Types of gas venting materials 

Do you know if you can cut b vent. Does both chambers inner and putter carry gas out?

Do you know if you can cut b vent. Does both chambers inner and putter carry gas out?

@@Adamn7210 Can't cut B vent.

Thanks, but save the hero stuff for the medical staff that are doing for us every day. GFM

Very common I don’t install 90% in attics because of freezing don’t know any one who does

grayfurnaceman

It probably is not strictly code. You should have 1 inch air space. GFM

Cheap materials

As the B-vent requires 1" clearance from combustibles, enclosing the B-vent with C-vent (26 gauge single wall pipe) will suffice. GFM

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

The diameter is determined by installer instructions and local codes. GFM

Welcome GFM

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If you are condensating, replace the vent connector with B-vent. GFM

Yes, and B vent should have been installed originally. Very common mistake back then. GFM

+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

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

I haven't done that one yet. The water heater should have instructions on venting with it. GFM

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

You can insulate it if the insulation is not flammable. GFM

thank you so much for your prompt reply.

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

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

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

Single wall galvanized 26 gauge pipe. GFM

@@grayfurnaceman thanks very much for the reply. Is there a building code that governs this type?

I guess the rubber boot would prevent fire, NOT. GFM

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?

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.

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

If you have a chimney, you can connect from the furnace to the chimney with C vent (single wall 26 gauge black pipe). GFM

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

I have no preference. All brands pass the same tests. GFM

Its a single wall stainless steel vent for non-condensing appliances. It is air tight because the vent pressure is positive. GFM

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: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Vznf1cxycVs.html@@hangngoaigiare You can find all my videos on venting by going to my channel and typing "venting" in the search engine. GFM

It also means 1" clearance to combustibles and 550 max temp.. GFM

The stack temp is too high for PVC on 80% appliances. GFM

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