Mr. Gray is a great guy who has spent the time to provide professional advice to me on several occasions. He was always correct and nice about it. This type of generous help is greatly appreciated. I am reconditioning a “low-efficiency” gas boiler and the venting is rusted out. For this can C-pipe be used exclusively because there are no combustible materials nearby and the pipe entering a brick chimney is B. The burner hood on an old Raypac was rusted. It was tricky to clean-up the rust and mig weld in sheet metal.
I LOVE how this vids historical aspect is from a contractors point of view, a much more 1st person or applicable point of view, rather a 3rd person a historians point of view, very informative for a millennial such as i
Good stuff. We see a lot of C vent coming off the furnace and water heater that turns into B vent at the Y. And you're right, single wall rusts out big time after about 5 years. Thanks again for the videos.
@@Hvacnc you have to plan the rest of the parts accordingly. B vent is only to pass through tight clearances of wood and to prevent condensation rusting.
great trip down memory lane. I remember everything use to be single wall and B vent.... They've got everyone convinced 90% is the way to go. They cost a lot, and the secondary heat exchangers fail lickety-split. Now exactly what have they saved???? Contractors must love it.
good video. I'm up north and I'm changing out a 90 plus furnace that was installed in an attic space. with an 80 plus furnace. I know it sounds backwards but the problem is it freezes in the winter. the customer's request is get it the hell out of here! lol anyway like your videos.
@grayfurnaceman, thanks for great content! At 6:48 you mention plexvent, which is the pipe currently connected to my Rheem 80 plus furnace. We bought this house in 2009 and it seems the inspector didn't notice it was recalled years ago😲 I'm wondering what type of pipe I can replace it with so that the furnace can continue venting from the basement sidewall?
You can probably use B-vent as the manufacturer recommends B-vent as a replacement for flex vent. You will have to have 1" clearance to combustibles. GFM
G3 gas fitter student (ON, Canada) reading over my code book in prep for final exam. Vent types for natural gas are listed as: A, B, BW, L, BH, C, and direct vent. How on earth did the industry come up with this naming convention and is there a way to remember what each letter stands for? Thanks in advance.
I don't believe there is much difference as both must be used with low temp exhaust gasses and are not damaged by the chemicals in the gasses. Some jurisdictions require a specified venting plastic but I don't think it's important. GFM
B vent is only used for gas appliances. Oil furnaces can use C-vent (single wall min 26 gauge) with 18" clearance to combustibles. Commonly used for appliance to masonry chimney venting. Or you can use L-vent (insulated pipe) as a direct vent. GFM
@@grayfurnaceman no masonry chimney. The vent would travel 2’ from the top of the furnace to the ceiling than 6” through an insulated area than out the shingle roof. So I would use L vent for this? if so do you you know what the clearance to combustibles needs to be for that pipe? I also read that the pipe should be a minimum of 5’?
Hey what would you do for an empire natural gas space heater that will be vented into a masonry chimney that is fully inside my house except for the top 8ft. The chimney is not lined. It used to vent an oil burning furnace directly into the chimney. We now have a direct vent gas boiler venting out an outside wall. Nothing is in the chimney now but id like to put the space heater in it in the basement. I'm in Rhode Island. 2 story home with a full unfinished basement.
you can install single wall pipe on furnaces 80k btu or better and thing less than that requires B-vent. Can't find it in the book but the inspector says so
The single wall pipe issue seems to have legs. The IFGC code gives some cases where single wall can be used with induced appliances. However, field experience tells me to use only B-vent to avoid rustout problems. I will be coming out with a video on vent connector sizing that may help. GFM
@@grayfurnaceman Thanks. The roofers broke the flex 90 just below the roof and the flue is at least 25 years old. I'll see what I can find without replacing the entire flue.
I am moving by boiler and venting out and up the exterior of my house then closing it up. What do you suggest I use to secure the 90 degree elbow and the pipe that runs along the exterior?
so does that also mean you go down in diameter as well? or is that just for example? i would think you still need the 3 and 4 inch pipe inside diameter? the pvc has much thicker walls than the B or C
I tore down the chimney to the roof line. the chimney was to far gone. I have a Williamson furnace probably from the early 70's. What type of pipe should I use?
I have a carrier unit from about 93 it is installed with 4 inch to 7inch c pipe but it's all rusted and I am tearing it all out... Can I use b vent pipe to reinstall it???
I have an 80% furnace and the exhaust connects with b vent. The exhaust connection is leaking hot air back into the furnace and causing it to overheat. There doesn't appear to be any type of sealing between the connection (metal on metal). Should this be sealed with HVAC tape or is there another solution?
This does not sound right. There is no need to seal joints because the vent is under negative pressure. My thought is you may have a draft hood equipped furnace that is spilling out the draft hood. Do you notice heat coming from the top portion of the furnace when its on? If so, that is a dangerous condition. You either have a vent blockage or a negative pressure in your house. GFM
grayfurnaceman thanks for the feedback! Amazing that you knew something was off. I took another look and the draft actually appears to be caused by a leak from the heater air output (only happens when the blower motor is on) and blowing warm air through the sheet metal joint, right under the draft hood exhaust, next to the inducer. My little closet gets warm and then I get short cycling. Maybe time to call a pro?
What sucks is when you have substandard, code-breaking work done the “imposters” still get paid and scamper off without rectifying issues. Bad money spent. I too have several code-busters and will have to correct it myself. I could probably get the half-ass*d tech back but I don’t want him back. Should do a 50% COD upon satisfactory completion and even though I work overseas, someone in the know needs to monitor proper progression (MPP).
Wood burns. It is combustible. The 2 materials used in natural draft appliances are C vent (single wall) and B-vent (double wall, listing on the side). GFM
@@grayfurnaceman thank you very much. My boiler and hot water heater join right before they exit out of the side of the house into the chimney. Was wondering if there was an easier material to work with like the pvc instead of b vent. photos.app.goo.gl/E13CRUCUHFBvSN7h7
I can only find B vent and C vent at Home Depot. My furnace was installed in the early 90"s. The original builder used C vents and it corroded like hell. What vents do I use to be in compliance with housing codes? I live in CA.
Some of the 80% furnaces in the early 1990s were installed with C vent. The vent temps were too low and the gas condensed in the pipe. Use B vent from the furnace to the vent pipe. It should work ok. GFM
Try this one for cat 1: th-cam.com/video/Vznf1cxycVs/w-d-xo.html@@hangngoaigiare You can find all my videos on venting by going to my channel and typing "venting" in the search engine. GFM
It is in a b vent chimney that is for a gas water heater. The water heater is the on thing hooked up to the chimney. I use to have a gas furnace hooked up to it, but replaced it with a high efficiency model which doesn’t use the chimney. I was told that going from a 4” vent to a 6” b vent might not be good. A chimney company told me I would have to replace the b vent chimney and they didn’t recommend running a 4” stainless steel liner through the b vent. A water heater manufacturer recommended having a 4 “ vent and not going to the 6”. A liner would be less expensive to put in than a whole new b vent system. But I am not sure if it is legal or not.
You can just put 4" B-vent inside the 6" if the vent is straight. You can use a flexible SS inside the existing vent if it is not straight. I would not use the 6" B vent as a vent, but using it as a chase is ok.. GFM
I want to install an old school furnace in my shop, a Lennox G 20 series, 100,000 btuh. I see from your video I need to use B vent. The furnace outlet is 6 inch oval, and wondering if I can reduce down to 3 or 4 inch thereafter. A 2 foot horizontal run will get me through the exterior wall and asking, can I cap it off there, or must I 90 up and go vertically through the roof?
Mr. Gray is a great guy who has spent the time to provide professional advice to me on several occasions. He was always correct and nice about it. This type of generous help is greatly appreciated.
I am reconditioning a “low-efficiency” gas boiler and the venting is rusted out. For this can C-pipe be used exclusively because there are no combustible materials nearby and the pipe entering a brick chimney is B. The burner hood on an old Raypac was rusted. It was tricky to clean-up the rust and mig weld in sheet metal.
You can use C-vent for the vent connector, but I would use B-vent, mostly because you have existing problems with rust.
GFM
I LOVE how this vids historical aspect is from a contractors point of view, a much more 1st person or applicable point of view, rather a 3rd person a historians point of view, very informative for a millennial such as i
Good stuff. We see a lot of C vent coming off the furnace and water heater that turns into B vent at the Y. And you're right, single wall rusts out big time after about 5 years. Thanks again for the videos.
Do you know if you can cut b vent. Does both chambers inner and putter carry gas out?
@@Adamn7210 Can't cut B vent.
@@HN-gj2iqhow you get shorter pieces for b vent? If you can’t cut it
@@Hvacnc you have to plan the rest of the parts accordingly. B vent is only to pass through tight clearances of wood and to prevent condensation rusting.
I just discover this channel a few days ago. awesome as I am new gas fitter. this helps allot. I am grateful for the time you put in here.
Do you know if you can cut b vent. Does both chambers inner and putter carry gas out?
Always entertaining,always informative. Keep em coming. Thanks
Thanks for the thoughts. Our local codes have eliminated most single wall for 80% furnaces.
GFM
My guy yesss excellent flawless, perfect video you're the best
great trip down memory lane. I remember everything use to be single wall and B vent.... They've got everyone convinced 90% is the way to go. They cost a lot, and the secondary heat exchangers fail lickety-split. Now exactly what have they saved???? Contractors must love it.
Cheap materials
Yes, B-vent. That is the AGA designation. Hope this helps.
GFM
grayfurnaceman
good video. I'm up north and I'm changing out a 90 plus furnace that was installed in an attic space. with an 80 plus furnace. I know it sounds backwards but the problem is it freezes in the winter. the customer's request is get it the hell out of here! lol anyway like your videos.
Very common I don’t install 90% in attics because of freezing don’t know any one who does
this is a great video!!!!!!!!!!!!! amazing thank you so much for sharing this valuable information
@grayfurnaceman, thanks for great content! At 6:48 you mention plexvent, which is the pipe currently connected to my Rheem 80 plus furnace. We bought this house in 2009 and it seems the inspector didn't notice it was recalled years ago😲 I'm wondering what type of pipe I can replace it with so that the furnace can continue venting from the basement sidewall?
You can probably use B-vent as the manufacturer recommends B-vent as a replacement for flex vent. You will have to have 1" clearance to combustibles.
GFM
Great job. Thanks for posting
Thank you for the video! You just completed a HVAC school assignment for me. Haha THANKS!!
Welcome
GFM
.
G3 gas fitter student (ON, Canada) reading over my code book in prep for final exam. Vent types for natural gas are listed as: A, B, BW, L, BH, C, and direct vent. How on earth did the industry come up with this naming convention and is there a way to remember what each letter stands for? Thanks in advance.
Great video thanks 🙏🏽
Thanks for the support
GFM
You're a hero.
Thanks, but save the hero stuff for the medical staff that are doing for us every day.
GFM
We used to use ABS for condensing furnaces. Was legal in our area.
I don't believe there is much difference as both must be used with low temp exhaust gasses and are not damaged by the chemicals in the gasses. Some jurisdictions require a specified venting plastic but I don't think it's important.
GFM
Person at depot told me to use c vent thru the roof with a rubber boot for a gas water heater wonder how long until that burned
I guess the rubber boot would prevent fire, NOT.
GFM
i have yet to see any of that stainless stuff up here in northeast in all my years doing this....sure i will one day
What kind of vent is suitable for exhausting outdoor kitchen/propane BBQ grill through an attic space?
Single wall galvanized 26 gauge pipe.
GFM
@@grayfurnaceman thanks very much for the reply. Is there a building code that governs this type?
Can B-vent be used for a forced air oil furnace? If not is there a reason and alternative?
Thanks
B vent is only used for gas appliances.
Oil furnaces can use C-vent (single wall min 26 gauge) with 18" clearance to combustibles. Commonly used for appliance to masonry chimney venting.
Or you can use L-vent (insulated pipe) as a direct vent.
GFM
@@grayfurnaceman Thank you very much. Is there a difference between the inner pipe that makes B and L different?
Always entertaining Good stuff.this helps a lot, thank you
I need to install an oil furnace but I’m not sure what kind of flue pipe to use.
If you are venting to a masonry chimney, you can use 26 ga C-vent (single wall) for the vent connector. If venting is metal, you will need L-vent.
GFM
@@grayfurnaceman no masonry chimney. The vent would travel 2’ from the top of the furnace to the ceiling than 6” through an insulated area than out the shingle roof. So I would use L vent for this? if so do you you know what the clearance to combustibles needs to be for that pipe? I also read that the pipe should be a minimum of 5’?
@@johnwhite6538 3" clearance to combustibles. Size depends on size of appliance. Never seen anything less than 6".
GFM
Thanks for the support.
GFM
Why were the stainless steel pipes a failure? Virtually nothing will eat stainless steel. Did they make double-walled stainless steel pipe too?
Hey what would you do for an empire natural gas space heater that will be vented into a masonry chimney that is fully inside my house except for the top 8ft. The chimney is not lined. It used to vent an oil burning furnace directly into the chimney. We now have a direct vent gas boiler venting out an outside wall. Nothing is in the chimney now but id like to put the space heater in it in the basement. I'm in Rhode Island. 2 story home with a full unfinished basement.
What about venting for mobile homes, can you explain how it works?
you can install single wall pipe on furnaces 80k btu or better and thing less than that requires B-vent. Can't find it in the book but the inspector says so
The single wall pipe issue seems to have legs. The IFGC code gives some cases where single wall can be used with induced appliances. However, field experience tells me to use only B-vent to avoid rustout problems. I will be coming out with a video on vent connector sizing that may help.
GFM
Do you know if you can cut b vent. Does both chambers inner and putter carry gas out?
Will different brands of B vent pipe and fittings work with each other?
Generally, no
GFM
@@grayfurnaceman Thanks. The roofers broke the flex 90 just below the roof and the flue is at least 25 years old. I'll see what I can find without replacing the entire flue.
do you have a youtube on venting a hot water tank through the roof?
I haven't done that one yet. The water heater should have instructions on venting with it.
GFM
I am moving by boiler and venting out and up the exterior of my house then closing it up. What do you suggest I use to secure the 90 degree elbow and the pipe that runs along the exterior?
As the B-vent requires 1" clearance from combustibles, enclosing the B-vent with C-vent (26 gauge single wall pipe) will suffice.
GFM
Can you wrap short runs of c-vent with an insulation blanket to stop the condensation?
If you are condensating, replace the vent connector with B-vent.
GFM
So what does BH stands for?
Its a single wall stainless steel vent for non-condensing appliances. It is air tight because the vent pressure is positive.
GFM
so does that also mean you go down in diameter as well? or is that just for example? i would think you still need the 3 and 4 inch pipe inside diameter? the pvc has much thicker walls than the B or C
The diameter is determined by installer instructions and local codes.
GFM
I tore down the chimney to the roof line. the chimney was to far gone. I have a Williamson furnace probably from the early 70's. What type of pipe should I use?
I have a carrier unit from about 93 it is installed with 4 inch to 7inch c pipe but it's all rusted and I am tearing it all out... Can I use b vent pipe to reinstall it???
Yes, and B vent should have been installed originally. Very common mistake back then.
GFM
is it ok to use the spray gap filler around B vent going between interior and exterior sidingthis is on a vent pipe for propane water heater
It probably is not strictly code. You should have 1 inch air space.
GFM
Can you use the B vent for a horizontal application? I have a 12 foot span with plenty of clearance for the .25 to 1 foot run.
+M Fitch It can be used as a vent connector horizontally if the vent has a minimum 1/4" per foot rise. Higher is always better. Hope this helps.
GFM
M Fitc
I have an 80% furnace and the exhaust connects with b vent. The exhaust connection is leaking hot air back into the furnace and causing it to overheat. There doesn't appear to be any type of sealing between the connection (metal on metal). Should this be sealed with HVAC tape or is there another solution?
This does not sound right. There is no need to seal joints because the vent is under negative pressure. My thought is you may have a draft hood equipped furnace that is spilling out the draft hood. Do you notice heat coming from the top portion of the furnace when its on? If so, that is a dangerous condition. You either have a vent blockage or a negative pressure in your house.
GFM
grayfurnaceman thanks for the feedback! Amazing that you knew something was off. I took another look and the draft actually appears to be caused by a leak from the heater air output (only happens when the blower motor is on) and blowing warm air through the sheet metal joint, right under the draft hood exhaust, next to the inducer. My little closet gets warm and then I get short cycling. Maybe time to call a pro?
Probably
GFM
What sucks is when you have substandard, code-breaking work done the “imposters” still get paid and scamper off without rectifying issues. Bad money spent. I too have several code-busters and will have to correct it myself. I could probably get the half-ass*d tech back but I don’t want him back. Should do a 50% COD upon satisfactory completion and even though I work overseas, someone in the know needs to monitor proper progression (MPP).
What is considered conbustables Joists and subfloor?
How do i know if my boiler and hot water heater use different materials?
Wood burns. It is combustible. The 2 materials used in natural draft appliances are C vent (single wall) and B-vent (double wall, listing on the side).
GFM
@@grayfurnaceman thank you very much. My boiler and hot water heater join right before they exit out of the side of the house into the chimney. Was wondering if there was an easier material to work with like the pvc instead of b vent.
photos.app.goo.gl/E13CRUCUHFBvSN7h7
Do you know if you can cut b vent. Does both chambers inner and putter carry gas out?
No. But there are adjustable lengths.
GFM
grayfurnaceman how do you attach it right at the collar of the furnace
@@Adamn7210 At the collar and only at the collar, you can screw it to the furnace discharge if the manufacturer's instructions allow it.
GFM
grayfurnaceman ok so just cut it flush and put right on top of the hole?
@@Adamn7210 Yes
GFM
B vent you said?
you mention 1" clearance to combustible on the B vent, is it OK to have insulation around it? Thanks
You can insulate it if the insulation is not flammable.
GFM
thank you so much for your prompt reply.
Hey this is new to me,thanks for sharing chief....
informative. tyvm Sir
I can only find B vent and C vent at Home Depot. My furnace was installed in the early 90"s. The original builder used C vents and it corroded like hell. What vents do I use to be in compliance with housing codes? I live in CA.
Some of the 80% furnaces in the early 1990s were installed with C vent. The vent temps were too low and the gas condensed in the pipe. Use B vent from the furnace to the vent pipe. It should work ok.
GFM
Please do a venting video
I have some venting videos but tell me what specifically you want.
GFM
@@grayfurnaceman everything about venting i guess, cat 1 , to cat 4. Multiple equipments
Try this one for cat 1: th-cam.com/video/Vznf1cxycVs/w-d-xo.html@@hangngoaigiare
You can find all my videos on venting by going to my channel and typing "venting" in the search engine.
GFM
Can you put a 4” SS liner in a 6” b vent?
That depends on what the use of the vent pipe is. If its for a wood stove, the B vent is not rated for that high of temps.
GFM
It is in a b vent chimney that is for a gas water heater. The water heater is the on thing hooked up to the chimney. I use to have a gas furnace hooked up to it, but replaced it with a high efficiency model which doesn’t use the chimney. I was told that going from a 4” vent to a 6” b vent might not be good. A chimney company told me I would have to replace the b vent chimney and they didn’t recommend running a 4” stainless steel liner through the b vent. A water heater manufacturer recommended having a 4 “ vent and not going to the 6”.
A liner would be less expensive to put in than a whole new b vent system. But I am not sure if it is legal or not.
You can just put 4" B-vent inside the 6" if the vent is straight. You can use a flexible SS inside the existing vent if it is not straight. I would not use the 6" B vent as a vent, but using it as a chase is ok..
GFM
thanks!
I want to install an old school furnace in my shop, a Lennox G 20 series, 100,000 btuh. I see from your video I need to use B vent. The furnace outlet is 6 inch oval, and wondering if I can reduce down to 3 or 4 inch thereafter. A 2 foot horizontal run will get me through the exterior wall and asking, can I cap it off there, or must I 90 up and go vertically through the roof?
You can't reduce the vent below the size of the draft hood connection. You do need a a vertical riser and termination of the vent.
GFM
great stuff, thank you...
What is your preference on brand of B vent?
I have no preference. All brands pass the same tests.
GFM
What can I use for my air temp oil furnace 85%
If you have a chimney, you can connect from the furnace to the chimney with C vent (single wall 26 gauge black pipe).
GFM
As I get ready to install my 81% shop furnace bought from NORTHERN Tool.. 🤔
B vent that’s double wall pipe
I never see pvc on 80% only 95ers
The stack temp is too high for PVC on 80% appliances.
GFM
"Its called B vent because it has a 'B' on it".
🤔🤔🤔🤔😂😂😂😂😂
Classic
It also means 1" clearance to combustibles and 550 max temp..
GFM
Too much yap more splat