sealant @ Furnace vent cap

[BURNZEE]

Hi all,
Finishing the replacment of a new suburban furnace in my 66 safari. Is it OK to use Velkum at the exterior vent cap. Install instructions don't specify which type.
Thanks for the help. A/C is next.

[Chuck]

I actually called Suburban tech support when I was re-installing my original furnace. I was actually looking for replacement parts, but while I had them on the phone, I asked the same question. The guy told me that any urethane sealant would be fine, as that spot doesn't actually get all that hot. your "new" furnace might be a different situation, though...main point is that you can call them and ask.

[BURNZEE]

Thanks Chuck,
Heat was my main concern. It seems like the heat resistant stuff is usually silicone (a big no no ) Thanks for the response.

[sfixx]

Originally Posted by BURNZEE

...Heat was my main concern.

I don't know about Vulcum but Sikaflex-221 has pretty good heat characteristics: up to 355 degrees for 1 hour and 320 for 4 hours constant.(See attached PDF) How hot do you think that the exhaust gets?

I bought some Vulcum after using up my first tube of Sikaflex-221 and didn't like it as much. It seemed to dry a lot slower and didn't have as much initial tack.

Now I'm using Sikaflex 295 on my windows where the weather stripping has hardened and it's working really well.

Good luck,

Steve

[BURNZEE]

Thanks Steve,
If it gets hotter than that I'll have other things to worry about besides the exterior sealant. I've actually got a tube of 221 but haven't opened it yet. Been using Velkum 636, but just ran out. You mean I've got just what I need,, that never happens. Thanks