a very good smooth contact surface. Rebuild of the dome did not allow me the same convenience.

Leaning more toward something flexible such as rope, blanket or high temp silicone to fill but still unsure.

Chip

[mrchipster]

Originally Posted by Tscarborough

Glass rope if the gap is big enough, silicone if it isn't (although it will probably burn out at the top).

I may be able to grind the gap a little larger and get some rope in there but I have to be very careful as I do not want to mess up my door seal area.

Thanks for your reply.

Chip

[SCChris]

What about liquid glass? or I also know that Kaowool comes in an air drying moldable putty in caulking tubes. Foundry service and supply is a source..


Chris

PS good to 2300F

[mrchipster]

Originally Posted by SCChris

What about liquid glass? or I also know that Kaowool comes in an air drying moldable putty in caulking tubes. Foundry service and supply is a source..


Chris

PS good to 2300F

Chris,

I looked up the liquid Glass and it appears that it is only rated or a short time period for fire resistance rated in 30 and 60 minutes. It also seems to be difficult to find in less than case lots and is very expensive.

The Kaowool putty may be the clear ticket I found a source. The stuff is not cheap $20 + shipping for a caulk tube but I guess it need to be done. And I only need one tube.

Chip