Dryer Duct Output

PCMLR · 10-19-2010, 01:19 AM

Hi, I first posted this in HVAC but decided to put it here too as it can't hurt. The window in my basement where the dryer duct will go was half built over by a shed. If that isn't clear, the window is literally half covered by an outdoor shed. It is an electric dryer.

Normally I realize the side of the window going directly outside is ideal. There are specific difficulties going that route. The shed is large and has nothing in it but rakes and garden hand tools. No electric or gas operated anything. No cleaners or solvents or chemicals whatsoever. It is a big open space where nothing is stored. Is it feasable to vent into this shed if the window directly opposite the vent is left open? Thanks in advance for your advice.

H. A. S. · 10-19-2010, 04:15 AM

If you vent into a shed, you know everything in there will rust up, right?

No, I wouldn't do it that way.

Michael Thomas · 10-19-2010, 07:24 AM

Exhausting within the shed will not comply with current national standards or any manufacturer's installation instructions (except for "condensing" type dryers):

IRC M1502.2 Exhaust ducts shall terminate on the outside of the building or shall be in accordance with the dryer manufacturer’s installation instructions. Exhaust ducts shall terminate not less than 3 feet (914 mm) in any direction from openings into buildings. Exhaust duct terminations shall be equipped with a backdraft damper. Screens shall not be installed at the duct termination.

secutanudu · 10-19-2010, 09:25 AM

What about venting through the shed, 90 upwards, then out the shed roof?

Michael Thomas · 10-19-2010, 09:32 AM

Assuming that the developed duct length (including reduction for turns) meets the manufacturer's requirements, that's a better idea.

Keep in mind:

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.

secutanudu · 10-19-2010, 09:40 AM

Can he use 4" PVC pipe?

And if he does go out through the roof, would he need an upside-down trap on top to prevent rain from coming in? And some sort of a cage to prevent critters?

Michael Thomas · 10-19-2010, 09:57 AM

Quote:

Originally Posted by secutanudu

Can he use 4" PVC pipe?

And if he does go out through the roof, would he need an upside-down trap on top to prevent rain from coming in? And some sort of a cage to prevent critters?

The IRC specifies metal pipe - there are around 15,000 dryer related fires a year in the US, and the duct must be a non-combustible non-outgassing material. Also, M1502 requires a duct "having (a) smooth interior surfaces with joints running in the direction of air flow", so you can't have a connection which slips over the PVC (unless it was somehow constructed to produce a smooth interior transition). The practical way to do this would be to construct a connector which forms the male end of the connection, but I'm not aware of any such factory made connection, and if they do not exist this would have to be factory or field fabricated.

There is a previous discussion of PVC dryer exhausts here:

Using 4" PVC for dryer vent

These are terminations ("roof-jacks") intended to vent dryers at roofs, both for flat roofs:

And pitched roofs:

I'm not especially fond of these as they often are not cleaned and become obstructed:

But if properly serviced, they work properly.

RST · 10-19-2010, 10:26 AM

Perhaps you could extend the ductwork through the shed and have it come out the other side of the shed, near the window? If so, consider insulating the duct to reduce internal condensation, and set the pitch so water drains outside.

As I understand it, dryer venting should use shortest, straightest run possible. When I moved into my current house, there was 25 feet of duct with numerous bends. After we noticed that clothes were not drying, I took it down to find 3" of lint buildup. We rerouted the duct straight out the roof (10 foot of duct) and put something similar to this on (without the screen): http://www.amazon.com/Broan-Nutone-6...ref=pd_sbs_k_1

RST

PCMLR · 10-19-2010, 10:29 AM

Quote:

Originally Posted by secutanudu

Can he use 4" PVC pipe?

And if he does go out through the roof, would he need an upside-down trap on top to prevent rain from coming in? And some sort of a cage to prevent critters?

For the record "she" not he but thanks to all! It's a 1950's home with complicated window boxes and other unexpected things to work with.

PCMLR · 10-19-2010, 10:39 AM

Quote:

Originally Posted by RST

Perhaps you could extend the ductwork through the shed and have it come out the other side of the shed, near the window? If so, consider insulating the duct to reduce internal condensation, and set the pitch so water drains outside.

As I understand it, dryer venting should use shortest, straightest run possible. When I moved into my current house, there was 25 feet of duct with numerous bends. After we noticed that clothes were not drying, I took it down to find 3" of lint buildup. We rerouted the duct straight out the roof (10 foot of duct) and put something similar to this on (without the screen): http://www.amazon.com/Broan-Nutone-6...ref=pd_sbs_k_1

RST

Now that's a thought. I actually have really good ductwork. The dryer is Whirlpool Duet, Very large , produces much heat. I bought really good ductwork because of the annual snowfall here in NH. At my last house there was a laundry room so it couldn't have been easier.
25 Feet sounds like a tough journey for lint and exhaust! My laundry area is in the basement. Maybe I should check in at electrical and see if there are extension cords for dryer plugs, that would solve a bunch of problems. Thanks for your help.

secutanudu · 10-19-2010, 10:56 AM

She...sorry!

You should move the outlet if you want to move the dryer. Extension cords (this would likely be a homemade one anyway) are not intended for permanent installations, especially for a high-powered appliance.

Where would you move the outlet? Is it somewhere along the feed to the current outlet (like back closer to the electrical panel)?

Michael Thomas · 10-19-2010, 11:13 AM

The installation instructions for your dryer are here (GOOGLE is your friend in such cases):

http://www.whirlpool.com/assets/pdfs...ruction_EN.pdf

Extension cords are prohibited (page 6).

The dryer MUST BE EXHAUSTED OUTDOORS (caps theirs, page 11).

The maximum allowable duct length is 64 ft, depending on the number of elbows ("vent system chart", page 13).

There's lots of other useful venting information as well.

PCMLR · 10-19-2010, 11:31 AM

Quote:

Originally Posted by Michael Thomas

The installation instructions for your dryer are here (GOOGLE is your friend in such cases):

http://www.whirlpool.com/assets/pdfs...ruction_EN.pdf

Extension cords are prohibited (page 6).

The dryer MUST BE EXHAUSTED OUTDOORS (caps theirs, page 11).

The maximum allowable duct length is 64 ft, depending on the number of elbows ("vent system chart", page 13).
.
There's lots of other useful venting information as well.

Michael Thomas, Thank you very much. Ignorance is no excuse, but it applies. I was unaware that beyond local and state code restrictions, limitations, etc...that each individual dryer had its own specs. Flawed reasoning based on the fact that only one type of dryer ducting is available locally. Lesson learned, will heed in the future. I'm going to the laundromat.

Michael Thomas · 10-19-2010, 11:52 AM

My apologies, the GOOGLE comment was not meant in a snarkey way, it's just usually the fastest way to find such information.

Yes, each major appliance you buy will come with a set of installation instructions, the building codes specifically "incorporate" the manufacturer's installation requirements for each appliance, and the installer is supposed to leave a copy - my first mistake was assuming you had received it.

PCMLR · 10-19-2010, 12:18 PM

Quote:

Originally Posted by secutanudu

She...sorry!

You should move the outlet if you want to move the dryer. Extension cords (this would likely be a homemade one anyway) are not intended for permanent installations, especially for a high-powered appliance.

Where would you move the outlet? Is it somewhere along the feed to the current outlet (like back closer to the electrical panel)?

The ideal place below a good window, is both on the same feed and closer to the electrical panel.

I know the question about an extension cord is odd but I bought this Sunpentown, I'd never heard of the company, portable AC, heater, air purifier. dehumidifier, (won't cook dinner though) which has optional ad-ons, one of which was some kind of cord extender. This unit is easy to use, I just place the built in duct in a window!