electric dryer venting

[mdshunk]

Is it permissible to run an electric clothes dryer vent substantially in Sch 40 PVC or thinwall PVC vent pipe instead of sheet metal? I see this often done, but I'm troubled by it somewhat. Obviously, you'd never want to do this with a gas dryer. This question is with respect to electric clothes dryers only.

I know why installers choose the PVC. It normally comes in longer sections, and is generally easier to work with than sheet metal.

In new construction, it is often somewhat ambiguous who will run the dryer vent. Sometimes it's the electrician, sometimes it's the plumber, sometimes it's the HVAC contractor, and sometimes it's the general contractor. I'd just like to know the compliant material to use for the times when it falls on my shoulders.

[Wgoodrich]

Best way to answer your question as you stated is to provide a copy of that rule that applies. Hope this helps.

Also notice that the flex hose is only allowed in transition from the dryer to the dryer building vent. Also notice that it is forbidden that flex hose be buried in the building's structure.

Also notice the bold print dictating metal piping.
Also notice no screws are allowed to penitrate the ducting to the entirior of that vent pipe. This will catch lint and clog the vent pipe. The joints are required so that the pipe sliding into the other pipe slide inside facing toward the exhaust of the building. It is forbidden to install any screen across this venting system also, this too would plug the system.

COPIED SECTION IRC 2003;

SECTION M1501
CLOTHES DRYERS EXHAUST
M1501.1 General. Dryer exhaust systems shall be indepen-
dent of all other systems, shall convey the moisture to the out-
doors and shall terminate on the outside of the building. Ex-
haust duct terminations shall be in accordance with the dryer
manufacturer's installation instructions. Screens shall not be
installed at the duct termination. Exhaust ducts shall not be con-
nected with sheet-metal screws or fastening means which ex-
tend into the duct. Exhaust ducts shall be equippedwith a back-
draft damper. Exhaust ducts shall be constructed of minimum
0.016-inch-thick (0.406 mm) rigidmetal ducts, having smooth
interior surfaces with joints running in the direction of air flow.
Flexible transition ducts used to connect the dryer to the ex-
haust duct system shall be limited to single lengths, not to ex-
ceed 8 feet (2438 mm) in length and shall be listed and labeled
in accordance with UL 2158A. Transition ducts shall not be
concealed within construction.
Exception: This section shall not apply to listed and labeled
condensing (ductless) clothes dryers.
M1501.2 Exhaust duct size. The diameter of the exhaust duct
shall be as required by the clothes dryer's listing and the
manufacturer's installation instructions.
M1501.3Length limitation. Themaximumlength of a clothes
dryer exhaust duct shall not exceed 25 feet (7620 mm) from the
dryer location to the wall or roof termination. The maximum
length of the duct shall be reduced 2.5 feet (762 mm) for each
45-degree (0.79 rad) bend and 5 feet (1524mm)for each 90-de-
gree (1.6 rad) bend. The maximum length of the exhaust duct
does not include the transition duct.
in accordance with the dryer manufacturer's installa-
tion instructions.


Hope this helps

Wg

[mdshunk]

Thanks a bunch! Then, with regards to fastening lengths of duct, would rivets be the fastener of choice? (seems like they would catch lint just the same as zip screws)... or would foil tape be used alone with no mechanical fastener? or are the lengths of duct just banged tightly together?

[Wgoodrich]

Only banging tightly together then use of the tape is allowed. No penetration that will extrude into the interior of the piping that can snag lint.

Good Luck

Wg