seal the union between the insert and the ss liner?

[Cedrusdeodara]

Hi folks,
I just pulled my 6" ss liner and did an insulation kit job. I also installed a blockoff plate in the firebox. When reinserting the insulated ss liner, I noticed the male/bottom side of the adapter fitting, where the ss liner goes into the insert, was a bit buggard. I repaired it as best I could with pliers. Anyway, when reattaching to the stove, the fit was not as perfect, as the block-off plate slightly pitched the ss liner/adaptor. I was able to reattach two of the securing screws, but the middle one wouldn't go in because the blockoff plate slightly pitched the direction of the adapter. The pitch is very slight and all I need to do is redrill another hole for the center screw, but I do have a concern that the slight pitch and bent/fixed end on the adapter might leave slight spaces for carbon monoxide to escape. This is especially of concern now that I have a blockoff plate that was insulated above with 1" Kaowool.

Here's my question(s):

1. Would it be a good idea or bad idea to caulk the union area where the adaptor meats the top of the insert with that red high temperature caulk? This red caulk is sometimes used to seal the exhaust ducts for boilers.

2. Would it be a good idea or bad idea to wrap the adaptor/union area with Kaowool and secure the wrap with HVAC tape? My entire ss liner is insulated from the blockoff plate to the top of the chimney, but I did not insulate the 8" or so below the blockoff where the adaptor is. Can Kaowool touch the top of an insert stove?

Thanks for any advice. I can't wait to fire up my safer and more efficient stove. I swept the 25' liner today and recovered about 1/2 gallon of creosote (about a years accumulation). I hope the insulation will make it a cleaner/safer system.

Brian

 

[Cedrusdeodara]

Another similar thread going on now suggested using furnace cement to seal the union. That would be a better idea probably than the red caulk, as the high temp caulk I believe is only rated to 500 degrees F (just read up on it on the web).

 

[bren582]

I'm with ya Brian, I would not use rtv or any silicone based product on the liner/flue connection at the stove.. The temperatures reached there could cause burn off to some degree and possibly create a stinky situation. High heat mortar is 100 percent silicate and rated to 2000 degrees so no issue with burn off once the product is heat cured.

The only down side to mortar is it cures hard and will crack with expansion/contraction. My install lined up pretty good regarding the block plate leaving a small gap at the stove collar and at the connection to the flex liner but I still plan on putting just a small amount in the gaps. I'm not worried about air leaking out, it's more an issue of air being drawn inward and reducing draft to the stove to some degree. I want the best draft possible in my situation.

I plan on using DAP high heat mortar, picked it up at HD.. Good luck with your install...

 

[budman]

That's a really neat install Bren,great job.

 

[Bubbavh]

You want to use Mill-Pac Black.

 

[Black Jaque Janaviac]

I had a similar problem although it was mainly because the crimped portion of the adapter was so long and the connector neck on the stove would not accept an adapter that deep.

I used a foot or so of that stove gasket (fiberglass braided rope) and tucked it in the gaps with a screw driver. Made a big difference on stove performance. When damper is closed as far as it goes that gap becomes the path of least resistance and the chimney begins sucking through the gap. This starves the burn box for air, cools the fire.

 

[mellow]

Mill Pac is worth every penny, once it cures it will seal any hole. Not that bad to remove either, it gets really hard but is semi-brittle if you smack it. The tubes last for a long time as well, since I go through inserts I have just about used my tube up over the past 3 years.