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Roof Vent Height

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roof vents
11K views 46 replies 6 participants last post by  Klawman 
#1 · (Edited)
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#2 ·
Termination must be a min 2' above anything within 10' of it horizontally. And comply with manufacturers min height requirements.

International Fuel Gas Code has the section your looking for.
 
#4 ·
High efficiency gas furnaces have different venting needs than the old classical gas furnace that required double wall chimney. The high effeciency furnances use PVC pipe for venting, and you need not only a vent out, but a dedicated freash air source (i.e. two pvc pipes). Many of these furnances can vent through a wall. There's certain requirements like it has to be at least 12" off the ground and you can't vent under a deck (you wouldn't want to as the exhaust gas is warm and moist).
 
#6 ·
Ok. Does the furnace gets it combustion air from outside. Or does it use combustion air from the house.

If from the house, its a mechanical vent system.
If from outside its a direct vent system.
 
#8 ·
I don't know, but I only believe there is one pvc pipe and it is on the roof. It has a downfacing "u" at the top and the manual has a figure labeling what looks like it an intake. The City has now chimed in and it says the minimum is 3" if the unit is in the attic, which it is.
AHJ/Authority Having Jurisdiction.

can add additional requirements to any national or international code.
So if the city is saying 3'. Then they probably have a printed version of their code. that you can get a copy of, and show to the HOA. They can not legally force you to violate an International, or local building/safety code.

Although a down facing U is for an intake. Nothing says it isn't the flue pipe, and terminated wrong.

Might want to recheck the piping.
And post a pic of the furnace and its PVC piping.
 
#10 ·
Got better info. It is an exhaust vent and the unit isn't in the attic. Downturn U wasn't required. I was thinking that he had a larger unit. Sorry. 3' only applies to attic installs. While 12" is the minimum, it depends on pitch of roof. Believe roof is steeper than average. Have forwarded pictures to the city so that it can try to determine pitch.
Direct vent has a different requirement then mechanical or natural.
However. if it doesn't have an intake pipe, it is not a direct vent system.
 
#25 ·
Even if using household air is permitted, I believe someone may have indicated it is better to use outside air. I would think that would increase utility bills.
Either way, you are essentially burning outside air, because everything going out the exhaust is coming from some where, and that air from some where is getting replaced by outside air. If anything I would think it would be less expensive to have a dedicated air supply, less friction and you don't loose any of the house heat through the air getting burned... but I'm only speculating.

Assuming the installer suggested a bayvent and my buddy didn't opt for one. It may have been more expensive.
Sounds like they are. My installer made some sort of reference that most local intallers do no use the bayvent and instead just use the turned PVC pipes.
 
#16 ·
Looks to me like the guy used an existing 4 or 5" chimney to run his exhaust pipe thru as a "single pipe" setup. That is legal with some furnaces and not with others. Depends on the brand and model of furnace. It is more efficient to take the combustion air from outside but in a moderate climate probably would not save huge $$. In a COLD climate YES. My concern is that if the wind is strong and blowing into that elbow it can cause pressure tripping problems with the furnace or flame rollout. We always vent ours vertical with no elbows. Any water in the smoke runs straight down anyway so there is no need for that elbow. Ugly setup and the local code will prevail.
 
#17 · (Edited)
I have seen those Bayvents and something very similar used with some high efficiency Rheems. Not sure if that is standard with Rheem or their idea of a concentric. I do not like them as the intake is very close to the house and VERY easy to plug with snow and spider webs/leaves and difficult to clean.
 
#20 ·
Your problem is not unique. Condos can be very anal about sightlines, drapery or anything that offends their sensibilities that someone wants to change. Not sure what to do other than camouflage it to match the color of the roof or get a lawyer to read the fine print of the purchase agreement/condo rules to see if there is any leeway for changes.
 
#24 ·
Unless the intake is connected directly to the furnace. Its not a direct vent system.

Sounds a bit like your son's friend fell for a good sales pitch.

Now you know why the contractors license isn't valid anymore.
 
#28 ·
You'll need to check to see if its directly connected.

If it comes from the roof the same as the flue is. Then you only need 12" above normal snow accumulation.
 
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