Smelly Evaporator Coils Air Con

[grump]

Hi, In the years 1976-2007 The one problem (over all others) that came up time and time again was the stench produced in ac systems by evaporator coils,ranging from cats urine to decomposing flesh. I have used powerful cleaning agents,to solve the problem, in some cases it would return,there did not seem to be any consistency.Please let me have your input,I am expecting a big bag from this post do not disappoint.
Retired nothing better to do
PS is there any way you can delete a post when it fails to get a reply? (cant cope with rejection )

[Buddha]

Don't laugh when I suggest this. I know from first hand experience exactly the problem you are talking about. I lived with a friend for a time that had 3 young children and they were always dropping/spilling something on the a/c units and they too stunk. This is what we did with relative success, honestly don't laugh.

Find a 'Head shop' around your area. The place that sells pot-heads their pipes and such, LOL. Well they use a strong citric cleaner on those pipes. I forget the name, but if you ask the guy behind the counter, he WILL know what you are talking about. This cleaner works miracles, and is relatively mild on other surfaces if you spill it. Just rig it up so that you can soak the coils for about 15-30 minutes, spray it off with water, and they will be shiny like new, with nothing remaining on them.

[paul_h]

Being warranty support I get this a lot. I'm interested in any answers.
My own theory is it mainly happens on systems with poor drainage, allowing mold and mildew buildup on the coil and drain.
Or of course where the drain ends up, if it is really short and ends up on the roof, gutter or household water drain, it's more likely to get these smells than the drains that are ~1.8m high and drain onto the ground.

Edit: Cars seem to get it a lot more than building a/cs have you noticed?
ALmost every car I've owned with a/c has the smell when the a/c cuts out.

As far as dealing with the house a/c problem, after cleaning it as it's a reoccuring problem, I tell them never to switch cooling straight off when they're done with it. Put it on fan only mode to dry the system out. I've even notice some brands now have a "coil dry" mode to do this which they suggest owners use occasionally

[Argus]

.

In a previous incarnation I was a senior manager with one of the larger manufacturers and the problem of split-system coil stinks came up regularly.

Of course, in every case, the world and his dog knew that it was a manufacturing fault, so that was OK.

But there were some un-common denominators.
It was specific to certain areas, not others.
It could affect certain units, but not others of the same type, on the same site.
It came and went, in other words it was not constant all the time.
…. I could go on.

So, I spent some budget and commissioned some laboratory analyses entailing swabs from the coils, condensate tray and drains.

The one thing to emerge is that the samples all contained large amounts of bacteria of all kinds – mostly harmless or in non hazardous quantities - and occurring naturally. They also contained, depending on the season of the year, pollen, wild yeast, fungus spores and a quantity of man made substances, mainly growth from decomposed VOCs (volatile organic compounds). VOCs are present as the propellant in all chemicals we use, paint, deodorants, sprays aerosols etc.

In none of the cases were the exact contaminants identical and this explains the geographical nature of the complaint. But in general they were present in varying quantities and compositions.
Cars cover a great area in their travels and are liable to collect a greater ranger of contaminants. My own car has an efficient pollen filter and I've never had this problem, but plenty have, so it does exist..

The smell is simply all this flora and bacteria reacting with each other, living, breeding, dying and giving off gasses when they decompose.

So we know the cause. But as it’s unpopular to admit this with all involved it’s often ignored and it really is a manufacturing fault as everybody knows.

The answer? Good hygiene and cleaning. There are proprietary coil cleaners, but many of them simply add to the problem or are not used often enough.

The biologist explained to me that the coils need cleaning as often as it takes, not just once a year or every maintenance visit.
“After all”, he said, “you wouldn’t wear the same socks or not wash for 6 months at time would you?”
I wouldn’t…. but ……… you meet all sorts in this trade.

.

[nike123]

I use Clean-and-safe and Coil disinfectant of Rectorseal with great success.
But, when condensate drain pipe is purely done, I mostly make new condensate drain before cleaning with chemicals.

[paul_h]

.

In a previous incarnation I was a senior manager with one of the larger manufacturers and the problem of split-system coil stinks came up regularly.

Of course, in every case, the world and his dog knew that it was a manufacturing fault, so that was OK.

The one thing to emerge is that the samples all contained large amounts of bacteria of all kinds – mostly harmless or in non hazardous quantities - and occurring naturally. They also contained, depending on the season of the year, pollen, wild yeast, fungus spores and a quantity of man made substances, mainly growth from decomposed VOCs (volatile organic compounds). VOCs are present as the propellant in all chemicals we use, paint, deodorants, sprays aerosols etc.

The smell is simply all this flora and bacteria reacting with each other, living, breeding, dying and giving off gasses when they decompose.

So we know the cause. But as it’s unpopular to admit this with all involved it’s often ignored and it really is a manufacturing fault as everybody knows.

The answer? Good hygiene and cleaning. There are proprietary coil cleaners, but many of them simply add to the problem or are not used often enough.

I'm interested in your theory and have a few questions.
How is it a manufacturing fault when most units don't produce smells?
How are manufacturers going to design a system that only gets used in clean air and produces no condensation?
I agree with the causes of the smells, dirtier units with poorer flowing drains tend to have more smell than units in cleaner air, faster flowing long drains.
As a warranty repairer I do attend lots of units accused of smelling bad at no charge. But after service units in the six digit+ numbers, and owning a lot myself but only seeing this "bad smell" incidence in the sub 100 number, how can this be put down to design, or a manufacturers problem?
I'm only asking to gain better understanding, as I don't have any type of white paper analysis or reseach facility. I'm just basing it on experience, which is the drains are normally poor and the condition of the coil is normally dirty on the units that have smells, while millions of units don't suffer the bad smell problem.

edit: VV
Ok I feel stupid now. I am really after a way to get rid of these jobs though. I don't want to strip and clean units all the time throughout the whole city. It's warranty so unless you can prove otherwise you have to attend and nod sympathetically and go through the motions to make them feel happy.

[Argus]

I'm interested in your theory and have a few questions.
How is it a manufacturing fault when most units don't produce smells?
How are manufacturers going to design a system that only gets used in clean air and produces no condensation?

Joke, dear boy, its what passes for humour in this part of the world and a poke at the mentality of our customers, some of whom really do believe that it's a design flaw.

.

[grump]

Pleased to see the problem is world wide>I am talking cats piss dead rats or perhaps six months unwashed feet & socks .Its been happening since i installed my first split
thirty two years ago.(Brown wooden sides on metal cover
who made them (UK) ? ) Now it could be perceived that it has something to do with me.don,t go there.
The only common denominator is ALUMINIUM evaporator
coil fins on AC + HUMANS + AIRBORNE SPORES.The condensate drain theory does not wash( ha ha )with me as i am sure it exists on pumped systems back to back splits etc.
I am sticking to my theory that aluminium interacts with certain airborne pollutants and the conditions are right the result is quite obnoxious.
Thank you all for the input so far,lets get to the bottom!!! of the dreaded pong.

[bernard]

Hi

Every smell in the room passes through the a/c unit,how many times have you had a call to say there is a burning smell from my a/c unit,then eventually find that a condensate tray heater on a fridge has a smelly peice of melted plastic over it,or a lighting ballast has burnt out.Perfume shops are the worst,we just tailored our service to suit the unit,customer and surroundings.It dosent take long to spray the coil with cleaner every 3 months and a full strip evey 6.

The cats piss smell is mainly from heat pump units,you get the same smell from electric heater condensate trays that have never been cleaned.

Regards Bernard

[grump]

HI Bernard I don,t think the problem is that simple many units that get poor maintenance do not have the problem.
I have had service contracts with Perfume outlets don,t remember having this over powering odour to deal with.
Yes burning smells,musty smells,not in the same league.

[bernard]

HI Bernard I don,t think the problem is that simple many units that get poor maintenance do not have the problem.
I have had service contracts with Perfume outlets don,t remember having this over powering odour to deal with.
Yes burning smells,musty smells,not in the same league.

Yes but were they heat pumps or cooling only??

Regards Bernie

[grump]

Could be, but the problem is particularly bad in the summer.

[completehvac]

we have tried everything too on many sites, found the best thing is neutrasol car airfresheners, they even come in a little black box self adhesive and fit into most indoor units! We fit these after a chemical clean every 6 months on problem units.

[grump]

hi completehvac,now that is covering one smell with another.Which i am sure many of us are guilty.
A more detailed analysis like the Argus contribution is necessary.The industry as a whole should provide answers. Grump

[IceMan08]

I tell them that a cat caught a rat, had a piss and left his rotting body up there!!!
I dont believe its a manufacture problem, although I do think they should incorporate a high heat type mode that kicks in on shutdown, most bacteria can be killed by heat (if its high enough, as some bacteria thrive in warm temperatures) and water evaporates. Some previous sites I've attended didnt have traps on them and went to open drains, they were easy to solve!
Also maintenance is key, but customers dont want to pay for it, time and time again its been proved maintenance saves you money but tell a customer that......

[paul_h]

It's not a manufacturing problem it was joked about previously with me being the punchline But not as serious thought.
These days as I'm into homebrew I deal with a lot of sterilising agents (made for the dairy industry BTW).
I keep a Starsan bottle handy, it's a food grade acid that kills any micro organisms. You only need 10ml/L of it in a trigger pack with water. Give the coil a good spray of that and let it sit for 2-3 min, then rinse it off with water and flush it out, then give it a spray of de-odoursing agent .

[scottishladx]

RTU and smelly jelly lol

[BritCit_Juve]

This is a relatively common problem that is basically as old as the evaporator.
The air we breath contains a lot of contaminents some natural and a lot man made.
Add in an evaporator and along with the water that condenses on the coilyou will also get a lot of the cotaminents. As long as the coil is wet these will go straight down the drain and we can all breathe easy.
However when the unit stops cooling the residual water on the coil evaporates back into the airstream leaving the contaminents on the coil.
after a while the contaminents will reach a point where at the start of the next cooling cycle the smells will be noticable as soon as the coil gets damp.
The usual culprets are strong aftershaves or perfumes, cigarette smoke, some printer or copier toners and formaldehyde from construction and furnishings.
As inverter systems tend to operate a little drier (higher evap temp) they don't suffer so badly but still some of the manufacturers are now including a clean cycle.
The only way to reduce the problem is regular cleaning of the coil and driptray.
Note also the slime in the driptray is also from the same source and is usually down to bad drainage.
Brit