What is the best way to clean an AC or secondary heat exchanger coil?

PF4DIY · Nov 30, 2014

Here is what my coils look like this morning

This is the AC coil

This is the Secondary heat exchanger coil

So now I hope that it is clear that my installer did not want to help me
The furnace is dirty and I have to clean it up.
What is the best way to clean these coils

I am thinking about vacuum first for a rough cleaning
Next I would use one of these if you guys are telling me that is right

and the last step would be to vacuum it again

SeniorSitizen · Nov 30, 2014

The vacuum with a soft brush attached. I would not use a steel brush. In some situations I've used a 3" diameter bottle brush rotated with a cordless drill motor to loosen debris a little deeper. May not work for yours.

PF4DIY · Nov 30, 2014

Did anybody try this?
https://www.youtube.com/watch?v=ZwT6Rq9ojMU

beenthere · Dec 1, 2014

While those spray cleaners do work well. You have to use them correctly. Which the guy in that vid doesn't do. Spraying at an angle like he does, it doesn't penetrate the coil, and get the dirt in the fins between the tubes. The can has to be held straight and spray straight into the fins. And you don't wipe it off. You run the A/C so that the condensate rinses off the coil.

PS: Wet A/C coils are not self cleaning. A wet evap coil is equal to a MERV 8 air filter. it catches dirt, and the dirt sticks to it.

user_12345a · Dec 1, 2014

^Are you saying that a merv 7 filter won't adequately protect a coil?

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Based on those pictures, it's safe to say the the filter wasn't doing it's job, possibly due to leakage around the frame or not changing it.

beenthere · Dec 1, 2014

Anything under a MERV 8 prevents the larger dust particles. But doesn't stop the dust/dirt that the coil will stop. So a 7 doesn't give the coil the dirt protection it should have.

PF4DIY · Dec 1, 2014

OK I am done with the cleaning.
Kind of. It was an in place cleaning and I did manage to lower the temperature of my furnace pretty well.
For those who are following my saga, the airflow downstairs did not improve.
The temperature of the furnace is better on the back side.
If the temperature measured on the ducts (outside) is pretty much equal with with the temperature in the duct then these areas improved as well.
Next step will be to clock the gas meter to see if I can fully open the gas valve

Regarding that spray used in the video above:
from the experience with my furnace I can tell you this: the spray is good to moisture the dirt that can be easier removed after that.
I did use it on the coil of my secondary heat exchanger and it help as mentioned above. Next was to use a brush attached to my vacuum and to clean the coil the best I could. This coil had stronger fins. I could not test the spray on the AC coil because I did not have the spray at that time

What is the best way to clean an AC or secondary heat exchanger coil?

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