Install dryer duct

Developed in 19th-century England, the first mechanized clothes dryers were perforated barrels that rotated over flames. But where does the air go once it has stolen moisture from your socks, shirts, and hand towels? The ridged design of these ducts, however, tends to pose a fire hazard : In short, they trap lint. For that reason, experts now instead recommend the use of rigid or semirigid hose; either can be found easily and purchased inexpensively in the diameter appropriate for your appliance for most dryers, the correct duct size is four inches.

The shorter, the better. A straight path is the shortest possible route, but not always practical. If, say, your dryer sits in the basement, then the hose needs to make at least one turn. From that maximum, deduct five feet for degree bends, and two and a half feet for degree ones. Now comes the most challenging part of dryer vent installation: putting a hole in the exterior wall. In most cases, the opening must be four and a quarter inches wide for confirmation, consult the instructions provided by the manufacturer.

I suggest drilling a pilot hole first, then going outside to double-check its position. Install the dryer vent cap against the side of your house, being sure that its attached pipe fits through the wall opening you have made. Now go inside and connect the dryer duct to the vent cap pipe a degree elbow may be needed , securing the connection with a hose clamp.

Having moved the dryer into the desired spot in your laundry room, measure the distance from the back of the machine to the vent opening, accounting for all the necessary turns in the ductwork. With a pair of tin snips , proceed to cut the tubing to the length of the measured distance. If you are joining more than one length of tubing, reinforce all joints with foil tape. Switch on the dryer, then go outside to inspect the vent cap: It should be emitting warm air.

The most likely explanation is that one of the connections has come undone. Above you can see that we had to use a pair of elbows to lift the dryer vent duct into the building ceiling cavity.

Watch out : some manufacturers recommend against using sheet metal screws to secure dryer duct sections because the screws collect lint. Also if you have ever tried reaching into a dryer exhaust duct to clean it by hand and had your arm ripped open by the SMS screw you may have another objection. At above right our second dryer vent duct photo illustrates passage of the duct through the rim joist. Notice that we carefully caulked this opening both inside shown and outside the wall not shown.

This duct section can be inspected and if necessary cleaned by removing the outside vent cover. Photos courtesy of Eric Galow, Galow Homes. We secure connected dryer vent duct sections using metal foil tape at each vent section.

See the dryer vent duct photos just above. Watch out : manufacturers typically advise against using screws to secure dryer vent duct sections as the end of the screw protruding into the duct interior increases lint-trapping and may make the vent duct harder to clean. Specs for using flex duct for dryer venting : If despite our recommendation for metal exhaust duct material you nevertheless are using flexible fan duct, stretch the flexduct tight to keep it as straight and smooth inside as possible.

Long sloppy bending flexduct runs significantly reduce the performance of the vent fan. Connect the flexduct to the fan itself using plastic ties, or second best, duct tape.

Keep all connections tight and avoid air leaks. Connecting the dryer vent to the back of the clothes dryer : space is usually tight between the clothes dryer and its exhaust vent because homeowners want to push the dryer back as close to the wall as possible. If you use flexible or even semi-rigid duct for the dryer connection at this location a most common practice the duct is likely to be bent and crushed closed, increasing dryer operating time, cost, and fire risk.

Our photo above illustrates how we connected a clothes dryer outlet through a laundry room wall into an adjoining utility room where the duct could rise to its ceiling and outdoor exit destination. On the other side of the wall in the photo shown above a periscope type connection adapted the dryer outlet to the through-wall vent. A "banjo-type" or "periscope type" metal dryer vent connector makes the 90 degree bend connection at the back of the clothes dryer where space is limited.

Our photo below illustrates a typical clothes dryer periscope vent that permits the back of the dryer to be placed closer to the wall than would be possible with round dryer vent ducting.

Periscope dryer vents are usually telescoping in length and sold in ranges such as " tall, or longer. The vent provides better air flow than a partly-squashed flexible duct dryer vent, and it resists crushing, therefore it's safer. Keep the vent duct sections as short, straight, and directly routed to the building exterior as you possibly can.

Our metal dryer vent installation shown just below has the right idea, though not a very neat installation and not properly sloped. Industry standards recommend that the maximum "concealed" rigid metal ducted clothes dryer vent length be no more than 25 feet IRC; some codes permit feet. That's because a normal 4-inch degree metal dryer vent elbow bends 90 degrees in a 4-inch radius while the Dryer-Ell product makes its bend over a more gradual inch radius.

Section M However the installation instructions and recommendations from the individual clothes dryer manufacturer are the final authority on how the dryer should be installed. Some dryer manufacturers permit installations with dryer exhaust venting of much greater lengths [though perhaps combined with a requirement to avoid use of 90 degree turns in the duct system].

Note: Fantech notes that. The maximum length for dryer exhaust duct cannot exceed 35 feet from the dryer location to the wall or roof termination. Slope the clothes dryer vent duct downwards towards its building exit - this will avoid condensation accumulating inside the ductwork and dripping back into the building ceilings or insulation.

It's fine for the dryer vent to rise vertically to enter the building ceiling, but within the ceiling the vent should slope downwards towards its exit point at the building exterior wall. Provide one or more dryer vent duct inspection access points at which you can disconnect and open the dryer duct system for inspection and cleaning.

This is especially critical in long dryer runs through ceilings and walls where the risk of blockage and fire would be increased. There should be no section of dryer exhaust vent ducting that is inaccessible for inspection and cleaning. Insulation around the dryer vent is not normally necessary if you install straight, well-supported metal ductwork sloping to its exit point at the building wall.

But if ductwork must be routed up and down through space such as an attic, air conditioned interior, or dryer vents routed through a cool crawl space where otherwise the duct will be exposed to cold air the result will be a significant level of condensation within the dryer vent duct system. For such areas and routing you should consider using insulated solid metal ducting or insulated flex duct to avoid condensation buildup, corrosion or leaks into the structure.

Install a secure, self-closing screened exhaust vent cover - the vent hood, outside the building at the end of the clothes dryer vent line in order to prevent rodents or birds from entering the ductwork. Every manufacturer's clothes dryer vent fan installation guide that we reviewed emphasized: make sure that the vent ducting carries moist air all the way outside of the building.

The preferred or most-recommended dryer vent routing is shown above, adapted from Whirlpool dryer vent instructions cited in detail below. Our sketches shown here, adapted from Whirlpool clothes dryer installation recommendations cited at the end of this article, show typical clothes dryer vent routing options includint a special provision for routing the dryer exhaust outside through a crawl space below a mobile home.

In some areas where winter air is very dry homeowners may choose to temporarily spill dryer vent air directly into the building interior in order to try to raise the indoor humidity level. This approach violates manufacturer instructions and is unsafe. Do not spill the laundry vent air directly into the building attic or roof cavity, basement, crawl space, or other hidden building interior areas. Doing so will lead to moisture condensation on building surfaces, wet, damaged, moldy building insulation, wet building framing members, wall, floor or roof sheathing.

In these locations spilling laundry dryer vent moisture will certainly encourage mold growth. And Cranor points out that spilling dryer vent products into the building can be a dangerous carbon monoxide hazard as well, at least for gas-powered clothes dryers.

Even if the dryer exhaust vent does extend to the outdoors, an improperly sloped, damaged, or disconnected dryer vent can leak moisture, lint, dust, and even dangerous carbon monoxide CO into the building.

Leak stains in building ceilings may be traced to condensate leakage from an overhead clothes dryer vent. Complete details about clothes dryer exhaust vent installation are provided below in this article.

Clothes dryer exhaust vents should be directed to the building exterior. Do not vent the clothes dryer indoors nor into an attic, crawl space, or other enclosed area. Vent the dryer duct to outside : Our photo above shows a dryer vent spilling directly below the building first floor into a soaking wet crawl space. Along with trash, debris, and other water entry sources, this crawl space was a moldy mess that had led to wet building insulation, mold contamination, and damage to the structure.

Do not vent clothes dryers directly into the attic space : you're only putting more moisture into an area where it is already going to be a problem, inviting mold growth on wood surfaces and hidden mold growth in building insulation. Avoid through-roof dryer vent exits : Our photo left shows a typical attempt at venting a upper floor clothes dryer through the attic and into a ridge vent - this direction of vent exit may seem convenient but we don't like it much.

In the photo left the droopy flex-duct will certainly invite clothes dryer moisture to condense and run back to the home's ceiling rather than exiting at the ridge. The through-roof vent approach gives us another roof penetration, a possible leak spot, and it almost assures that condensing moisture will drip down the vent duct and into the building ceiling. Additional roof top dryer vent photos below illustrate a vent that became lint clogged and that was snow-covered and blocked in winter.

Our second clothes dryer vent exhaust mistake is shown above: the installer hung the vent opening at the crawl space vent screen. Not only did lint clog the crawl space vent, but most of the damp dryer exhaust air soon was being spilled into the crawl space ceiling. Above: a clothes dryer exhaust vent installed in a mobile home can be vented down through the crawl space and outside through the skirting wall, but must never be vented to terminate right in the crawl space.

Exhaust vent must be securely fastened to a noncombustible portion of mobile home and must not terminate beneath the mobile home. Terminate exhaust vent outside. We include a table of the tempeatures that occur inside of clothes dryers at different places in the equipment and in its venting system and we describe unsafe dryer operating temperatures.

Clinton, I don' t understand the question. If you are asking if it is possible to route a dryer vent up a wall, across a ceiling, and outside the answer is yes - as long as the number of bends and total length are within the specifications in the dryer installation manual.

Derrick, That's a good photo to let me understand the type of problem at the wall, a picture of failure on a wall that has been repainted at least once, typically associated with moisture. It will be useful to have an opinion about the moisture source. It also would be useful not essential to have a photograph of the wall before it was painted.

But I need to see some other photos showing the whole area of the wall as well as groups of photo giving perspective showing the relationship of your structure to your neighbors.

Surface spalling on painted and even un-painted concrete is common and is pretty much always related to moisture; If the spalling were caused by your dryer exhaust vent then we'd expect to see the spalling pattern matching the dryer exhaust pattern where it would blow against that wall - and nowhere else. Dan, thank you , I have attached an Image of the alleged concrete damage.

Distance to his wall from our vent is 6ft exactly to where the damage is it is at least 10 ft from the vent. As for the siding I cannot see anything wrong at all.