Good source for 5" B-vent?

[75gmck25]

As part of a renovation project I demolished the old clay flue where my gas boiler was vented. Now I need to install a new flue using 5" B vent that I can frame around. Timing is not as critical right now because I don't need heat, but I would like to get it installed so that the framer can ensure the chase has the right clearance.

If possible I would also like to connect a 3" water heater flue to the same 5" vent so that I don't need to have a separate flue for the water heater. My boiler and water heater do not have fan-forced exhaust, so my understanding is that they can use a common flue.

Can anyone recommend a good source/brand for B-vent that would have all the elbows, pipe, terminations, etc.? I've found a few local and a few online suppliers, but many seem to have a few components and then have to special order others. Prices also seem to vary a lot. I need a 90 degree, two 45's, Y for the water heater flue, about 30 feet of pipe, and the termination at the shingled roof.

Also, can you mix/match B-vent brands, or are the connections unique?

Thanks,

Bruce

 

[brewchief]

B-vent is designed to be used as one one brand from top to bottom, some brands do sell adapters that allow you to connect to another brand but those shouldn't be used unless you have no choice, sometimes you have to extend or replace a brand no longer available so the adapters are fine for that.

With multiple appliances you may need larger then 5", need to look at vent charts to see.

I would suggest running water heater in 4", while many of them still come with a 3" outlet it's pretty common to need a 4" vent connector to meet code.

Sent from my SM-G965U using Tapatalk

 

[59 wagon man]

if your going to tie a water heater and furnace together 5" is probably undersized

 

[Jim greengo]

Why not 6" ?

 

[mrobins297aaa]

Not sure by your post if your concerned with the size of the stack, but the old formula we used to size a "B" chimney with more than one appliance was:
100% of the area of the largest flue and 50% of the area of the rest.

so a 5" = 19.625 sq in.
a 3" = @ 50% = 3.53 sq in.
the total = 23.16 sq.inches

so the flue should be at least a 6" (at 28.26 sq. in.)

also the largest appliance always connects lowest on the chimney

 

[75gmck25]

I didn't think about needing a larger flue if I combine the two appliances.
Upsizing to 6" shouldn't be an issue, other than making a larger hole in the clay flue. The existing 3" water heater connection is about a foot higher on the same clay flue, so I would probably just upsize that to 6" and close off the lower connection. The new metal pipe would route through the first section of existing clay flue and then transition to a framed chase when it passes through to the 1st floor.

If it makes sense, I believe I could just run 6" single wall (after adding the water heater connection) from the basement up to the 1st floor, since its inside a non-combustible clay flue that used to serve both appliances. The clay flue would just serve as a chase. Then I could use the firestop (from basement to 1st floor) to transition from single wall to B-vent, and go up from there. Does this sound reasonable?

Amerivent and Duravent seem to be common suppliers of B-vent, but availability and price seems to be spotty. For example, When my renovation contractor looked up prices one vendor had a 90 degree at a cheaper price, but their straight pipe was more expensive, and another vendor was just the opposite on pricing.

Thanks,

Bruce

 

[All]

DuraVent is made in the USA. AmeriVent (available at Home Depot) is made in Mexico and China. SellKirk (another brand of B venting products, available at Lowe's) is made in Mexico.

Each system has different engagement schemes. You might consider going into the stores to engage and disengage the different systems, as you may quickly find a preference for one type over another. For DuraVent, check your local professional plumbing supply houses (Ferguson etc).

I recently replumbed my water heater vent with DuraVent. I have used AmeriVent and Sellkirk products also. It is not possible for me to say to you which system is best, as each system has good and bad points. Sometimes, it's a matter of what ***** the least. I chose made in USA DuraVent... which costs more, given that it was not available at the big box stores like AmeriVent and Sellkirk.

If your water heater is a tank type, and is 50 gallons or less, and is atmospheric vented, and originally came with a 3" flue vent... then I recommend maintaining the 3" diameter vent size up until the Y pipe transition into the 6" vertical stack inside the chimney... in order to maintain the heat in the water heater exhaust to encourage convection flow upward and discourage back drafting.

I ran B pipe all the way to the water heater itself. Immediately above the water heater's draft hood, I attached a 3" C to B appliance connector to transition to B pipe (recommended by water heater manufacture) , and then went straight up for 12" above the water heater (another recommendation) and then used a 60-45 degree B Elbow (instead of a 90 degree, yet another recommendation) to connect to a 4' long diagonal run (minimum 1/4" per foot slope) to the stack connection.

 

[Jackfre]

I would stick with Dura-vent or Selkirk products. Their locking systems are superior. I would not increase the size of the vent. Run the 5". I would run the water heater in 4" for future flexibility in water heater selection. If you can, run the entire system in B-vent. The system performance is improved that way. Should you choose to run a single wall vent connector you can run 1.5'/"diameter of the stack. You can source everything from a local supplier like RE Michel, Ferguson or assorted P&H/HVAC distributors in your area.
In this type of re-model you might consider an upgrade to the furnace. If you do this new B-vent stack you may be throwing good money after bad, depending upon the age of the furnace. When the old one goes you will likely go to a 95% vs the standard 78% efficient unit. the high efficiency unit cannot use a B-vent stack. Don't you love re-modeling?

 

[All]

I definitely agree about AmeriVent locking systems spinning 360 past their engagement tabs. One of the main reasons I stopped using them.

 

[75gmck25]

I appreciate all the input, and I think I've now simplified my requirement. I need to replace my water heater anyway (1992 vintage), and buying a power vent gas water heater would allow me to use a PVC flue that is not shared with the gas boiler. That means I only need a 5" B vent flue for the gas boiler.

All I need now is a transition from single wall to B-vent, a 90 degree elbow, a fire stop for each floor, about 25 feet of straight pipe, and the termination at the roof. It still won't be cheap, but I think the local suppliers will have what I need.

Thanks again.

Bruce