Jim Rooney On The Level

Q. We had our vents cleaned out recently and the tech noticed that there is an accumulation of dryer lint inside the wall. Apparently at some point the dryer duct hose was not properly attached so the lint was being funneled into the wall instead of outside. We don't know how long this had been the case. Do you think this could be a possible fire hazard? If so, would we have to tear open the wall to scoop it out?

A. You have hit on one of the most overlooked maintenance items in the modern home-- dryer vent maintenance. I commend you for having your duct cleaning efforts to include the dryer vent. I normally only recommend HVAC duct cleaning if they really need it. You can tell if it’s due by taking a flashlight and peeking into the return air grille and if you see it packed with dust and pet hair it’s time. Folks with pet allergies will react negatively if the air system has been exposed to cats and dogs for a long period and they accumulate lots of pet dander and hair. Ducts exposed to years of tobacco use also are strong candidates for cleaning.

Normal household dust resides in ducts and stays put, often referred to as resident dust, and does’t restrict air-flow. The fan speed of the furnace or air-handler is not powerful enough to dislodge so it stays put. If you graph air quality on a common air system it will actually go down during and just after duct cleaning and will return to where it was prior to the cleaning effort after a short while.

Dryer ducts, on the other hand, are susceptible to lint accumulation. Most homeowners think that the lint screen in the dryer catches all the lint-- not so. It catches most of it and while good dryer users clean the lint screen after each load of laundry drying the vent never gets a look. I’ve seen some amazingly bizarre venting errors. I was called to a house by a friend after Tropical Storm Isabel. The finished lower level had flooded up to about the four foot level and the insurance company had all the drywall and insulation in the walls removed. I was asked to look at the frame to see if the damage went any further. When I got to where the washer/dryer had been I saw a wall cavity packed solid with lint-- why the flood remediators didn’t pull it out I’ll never know. The vent had become blocked, never cleaned and just continued to dump lint into the wall. I asked how well the dryer worked and was told it was taking longer and longer to dry clothes and they had been thinking about getting a new dryer. I pointed out the problem and noted that they probably didn’t need a new dryer had the old one not been submerged.

I’ve seen dryers vented into crawl spaces, garages and attics. The worst I ever saw was some enterprising nitwit who couldn’t see his way to properly vent the dryer where he wanted to locate it and took a four inch PVC plumbing sewer line T fitting and spliced it into the main sewer drain, waste and vent system. Worked for him but turned his dryer into a sewer vent when it wasn’t drying. Venting dryers to the exterior of the house has been in the building code for as long as dryers have been in use. Residential drum style dryers really became common in the 1950s and are considered a household essential these days.

When I spot a disconnected or misdirected dryer vent that has been dumping lint around its space I recommend, after fixing the leak or misdirection, that someone take a shop-vac and clean all the lint from the joists or rafters for just the reason you cite-- fire danger. One spark and it’s off to the races. Lint burns rapidly and when I read about a fire I always pay attention to the cause if it’s listed in the report. Dryer fires aren't uncommon.

The first thing to do with any dryer installation is to look at the vent material. The most common cheap stuff is vinyl hose. Replace that with aluminum or stainless steel dryer vent tubing. It’s not expensive and easy to work with. The other trick that is commonly overlooked is to install the dryer first so you can stand where the washer will go and get the dryer vent short and straight. Most folks install the washer first-- probably because there are four items to connect-- two feed water hoses, one drain hose and the 120v plug. Then they hook the dryer vent hose up three feet from the wall and shove it in next to washer, kinking the hose. Each bend in the dryer vent hose creates resistance of air flow and will be a lint catch point. Take a flashlight and look behind almost any dryer installation and you’ll see the vent snaking all over-- next to the missing socks.

In your case, the lint that’s in the wall cavity will be confined to one stud bay-- the fourteen and a half inch wide by ninety two and half in space between the studs through which the vent passes. Just pull out the vent and using a shop-vac hose suck all the lint out. That should be an easy job. Check your progress with a flashlight and a hand mirror.

Keep the mail coming. If you've got a question, tip, or comment let me know. Write "On The Level," c/o The Capital, P.O. Box 3407, Annapolis, MD 21403 or e-mail me at jimrooney@jimrooneyonthelevel.com or inspektor@aol.com.