Submitted by Randy Yates, Technical Supervisor and Technical Training Administrator, NPI/GPI Corporate Office
One of the most common household components installed by HVAC contractors — and one of the most common elements that requires maintenance other than changing a furnace filter — is a clothes dryer vent. According to statistics, clothes dryer vents are among the leading cause of home fires in the United States and Canada. How often to you look at the vent opening on the outside of your house let alone think about cleaning and maintaining the vent system?
The above-pictured positive-flow louvered dryer vent opening in itself looks like it is time for replacement let alone time for clean out, as pictured below.
Dryer vents require normal maintenance — meaning, yes, you do have to clean out your dryer vent at least annually and maybe more often because of the material that was or is used or the actual total length of the vent pipe itself that comes off the back of the dryer and goes to the outside of the house. The International Residential Code (IRC) states the following:
Material used for the vent pipe should be smooth metal duct with no screws.
Hm, wonder where somebody came up with the idea to use the white plastic accordion-like flexible tubing found at most of the big-box stores and, believe it or not, sold in the aisle with the right type of material. The white flexible material is for exhausting maybe a vent fan or something that doesn’t produce heat like a dryer vent can. The foil-like looking material is almost as bad.
Next is the length of the vent pipe. Again, IRC states maximum length can be according to manufacturer’s instructions (AMI) or 25 to 35 feet — this is depending on what version of the IRC you are looking at. Regardless, you have to take into account that elbows — 90- and 45-degree elbows — add to the total length of the vent. A 90-degree elbow adds 5 linear feet and a 45-degree elbow adds 3 linear feet to the total length. So, in some cases, you may have a longer vent pipe than what you realize. In some cases you may have to deal with longer-than-normal allowances.
Having the right type of material and length of pipe can reduce your maintenance. It is advised, though, to periodically check the louvered door on the outside of the house. Furthermore, annually, if not biannually, you should have the vent pipe system cleaned and inspected.