PLEASE DO NOT MOVE DRYER CLOSER TO REAR WALL.(Part 3) Dryer Vent Safety

 

PLEASE DO NOT MOVE DRYER CLOSER TO REAR WALL. (Part 3) Dryer Vent Safety

In this series I have included this article (which is reproduced with permission) from my professional association; InterNACHI.  I’m reprinting it with a view to providing some of the reference data for the earlier articles that home owners and renovators can use to understand and plan laundry room and exhaust vent installations.

It will also give people a perspective on why inspectors will be talking about this problem whereas it was not only a few years ago.

Wall note

Dryer Vent Safety    by Nick Gromicko, Rob London and Kenton Shepard

Clothes dryers evaporate the water from wet clothing by blowing hot air past them while they tumble inside a spinning drum. Heat is provided by an electrical heating element or gas burner. Some heavy garment loads can contain more than a gallon of water which, during the drying process, will become airborne water vapor and leave the dryer and home through an exhaust duct (more commonly known as a dryer vent).

 A vent that exhausts moist air to the home exterior has a number of requirements:

1.            It should be connected. The connection is usually behind the dryer but may be beneath it. Look carefully to make sure it’s actually connected!

2.            It should not be restricted. Dryer vents are often made from flexible plastic or metal duct, which may be easily kinked or crushed where they exit the dryer and enter the wall or floor. This is often a problem since dryers tend to be tucked away into small areas with little room to work. Vent hardware is available which is designed to turn 90° in a limited space without restricting the flow of exhaust air. Restrictions should be noted in the inspector’s report. Airflow restrictions are a potential fire hazard!

3.            One of the reasons that restrictions are a potential fire hazard is that, along with water vapor evaporated out of wet clothes, the exhaust stream carries lint – highly flammable particles of clothing made of cotton and polyester. Lint can accumulate in an exhaust duct, reducing the dryer’s ability to expel heated water vapor, which then accumulates as heat energy within the machine. As the dryer overheats, mechanical failures can trigger sparks, which can cause lint trapped in the dryer vent to burst into flames. This condition can cause the whole house to burst into flames! Fires generally originate within the dryer but spread by escaping through the ventilation duct, incinerating trapped lint, and following its path into the building wall.

inferno

 InterNACHI believes that house fires caused by dryers are far more common than are generally believed, a fact that can be appreciated upon reviewing statistics from the National Fire Protection Agency. Fires caused by dryers in 2005 were responsible for approximately 13,775 house fires, 418 injuries, 15 deaths, and $196 million in property damage. Most of these incidents occur in residences and are the result of improper lint cleanup and maintenance. Fortunately, these fires are very easy to prevent.

The recommendations outlined below reflect International Residential Code (IRC) SECTION M1502 CLOTHES DRYER EXHAUST guidelines:

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.

This means that the flexible, ribbed vents used in the past should no longer be used. They should be noted as a potential fire hazard if observed during an inspection.

M1502.6 Duct length.

The maximum length of a clothes dryer exhaust duct shall not exceed 25 feet (7,620 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 (0.8 rad) bend, and 5 feet (1,524 mm) for each 90-degree (1.6 rad) bend. The maximum length of the exhaust duct does not include the transition duct.

This means that vents should also be as straight as possible and cannot be longer than 25 feet. Any 90-degree turns in the vent reduce this 25-foot number by 5 feet, since these turns restrict airflow.

 

A couple of exceptions exist:

1.            The IRC will defer to the manufacturer’s instruction, so if the manufacturer’s recommendation permits a longer exhaust vent, that’s acceptable. An inspector probably won’t have the manufacturer’s recommendations, and even if they do, confirming compliance with them exceeds the scope of a General Home Inspection.

2.            The IRC will allow large radius bends to be installed to reduce restrictions at turns, but confirming compliance requires performing engineering calculation in accordance with the ASHRAE Fundamentals Handbook, which definitely lies beyond the scope of a General Home Inspection!

M1502.2 Duct termination.

 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.

Inspectors will see many dryer vents terminate in crawlspaces or attics where they deposit moisture, which can encourage the growth of mold, wood decay, or other material problems. Sometimes they will terminate just beneath attic ventilators. This is a defective installation. They must terminate at the exterior and away from a door or window! Also, screens may be present at the duct termination and can accumulate lint and should be noted as improper. 

M1502.3 Duct size.

The diameter of the exhaust duct shall be as required by the clothes dryer’s listing and the manufacturer’s installation instructions.

Look for the exhaust duct size on the data plate.

M1502.4 Transition ducts.

Transition ducts shall not be concealed within construction. Flexible transition ducts used to connect the dryer to the exhaust duct system shall be limited to single lengths not to exceed 8 feet (2438 mm), and shall be listed and labeled in accordance with UL 2158A.

 In general, an inspector will not know specific manufacturer’s recommendations or local applicable codes and will not be able to confirm the dryer vent’s compliance to them, but will be able to point out issues that may need to be corrected.

 

 

Original blog post on ActiveRain: Link to Blog Post

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PLEASE DO NOT MOVE DRYER CLOSER TO REAR WALL. (Part 1)

PLEASE DO NOT MOVE DRYER CLOSER TO REAR WALL. (Part 1)

wall note

I believe that says it all.  But you must ask, why. Well. a quick glimpse behind the dryer reveals all (photo below).

There you can see the plastic flexible duct that will crush if the dryer is pushed any further.

exhaust vent ductIt looks like the home owner has used pipe strapping to hold the flex duct up off the floors so it wont be folded over itself or squished side ways like a ‘slinky’ toy could be.

This ducting is little more than a ‘slinky’ type coil that has been skinned over with plastic, so it is notorious for folding over on itself, sometimes more than once.

Obstructed: When this happens it is no longer a functioning duct and your dryer is going to take a long time to dry the clothes, basically baking them dry.

The other thing these ducts excel at is collecting lint. Sometimes the barely pass any air for years worth of lint in there. All those ribs make it easy for dust and lint to catch onto.

Now factor in the warm moist air and you have all the ingredients for mold proliferation.

Lovely!  But that’s not the most serious problem.

What? You say, could be more important than the dryer not drying the clothes or creating conditions conducive to mold?

Thats easy: fire! 

duct fire

Dryers that can’t vent, overheat and can cause mechanical failures that will produce sparks. That metal drum spins at a high speed.

Then of course thee’s always electrical arcing to set it off. Loose plugs, electrical motor bushings and short faults.

And some dryers are heated with gas. You get the picture.

It should not come as a surprise the fire codes address this problem directly.

In short, they ban the plastic flexible duct use and require that the first 3 feet from the machine be rigid metal ducting. This will be the hottest zone and will tend to collect the greatest concentration of lint.

Home owners need to install the attachment ducts in such a way so as to make the final connection after the dryer is pushed into place.

Wise dryer installers will place removable caps and ‘T’s in appropriate positions to make it possible to open and vacuum lint out of the ducts.

This is something progressive builders will plan for too.

 

So don’t bake your clothes, grow mold or burn your house down for want of a little ducting. Look for part 2 on how to do the duct well.

 

 

Original blog post on ActiveRain: Link to Blog Post

(AP) The apartment was dirty with mold. Insurance wouldn’t settle. An OMG File.

 The apartment was dirty with mold. Insurance wouldn’t settle.    It was A.P.          An OMG File.

girl wearing mask

I was calling to investigate a ‘mold’ problem that turned out to be dirt, soot in fact.

I asked my client why she thought there was mold. She brought out the air quality test report.

As I was reading it, her daughter came in from the other room. She was home sick from school and wearing a face mask.

She had respiratory problems. My hair stood on end.

“When is her medical appointment?” I asked. “Tomorrow” was the answer.

“So when you go see the doctors bring this air quality report and show them theses two words that I’ve underlined here.” So they did.

I called to follow up a week later and asked how the appointment went. Both the mother and daughter, as well as everyone else who lives in that building (8 people), are being sent to see specialists.

Oh yeah the two words; aspegillius penicillii ………(AP)

This is the plural form of aspergillus penicillium. This is a seriously severe group of molds that are toxic to humans and animals.

So if you have any reports or documents that read as if they were latin, have them explained to you.  A lab technicians report is only data.  It won’t tell you if a condition is serious or what to do about it.

Report interpretation and remedial consulting is a part of our service in the Montreal area.

 

 

Original blog post on ActiveRain: Link to Blog Post