Need sealing advice

[jtech1]

I am looking for some advice on a few things related to sealing flu and air ducts off a sealed combustion gas fireplace...

1) Specs require inside joints of Duravent to be sealed with Mill-Pak. I know this is not a sealant/adhesive, so looking for advice on the best way to apply it to get a good seal on inside joints.

2) Specs do not require any sealing of outside joints on duravent, although I prefer to do it anyway so no room air is sucked in intake. Is any high-heat silicon sealant ok here? I do not think there is any code requirement for the red stuff... right?

3) I have two hot air ducts off the unit (plain old 6" rigid duct carrying heated room air to another location). Specs say no contact with combustibles within first 6 feet off unit. Thereafter direct contact is OK. I'd like to seal these joints. What can be used to seal the joints in the first 6 ft where no contact with combustibles? Also, specs say to insulate the ducts and make no restriction about first 6 ft. Is non-faced fiberglass considered a non-combustible and OK to use in first 6 ft of air duct off unit?

Any feedback is greatly appreciated!

 

[DAKSY]

I am looking for some advice on a few things related to sealing flu and air ducts off a sealed combustion gas fireplace...

1) Specs require inside joints of Duravent to be sealed with Mill-Pak. I know this is not a sealant/adhesive, so looking for advice on the best way to apply it to get a good seal on inside joints.

Take a look at where the inner surfaces join together. One diameter will fit inside the other. as long as the mil-pac is on BOTH mating surfaces, the seal should be adequate.

2) Specs do not require any sealing of outside joints on duravent, although I prefer to do it anyway so no room air is sucked in intake. Is any high-heat silicon sealant ok here? I do not think there is any code requirement for the red stuff... right?

On the outside, I would use aluminum tape for that seal, although it's not necessary. The amount of combustion air coming in through
the cap will mitigate anything that might enter through whatever the small clearance between the mating surfaces. There is not enough atmospheric pressure to force air in.

3) I have two hot air ducts off the unit (plain old 6" rigid duct carrying heated room air to another location). Specs say no contact with combustibles within first 6 feet off unit. Thereafter direct contact is OK. I'd like to seal these joints. What can be used to seal the joints in the first 6 ft where no contact with combustibles? Also, specs say to insulate the ducts and make no restriction about first 6 ft. Is non-faced fiberglass considered a non-combustible and OK to use in first 6 ft of air duct off unit?

RTV will seal gaps in that zone, & YES, you can wrap unfaced fiberglass around the ducting. Secure it with steel wire to keep it in place.

Any feedback is greatly appreciated!