I understand that it is possible to simply clean the AC / Heatpump coils with a gentle water spray (cooling fins are delicate). I found a can of Web coil cleaner and emptied it into 3 condensors. I have a fleet of 13 more coils: a mixture of heat pumps and ACs.

What is the incremental benefit of using the canned coil cleaner over simply hosing down the coil? I'd like to understand the answer to the question before I burn through 6 cans (~$50) of coil cleaner every year.

Any insight into the chemistry is appreciated. If you are a pro (service ACs for a living), please indicate this in your response: such experience would carry more weight

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    You ask good questions, 21 in the last year but you haven't accepted one answer. Just curious as to why. – JACK Apr 15 '20 at 23:25

I use concentrated liquid and will consider it the same as canned cleaner.

Condenser cleaner or coil cleaner is formulated to take grease and oil out on top of the dirt. I use Nu-Calgon , Nu-Brite this is a non acid cleaner that mixed with water cuts the grease and oil and actually removes dirt better because of its foaming action.

In my early days I used to use a surfactant this breaks the water surface tension and cleans the dust out better but you have to mix the surfactant and water (I use a 2 gallon pump sprayer)

Over the years I noticed that some brands coils really collected dust compared to other brands, it turns out it is oil left over from the manufacturing process. Cleaning with a non acid cleaner will provide superior results (even simple green is better than water) I found the Nu-Brite and it works better ,

I proved the cleaners worked better by flushing with simple green, rinsing well then spraying with Nu-Brite as the foam pushed out the remaining dust I was quite surprised how much was left. A quick rinse and for grins I repeated , the foam was coming out clean. This is why I switched to “canned cleaner” I also noticed after treating with the Nu-brite the coils were not as dirty the next time. I know part of this was cutting the oil and believe simple green did that but it did not push all the debris and residue out like the foaming cleaner.

This provides several reasons that cleaner is better than water, cutting oils, breaking surface tension and a foaming action.

  • Nice post. If the purpose of the incremental treatment is to remove oil / organics compounds. I wonder if Dawn dishwashing soap would be as effective as Nu-Brite or Simple green. I think your litmus test is the color of the foam? I like that you have a process to verify outcomes. – gatorback Apr 15 '20 at 16:21
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    Dawn would work but to get it in the center of the fins it would need to be well diluted I did not mention I have used it (I used to carry a 1/2 gallon to use as a pull soap for electrical) it will clean the oils off and when you get no more suds out you know you have the residue out (that’s why I don’t use it it suds forever :). Nu-brite is the best I have found but my time on a job adds up fast so that is also part of the evaluation I did not mention. – Ed Beal Apr 15 '20 at 18:50

Some cleaners contain acid or compounds that will accelerate the breakdown/dissolution of fins, and can increase corrosion between copper and aluminum. HVAC forums are full of posts of fins eaten away.

That said, a relatively new study showed 'dirty' fins create more turbulence and increased the cooling capacity (by no longer having a laminar flow region). It's considered very controversial given 'what everyone knows about dirty condensers', but having read the paper and methodology, I found it to be very spot on.

  • So if you use a acid based cleaner for cleaning every 6 months as recommended and even required by some warranty’s when the fins are gone and there is no warranty protection because you used an acid based product , there is No warranty. @j.hirsch do you have some interest in the replacements of condenser coils , like stock or work for a manufacturer? This is the worst advice I have ever seen! Even dog per is enough to damage or destroy a quality condensing unit.- – Ed Beal Apr 16 '20 at 1:41
  • @EdBeal Huh? What are you talking about? This is an outdoor unit, not subject to the vagaries of constant plumes of smoke, soot, oil. The worst they see is pollen and cotton wood. Why are you going to acidify it and destroy the coils? Reading 3 manuals it says Wash them/keep them clean. I don't understand your hostility or insinuations, nor your attempt to create a conspiracy. – J.Hirsch Apr 16 '20 at 21:02
  • I specifically stated acid free in my answer , All the ones I have serviced have oil residue on the fins that collects dust, I was commenting on your answer that talks about more turbulence. Manufacturers suggest a minimum of 2 cleanings a year. Based on your statement of more turbulence is where my comment came from. Yes outside units do get affects by soot. – Ed Beal Apr 16 '20 at 23:39

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