Can I Clean A Air Conditioner Coil With A Pressure Washer?

I asked my neighbor who hoses off his air conditioner condenser every bound why he does information technology. "Because my dad always told me I had to," he said.

Conventional wisdom like what my neighbor'due south dad imparted may e'er seem right. But through my HVAC scholarship – the study of heating, ventilation and air-workout systems – I've learned that this particular presumption is probably wrong.

Dirty equipment

The equipment I'm talking near washing is the outdoor office of central air-conditioning systems that move heat from homes into the outdoors.

Technically known as condenser coils, they are unremarkably virtually the size of a large garbage can but they can be every bit small equally a bucket or every bit large as a refrigerator. Some are protected by louvered grilles but almost are exposed to the elements. Their metal fins assistance transfer rut to the air. They contain tubes that acquit the hot refrigerant, which gives off heat as it condenses.

Stuff like windblown seeds, grit 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 estrus from inside to outside. Whatever debris that accumulates would also interfere with airflow over the curl, farther restricting the system'southward ability to miscarry heat.

The nitty-gritty

Mehdi Mehrabi, an architectural engineering graduate educatee, and I set out to learn the extent to which dirty residential air conditioners are less efficient than clean ones. What we found astonished u.s.a. – and many of the other experts in this field.

Previous work on this question simulated outdoor dirt with synthetic materials in a laboratory setting, or used reduced airflow every bit a proxy for the effects of dirty coils. Although it's 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.

This meant that they were coated in real-world dust and other crud in everyday amounts. We tested the dirty air conditioners, and so washed them thoroughly with a garden hose and tested once again. Nosotros besides used a commercial gyre cleaning fluid and tested them for a tertiary time.

Close-upwards of vii grams of dirt per square human foot on an air conditioner condenser and that same condenser later on information technology'southward cleaned. Mehdi Mehrabi, CC By-SA

Surprisingly, we found that dirty air conditioner condensers often perform meliorate than clean ones. The change in condenser coil rut transfer functioning ranged from a 7 percentage increase to a 7 percent decrease for the coils we tested. The boilerplate change was … none at all.

Close-up of 17 grams of dirt per square pes on an air conditioner condenser and that aforementioned condenser subsequently information technology's cleaned. Mehdi Mehrabi, CC BY-SA

The curlicue that registered a 7 percent improvement subsequently getting cleaned upwards looked quite dirty, with 7 grams of clay per foursquare foot of ringlet surface area. But the coil that performed seven pct worse was even dirtier, with 17 grams of dirt per square foot. It was so filthy, in fact, that information technology was nearly impossible to see the metallic fins earlier we gave it a wash. Nigh of the condenser coils we tested in the lab were cleaner than both of those.

No insulating blanket

To see how the equipment's performance could amend by getting muddy, we did farther testing.

That next round of written report suggested that the accumulated dirt stirs up the air passing over the condenser coils. Technically called "turbulence," these trivial gusts tin transfer rut abroad from the roll better. For some coil designs, this tin cause the equipment to perform meliorate when it'southward dirty than when information technology's clean. This is truthful even when the dirt has reduced the airflow charge per unit.

If your home has one of these things, you are probably wondering whether you should y'all wash your ain condenser. Here's what you should know.

The author, doing a job that his own research has found to be pointless. Florence Yuill, CC BY-SA

Cleaning your air conditioner might make it run improve. It might make it run worse. But information technology probably won't brand whatever difference. I at present personally believe in skipping this task, unless the curl is then dirty that it's hard to run across the metallic fins. Although, if it will make you lot feel better, go ahead and hose it downwardly. To exist honest, that's what I plan to do from now on.

Letting go of deep-seated beliefs of any kind is hard, whether it'due south that dieting makes yous lose weight in the long run – something recent studies do not support – or if this particular home maintenance ritual is justified. As news of our findings spreads, I'm bracing for some unpleasant responses from people who might lose out if the condenser-cleaning business dries upwards and others who merely refuse to accept that there was no ground for the conventional wisdom on this question.