Need high temp caulk for use around furnace external vent

[wacnstac]

Can anyone recommend a high temperature caulk that will stand up to the high temps around the furnace vent? Mine has some pretty big gaps that need to be filled.

[lewster]

Silicone RTV is about the only material that will go up to around 500 degrees and is formable for your application. I hate the stuff but in your situation....I think it is your only choice. Get the automotive type at NAPA that they use to form gaskets.

[wacnstac]

I can't think of anything else to use either. There are really some large gaps around the furnace exhaust/intake.

[Creampuff]

You may want to try 'muffler tape' or an exhaust pipe/ muffler cement available at any automotive supply. It is, however, not as flexible as caulk.

[Ultradog]

My Suburban furnace has an asbestos(or the modern equivelant) gasket where the pilot tube and thermocouple enter the combustion chamber through a little plate. It gets HOT. When I first got it the gasket was bad and allowed a draft to enter and blow out the pilot. Major PIA to put a new gasket in. I sealed it around the edges with ordinary GE silicone and it's still holding up after 3 heating seasons.
HTH
jerry

[lewster]

Originally Posted by wacnstac

Can anyone recommend a high temperature caulk that will stand up to the high temps around the furnace vent? Mine has some pretty big gaps that need to be filled.

You might consider some sheet metal or a new cover?..... or is this on the interior of the firnace?

[wacnstac]

This is on the exterior where the exhaust comes out of the wall.