Evap coil cleaning

[rattle_snake]

My home has 2 split units. Indoor air handlers are from 1999.

PO of home obviously didn't change filters and the main 3 ton unit's evap is a disaster. There were MANY other issues with HVAC system I dealt with over the first year or so, including unclogging drains and attempting to clean the coils. The home has a flat roof and essentially no attic, so handlers are vertical in dedicated closets. Intake at floor.
1st attempt was to flush, used LOTS of HOT water, but no noticeable change. Got drain fixed, balanced distribution. Moved on to life other challenges...

Recently tried again with Nu-Calgon 4171-75 Evap Foam No Rinse Evaporator Coil Cleaner

https://www.amazon.com/dp/B00DM8KQ3I/?tag=atomicindus08-20

I did 4 applications to both sides. Used hot water in a spray bottle to flush a bit (~1 quart). Again, no noticeable change. Lifeforms living on surface just laughed.

Nuclear option is to replace entire unit. Outdoor unit was replaced in 2011. Other than clogged evap, system is OK.

How to clean this or is it even possible? Access is rough from filter opening at floor level.

Filthy as hell.

 

[LXCam]

Oh that’s a lovely fossil. I’m sure there’s a better method but personally I’d try something that breaks down calcium deposits then your other stuff.

 

[FMB4]

Yep, carefully spray with white vinegar or CLR and than let it sit for several hours. Repeat until you see progress. Beyond that you'll need to replace the evp coil, etc (of course). That said, 1999 is slightly more than 10 years past it's 'due date' imo.

 

[rlitman]

Oh that’s a lovely fossil. I’m sure there’s a better method but personally I’d try something that breaks down calcium deposits then your other stuff.

It looks like calcium, but condensate water doesn't contain minerals, so where would the calcium come from?

I'd take the unit apart as far as I could so I could apply the coil cleaner from the clean side of the coil and let it work its magic for an hour. Then spray gallons of water through.

 

[LXCam]

It looks like calcium, but condensate water doesn't contain minerals, so where would the calcium come from?

Oh I know that and I'm not saying it is calcium, but its still what I'd try.

 

[rlitman]

Oh I know that and I'm not saying it is calcium, but its still what I'd try.

Fair enough. Since the rinse-free spray wasn't cutting it, I'd try an enzyme cleaner concentrate (not diluted). One of those things used to clean bathrooms. I'm betting the buildup is something between cardboard and felt. The acids that are sure to dissolve it will hurt the metal, but enzymes are safe as can be, though may not be entirely free-rinsing.

 

[karoc]

Those coils are a pity to clean so needless to say that they were not on schedule maintenance list. Back in my day when use to run roads I would try to get these type coils to clean during winter times. The coil would be dry, and I would work the fins with a wire brush combing in direction of the fins run only. Next I would put lot of old news paper( my age is showing) on floor under the coil to catch some of the water from sprayer then spray the Nu-calgon on fins from both sides and let it set while and foam up little. Next fill my pump up sprayer with just clear water and rinse and rinse and rinse off.
But there are some that is just about beyond cleaning this way, which next step is expensive. Meaning pump unit down, cut the coil loose and take outside then get serious with it.

 

[Terry D]

Almost looks like salt build up, but not likely in your area. Is the deposits hard? Only thing I could suggest is a delimer or descaler. Or maybe vinegar sprayed on it. I don't know if any of that will harm the aluminum or copper. You will have to remove the coil to clean and rinse it properly. If you can do it yourself, it might be worth it. If your paying a company, might be best to replace it.

 

[American Locomotive]

If your last resort is throwing the system out - I would try some Nu-Calgon Foam Brite. People in the HVAC field affectionately call it "Yellow Death". It's alkaline, so you cannot leave it on the coil or it will eventually damage it. You will need to thoroughly rinse it off - but it will definitely dissolve everything on that coil.

 

[Hobby_Man22]

Where are the coils if you have a horizontal air handler and the return air is on the bottom?

 

[Jim greengo]

My home has 2 split units. Indoor air handlers are from 1999.

PO of home obviously didn't change filters and the main 3 ton unit's evap is a disaster. There were MANY other issues with HVAC system I dealt with over the first year or so, including unclogging drains and attempting to clean the coils. The home has a flat roof and essentially no attic, so handlers are vertical in dedicated closets. Intake at floor.
1st attempt was to flush, used LOTS of HOT water, but no noticeable change. Got drain fixed, balanced distribution. Moved on to life other challenges...

Recently tried again with Nu-Calgon 4171-75 Evap Foam No Rinse Evaporator Coil Cleaner

https://www.amazon.com/dp/B00DM8KQ3I/?tag=atomicindus08-20

I did 4 applications to both sides. Used hot water in a spray bottle to flush a bit (~1 quart). Again, no noticeable change. Lifeforms living on surface just laughed.

Nuclear option is to replace entire unit. Outdoor unit was replaced in 2011. Other than clogged evap, system is OK.

How to clean this or is it even possible? Access is rough from filter opening at floor level.

Filthy as hell.

I've seen them a lot worse than that.
Blast it with some aerosol coil cleaner and call it a day.

 

[PoorUB]

I also would run with Foam Brite. If Foam Brite doesn't cut it, nothing will. Rinse it well and it will be fine. i have used it many times on evap coils. Wear rubber gloves! It won't kill ya, but it is nasty enough you might get mild chemical burns from it if you over do the mix.

Is there enough slack in the line s et to get it out of the AHU? I have pulled them out and suspended the coil over a tub to catch the water.

Also, take a wire brush and CAREFULLY "sweep" off the worst of it. Sweep in the direction of the fins.