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Evap Coil Question


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In my quest to do a better job on the HVAC end of my inspections, I've started taking off any inspection panel on the evap. coil housing to see if I can see the coil itself.

I found this one two days ago. The housing was rusted at the bottom pretty bad. I'm not sure if I'm looking at a coil that needs the scrap yard or a thorough cleaning. The temp dif was about 24 degrees.

BTW, the pic is on the downstream side so I imagine the upstream side is dirtier.

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I attempt to view all coils, simply because they are frequently clogged and dirty. Typically the blower is full of heavy accumulations also.

Can't say much about your photo if that's the output side. As you probably know, a clogged/dirty coil will give a high temp. difference.

Sometimes removing the coil to clean it and the cabinet can cost several hundred dollars, and risk damage when reconnecting. It may be smarter to replace an aging AHU.


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Thanks Dom, that's kinda along the lines that I was thinking. It's also what I told my Clients.

The condenser was a '96 model and I'm sure this evap coil was much older. At least the housing was.

This home was full of things the Seller stated "they fixed" or added but was not present when I did the inspection. The stupid thing is, they listed all the discrepancies off of their old report and wrote down next to each one that it was fixed. Things such as GFCI's (there were none), backflow preventers (there were none), new flashing around the chimney (it wasn't), new lead roof jacks (they weren't), etc.

Some people have the gonads.

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Good for you Donald, I try to get a look at the evaporator if possible too. I've seen some far worse than the one in your pictures. When they're caked-up you can bet those people don't change the filter, even if there's a new one in at the time. About half the time when I find a really bad one the filter is soild with dirt, often party sucked into the plenum because the air can't get through the frickin' dirt layers. [:-yuck]

I don't understand why they can't use some kind of metal brackets at the ends of the coils that won't rust. Haven't they heard of aluminum? I've seen units only weeks old that already had surface rust on those brackets. Built-in obsolescence?

I wish it were code that there had to be an access panel on the intake side of the evaporator coil, none of that "build it into the plenum" stuff.

Brian G.

Panel Puller [:-magnify

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I, too, would like to check out evap. coils in all the houses I'm in, but most of the coils are heavily taped to prevent air leakage. Are you removing the tape, Donald, and then reapplying it? I can almost hear a fussy seller now, saying, "Well, it was working fine until the inspector dude took it apart."


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No Bain, I'm not.

I'll only remove an access panel if it's not sealed. Some have plates on the side, some have plates on the downstream side.

One thing that got me to thinking about removing the plates is the cost of an evap coil. One of my clients received three quotes for a 5 ton evap coil and housing in the $2000 to $2500 range. I never knew they were that much.

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I don't unseal either, though I've thought about it a time or two when the filters were really bad. That's a slippery slope I think. I've also thought about getting a boroscope or something, but never have. So far I've settled for recommending invasive inspection (and cleaning or replacement if needed) based on the clues, past experience, and the significant potential expense. I typically cite conditions like clogged filters, poor air flow, age, visible areas are dirty, etc., as clues.

Brian G.

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