PVC Dryer Vent

Jon mackay · 05-16-2009, 07:48 AM

I have never seen PVC used as a dryer vent until today. Is it ok to use PVC?
It seemed that it would work but are there any rules on this?

Thanks

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Daniel Leung · 05-16-2009, 07:55 AM

Why not? if it's size is big enough for the airflows. I think the smooth inner surface is better than the flexible ducts.

**Scott Patterson** · 05-16-2009, 08:20 AM

Originally Posted by Jon mackay

I have never seen PVC used as a dryer vent until today. Is it ok to use PVC?
It seemed that it would work but are there any rules on this?

Thanks

PVC is not approved by the various manufacturers or the codes. Just think what would happen if you had a gas dryer venting through a PVC pipe! With an electric dryer, the most likely scenario would be a dryer lint fire and the PVC pipe melting.

**H.G. Watson, Sr.** · 05-16-2009, 08:32 AM

Moisture deposits, burrs on joining sections, and the static charge collecting lint deposits are all hazards for a dryer vent made from PVC.

PVC flexes, expands and contracts with changes in temperature, that coefficient is huge - another hazard using for dryer vent be it electric or fuel fired.

The thin expanding PVC dryer connectors are notorious for problems and are not listed for use with fuel fired dryers.

There is a distinct difference the dryer vent and the connector from the clothes dryer to the vent.

On a side note, low temperature, high efficient, condensing fuel fired appliances CPVC not PVC is preferred.

**Jerry Peck** · 05-16-2009, 09:13 AM

Those thin plastic and foil dryer connectors are NOT ALLOWED either.

Only rigid metal and flexible metal (typically aluminum) are allowed to be used for the dryer connector, which is what connects the dryer to the dryer exhaust duct and are visible outside the wall.

The dryer duct, some, most, or all of it concealed in the wall is no longer visible to any damage.

As Scott said:

Originally Posted by Scott Patterson

PVC is not approved by the various manufacturers or the codes. Just think what would happen if you had a gas dryer venting through a PVC pipe! With an electric dryer, the most likely scenario would be a dryer lint fire and the PVC pipe melting.

That is why they are required to be: (bold and underlining is mine)
- M1502.5 Duct construction.Exhaust ducts shall be constructed of minimum 0.016-inch-thick (0.4 mm) rigid metal ducts, having smooth interior surfaces with joints running in the direction of air flow. Exhaust ducts shall not be connected with sheet-metal screws or fastening means which extend into the duct.

Note that the codes used to state 26 gage, however, in making them compatible to metric dimensions the 0.4 mm thickness is equivalent to 0.016 inches, which is 27 gage (27 gage is 0.0164 inch, with 26 gage being 0.0179 inch but not as close to 0.4 mm).

Thus, has happens frequently with code changes and adaptation to other standards, the standard as been weakened slightly.

Jon mackay · 05-16-2009, 11:28 AM

OK, so I'm going to recommend replacing with the smooth metal dryer vent then. The pvc is schedule 40 also but I suppose that does not really matter since it is still not metal.

Thanks for the info everyone.

**Scott Patterson** · 05-17-2009, 09:34 AM

Originally Posted by Jon mackay

OK, so I'm going to recommend replacing with the smooth metal dryer vent then. The pvc is schedule 40 also but I suppose that does not really matter since it is still not metal.

Thanks for the info everyone.

When I was inspecting down in Mississippi, we had several areas that the AHJ allowed for schedule 40 PVC pipe to be used for dryer vents. It took about five years of my reporting that they were wrong in new construction for a few of them to stop allowing them. I even had it in my own home, my dryer vent went under and through the slab of my home. I had so much trouble with it that I had to reroute it, to the garage!

When I sold my home I just connected it back to the underground vent and sealed up the hole to the garage.

**Jerry Peck** · 05-17-2009, 10:37 AM

Originally Posted by Scott Patterson

When I was inspecting down in Mississippi, we had several areas that the AHJ allowed for schedule 40 PVC pipe to be used for dryer vents. It took about five years of my reporting that they were wrong in new construction for a few of them to stop allowing them.

When I was inspecting (code inspections for the city) in the Florida Panhandle they also allowed Sch 40 PVC to be used as Scott described.

Before I left there (just helping out) I have convinced them that it was not according to code and was therefore not allowed. I have no idea if they went back to allowing it after I left or if they actually understood it was not to code and no longer allowed it.

Their reasoning was that the galvanized duct in the ground would rust out and not last. I explained that, while they were correct on that, there was no requirement to put the duct underground and therefore no need to allow the wrong material to be used just because someone wanted to do something like that, that if they wanted the dryer exhaust to go underground then make the duct out of stainless steel duct so it would last - don't allow something wrong just to make up for something stupid being done.

The result was: stainless steel cost to much to do that, so they routed the dryer duct differently, and a lot shorter distance. Duh!

**Jim Luttrall** · 05-17-2009, 02:38 PM

Yep, nothing but trouble on underground pvc vents. I tried it in two houses I built and then lived in and found out the hard way.
The real issue was the underground part causes a heat sink keeping the vent pipe cold and the warm moist air from the dryer exhaust will condense inside the vent pipe and collect lint. I usually had to unplug the pipe regularly to get clothes to dry. Go overhead with metal. Even stainless in the slab or underground will cause problems, IMHO.

**Jerry Peck** · 05-17-2009, 06:08 PM

Originally Posted by fritzkelly

OK for a furnace but not a dryer?

Yep, because it is NOT okay for a furnace using a Type Gas Vent, only a high efficiency furnace (condensing type), which the dryer is not.

David Crawford · 03-01-2011, 04:09 PM

Originally Posted by Scott Patterson

When I was inspecting down in Mississippi, we had several areas that the AHJ allowed for schedule 40 PVC pipe to be used for dryer vents. It took about five years of my reporting that they were wrong in new construction for a few of them to stop allowing them. I even had it in my own home, my dryer vent went under and through the slab of my home. I had so much trouble with it that I had to reroute it, to the garage!

When I sold my home I just connected it back to the underground vent and sealed up the hole to the garage.

Any chance you shared this info with the buyers?