What's your location? Where is the house located? Is the house a new build? Or was this a retro fit installation?

We are located in Los Angeles about 3 to 4 miles from the beach in the foothills at the end of a canyon. The house is from 1959, built into the hill with the HVAC and ducting installed in the crawlspace underneath the house. The crawlspace is vented and sits on dirt (most likely clay). We did extensive remodeling of the house, but used zero VOC paints and glues (just fyi, in case off-gassing could be an issue) and we are not using any harsh household cleaners or detergents now. The installation relied mostly on existing floor vents and plenums (all new R-8 flex ducting with some rigid ducts through the garage and storage space), but we also installed a couple new supply and return vents. Let me know if you need any more information or pictures. Thank you for your help!

Mostly likely salt from the ocean would be my guess. Coastal areas have all kinds of problems due to salt. Enjoy the beach, you're paying for it.

As a side note: trying to treat a coil by dipping can help extend life but I've replaced just as many dipped / treated coils as I have regular ones with no treatment. There is nothing to prevent something from wearing out when you live in a harsh climate (near the ocean). Salt spray never stops coming.

I have corrosion looking like that inside my plenum above my AC. But it is an old plenum. The white stuff by the vent either drywall dust (from said extensive remodeling) or the salt idea, which I have no experience dealing with. Salt staining would also explain why you have it after only a year of use. I guess the only way you could know for sure it is salt is to taste it :D

Perhaps you will need yearly maintenance involving spraying the coil with some saltbuster. Might lower corrosion and the white residue.

Thank you for your suggestions. Vith, the white deposits are definitely not drywall dust. The HVAC was replaced 2 years after the remodel was complete. We are pretty sure it's aluminum oxide, but I am not planning to stick my tongue on it to confirm it. I looked into sending it to a lab, but the test would have cost $750.

sktn77a, I am looking into the matching Trane/AS coil as a replacement, but I am worried I will be hit with a big expense. I am not sure what the price of it would be compared to getting a new ADP coil coated (the coating was quoted at $600). I contacted AS to look at the heat exchanger for a 2nd opinion.

Austin Air, how long is the typical lifespan of a coil/furnace when one lives close to the ocean? It has to be more than 6 months, right? That is the amount of time we had the system. Will the coating extend the life span significantly, or is it a waste of money which would be better set aside for a coil replacement at a later stage?

Could there be something else at play that causes the corrosion? The contractor and distributor claim that they have never seen anything like it. Could it be the composition of our dusty clay soil in the crawlspace where the unit is installed (suspended from the subfloor)? Or the way the system is set up? I read somewhere if the air enters the furnace/coil at too high velocity or if the flame in the furnace burns at too high heat it can create condensation loaded with acidic substances, thus speeding up corrosion.

I agree with SKTN...you want an AHRI matching system....there has to be a very good reason to install a 3rd party evap coil in a new system...I doubt it is an AHRI match....usually the reason for the 3rd party coil is only to help the installer's wallet....as far as heat exchanger, I would get an AmStd factory residential rep out to your house and take a look at this and the evap coil...one should be available based on your metropolitan location.

Good Luck!

IMO

Lifespan of any AC system is roughly 15 years. That is the national average and this isn't broken down to say if you live near the ocean it's somehow different. But when we say lifespan of an AC system we don't mean you won't replace something within that life span. NOTHING --- no brand is immune to failure. How could I stay in business if this were the case?

Now with that said, some brands are worse than others and some national brands make inferior lower end parts.... even while the higher end parts fail as well.

Realize this there are only 7 air conditioning and heating manufacturers. But I could name off a long list of brands a mile long, many with different models of the same brand. You wouldn't be able to use them all in your lifetime.

Nothing stays the same... Trane was sold to Ingersoll Rand / Goodman was sold to Daikin / Watts Co has a 'unique agreement' with Carrier. All of this transpired within the past decade.

What's in a name? Nothing, other than the history of the name... unless the actors behind the name have changed something - for the worse - for the better?

Every major brand evaporator coil fails. There is no 'perfect' evaporator coil. However, ADP is known for making builder grade coils. The one you show in the picture looks better than most, but with so many aluminum to copper connections on that coil that is likely where the coil failed and 'could' have nothing to do with the environment you're in.

With that said... every manufacturer has problems with Evaporator coils. (Freon leaks)

In my climate I would say the average is a little less than 15 years. But these days there a whole host of reasons to replacing equipment and when I say equipment I am referring to more than one piece. Replacing one piece of equipment is a repair... it's not replacement.

Thank you, tigerdunes and Austin Air. I am waiting for AS to send out a rep and assess the situation. I hope this will give me an answer in respect to what could be the culprit for the corrosion of the heat exchanger. But it would probably not resolve the issue with the coil. I assume an installer/distributor would probably not exchange an ADP coil for an AS one as a warranty replacement, right?

Do you happen to know what would be the model no of a matching AS coil based on the specs of furnace and condenser (furnace: Model# AUD2C100A9V5VBB; condenser: Model# 4A7A7060A1000AA)?

Austin Air, not sure if you saw my question in response to your earlier remark about coated coils failing? Do you think having a coil coated is a waste of money? By the way, our coil did not fail at an aluminum to copper connection but developed the white build-up shown in the photo (which I believe is corrosion) and spewed that out of the vents.

Well when you said coil failed, I assumed it was due to refrigerant leaks. A coating is not likely to help in the spewing out of stuff from vents. Because a coated coil will likely exhibit the same thing after awhile of use. If the particles of what is being spewed is in the air it will just accumulate again on the new coated coil until it is spewed from the vents.

Spewing of particles from vents would be considered a maintenance issue. Manufacturer's don't cover maintenance issues in my experience. I would install a better filtration system first and try to minimize what is being sent thru your HVAC system. That would likely have a far greater impact than merely coating a coil, IMHO.

Thank you, Austin Air. We have a pretty good filter cabinet installed upstream of the furnace (at least I think so). It's by Lennox and features a 4" thick filter with a higher MERV rating (11 or 14, not 100% sure). I am pretty confident that the white flakes are coming from the coil. You can see the build-up on the coil in the photo and the flakes coming out of the vents match that build-up in consistency, thickness, color, etc. Also, since we have taken out the coil, we do not see any white flakes coming out of the vents anymore when using the furnace to heat.

If we will encounter the flakes again in the future, even with a new coil, is it possible to install a filter downstream of the coil? Would it have to replace the upstream filter or can I install two filters without putting too much strain on the system?

I wouldn't install a filter downstream of the coil this would be impractical.

The flakes coming from the coil and the color of them... put in a new coil and the flakes disappear. One can only guess what these white flakes are. Due to the area in which you live (coastal) leads me to believe it has something to do with the salt spray in the air.

When the air blows do you see the salt? no.

Take out your filter, hold your hand under it while pouring salt into it from the other side... does any salt fall thru the filter?

Realize the salt you just poured is visible by you. The salt in the air is not.

Why is there a build up of salt on the coil? Moisture. When you run the AC the coil gets wet what happens when dry salt in air becomes wet? It sticks. It accumulates.

What happens when you run your furnace? It bakes the coil PLUS whatever is stuck to it.

What happens when you bake salt that was wet and probably mushy to a certain extent? It flakes.

What can you do?:

Use better filtration before the intake (return) of the furnace and try to prevent it. REPLACE filters more frequently. (Trying and being successful are 2 different things as the source is microscopic)

Ignore the flakes and clean them when they spew out.

Replace the coil every time they reappear.

Move.

Thank you, Austin Air. I don’t think moving is really an option. ; /

I felt we installed a pretty good filter upstream from the furnace. But that’s obviously a filter that only captures solid particles. What kind of filter would have to be used to capture substances that are carried by the humidity of the air? I assume that's a different kind, right? And would it put too much strain on the system if we install it at the return vents (we have 3 return vents) in addition to the filter in front of the furnace.

Btw, I finally heard back from American Standard/Trane. I submitted photos of the corrosion of the furnace. In response, they stated that it is normal to see that kind of corrosion. I must say that I am surprised that they claim for it to be normal. Sounds to me that they do not want to take any responsibility. I can understand that a furnace which has seen years of use shows corrosion, but not a unit that is about 6 months old! Am I being unreasonable by requesting AS/Trane to fess up to the issue?

Lastly, to address a separate potential problem of mold and ‘stinky sock syndrome’, does it make sense to install a UV light in close proximity to the coil? I read different opinions about it - some say it’s great, others say that over time it breaks down a plastic drip pan and that the exposure to the UV light is typically not long/strong enough to kill mold spores, even if installed within the coil enclosure.

Thank you all for your help.

Trane / American Standard is not the same company of years ago. They were bought out by Ingersol Rand. There is occasionally a 'rumor' that they really don't care too much for the residential market that the reason they bought the company was for the commercial end of it.

In the end they are an equipment manufacturer. They exist to sell equipment, not to admit fault in design or problems with materials within those designs.

UV lights are a method of treating a 'symptom'. They don't work all that well and must be continually maintained and replaced every year, even if the bulb doesn't burn out. Additionally if the UV light creates ozone I wouldn't use it.

Dirty sock syndrome in my experience is an over abundance of humidity built up with in the system that has a musty smell to it when the system turns on. The best way IMO is to reduce humidity within the home and when it comes to equipment a 2 stage communicating HVAC system is the most cost efficient way to achieve this.

Thank you, Austin Air. Since we have to replace the coil, I was thinking about using the opportunity to install a UV light to avoid any future problems related to mildew and mold. This thought was triggered by a discovery we made a few months ago: We noticed some mold on clothes in our closets. Since we never had that problem before we started using the AC, we were wondering if it had to do anything with the AC or it was unrelated.

But it sounds like the UV light is not all that effective.

Our indoor humidity always hovers around 48% or so, and it is pretty much consistent between the use of heating and cooling.

aluminum oxide. CHeck out the photo of a condenser I cleaned with aluminum oxide corrosion. I also UN buried the outdoor unit due to it being 4 inches in dirt (see all the weeds) . There is nothing you can do with aluminum oxide other than change the enviroment surroundings which I did in this case for this outdoor unit - luckly no leaks (yet) on the condenser copper coils.

Yeah this is something that I wouldn't worry too much about. It's obviously salt from the air I worked in Miami for six years and had to deal with this type of thing all the time. One way that we fix the problem if it is in a crawl space you should frame out a wall around the unit to keep the outdoor air from being around the air handler it so that help more times then not good luck

www.heating-repair-chicago.com

Like Heating Repair suggested is trying to create more of a "conditioned" air situation. In FL they love to still stick the air handler/indoor coil/evap coil in the attic unconditioned space. I actually have been successful installing solar air circulation systems in the attic with a radiant barrier- much much less expensive and less risks than with closed cell foam. Keep the air circulating, keep it managed in a high humidity circumstance. A home needs to breath properly.

Remember you can never install the indoor part of the system anywhere near the ocean air unless you box it in. Keep us updated with what what an up doing here.

www.heating-repair-chicago.com

We have a 6 month old Lennox HVAC, and the same white flakes started coming out of all of the vents when we turn the heat on a couple weeks ago. I have called so many people, and now waiting to hear back from Lennox.. We have cleaned our entire house so many times, and even stayed at a hotel. (We have a toddler)

Has anyone found these answers?

What is this white stuff?

How bad is it to inhale a little?

And obviously, how do you fix it?\

Thank You!

The question and actions are to identify the unknown. Collect and bag some of the foreign material and utilize your CDC office (yes some CDC will offer to analyze or point you to the correct institute) and or a private mold kit institute- amazon has a mail kit. Google and you will find one. The analysis will determine material compound, mold/fungi. metal, organic- nonorganic. Looking for answers on website forums without evidence of the material identifies just further jeopardizes your families health and pure guesses instead of facts.

Hi there, I originally posted our problem of white flakes and I think we were able to get to the bottom of it and address it (fingers crossed!). We are pretty certain that it was corrosion that accumulated on the coil during the use of the AC. Interestingly, the corrosion did not really appear on the fins but on the aluminum pipes at the end of the coil. Once we started to use the heat the warm air passing through the coil must have loosened the white corrosion somehow and blow it out of the vents in flakes. We had the coil replaced and coated with a protective coating before installation. A few companies do that (in our case, the HVAC distributor sent a new coil to the coating company in Texas and they returned it for installation). We have now entered the cold season and used the heat a little bit (we are in Los Angeles, so use of heat is pretty minimal, however). So far, no flakes!

I also believe that other people who have provided advice on this thread are correct when they state that a coil should not be installed in an unconditioned space. Unfortunately, there is not much we can do it about, unless we would encapsulate the entire crawl space where the unit is located. However, I have learned that the retroactive encapsulation of an existing crawlspace isn't really a good idea either. Proper ventilation may be the better approach, as far as I understand from talking to a few local experts.

Doug, let me know if you need more info on this, as we spent quite a bit of time on researching this and I could probably save you some of the hassle!

For some reason, I just now saw this post you sent. I have almost gotten to the bottom of it as our local rep is ordering a new furnace coil or whatever, and said he actually had the same problem in his house in November. I do very much appreciate Your help in responding, and I will make sure to show the HVAC guys what solved your issue in case they think it's something different. Thank you very very much! Wish you a warm CA winter!

We purchased an evaporator coil from ADP, and when we turned on the furnace--tons of white dust came out...about the size of dandruff. The contractor soon replaced the coil with one from a different manufacturer. They told me that the ADP coil had "defective metal"...whatever that means. I'm still curious what we inhaled though. Has anyone experienced anything similar?

" Has anyone experienced anything similar? "

You mean inhaling white powder? Not since college.

I have read various posts about white dandruff like flakes spewing from AC unit (vents) and a number of posts suggest it is from “corrosion” or substance build up on the AC coils (the cause of which could be things such as humidity, salt from proximity to ocean, turning the heat on after using the cooling throughout the summer months, lack of coating on coils).

I have also read that the substance in cases was Aluminum Hydroxide (or perhaps Aluminum Oxide).

My question has to do with the health risk.

Has anyone investigated the health risks of inhaling Aluminum Hydroxide/ Oxide, and if so, could you share your findings please.

i wouis imagine that in addition to the heavier flakes falling to the floor, there would be finer / more granular amounts of the Aluminum Hydroxide/ Oxide in the air that would have been inhaled.

If inhaled for a short period of time, has anyone investigated if that could cause health issues?

Thank you

Lou G

As it appears that people are still replying to my original post, I thought I'd give a quick update: Since we have had the coated coil installed, we have not experienced the white flakes anymore. We recurrently using the heat quite a bit and do not see any problems. Therefore, I assume that the protective coating works. I plan to open up the coil during spring for a cleaning (as recommended by the manufacturer). If I see anything noteworthy, I will provide an update.

" If inhaled for a short period of time, has anyone investigated if that could cause health issues? "

If you're a smoker, perhaps. But the smoking is probably worse. Aluminum oxides are for the most part inert. It is sometimes used as an additive in sunscreens and makeup. Also in sandpaper as an abrasive.

Remove ALL aluminum coils and replace with copper coils and white flakes will most likely go away. Yes, it is toxic and the HVAC companies within the past several years all switched from aluminum coils to copper coils to save money. Its flakes from the aluminum coils expanding and contracting throughout the day.

I just had Air around the clock, a higher end company, show me white mushy clumps in the interior pan and said it was from the coating on the coils and for $650 they would remove coating from aluminum coils and that replacing the uv light would improve the situation at a cost of $250 more.

"Remove ALL aluminum coils and replace with copper coils and white flakes will most likely go away. Yes, it is toxic and the HVAC companies within the past several years all switched from aluminum coils to copper coils to save money. "

What utter rubbish! Manufacturers replaced copper coils with aluminum because of multiple problems with the quality of copper available today leading to leaking from the various forms of corrosion (formicary, acid, oxidative, etc). Aluminum coils are less conductive than copper but that's pretty much their only limitation. They have been designed to offset this limitation and should last MUCH longer than any current copper coil.

They have been designed (aluminum E-coils) to offset this limitation and should last MUCH longer than any current copper coil.

"Should" is the operative word, the fact however is they often DO NOT.

Just over the last couple of years into 2021: Lennox --- all aluminum coil, leaked after 3.5 years. Replacement coil under part warranty? leaking again at just over 12 months... now out of warranty.

Carrier / ICP: Warranty coil all aluminum leaking after 5 years. --- Replacement 2021 ---ICP leaked after less than 4 months [My very first freebie replacement -- EVER]. These refrigerant leaks were all inside the fins type leaks.

All manufacturers have issues with leaky E-coils, aluminum isn't going to change this problem from my experience (stop kidding yourself). The cost of refrigerant only going up, your back is against the wall if you are trying to get cool in 2021 and beyond. 2023 brings new levels of fun... buckle up kiddos.

Good night, and Good Luck. [Job security for me ;-) ]

Hi, I am the one who originally started this thread and I wanted to give a quick update: Our cotated coil has been working fine. No white flakes at all. The original issue may have been due to the fact that we are in a suprisingly humid micro climate, our coil is located in an unconditioned crawl space, and our AC system may have been oversized. Therefore, salt deposits/corrosion started to accumulate on the bare aluminum of the originally installed coil and started to flake off when we switched from colling to heating, as the warm air was passing the coil.

To my knowledge, the white flakes were insoluble salt/corrosion deposits on the coil and therefore are not toxic!

Anyway, if you have the same issue of white flakes comig off your aluminum coil, coating it may do the trick. I did not want that coating to be done on site and requested it to be done at the factory to a brand new coil in a more controlled environment in order to achieve the best results.

One important note: if you decide to get a coated coil cleaned, do NOT use standard coil cleaners as they will destroy the coating. You need to use a specially forumlated ph-neutral cleaner. Most coil cleaners are not ph-neutral.

I hope this helps.

It is a manufacture defect the galvanization process was done incorrectly if you get the white powder tested you will see it is aluminum oxide.