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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 7914
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have mold coming out my air conditioning vents in my ceiling.

Resolved Question:

I have mold coming out my air conditioning vents in my ceiling. What can I do to get rid of it.?
Submitted: 6 years ago.
Category: HVAC
Expert:  Phil replied 6 years ago.
Chat Conversation Started
Phil :

Hi,This is risky business in the blind, not responsible for damages on your end. Click 'accept' when satisfied.. or we can get another expert,

Phil :

Is it mold or just black lint, check that we can go from there,

Phil :

If its mold its caused by the supply air being too cold,, condensing moisture on the metal supply air grill and ceiling. growing mold.. thats dangerous,,,

Phil :

In any event a duct cleaning in order, there are companies that specialize in that,

Phil :

Look these issues over, we can go from there, Phil

Customer :

It doen't look like any kind of lint. It is green to dark green in color. It appears to be coming out the edges of the ceiling vents . I have an "A" frame ceiling in my den with 2 light fixtures hanging down and the mold is also coming out the edges of the base of the light fixtures connected the center ceiling beam.. Also my recliner sets under one of the air vents and off and on during the day or night drops of water drop on me.I assumed this was due to humidity. Is there any thing that I can do with the thermostate that will make the air conditioner change the humidity?Two years ago this summer I put in a new compressor unit outside. Until I got this unit I have never had this problem.

Phil :

Thanks for the information.

Phil :

AC units cool and dehumidify by means of the cold evaporator coil... the colder the coil the more dehumidification..... just a few ounces too much refrigerant in the system will run the pressure and the temperature up in the evaporator coil and reduce both cooling effects and dehumidification.

Phil :

Let that sink in a bit... its a key bit of information.

Phil :

.

Phil :

The people who changed the compressor could very easily have over charged the system by a few ounces and you would then have a more humid home inside and this would be a problem in a very humid location, South Florida for example.

Phil :

***'

Phil :

However thats one of several issues. The other issue is not enough air flow through the cooling coil, in a properly charged system. That allows the air that comes off of the cooling coil to run below the usually designed 55 degrees F.

Phil :

the reason we dont run air below 55F is because it causes drafts. However in very hot and humid environments if the ducts get much below 50F, especially around 45F,,, the air ducts and the metal grills attached get so cold that the humidity in the surrounding air condenses on these metal survaces...that would be the drip you are experiencing.

Phil :

***

Phil :

With cathederal ceilings, the space between the roof members is often used as a an air duct... so that any electrical fittings, conduit, and attached lights or fans also get too cold and condense water, rusting the fixtures and dripping wate as well.

Phil :

This moilst environment hosts the mold you see... it is not a good situation and all, and can be quite toxic and can ruin the value of your home,.. its a serious problem. Getting rid of it once established can be difficult.

Phil :

***

Customer :

Is this something I should call the air conditioning man to fix. If it is fixed will the mold dry up?

Phil :

Here is what i would do... first I would call a different HVAC outfit and ask them to check the supply air temperature, using a 2 day electronic recorder, those cost 25 dollars...and read out on an IBM pc.

Customer :

What is HVAC?

Phil :

and speed the supply fan up enough so that the suppy air runs no colder than 55F. and between 15 and 18 degrees cooler than the air temperature in the room.

Phil :

Then I would have them put a humidity recorder in the home for 2 days and insure the humidity runs between 35 percent relative humidity when heat mode and no higher than 70% relative humidity in the cooling mode.

Phil :

Too large an AC for the home will cause it run in short bursts, and cool the home but not run long enough to dehumidify. that would be cured by some degree if the thermostat temperature differential is increased a degree or two.

Phil :

All through this they need to insure the system has the proper refrigerant charge in it.

Phil :

***

Phil :

Next I would go to www.alpine.com and look at the line of alpine ozonator / air cleaners.. these are quite advanced and put out variously reactive forms of oxygen (same as a lightning storm produces, a very pleasant smell)...that clleans odors and some molds and spores in the air by radically oxidizing them.

Phil :

$1500 to $2500 new from Alpine, some smaller units very nice ones $500 but on Ebay, used $1500 machines for $259 or so.

Phil :

Or i would call a mold remediation firm... or i would do both... its a tough problem to solve, some buildings with black mold, very large buildings have been torn down because of black mold permiated throughout the building.

Phil :

Let me know what you think of all this, I can elaborate, Phil

Phil :

I will be back on line in a few hours. Phil

Customer :

I am having some difficulty understanding all this. Should I contact the air conditon service man first and see if it is over charged.. If that is corrected would that stop the mold from continue to increase?

Phil :

Hello again... to understand this, think of a cold glass of iced tea... sitting on your table. notice who water collects on the *outside. thats condensation. thats what you are having in your air vents... the air is running too cold.

Phil :

Most AC outfits in florida know this phenomena, but you need a competent outfit.. try a larger Carrier or Trane dealer... show them my remarks and hire the one that understands the issues ...

Phil :

The go over what Ive written a few times... It is in laymans terms, you will be able to figure it out,

Phil :

Meantime put a cheap thermometer flat against the face of your cold air supply grills, and read it a few times a day, tell me what it reads.

Phil :

I will be back in a few hours, Phil

Customer :

Okay I will try to print this out and reread it.....thanks Ill be back

Phil :

You have a much more serious problem... the HVAC guy might know how to charge your unit correctly or not... you need to call a first class outfit, tell them have a mold problem... show them my report to you here.

Phil :

You need to have the AC adjusted for more air flow, and air temperature at the cold air outlets not below 55F and that needs to be proved with a recorder.. thats all in my report above.

Phil :

Then you need to call a duct cleaning outfit. take the HVAC contractors recommendation....then you need some kind of whole house mold treatment, there are companies that specialize in that.

Phil :

Let me know how that might work with your budget, we can go from there. Phil

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