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[OP]
Deal Guru
Jan 25, 2007
10084 posts
5339 upvotes
Paris

B-Vent question

In-laws water heater died. Guy red tagged the furnace when he came as the furnace and water heater are mid/low efficiency and use B-vent. They are tied in to the same vent, but from each appliance is normal piping into a Y that then goes to B-Vent. They told him to call the furnace installers (from 1999) to fix it, but they say they did it to code from 1999.

I have a garage furnace (tagged by a gas installer) and he said I could do some normal piping but once i got going through walls or ceilings I needed proper B-vent stuff.

So, questions:
1) Can you still run 2 appliances into 1 b-vent that runs up and out?
2) If 1 applies, what must be the runs/max distance from the appliances to the wye and what piping type?

I assume neither is over 3" from the appliance and I believe the bvent stack is 4" or 6".

It's not easy/he isn't willing to run high-efficiency. Yes he should. Yes the house is probably worth a million bucks in Miss and yes everything else in the house has been upgraded so he should do this but just assume its all going to continue to be b-vent. Yes the furnace is old and will be replaced eventually but not with the water heater.
8 replies
Deal Addict
Dec 19, 2009
4054 posts
1996 upvotes
Because you would be changing the water heater you would also have to follow the updated codes pertaining to venting. Y branches are no longer allowed and if the chimney is B-Vent than the two appliances would have to connect via a B-Vent tee with one appliance entering the tee part and the other the bottom of the tee.
Sizing of the chimney and the vent connectors are based on the btu's of the appliances, which category of venting the appliances fall into and the total height of the chimney. In some instances you may also have to run B-Vent all the way from the appliance to the chimney instead of single wall aluminum as the vent connector.
Venting codes seem to change all the time so they may have even changed from this.
Deal Addict
User avatar
Aug 5, 2003
2409 posts
365 upvotes
North York
We had our b-vent water heater replaced a year/two ago now, it's still B-vent (along with the furnace) with no changes to the venting needed when the install was done. Have things changed since then, maybe? (but I'd want to see proof before giving any more work to the red-tag guy/company.)
[OP]
Deal Guru
Jan 25, 2007
10084 posts
5339 upvotes
Paris
pootza wrote: Because you would be changing the water heater you would also have to follow the updated codes pertaining to venting. Y branches are no longer allowed and if the chimney is B-Vent than the two appliances would have to connect via a B-Vent tee with one appliance entering the tee part and the other the bottom of the tee.
Sizing of the chimney and the vent connectors are based on the btu's of the appliances, which category of venting the appliances fall into and the total height of the chimney. In some instances you may also have to run B-Vent all the way from the appliance to the chimney instead of single wall aluminum as the vent connector.
Venting codes seem to change all the time so they may have even changed from this.
So the branch would need to be b-vent but could the piping into the b-branch be just single wall as it was? Is it possible the only change they need to make is to get a b-vent wye?

I think he has someone from church who is a fitter coming over for a second opinion. I have counselled to string schedule 40 gas vent plastic piping as if the furnace goes he will most likely do high efficiency anyway but...
Member
Jul 14, 2012
322 posts
136 upvotes
Hamilton
Does the B-vent go up the side of his house (outside), or does it go up through the inside of his house?
"...I started playing porn REALLY loud with speakers facing my back yard. The kids stopped going out back after the parents heard that." - TheGreatGazoo
[OP]
Deal Guru
Jan 25, 2007
10084 posts
5339 upvotes
Paris
Android412 wrote: Does the B-vent go up the side of his house (outside), or does it go up through the inside of his house?
Straight through the middle. Subdivision built in 1980-1982 in Mississauga. The whole neighbourhood has centrally located b-vent stacks.
Jr. Member
Feb 9, 2006
163 posts
48 upvotes
Jerico wrote: So the branch would need to be b-vent but could the piping into the b-branch be just single wall as it was? Is it possible the only change they need to make is to get a b-vent wye?

I think he has someone from church who is a fitter coming over for a second opinion. I have counselled to string schedule 40 gas vent plastic piping as if the furnace goes he will most likely do high efficiency anyway but...
The Y fitting will be b-vent and up to 6' from the water heater can be c-vent but with the furnace there is a formula and I've found most are below the standards and it needs to be an entire run of b-vent from the furnace. Installs pre 1996 are grandfathered in but everything after needs to be looked at...or just upgraded.
[OP]
Deal Guru
Jan 25, 2007
10084 posts
5339 upvotes
Paris
Hexavalent wrote: The Y fitting will be b-vent and up to 6' from the water heater can be c-vent but with the furnace there is a formula and I've found most are below the standards and it needs to be an entire run of b-vent from the furnace. Installs pre 1996 are grandfathered in but everything after needs to be looked at...or just upgraded.
I hate b-vent. I would have changed things in my garage heater install significantly had I known more about b-vent at the time.
Deal Addict
Nov 12, 2006
2012 posts
995 upvotes
London
Jerico wrote: In-laws water heater died. Guy red tagged the furnace when he came as the furnace and water heater are mid/low efficiency and use B-vent
You maybe should ask some questions about the "red tag".
I had a similar situation, except chimney vent and low efficiency furnace.
There was a 10 day window under code to comply, before an infraction would be issued.
Appliances were still allowed to operate.
Then there was something like 45 days until gas was shut off.
pootza wrote: Because you would be changing the water heater you would also have to follow the updated codes pertaining to venting.
That was my scenario.
I installed new water heater.
It was the same type as previous, and should have been a simple swap, but current code said it could no longer use the same venting.
If I was to theoretically just not bother with any water heater, and disconnect it, plug the pipe, the venting system was "touched" (by simple removal of the heater) and therefore needs to be brought to current code.
In my situation, that was either a chimney liner, or cap the chimney.
Leaving it as is was not an option.

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