On 8/18/2010 10:01 AM, Bob F wrote:
N8N wrote:
On Aug 18, 11:08 am, wrote:
On Aug 17, 8:36 pm, wrote:

I just was cleaning my water heater and see the exhaust pipe on it
has come loose in the middle. Can I just duct tape it for now and
not expect it to melt?
--
Uno

Sounds dangerous to me. Isn't exhaust pipe leaks where carbon
monoxide gets into the house or do water heaters burn so little fuel
that it doesn't give off much exhaust?

no, it's definitely a concern. Most residential water heaters are in
the neighborhood of 30-40K BTU or higher IIRC. I would follow the
advice already given and screw it together. If it was put together
properly in the beginning, the smaller, crimped ends of all the
connections should be pointing in the direction of the exhaust flow to
minimize the possibility of backdraft, even without sealing the
joints. I suppose if you are anal retentive using some muffler cement
might work, covered with metal foil tape (as others have said, NOT any
other kind of "duct" tape - that would be doomed to a presumably
quick, smelly failure.)

My understanding is that the crimped ends should be pointed down to contain
condensation within the pipe instead of letting it drip out at the joints. This
is important for wood stoves.





Thanks all for replies. Once I read them all, I realized that screwing
them together is what I wanted to do. If they are not together in a
convincing way (screws are very convincing), there is definitely a CO
exposure you don't want to have in the place where you hang out to
prepare your meals. (Yes, here in New Mexico, many of us have water
heaters in our kitchens.)

So here's how it went down:

1) Refrain from using hot water for a half hour so that ducts won't be hot.
2) Duct tape up the back of this joint so it stays together for the
next 5 minutes.
3) Use an 1-1/4 screw to make a penetration right on the knuckle. When
you get through the top, stop.
4) Use drill bit to prepare hole for screw.
5) Install screw.
6) Remove duct tape.
7) Thank the nice folks on usenet who helped me out here.

I think I'll foil tape it for good measure. Cheers,
--
Uno