Base stack

[YAZER]

What is the general consensus -- Do you screw the base stack to the arch? or let the weight of the smoke stack hold it in place?

What do you do to make it a tight fit around the arch?

On the storm collar, above the roof jack, do you put any high temp silicone on this to seal it completely?

Thanks for the input!
Greg

[spencer11]

not positive about my answer as im kinda wondering the same thing but i think you let the weight hold it down and you could always use ceramic blanket if it leaks or even aluminum foil. not sure about the roof jack but it couldnt hurt to silicon it right? just use the same silicon you would use on header gaskets, its rated to 2000*+

[Dennis H.]

I just let the base stack sit on the arch, no bolt, screws or anything to attach it.
I do not seal the base either, maybe that is wrong but it works for me, if someone can add insght on this I would change it. Probably add some of the 2" ceramic blanket that you use as seal for the pan to arch.

As for the storm collar on the stack I just got a tube of the high temp silicone. The only kind I could find when I needed it was the red kind. If you are neat with applying it, it won't look too bad.

[maple flats]

Mine have just set on the arch flange on all 3 evaporators I have had and I never saw any hint of any leakage. The stack draft will be pulling hard. I even have high pressure air over and under the fire and never a hint of a leak. The stack is not even a tight fit either, but no seal needed. On top, I have no seal either, never have, but I might try someday. I just wonder if the high temp silicone can take the movement. There must be some considerable expansion as the stack goes from cold to 800 degrees (this is my high temp with high pressure air). My old high temp before I went high pressure was in the 1100-1200 degree F range max.
The high temp silicone might be good if it will take the expansion/contraction everyday.

[Dennis H.]

The further up the stack you go the better the silicone will hold up.
My storm collar for the roof jack is maybe 6' above the arch and the silicone is now 2 yrs old and when I checked things out up there after this season it was still flexiable.

This whole topic got me thinking though about sealing the base stack. Think about it, you want to have the draft pull the air thru the draft door. If it pulls air from around the pans you will get a cold spot and have a poor boil where the leak is, now having it suck air around the base stack will not cause a cool spot on the pans but wouldn't it cause secondary combustion in the stack?
I mean it may be superhot gases at the point and the sudden induction of cool oxygen rich air could cumbustion in the stack, waste of heat.
Is my think way out there?

It would be interesting to hear everyones thoughts on this.

[ennismaple]

The stack on our Force 5 just sits there with nothing attaching it to the flange that sticks up from the top of the evaporator. Since the top section with the flat cap is tied down to the roof in 3 places there's no way it can lift off.

[PerryFamily]

My base stack did not fit super tight. I put a small strip of ceramic blanket around the base collar and slid the stack over. The weight of the stack pushed it down tight. Now it fits super tight. Does it help? I dunno. Does it hurt? Most likely not.

I do have a "rain cap" over my roof jack. It is silicone sealed with high temp red. Seems to be holding up fine. No water at all.

[red maples]

no it just sits there. even if it leaks a little it doesn't effect the air flow. it sits pretty tight on the evaporator. and besides all the actual weight of the stack holds it in place pretty good!