Evaporator Coil Cleaning

What is a recommended schedule for AC Evaporator Coil cleaning? I am in the process of creating a Preventative Maintenance program at our facilities and find that the Air Handler coils inside the apartments are only cleaned on an "as needed" Work Order basis.

Is that the industry practice?

MS's point to the poor design of up-draft type AHUs and the likelihood that the solvent will drip down on the water heaters that are usually installed in the closet below the AHU.

Thought's?

We always clean the coils at each apartment turnover. We change air filters every 6 months, and they check them then for cleanliness. If it needs it, they'll clean them when they change the filters, but we don't schedule it for more than that.

We typically cleaned the coils upon turns and/ or once per year. Be careful with what materials you use to clean them.

Okay, are we all on the same page? The Evaporator coils in a through the wall or window mount air conditioner are the ones behind the filter that are colder than the condenser coils. Right? The evaporator coils usually don't get too grody because they are not exposed to the outside air. It's the condenser coils that need to be cleaned usually. If the unit is running inefficiently, as in the air going in is significantly less than 15 degrees F hotter than the air coming out, clean the coils. Otherwise, the maintenance goofs (and I'm one of them) will probably do more harm than good.

The condenser coils are the ones usually outside with the compressor being a part of the assembly. The Evaporator is where the interior air is either cooled or heated depending on what phase the unit is operating in.
On the units at several of our facilities the Condenser and the Evaporator (Air Handler or AHU) are separate with the AHU being in a closet, often with the water heater installed at floor level and the Air Handler above.

The problem this presents is that the style of AHUs I have seen in most apartments is such that the box for the unit is open at the bottom for the air to draft up and through the coils. When cleaning coils you typically want to spray cleaner in the reverse direction of air flow so dust, debris, gunk etc. is pushed back though and not further between the coils.

Once you pull the filter the bottom is open so that if you clean with coil cleaner, water etc. all of the sludge can drip down on the water heater below (as shown in photo) and there really isn't good access to the top side of the coils in the AHU in the first place.

I am struggling with how to have a good Preventative Maintenance approach to AHU care while not creating an overly burdensome task for our Maintenance team.

This is my dilemma.

My mistake, you're talking about a heat pump or the like. Tools you will need: A Type II EPA 608 license or Universal license. If you're dealing with a device using more than 5 and less than 50 pounds of refrigerant. Access to a UL (or other certified) recovery device (very spendy.) Yeah, it's a stupid law based on poor science IMHO, from the 1970's but it's the, well, I'm not a lawyer so I can't say what the law is. The first paragraph of EPA 608 if I remember correctly deals with the requirements for those working on devices containing refrigerants. The fines can be huge. My advice in this case is "If it ain't broke don't fix it."

If you are cleaning the evaporator coils and replace the air filters once a year, you are doing more than 80% of your industry peers. You should also consider cleaning the condenser coils once a year.

The quick answer to your question is "as needed" with a corollary statement of "they are currently not cleaned often enough."

The challenge is that this procedure can be time consuming due to the vast variety of challenges encountered to do the job. Here are some thoughts for the situation pictured after you deal with the chemical dripping on the water heater issue. (by the way, I find that using a cat litter pan or other wide flat shallow tray that will fit under the coil opening can catch the chemical being sprayed.)

- Access: To fully and correctly clean the technician would need to spray the chemical ABOVE the coil and let it soak in for best cleaning. (as Bill Mentioned)
- Tools: The coil pictured would need to not only have the coil rinsed, chances are the fins would need to be brushed. (Technicians need to be aware there is a "grain" to the coil so air flow is not decreased. In the coil shown, I believe the brush must go up-down, not side to side) Getting this brush or other tools in can be a challenge due to the limited space.
- Add on job: What about making this a part of Water heater maintenance? When the water heater is removed for Anode Rod, or water heater replacement, clean the coil...
- If the technician does not touch the refrigerant, EPA certification is not required. Admittedly, the best way of cleaning the coil is to recover the refrigerant, remove the coil, thoroughly clean and re-install the coil and recycle the refrigerant back into the system. (Alternatively pull the refrigerant into the outside unit.) If technicians don't have the certification, a passable job can be accomplished in place with access.
- Refrigerant use: if the indoor coil (pictured) is clogged, the refrigerant pressure will generally decrease leading the technician to perform a quick fix of adding refrigerant. In reality, the only time refrigerant is added is when the system has a leak; provided the correct amount was installed prior. This means that if a leak is suspected, the first thing a technician would do is verify airflow. A clean coil and to other items such as open supply vents, and room circulation even when the bedroom doors are closed (undercut doors) must be checked before adding refrigerant.
- Chemical: Be sure that the technicians are NOT using Condenser cleaner or any other non approved product to clean the indoor coil. Bleach, Window cleaner, Biodegradable cleaner (the green one), or any other chemical not designed to be potentially circulated in the air of the apartment should NOT be used unless the coil is removed and thoroughly rinsed before re-installation. A warning to residents is a good idea as well.

If I were in charge, and the community had a stabilized maintenance operation in place, I would schedule Interior coil cleaning every 2-3 years and exterior coil cleaning every other year.

(Interesting aside... This past year I spoke with a Mgt company that had started giving residents a good vacuum cleaner as a present at move in. By doing this they were hoping that residents would vacuum the floor more frequently increasing the carpet life and decreasing the amount of dust that would attach itself to the coil... Creative solution that in theory might work...)

Good Luck!

Paul, thank you so much for your response. This is what I needed to understand.
I really appreciate it!

Paul: I always learn so much from your posts. Are you sure about not needing certification to replace a starter cap or such? It only makes sense of course, but as I remember the law it says that those people charged with maintaining, disposing of, or opening a system must be appropriately certified. It didn't say anything about "opening" meaning access to the refrigerant itself that I can remember. It could be construed to mean opening the cover. I would like to be sure... you know our government.

I think the whole thing is bad science myself. A very stable molecule such as R-12 which (according to the EPA) is many times heavier than air, jumps ten miles into the sky and then breaks apart to cause a catalytic reaction with the O3? Ah...really?

Thank you for the compliment Perry,

Yes, I'm sure. Section 608 until recent changes has always been directly about protecting the Ozone layer. New changes take the focus away from ozone layer protection into decreasing Greenhouse Gases since all currently useful refrigerants are at their heart: Hydrocarbons.

There may be local, state or other regulations that prevent service on equipment itself and/or there may be limitations added to EPA standards that impose limits and add liability. None of those rules state or imply that replacing a Capacitor (which in and of itself has it's own EPA rules for disposal) or any other electrical/mechanical repair is illegal.

Opening a system in the context of the Federal Clean Air Act is discussing refrigerant system only.

More detailed info can be found at: www.epa.gov/section608/stationary-refrig...ractice-requirements

Thanks for the link.

I'm probably just being paranoid but this worries me. From the same web site:
"EPA regulations (40 CFR Part 82, Subpart F) under Section 608 of the Clean Air Act require that technicians who maintain, service, repair, or dispose of equipment that could release ozone depleting refrigerants into the atmosphere must be certified. Starting on January 1, 2018, this requirement will also apply to appliances containing most substitute refrigerants, including HFCs." Just to nit-pick, Ammonia isn't a hydrocarbon nor is R-718 (water.) But, you won't find those in apartment air conditioners either.