Appliances with Common Venting

**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?

Similar Threads:

**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.

**Billy Stephens** · 08-18-2008, 04:09 PM

?????
.

**Dana Bostick** · 08-18-2008, 04:27 PM

Originally Posted by Billy Stephens

?????
.

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

Originally Posted by Reis Pearson

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

Originally Posted by Nick Ostrowski

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!