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  • OT- Cleaning Evaporator Coil

    I want to clean the evaporator coil in my heat pump. It's not easy to get to, so I made up a spray wand that fits a pump up sprayer and a 90 degree turn, so I can spray a cleaning solution direct into the coil fins and not at an angle. Then I would flush it out the same manner.

    My question is, what would be a proper cleaner? Thoughts are Simple Green diluted, or dish washer detergent (no foaming), or laundry detergent, or? I want to clean but not harm the aluminum fins. Suggestions please?

  • #2
    There is a specific product designed for coil cleaning available from HVAC suppliers. I lost the packaging for the cleaner I bought and only have the remainder in a spray bottle so I can’t quote the brand.
    Joe

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    • #3
      Evaporator coil cleaner comes to mind. Its readily available and made for the purpose.

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      • #4
        this is what I used, also with a pump sprayer
        https://www.amazon.com/Nu-Calgon-416...63&sr=8-6&th=1

        works well, doesn't harm the fins and gets flushed out with the condensate. My house HVAC evaporator had an inch thick layer of animal fur, dust and mold on it from the previous owner not using a properly fitting filter. Took a while to scrub it off but the HVAC works alot better now (unsurprisingly). I give it a soak and scrub once a year. You can also use it on the outside unit too.

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        • #5
          DO NOT USE HOUSEHOLD CLEANERS! coil cleaners for aluminum are neutral to slightly acidic. Home Depot has a coil cleaner back in the plumbing section. Lowes probably does too. HVAC supply houses will carry several different brands, but are usually located in major metro areas.

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          • #6
            Originally posted by mattthemuppet View Post
            this is what I used, also with a pump sprayer
            https://www.amazon.com/Nu-Calgon-416...63&sr=8-6&th=1

            works well, doesn't harm the fins and gets flushed out with the condensate. My house HVAC evaporator had an inch thick layer of animal fur, dust and mold on it from the previous owner not using a properly fitting filter. Took a while to scrub it off but the HVAC works alot better now (unsurprisingly). I give it a soak and scrub once a year. You can also use it on the outside unit too.
            Thanks Matt! Just ordered mine.

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            • #7
              This is what the HVAC guys use around here. The coil cleaner is from a different company. The deodorizer/antibacterial is sprayed on when done supposedly to inhibit bacteria and mold. I had something, probably mold, that was making me systemically ill. I don't have anything to compare it to but it seemed to work okay. Has to be reapplied periodically. Nu-Calgon seems to have a number of products IIRC.

              The local installer said the A-coil really needs to be removed from the unit to get a complete cleaning, but it didn't seem to make a big difference from cleaning it in place.

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              • #8
                Remove the A coil? Seems like a $ generator to me...requires an evac and recharge with a recycle fee. Plus the mechanical labor. Wow! I’d like to have an HVAC tech explain that and be able to justify the value added amount.
                Joe

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                • #9
                  Originally posted by Joe Rogers View Post
                  Remove the A coil? Seems like a $ generator to me...requires an evac and recharge with a recycle fee. Plus the mechanical labor. Wow! I’d like to have an HVAC tech explain that and be able to justify the value added amount.
                  Joe
                  Ok, I will explain it. Most times it is NOT necessary to disconnect the lines and so no evacuation or recharge is necessary. There is usually plenty of slack on the lines to allow removing the covers and pulling the coil nearly all the way out of its case. In that position the underside of the coil can be accessed and cleaned also which cannot be done generally without pulling the coil out. Its not uncommon to find something similar to a wool blanket on the coil underside which peels off quite easily once access is gained, then a normal chemical cleaning is done.

                  BTW Most of the dirty/plugged coil issues stem from poor filter maintenance. Those cheap $1.00 fiberglass filters are all but useless but yet the most common ones people buy. A better pleated type filter (higher Merv rating) is far more effective at stopping the dirt from reaching the coil, the real good ones even filter smoke. The root cause of a large percentage of service calls stem from poor filter maintenance, plugged drains being a big one.

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                  • #10
                    Ok, now I will explain it.
                    The mode of failure on evaporators and condensers
                    is corrosion. They corrode because the tube sheets
                    are zinc plated steel, and the tubes are copper.
                    Over time, the steel corrodes and starts pinching
                    in on the copper tubes. Then the tubes start to
                    corrode and soon cell forms between the different
                    metals. Eventually a leak happens. Evaporators
                    and condensers are fragile after a few years of use.
                    I would not touch one or even expose one to vibration.
                    I sure as hell would not take one out of it's housing
                    just to clean it. Bad bad bad advice.


                    -Doozer
                    DZER

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                    • #11
                      As to filters... the pleated paper filters are way way too restrictive.
                      They clog in 2 weeks. The fiberglass ones flow way more air.
                      The tradeoff is to clean the evaporator more often. It is not
                      difficult to get in there with a 100psi air hose and get it clean.
                      Not sure fancy cleaners are really needed.

                      -Doozer
                      DZER

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                      • #12
                        Originally posted by Doozer View Post
                        As to filters... the pleated paper filters are way way too restrictive.
                        They clog in 2 weeks. The fiberglass ones flow way more air.
                        The tradeoff is to clean the evaporator more often. It is not
                        difficult to get in there with a 100psi air hose and get it clean.
                        Not sure fancy cleaners are really needed.

                        -Doozer
                        Your opinions go against all the industry standards, seems you wrote your own book.

                        The filter opinion is especially funny, "they clog in 2 weeks" LOL That is because they are capturing the dirt they are supposed to, instead of letting it collect on the wet coil and form mud plugging both the coil and the drain. If they clog in 2 weeks, its time for you to do a little more housekeeping.

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                        • #13
                          Originally posted by Doozer View Post
                          Ok, now I will explain it.
                          The mode of failure on evaporators and condensers
                          is corrosion. They corrode because the tube sheets
                          are zinc plated steel, and the tubes are copper.
                          Over time, the steel corrodes and starts pinching
                          in on the copper tubes. Then the tubes start to
                          corrode and soon cell forms between the different
                          metals. Eventually a leak happens. Evaporators
                          and condensers are fragile after a few years of use.
                          I would not touch one or even expose one to vibration.
                          I sure as hell would not take one out of it's housing
                          just to clean it. Bad bad bad advice.


                          -Doozer
                          What you describe is known in the industry as galvanic corrosion. It became much more of a problem over the years when manufacturers went to thinner walled copper tubing often referred to as rifled tubing. The fin material is aluminum and the copper to aluminum joint is where the leaks often occur, not just on the steel end plates. IF the coil is so corroded that removing it to clean it causes a leak then the coil is extremely close to the end of its life anyway and probably already leaks.

                          Removing a coil is NOT a common practice, its only done for badly plugged coils as a last resort. Normal chemical cleaning is all that is normally required. Coils somewhat self clean by the condensate flowing down the fins provided they are not full of mud because of poor filter maintenance.

                          So, what you call bad bad advice, is widely accepted practice in the industry and follows most manufacturers recommendations. But then, I am pretty sure you are not in the industry and do have have EPA level 3 or higher licensing required by true HVAC techs. Sleeping at a holiday in express last not does not qualify.

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                          • #14
                            Originally posted by CCWKen View Post
                            Thanks Matt! Just ordered mine.
                            you're welcome Ken!

                            Originally posted by Dane Bramage View Post
                            the can on the left I used 2 or 3 of first time. Helped a bit, foamed nicely too, but couldn't make much of a dent on its own. Bought the pump sprayer, the Nu-Calgon stuff and a long handled soft bristled brush and now it's about as clean as I can get it. This was definitely one that would have benefitted from being removed to clean. Still not 100% as I can't get up into the corners and there's some corrosion too, but good enough for a 14 year old unit. Hopefully it'll keep chugging along for a few more years yet.

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                            • #15
                              My shop A/C consists of a Frigidaire belt-driven compressor condensing unit coupled up to a semi-circular evaporator that originally had a paddle fan in the bottom, drawing air upwards and blowing out through the coils. Uses R-12 refrigerant, and came out of a small walk-in cooler. The paddle fin crapped out, and I replaced it with a small furnace blower & plywood box holding 2 filters; I use the pleated type.

                              The unit is about 2 tons capacity, a bit more than my shop requires, so it doesn't run for long cycles, but does a heckuva job when it's 90 degrees out.

                              I noticed a kinda sick feeling sometimes, and figured that it was due to 'something' growing in the condensate pan. If/when I notice that, I pour a pint or so of bleach into the pan.

                              No idea how old this outfit is, but I'd bet on its being 70 or more. When did they quit using 'open' compressors?

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