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  1. #1

    Another dirty sock problem

    The history
    We live in a 5 YO home in Georgia. It's a 1 1/2 story all brick with a crawl space and upstairs and downstairs HVAC systems. 2 years ago, we discovered that our condenser coil, reversing valve, etc. had been installed incorrectly so our downstairs Trane system was not working properly. As a result, the AC and heat didn't work correctly and there was a lot of humidity in the summer. We wound up getting those issues resolved and all seemed OK. In Dec. of 2006, we had an especially wet fall/winter. We began to notice a horrible smell coming out of the system when it was cold outside and it was raining. Through all of our AC system checks, we found a leak had formed in our crawl space and water had seeped in under the vapor barrier. We had the crawl space issues fixed, all the vapor barrier pulled out and replaces, and had the AC evap. coil cleaned and the ducts checked and cleaned. The smell/DSS lingered on but eventually went away once the weather changed. We had the coil cleaned again just for safe measure and hoped that all would be OK. Well, this winter, on Xmas day to be exact, the problem popped back up again. We wound up getting the coil cleaned again and I also added an industrial sized crawl space dehumidifier just for good measure. However, it didn't help. After talking with Trane corp. and Trane of GA, we were told that we needed the replacement, sealed coil. We just had that put in last week and the drain pan cleaned, etc. for good measure. Of course, we had a lot of rain over the weekend and the smell is still lingering and the air blowing from the vents seems more humid than normal-in other words, nothing's changed.

    My question now is, could the lingering problem with dirty sock (it's far worse than sock odor-it's really, really bad) have anything to do with the condensing unit issue we had addressed previously? We didn't have any issues with smell from the system prior to the replacement. It's my understanding that the condensing unit exchanges heat and humidity from the inside to the outside. If it wasn't working correctly, could it be contributing to my problem? Also, since we've done the replacement coil and it hasn't seemed like it's helped, what is the most logical course of action? I've heard the talk about UV lights, etc. Does that stuff really work. Should I waste my time with them or look at replacing equipment?

    This dirty sock problem was bad enough before when it was just my wife and I. Now that we have a baby in the house, we're especially concerned with air quality.

    Sorry for the long post. Thanks in advance for any advice.

  2. #2
    Join Date
    Jul 2005
    Posts
    5,380
    I don't know what the history is, but the condensing unit, if you're calling it by the right name, only circulates refrigerant through the indoor coil, and can't be the source of the odor. If on the other hand it's a package unit rather than a split system, then it could be the source of the odor. Your best course of action is to track down the source of the odor and eliminate it. If you can't do that yourself then it's time to get out the phone book. Had a skunk living under the shroud on one a month or so back, stunk up the whole house. Who knew they could fit through a 2 in opening? They must be 90% fur.

  3. #3
    Join Date
    Jul 2007
    Location
    SA
    Posts
    127
    this may not be DSS. DSS is caused by bacteria building up on the evap coil when AC is not being used then when either ac comes on or unit goes into defrost the coil gets cold and wet and bacteria releases an odor. They do have treated coils that prevent bacteria from forming on the coil but cost alot. And yes U.V. lights work if installed correctly and coil is cleaned with a certain dual cleaner. The outdoor unit has nothing to do with DSS. The cause of DSS is bacteria in your house and has nothing to do with the unit so even changing the unit will not get rid of DSS.

    I would make certain that DSS is the cause of the problem before sinking money into UV and a treated coil.

    I wish you luck, I know that this can be frustrating situation.

  4. #4
    Quote Originally Posted by hvacrmedic View Post
    I don't know what the history is, but the condensing unit, if you're calling it by the right name, only circulates refrigerant through the indoor coil, and can't be the source of the odor. If on the other hand it's a package unit rather than a split system, then it could be the source of the odor. Your best course of action is to track down the source of the odor and eliminate it. If you can't do that yourself then it's time to get out the phone book. Had a skunk living under the shroud on one a month or so back, stunk up the whole house. Who knew they could fit through a 2 in opening? They must be 90% fur.
    Thanks for the quick response. The issue is definitely contained within the AC system. When you go into the crawl space, it's perfectly comfortable and zero odor. In 2006 I thought that this could be an animal but since we've had all the ducts cleaned and the whole system checked several times, I've ruled out fur covered sources for the problem. It also quit smelling pretty much all last summer, especially because we had a drought. It was only after it started raining regularly and the weather got cooler that the problem occurred again.

    The system is split. I really only threw out the part about the condensing unit because when it didn't work in the past (the condenser coil before replacement), the system didn't control humidity levels in the house. In trying to touch on every possible cause, I just wondered if this could be contributing. I'm going to be checking the drain lines today to make sure they're clean. They should be given the system check last Friday. I'm also going to make sure all of the trunk line connections and the intake to the handler do not have any leaks or gaps. Also, I'm still considering a UV light in the system. I've heard mixed things-there's no middle ground on them-they're love them or hate them. In the grand scheme of things, it seems like a relatively inexpensive add on.

    In the end, I'm wondering if I just need to replace the downstairs unit, intake line, and trunk lines all together.
    Last edited by Stinkhut 1160; 03-17-2008 at 10:34 AM.

  5. #5
    Join Date
    Apr 2001
    Location
    Arkansas
    Posts
    2,111
    Make sure drain line(s) are not run to sewer.
    "FIGHT CRIME: SHOOT BACK"

  6. #6
    Quote Originally Posted by srmfsr View Post
    Make sure drain line(s) are not run to sewer.
    It's not. We have a septic system but it's not run to that either. It was run to the exterior of the house.

  7. #7
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,270
    Drying the a/c coil/dcuts throughly between cooling cycles is way reducing biological growth in the coil/duct area. Is it a heat pump or straight a/c? Short term, operate the fan in the "on" mode to dry the ducts/coil as much as possible between cooling cycles. Drying the a/c/ducts makes the home higher RH. What is the capacity/brand of the crawlspace dehumidifier. If high enough capacity, more assist in drying ducts/coil. What is the %RH in the home at various weather conditions? <50%RH ideal for controlling biological growth. Regards TB
    Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
    Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
    Use +Merv 10 air filter. -Don't forget the "Golden Rule"

  8. #8
    Quote Originally Posted by teddy bear View Post
    Drying the a/c coil/dcuts throughly between cooling cycles is way reducing biological growth in the coil/duct area. Is it a heat pump or straight a/c? Short term, operate the fan in the "on" mode to dry the ducts/coil as much as possible between cooling cycles. Drying the a/c/ducts makes the home higher RH. What is the capacity/brand of the crawlspace dehumidifier. If high enough capacity, more assist in drying ducts/coil. What is the %RH in the home at various weather conditions? <50%RH ideal for controlling biological growth. Regards TB
    The system itself is an Electric HP. Unfortunately, we don't have a gas line available or I'd run duel fuel. The humidifier is made by Oscar Air. We use the 350 CFM unit. I've set it according to the manufacturer to run to attempt to keep the CS at 40-45% RH. It's fairly close to the air handler so I would hope that it's having some impact. I've seen the drain line and it's definitely pulling moisture from the air.

  9. #9
    One other comment. On a dry, relatively mild (low 60s) day like today, the air coming from the vents from the crawl space handler smells a bit musty. Only when it's cold and raining/damp and the system kicks over to defrost does the smell kick up from musty to flat out wrong. It's pretty much musty all the time now even with the fan permanently on. When it's not running, the house smells fine and when it's been running, the house has a mild hint of the musty smell. Not over-powering but you know it's there.

  10. #10
    All, another update I'd like to add to this to see if I get any feedback on how to proceed with this.

    As I posted previously, not only do we get the strong smell when it's cold (=<40 degrees) and damp/raining outside, we're also getting a pretty consistent damp/musty smell from the air discharge regardless of outside conditions, heat or AC. Yesterday, I checked the bottom of our trunk lines and the box that splits the trunk lines from the air handler. On the bottom of the trunk lines, there appears to be so sort of greenish growth on the foil-covered, fiberglass outer lining of the trunk lines for about 1-2 feet from where it splits. When we had the water issues in the crawl space, the water actually collected under the vapor barrier right underneath the trunk lines where the split into two occurs. Is is possible that this funk/mold/whatever has infected the trunk lines and splitter box causing the everyday musty smells and that this mold/bacteria is what fires up and smells so horrible when it's damp/raining and the system defrosts? Since the coil's been replaced and the drain line is apparently clear and OK, could the smell be being injected into the airflow after leaving the handler? Bottom line, should I be thinking about replacing the splitter box and trunk lines?

  11. #11
    Join Date
    Apr 2001
    Location
    Arkansas
    Posts
    2,111
    Highly possible the insulation in the plenum is contaminated.....either from the moisture of the ground or....the pan is overflowing into the plenum from either stopped up at the fitting where the drain line takes off or not level.
    "FIGHT CRIME: SHOOT BACK"

  12. #12
    Quote Originally Posted by srmfsr View Post
    Highly possible the insulation in the plenum is contaminated.....either from the moisture of the ground or....the pan is overflowing into the plenum from either stopped up at the fitting where the drain line takes off or not level.
    And could the trunk line be contaminated too?

  13. #13
    Join Date
    Apr 2001
    Location
    Arkansas
    Posts
    2,111
    Not likely. But on the other hand I have seen a drain completely flood a plenum for weeks and the the problem corrected and no smell after it dried out. That is why I am second thinking this thing. Are you sure you're not drawing air from under the house when the unit comes on? Is the trunk line connected solid and air tight?
    "FIGHT CRIME: SHOOT BACK"

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