Clothes Dryer Installation, Venting and Repair Issues

Here are some of the common clothes dryer questions and issues I've had to deal with over the years.  Hopefully they'll help you solve your own dryer problem!                    NH

My clothes dryer seems to get very hot, but the clothes are not drying. Why?

Though the problem can be caused by a faulty thermostat or other mechanical problem,  most of the time the cause is a blockage in your dryer's exhaust vent. Clothes dryers are not air-tight, and if a blockage in the vent occurs, the hot, damp air that would ordinarily safely blow out is instead trapped inside the drum, leaking slowly around the door and any other small exit points in the dryer body. The heating element, however, continues to warm the air in the dryer at full clip, causing the temperature within the dryer to soar, sometimes hot enough to damage delicate clothes inside.

I often get a call to do a repair, cleaning, or replacement on a dryer vent hose after the appliance guy has checked out the dryer and given it a clean bill of health!! Had the client called me first, they may have saved themselves a hefty bill for labor.

Do the following checkup before possibly wasting your hard-earned money:

• First, check the vent outlet. This is the gizmo on the outside wall of your house (or sometimes the roof) where the moist, heated air from the dryer escapes. Does the flapper or backflow valve open and close easily? If not, clean it by removing as much accumulated lint as you can. Once it is working smoothly, you can apply some silicone spray lubricant to it to improve the action.  
• Check the dryer vent hose itself. Is it crushed or kinked behind the machine? If you have a long length (a run across your attic floor or basement ceiling), there may be a blockage in it. You can disconnect it from the rear of the dryer and use a electric leaf blower to clear it. This doesn't always work, but it is worth a try, since the alternative may be to replace the entire hose.
• The last place to check is with the dryer itself. It is not within the scope of this site to get into the nuts and bolts of appliance repair and disassembly. If you are game to do a little surgery, you might find a blockage within the machine. If there is a visible blockage at the vent hose connection behind the machine, you may be able to remove much of it by hand and the balance with a vacuum cleaner. Also, the lint trap may provide access that may be vacuum-able without having to disassemble the dryer!
• If none of these remedies solve your problem, it may be time to call AAAAAAAA Appliance Repair (usually listed right before AAAAAAAA Pest Control)!!

How do I choose a dryer vent hose?

For many years, the material of choice for clothes dryer venting, and still widely used for bathroom exhaust fan venting, was common flexible plastic vent hose, 4" diameter. I have seen this material run across attic floors, basement ceilings, and even inside walls. There are two problems with this material. First, over time the heat can cause the plastic to stiffen and deteriorate. Secondly...

IT CAN BURN!!

Actually, this is a no-brainer when you consider the heat that a clothes dryer is generates, as well as the flammable lint that can accumulate in the hose. We must never use this material in any concealed area!

What are the alternatives to plastic vent hose? Most if not all local building codes restrict the use of plastic ducting to exposed locations only, and/or for use with appliances that do not blow heated air, such as bathroom vent fans. Fortunately, various manufacturers have developed products that are excellent replacements.

There are three commonly available types of dryer venting products: rigid pipe, expandable aluminum ducting, and flexible layered aluminum ducting.

Rigid metal pipe: If you are planning a long run, such as across a basement ceiling or attic floor, you need to use a material that provides the least resistance to air flow. Dryers are not designed to blow with great force, so once you get past 5-10 feet, they begin to labor. However, the inside of rigid pipe is smoother, so it lets your dryer breathe easier. You can use compatible elbows for corners.  You should have a minimum number of elbows in you installation... more than two is generally frowned upon by dryer vent gurus.

Expandable aluminum ducting: There are times when rigid pipe is difficult or impossible to install, so the second choice is expandable aluminum ducting. It comes packaged in different lengths, and is sold compressed. It can be stretched out, but can only be expanded to its full length if two people work together to stretch it out. If you try to expand this stuff alone, it will dent and could become unusable. However, it will bend enough to turn all but the tightest corners, giving more installation options. When fully stretched, it offers less resistance than the plastic pipe, but more than rigid aluminum. It is a good compromise for longer runs, but only if the rigid pipe cannot be used.

Flexible layered aluminum ducting: The third option is a composite material of aluminum foil layered with plastic fibers for strength. It is so flexible that it can be used as a direct connection from the dryer to the wall. It is similar in appearance to the plastic ducting (accordion-like). Like the plastic venting, it has a higher resistance to air flow than the previous two types. It should only be used in short runs under ten feet, or in unusually difficult locations, where its superior flexibility is needed.

A note about manufacturer recommendations on long runs of dryer vent hose...

Most if not all dryer manufacturers now routinely add to their list of 2 billion disclaimers the maximum vent hose length recommended for their machines. They also recommend the use of rigid pipe only. Obviously covering their "you-know-whats", they put 99% of all homeowners in immediate violation of their dryer's warranties by demanding hookup requirements that, in some older homes, are virtually impossible without great expense. Instead of supplying the homeowner with realistic recommendations and guidelines (such as given above) they leave most of you swinging in the breeze. Give a big country thank you to our litigious system for this state of informational constipation!

I have heard that disconnecting the dryer vent hose and allowing the dryer to vent into the house can be a good thing to do in the winter months. It both heats and humidifies the air. Any thoughts, NH?

When the energy crisis was in full swing back in the seventies, I purchased a type of combination air filter/valve that sat on top of the control panel of my clothes dryer. It was installed between the clothes dryer exhaust port and the outside dryer vent outlet. It had a moveable plate inside that you could switch to either let the heated air blow through to the outside, or block the flow to the outside and divert it through a small filter mounted on the front of the filter/valve. I haven't seen one in years, but they probably are still available.

A newer style (shown left) is attached to the hose between the back of the dryer and the exterior vent.  There is a door that opens with a lever to divert the moist, heated air into your home.  Not shown in the graphic is a lint cover, mandatory if you don't want a dust storm in your laundry room!

There is a third type (shown right) that is also used in situations where a home does not have an exterior vent.  Damp dryer air is blown into an apparatus filled with water.  The water traps most of the lint.  Unfortunately, using this in the summer will warm your home and tax your air conditioner... unless you do what I do and hang out your clothes.  Let Mother Nature do the drying!

Despite their potential drawbacks, since most people who live in colder areas find the need to seasonally add some moisture to the air in their homes , this type of apparatus could be helpful. There are, of course, three caveats:

• DON'T USE THESE AIR DIVERTERS ON GAS DRYERS!! Gas clothes dryers do not have separate flues for the byproducts of the burnt gas... it simply exits your home via the dryer vent.  Though there are some "unvented" gas appliances, such as some space heaters and gas ranges, dryers produce more byproducts... carbon dioxide, carbon monoxide, and others.  Not allowing them to vent as the manufacturer intended is unwise.
• You must use some type of filter. Though dryers all have a lint trap of some kind built into them, these traps catch most of , but not all, of the lint. The lint that slips by can be both messy and irritating to some people. If you decide to "build your own", be sure to use a good filtering medium, such as the type of filter used in a forced air furnace. They are available at any hardware store, and easily cut to any size.
• Watch for signs of mildew!!  Be aware that you will be releasing a tremendous amount of moisture into the air in your home, so watch for the danger signs of over humidification, such as excessive condensation dripping off your windows, off your metal window or door frames, or, in the worst possible case, fish swimming across your living room!