Duct Leaks

[Jerry Booher]

I have finally hung all my 7" and 6" ducts. When I check for leaks, I found leaks in the wyes at the factory joints, leaks in the elbows at the crimps, etc. So I painted all of them with latex roof paint. Still leaks at a few places I missed, plus the Lee Valley blast gates sound like they may be leaking a little also.

Do I have to keep sealing leaks until it is airtight?

Jerry

[Ken Fitzgerald]

I used foil tape on my snap-lock pipe. Around the the wyes...I used a silicon clear caulk. I also used silicon caulk around the mating surface where the pipe interfaced with the blast gates.

[Jack Porter]

I used snap lock pipe also and went with duct tape anywhere possible, otherwise used caulk, just make sure to clean the metal before caulking or you'll never get a decent bond.

I don't think you can ever get it airtight, and it proplabe doent's need to be.

[David DeCristoforo]

Only got two words for ya....DUCT TAPE! Every joint ("factory" or otherwise). And get the "good quality" heavy tape, not that cheap stuff. It will just peel off after a while.

YM

[Leo Graywacz]

I don't think you can ever get it sealed tight. Just get it very good and you should be all set. Any seam that goes around the circumference of the ducting should be taped. If you use snaplock pipe you don't need to tape the long seam, or at least that is what the instructions Oneida sent me said. So all the elbows have to have those seams taped, all the joints between the duct sections. Any screws to. Silicone anything else that tape can't get around. You gates will almost always leak a little.

[Jim Becker]

Get some HVAC caulk to seal up those welds. It's very common for them to leak as they are all spot welds in most products.

[Steve Rozmiarek]

I have finally hung all my 7" and 6" ducts. When I check for leaks, I found leaks in the wyes at the factory joints, leaks in the elbows at the crimps, etc. So I painted all of them with latex roof paint. Still leaks at a few places I missed, plus the Lee Valley blast gates sound like they may be leaking a little also.

Do I have to keep sealing leaks until it is airtight?

Jerry

Well, you could try my approach. Excess power, then figure the stubborn leaks are just dispersed air filter inlets.

[Mike Goetzke]

I just finished my DC piping for the second time. About 5 years ago I put in 4" snap-lock with duct tape not realizing the restriction I was putting on my system. When taking down the 4" stuff I was surprised to find out that almost all of the duct tape was loose or deteriorating. When I did the 6" I did a much better job, I used the aluminum foil duct tape. Once put down this stuff is impossible to remove in one piece. I actually went through the trouble of taping all the elbow joints with the tape. My joints are so tight now when I put a big restriction on the system I can hear a whistle near the blower - I need to get up there and seal this last leak.

Good Luck,

Mike

[Karl Brogger]

Well, you could try my approach. Excess power, then figure the stubborn leaks are just dispersed air filter inlets.

I'm with this guy. Your're being too anal.

[Steven Wilson]

I used clear silicone calk to seal mine. Then I lit some smoke sticks and checked for leaks. After a couple of rounds with the caulking gun all the leaks were eliminated.

[Josiah Bartlett]

A recent episode of Ask This Old House showed them sealing leaks with aluminum bearing mastic, which should work better than paint.

[Cliff Rohrabacher]

My HVAC guys used silicone caulk to seal the leaks. Worked really well in one application. A little flexing of the pipes won't break the adhesive seal cause the stuff is thick and flexible.

[Jerry Booher]

Thanks for the advice, guys. I should have asked before I started to tape. I used cheap duct tape - 3 layers on all connections. However, if it starts to peel, I will really be sorry!

I put the blast gates on with siliconized 35 year caulk. Then I put 2 coats of thick latex roof paint on all of the taped joints and the sheet metal seams. The blast gates make sounds like they are not perfectly sealed at the gate, but I can't do anything about that.

I am still trying to figure out how to get between the wall and the duct to paint that area. A complication is that my compressed air is behind the duct also. That keeps me from being able to paint the entire circumference. I guess I will just load the brush up with paint and stuff it down between the duct and the wall.

Once again, thank you for the help.

Jerry