# What is your code for water heater flue pipe/venting?



## crown36

As we all know, codes can vary from one place to another. What is your code for running flue pipe off a natural gas water heater? Are you required to use double wall? or only after you exceed a certain distance? Are you permitted to use 3" or 4" minimum flue pipe? What gauge for your single wall, if you're permitted to use single wall? I'm looking forward to hearing from you!


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## redbeardplumber

We can use 28 gauge, 3" 6'- 4" 8' then it's b vent. We can increase to 4" at draft hood.

However we cannot install these types of tanks in new construction anymore.


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## love2surf927

Not sure the gauge but we can use single wall in open spaces with a minimum of 6" clearance to combustibles, needs to transition to double walled b vent before going through the ceiling.

Size would depend on the appliance it's connected to.


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## plumber78

In Ohio, single wall to where it goes up through the floor above then double wall sized as needed for water heater. 40 gal gas would only need a 3" flue. The HVAC contractor usually runs the double wall for us on our plumbing only jobs. On jobs that we have CPVC or PEX on (which is 95% of them anymore), there must be 6" clearance from the flue pipe. We run copper off of the water heater until that clearance is met.


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## plbgbiz

No single wall here, period. Only type "B".

Sizing based on btu's.


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## GAN

love2surf927 said:


> Not sure the gauge but we can use single wall in open spaces with a minimum of 6" clearance to combustibles, needs to transition to double walled b vent before going through the ceiling.
> 
> Size would depend on the appliance it's connected to.



Yep same in our area, since there is not a State Code for venting. Never increase vent size without referring to vent charts, since you will loose velocity, which may be critical in a two story.


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## plumber78

GAN said:


> Yep same in our area, since there is not a State Code for venting. Never increase vent size without referring to vent charts, since you will loose velocity, which may be critical in a two story.


Yes, bigger is not always better in this case.


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## crown36

plbgbiz said:


> No single wall here, period. Only type "B".
> 
> Sizing based on btu's.


 What is the max BTU, before going to 4" in your area? We use to be allowed to run 3" up to 38,000, now it's 4 for EVERYTHING, regardless of btu. B required for anything past 6', here in MI.


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## younger-plumber

only double wall b vent here... we can use single wall on dryer duct tho lol


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## Tommy plumber

Type B in concealed locations. Type C {single wall} allowed only in exposed locations. Type L for oil burning appliances and such where heat would be too much for type B.

Sizing depends on BTU's and whether or not equipment is fan assisted or natural draft. Our code book for fuel gas has all the charts to size the vents and vent connectors.


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## LEAD INGOT

It depends on where you are at. And your code. Check with the fuel provider, and admin. Ive seen codes vary in counties.


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## Catlin987987

3" vents almost always backdraft and have lazy velocity, unless its a perfect vertical upshot right beside the Chimney


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## finkous

are you still able to install atmospheric vented hwt's in new construction in the states?? we can only install them in a replace only, all new construction must be power vented in my region


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## GAN

That is a loaded question in Illinois.

For the past few years Illinois has mandated compliance with the International Energy Conservation Code, currently the 2012.

With this in mind a house must be tested for air infiltration, which can't exceed 5 air exchanges per hour (modified & approved by Illinois not compliant with the text of the code) and whole house ventilation is mandated, a moderate sized home may for instance need a fan for continuous duty moving 60-75 CFM 24 hours a day, out of the home. 
So with this in mind a atmospheric draft unit may cause the home to not comply with the max 5 AHC per hour and may also with the negative pressure caused by the whole house ventilation cause the heater to vent back into the home.

Illinois does not restrict these W.H. but there are other factors to consider.


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## rjbphd

danielleyland said:


> The heater is installed the attic with a 3" B type pipe vent straight through the roof.


 Not a plumber here.... til introduction


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## BC73RS

Tommy plumber said:


> Type B in concealed locations. Type C {single wall} allowed only in exposed locations. Type L for oil burning appliances and such where heat would be too much for type B.
> 
> Sizing depends on BTU's and whether or not equipment is fan assisted or natural draft. Our code book for fuel gas has all the charts to size the vents and vent connectors.


Pretty much the same as here in B.C.


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