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Dirty Sock Syndrome

Dirty Sock Syndrome

My wife and I were fortunate to be able to build our new full-time home

in Kitty Hawk, NC.  It consists of approx. 1900 sq. ft. on the ground

floor (great room, utility, 3 bedrooms and 2-1/2 baths, and a

second-floor bonus area/play room (approx. 800 sq. ft.) above the

bedrooms & utility area.  Our HVAC contractor installed two

high-efficiency 14 seer Westinghouse heat pumps... one handles only the

great room and utility area, and the other has two "zones," one for the

1st floor bedrooms and one for the second-floor bonus area.  Both units

are housed in the insulated knee wall areas of the second floor - one on

one side of the room and one on the other. 

We moved into the home in June and had no problems with the systems

during the summer months using the AC.  When the weather turned cold

last month and we began to use the heat, we noticed an awful smell

coming from the system that handles the bedrooms and second floor. 

Smelled of stale moldy air, and was especially noticeable when the

system first started up each day (defrost cycle).

Our HVAC installer has tried a cleaning, an entire bottle of some other

freshening product, and made mention of it being "dirty sock" syndrome. 

He has also now utilized a "Dirty Sox" product, to no avail.  During

our last phone conversation, he stated the manufacturer will send a new

coil to install at no charge, but if we want it "dipped" by an outside

source, it will cost us approx. $500.

After much research on the internet, we have found this to be quite a

common problem with high efficiency heat pumps... mold growing on the

coils and producing this awful smell.  Some say it is due to recycled

aluminum being used to produce the coils, some saying the only way to

rid of it is by having coated/dipped coils, others saying UV lights are

the answer.

Do any of you have any "success" stories in dealing with "Dirty Sock Syndrome?"  Or any helpful info. we can use?


  • Techman
    Techman Member Posts: 2,144
    Old vs New Socks

    I have replaced some OLD coils[systems] w/ "Dirty Sock Syndrome " but,this my 1st on a new system.And this is a common problem you say . The things that make you go "hum" ! I've heard of "chinese sheetrock" killing the indoor/evap coils in lots of places.If it is mold on the coil ,or in the Air Handler,where did it come from? Where is it? A UV light will keep the evap coil clean, when installed correctly.Is there a "trap "in the condensate drain line? Is there an "electronic air cleaner"  in the ductwork?Is any of the ductwork  lined with  an internal liner?What kind of "room" is behind the kneewall where the air handlers are?
  • hvacr
    hvacr Member Posts: 5
    Dirty Socks Syndrone

    Dirty socks syndrone is caused due to the evap coil not having a self rising effect and having a build up of organic and biological growth.  High efficeincy heat pumps typically have a lower latent capacity and do not remove as much moisture or have as much condensate runoff.

    Causes may be due to:

    1. Oversized equipment with short run cycles.  Run cycles need to be long enough to build up condensate and rises the coil.  It may take 5-8 minutes of run time just to get to this point.  The contractor should have run an approved load caliculation (and duct sizing) as required by NC code.  You should request a copy of this and have confirmed by your local utility provider or local inspections department.

    2. Incorrect air flow for the unit based on the latent/sensible tables provided by the mfg.  To much will reduce the latent capacity, To little will cause expansion valve control problems.

    3. Verify refrigerant charge by checking liquid line subcooling & suction superheat.  This will affect latent/sensible ratios.

    4. Check TXV bulb mounting.  Should be tight on the suction pipe, no movement, 2 metal bands, & insulated. 

    Every problem job I've seen had a couple or all of these problems.  A coated coil allows the water to run off better and increases the latent capacity. 

    Once corrected if the same coil is used it should be throughly cleaned with a detergent coil cleaner.

     Other avenues of recourse are the Better Business B. and State licensing Board in Raleigh and if all else fails, Small Claims Court.

    FYI, I am a licenseed contractor in NC, VA, & GA; and worked for factory services of several companies and as a consultant.
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