{"id":15832,"date":"2019-03-24T16:42:44","date_gmt":"2019-03-24T16:42:44","guid":{"rendered":"http:\/\/www.lifeandnews.com\/articles\/?p=15832"},"modified":"2019-03-25T05:51:50","modified_gmt":"2019-03-25T05:51:50","slug":"skip-this-chore-cleaning-your-air-conditioner-condenser-probably-wont-make-it-work-better-2","status":"publish","type":"post","link":"https:\/\/www.lifeandnews.com\/articles\/skip-this-chore-cleaning-your-air-conditioner-condenser-probably-wont-make-it-work-better-2\/","title":{"rendered":"Skip this chore: Cleaning your air conditioner condenser probably won’t make it work better"},"content":{"rendered":"

David Yuill<\/a>, University of Nebraska-Lincoln<\/a><\/em><\/p>\n

I asked my neighbor who hoses off his air conditioner condenser every spring why he does it. \u201cBecause my dad always told me I had to,\u201d he said.<\/p>\n

Conventional wisdom like what my neighbor\u2019s dad imparted may always seem right. But through my HVAC scholarship<\/a> \u2013 the study of heating, ventilation and air-conditioning systems \u2013 I\u2019ve learned that this particular presumption is probably wrong.<\/p>\n

Dirty equipment<\/h2>\n

The equipment I\u2019m talking about washing is the outdoor part of central air-conditioning systems that move heat from homes into the outdoors.<\/p>\n

Technically known as condenser coils, they are usually about the size of a large garbage can but they can be as small as a bucket or as big as a refrigerator. Some are protected by louvered grilles but most are exposed to the elements. Their metal fins help transfer heat to the air. They contain tubes that carry the hot refrigerant, which gives off heat as it condenses.<\/p>\n

Stuff like windblown seeds, dust and grass clippings tends to collect on the coil surface. Most homeowners and HVAC companies envision that this untidy-looking stuff acts like an insulating blanket, slowing down the passage of heat from inside to outside. Any debris that accumulates would also interfere with airflow over the coil, further restricting the system\u2019s ability to expel heat.<\/p>\n

The nitty-gritty<\/h2>\n

Mehdi Mehrabi<\/a>, an architectural engineering graduate student, and I set out to learn the extent to which dirty residential air conditioners are less efficient than clean ones. What we found astonished us \u2013 and many of the other experts in this field.<\/p>\n

Previous work on this question simulated outdoor dirt with synthetic materials in a laboratory setting, or used reduced airflow as a proxy for the effects of dirty coils. Although it\u2019s necessary to carefully to control operating conditions, we took a novel approach: collecting condensers that had gotten dirty through ordinary residential use, and bringing them to the lab for study with a special test apparatus<\/a>.<\/p>\n

This meant that they were coated in real-world dust and other crud in everyday amounts. We tested the dirty air conditioners, then washed them thoroughly with a garden hose and tested again. We also used a commercial coil cleaning fluid and tested them for a third time.<\/p>\n

\"\"<\/a>
Close-up of 7 grams of dirt per square foot on an air conditioner condenser and that same condenser after it\u2019s cleaned.<\/span>
\nMehdi Mehrabi<\/span>, CC BY-SA<\/a><\/span><\/figcaption><\/figure>\n

Surprisingly, we found that dirty air conditioner condensers often perform better than clean ones. The change in condenser coil heat transfer performance ranged from a 7 percent increase to a 7 percent decrease for the coils we tested. The average change was \u2026 none at all.<\/p>\n

\"\"<\/a>
Close-up of 17 grams of dirt per square foot on an air conditioner condenser and that same condenser after it\u2019s cleaned.<\/span>
\nMehdi Mehrabi<\/span>, CC BY-SA<\/a><\/span><\/figcaption><\/figure>\n

The coil that registered a 7 percent improvement after getting cleaned up looked quite dirty, with 7 grams of dirt per square foot of coil surface area. But the coil that performed 7 percent worse was even dirtier, with 17 grams of dirt per square foot. It was so filthy, in fact, that it was nearly impossible to see the metal fins before we gave it a wash. Most of the condenser coils we tested in the lab were cleaner than both of those.<\/p>\n