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Reis Pearson
08-16-2008, 04:24 PM
This seems like a pretty easy question, I just can't find (or maybe I have) what I'm looking for to describe it, but here goes... I've got a furnace and a water heater (both gas) venting to a common B-vent. I'm fairly certain that there needs to be an increase in size of pipe above/at the connection of the two appliances. Am I remembering this correctly?
DavidR
08-16-2008, 05:54 PM
The GAMA venting tables might help you figure out the answer Reis.

Even though I don't trust them it will give you something to refer to.
Hope they help.

I don't know why they continue to allow common venting.
Dana Bostick
08-18-2008, 03:30 PM
Just in case you are not clear, I'm including a picture of the correct installation for double venting. :rolleyes:
http://i330.photobucket.com/albums/l426/Kizzyspop/Inspection%20Pics/HowNOTtoventdualW-H.jpg
Billy Stephens
08-18-2008, 04:09 PM
?????
.
Dana Bostick
08-18-2008, 04:27 PM
?????
.

It's a JOKE Billy! See the little "sarcastic" smiley at the end?

I almost fell over when I found this one I was laughing so hard. Talk about a hack job!
this was one of the wildest I've seen in a while. Good thing both units of this beachfront duplex were still vacant and the water heaters were not lit. I disconnected both gas lines (BTW, both were fed from one 1/2" gas line) so they would not be used until corrected.
Dana
Reis Pearson
08-19-2008, 06:22 AM
That's fantastic! Dana, can I use that photo for a presentation??

Cheers,
Reis
Jerry Peck
08-19-2008, 06:28 AM
That photo should be titled *How to Kill Someone Without Even Trying*. :)
Dana Bostick
08-19-2008, 06:30 AM
That's fantastic! Dana, can I use that photo for a presentation??

Cheers,
Reis

Be my guest Reis.
Dana
Nick Ostrowski
08-19-2008, 07:31 AM
Reis, I'm not sure about the vent pipe sizing thing but the setup in your pic already has a large condensate stain on it and is strap supported with what appears to be a plastic strap.
Reis Pearson
08-20-2008, 06:36 AM
Reis, I'm not sure about the vent pipe sizing thing but the setup in your pic already has a large condensate stain on it and is strap supported with what appears to be a plastic strap.

I got the condensate stain (it's worse in the unit) which is what sparked the whole "yes, I think this is wrong" movement. And the support strap is metal... I think if it were plastic it would have some pretty good warping happening by this point (6 yr old home). But, thanks!
Dylan Whitehead
08-20-2008, 06:41 AM
Reis, on any combo vent set up the common vent must be increased by one pipe size.