# Bathroom fan piping Q.



## Pcinspector1 (Mar 12, 2010)

Had a HVAC man ask me if he could use PVC piping to vent a bath fan out the wall or roof?

Flex pipe, solid aluminum and metal I have seen but not PVC. Two manufactured bath fans did'nt spec. the vent piping when I did some of the research. Is there any issue with static electricity because of the fan?

Any code againest PVC pipe for venting a bath fan?


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## klarenbeek (Mar 12, 2010)

Re: Bathroom fan piping Q.

See  IMC section 603.8.3 Plastic ducts and fittings.  They are allowed for underground duct only.  The only other exception I've allowed is for specialized exhaust where the manufacturer of a piece of equipment, for instance in a manufacturing process, required it.


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## JBI (Mar 12, 2010)

Re: Bathroom fan piping Q.

This is amusing. I can take what is basically Saran Wrap and a metal coil and vent a bathroom fan to the exterior, but I can't use SDR 35 or PVC Schedule 40?


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## klarenbeek (Mar 12, 2010)

Re: Bathroom fan piping Q.

As long as its listed to UL 181, yes.  I didn't write it, I just enforce it.  Although I've never seen it happen, I've heard of above ground exhaust using pvc that became plugged because of static electricity buildup.  Maybe that's the reason.


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## Pcinspector1 (Mar 12, 2010)

Re: Bathroom fan piping Q.

I did find a booster fan in a PVC housing to complicate this posted question.


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## Rider Rick (Mar 12, 2010)

Re: Bathroom fan piping Q.

Some contractors in this area use the light weight pvc pipe that you would use in ground to hook up to down spouts from roof gutters to duct there bathroom exaust fans.

It looks like a clean way to vent the fans and everyone says it is easy to work with. I approve it.

Rick


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## McClary's Electrical (Mar 12, 2010)

Re: Bathroom fan piping Q.

I see it used often to vent gas water heaters. Renai's.


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## klarenbeek (Mar 15, 2010)

Re: Bathroom fan piping Q.

Venting gas appliances is a different matter.  That is a manufacturer's instruction requirement that needs to be followed.  The fan housing is also different because it is a fan, not duct. 603.5 is clear in saying nonmetallic ducts need to be ul181 listed.  By the way, the vynil hose that comes in the fan kit from the big box stores is not ul 181 approved. Then read 603.8.3. Seems pretty clear to me.  Plastic duct and fittings for underground use only.  I can't just ignore code sections if I want to.  This is actually one that seems to be pretty clear without much (if any) gray area.


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## Rider Rick (Mar 15, 2010)

Re: Bathroom fan piping Q.

Nice call Klarenbeek,

Plastic ducting for underground only.

Rick


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