Why is it bad to have a clothes dryer vent near an air conditioning condenser (outdoor unit)?

Thursday, July 12, 2018

Most air conditioning condensers dissipate the heat that the system absorbs in the process of cooling a home with a large fan mounted under a grille at the top of the condenser (outdoor unit) that sucks air through the closely-spaced fins in the condenser coils on the sides, and blows it out the top.  Combine this with the fact that clothes dryers have a filter screen to catch lint, but the screen is not 100% effective and some lint particles get exhausted at the termination of dryer vent duct, and the result is that a condenser unit near a dryer vent will suck the lint onto the fins, where it gets trapped. 

    As the lint builds up over time, the air flow through the fins is impeded, reducing the efficiency of the condenser and making it work harder to dissipate the heat through clogged fins. This is why some manufacturers specify that a condenser should not be installed near a dryer vent termination and also why we call it out as a defect during a home inspection—to avoid the lint crud layer on the surface of the condenser too close to a dryer vent shown in the photo above. 


    But there is no specification in the International Residential Code for a minimum distance between the dryer vent termination and an air conditioning condenser. The IRC defers to manufacturer’s instructions and only states that “if the manufacturer’s instructions do not specify a termination location, the exhaust duct shall terminate not less than 3 feet (914 mm) in any direction from openings into the buildings.” But the air conditioning condenser shown in the close-up photo above sits 8 feet away from a dryer duct termination and it was heavily caked with dryer lint on all sides. So, keeping the dryer duct termination and a/c condenser as far apart as possible is the best solution.

    Also, see our blog posts Why does venting a clothes dryer into a garage, attic, or crawl space cause problems? and  What are the most common problems with washing machine installation and maintenance?

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  To learn more about heating and air conditioning systems, see these other blog posts:

How can I find out the SEER of my air conditioner? 

My air conditioner won't turn on. What's wrong? 

How can I find out the size of my air conditioner? 

How can I tell whether the condenser (outdoor unit) is an air conditioner or heat pump? 

Where is the air filter for my central air conditioner and furnace? I can’t find it? 

Does an old air conditioner use more electricity as it ages? 

How did homes stay cool in Florida before air conditioning? 

What is wrong with an air conditioner when the air flow out of the vents is low?

Why has the thermostat screen gone blank? 

Why does it take so long to cool a house when an air conditioner has been off for a while? 

Why is my air conditioner not cooling enough? 

What are the most common problems with wall/window air conditioners?  

Will closing doors reduce my heating and cooling costs? 

    Visit our APPLIANCES and HEATING AND AIR CONDITIONING pages for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

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