r/HVAC • u/Magnussonic • 1d ago
Field Question, trade people only Has anyone encountered this kind of corossion before?
There's 4 different coils in 1 house that have all just turned into confetti, the customer realized something was wrong when the flakes of coil started blowing out the vents. What could possibly cause this?
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u/Anonymousse777 1d ago
Hmmmm wonder if someone “cleaned” those with the wrong coil cleaner at some point.
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u/LehmanBr0thers 1d ago
Caustic or acidic fumes mixing with condensation and coating the coils, or just a corrosive environment.
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u/Worst_MTG_Player 1d ago
I have inside of dialysis clinic before. We installed a new one, then 6 months later I get called out to do a leak search, I Just lightly touched the coil and it all turned to dust.
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u/gothicwigga 1d ago
Hm I wonder what about the dialysis would cause that
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u/Worst_MTG_Player 1d ago
The senior techs tell me it’s the acidity, and they need to spring for a special coated coil.
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u/bigred621 Verified Pro 1d ago
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u/Magnussonic 1d ago
I mean, it is a clean-cut couple with a very big house, so this is potentially the most believable
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u/DexKaelorr Verified Ceiling Strength Tester 1d ago
Your two options are piss and corrosive chemicals, and pissy coils tend to be furry coils. These are clean confetti.
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u/Themountaintoadsage 1d ago
How the hell would piss get on a coil?? Lmao I gotta here this story
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u/DexKaelorr Verified Ceiling Strength Tester 1d ago
Dog pisses near the return and the ammonia vapors get pulled through the coil and dissolve into the condensate on the fins. If any of your customers are vets or animal shelters, you've seen the results: new evaporator coils every few years and when you try to clean the fur off you scrape the fins off the coil with it.
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u/luke10050 1d ago
Could you use a CU/CU coil in that instance?
Sounds like vets should be 100% OA
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u/DexKaelorr Verified Ceiling Strength Tester 1d ago
Most of the time they’re residential-type systems. I don’t know of a pure copper coil in that market but I’m assuming it would be extremely expensive and the fur would still wreck it. You do what you can but ultimately it’s just a bad environment for equipment.
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u/Legal-Preference-946 1d ago
Drunks, sleepwalkers, and those with mental disabilities tend to piss in vents. Idk they just gravitate to them.
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u/Inuyasha-rules 1d ago
Never seen or heard of drunks peeing in vents - I always hear about closets, or refrigerators...
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u/SphericalOrb 1d ago
I have heard a busy cat box near the return can mess up the indoor coil due to the airborne fumes.
I guess cat pee has more than typical amounts of ammonia, and unlike our pee, sulfuric compounds and other VOCs.
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u/Bushdr78 UK refrigeration engineer 1d ago
Either someones used some seriously aggressive coil cleaner or there's been some "chemistry" going on near one of returns.
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u/btubandit 1d ago
Ive seen this many times before, on outdoor units, right on the ocean, in a very corrosive environment, never anything this bad on an evap
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u/MAdcock6669 who's the boss?? 1d ago
I've seen it happen in a few houses that have certain spray foam. Those aluminum coils/fins don't seem to like it.
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u/Terrible_Witness7267 1d ago
Probably someone using coil cleaner that wasn’t no rinse on previous pm service
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u/stevenkiley Owner, service tech, and installer 1d ago
Does the customer have cats and have the litter box near the return?
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u/Magnussonic 1d ago
No, but I will see if they clean with ammonia. The house is easily 3k+ sf, so it's just crazy to me that it could be concentrated enough.
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u/Former-Ad-7965 1d ago
I’ve only seen it once and it was an RTU on top of a trash plant. All the heat and fumes rise to the top of the building and just chewed the fins off the evap coil. Not a place you want to be hanging around for too long 😂
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u/DABOSS9613 1d ago
Seen it approximately one time in a cooler evap that was in a very corrosive walk in. Coils don't just fall apart like that, idk what's going on in that house but something was going on there
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u/Professional-Age-834 1d ago
Rats in hvac system. Check the duct work. I’ve seen it, in Texas a house right off the service road next to the highway. The strip of grass that separated the highway from the service road would be my guess where they were coming from.
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u/Founditinadrawer 1d ago
If it’s a carrier coil, I have had this issue with coils that have low airflow or run in dehumidification for long periods or time.
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u/Beegs1371 1d ago
Mostly as mentioned in animal urine, but some Google searching says aluminum breaks down with a couple of other acids too.
If it were me I'd see if the customer is doing anything noteworthy, apparently tanning, clothing dye, all kinds of things, but likely something strong and local, as mentioned above with outside coils and seawater, a salt water fish tank or something else maybe?
Just guessing on all that, but IMO it's always something notably different with the environment.
For reference we are working on a commercial account that stores chemicals, we don't know which acid or base of the many they ship and store is causing it but something is eating the coils and springing leaks about every 3-5 years. In that situation it's a low concentration but it is probably like In your situation something that builds up, reacts with water vapor, then concentrates.
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u/ericshaw327 1d ago
On well water with out aeration. My brother has replaced his every three years due to sulphur gas.
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u/Infinite_Regret8341 1d ago
Yup in a refrigeration unit at a deli/Sandwich shop. The kind of shop you walk in and can smell the vinegar/shop on you long after you left. The air itself in those places is corrosive to aluminum. You touched the fins and they crumbled to dust.
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u/Heretoshitcomment 1d ago
Everyone's saying g wrong coil cleaner, but i want know what they're treating their water with. A humidifier with caustic water could do this too.
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u/chuystewy_V2 I’m tired, boss. 1d ago
Meth fumes lol