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  1. #1

    Musty Smell In A/c

    airman1, i have been reading the posts on musty smells in a/c systems as i have the similar problem with my in the attic unit. i have a hydro air system, triple by-pass 1 1/2 years old in my new house. this is the first time i have ever had this problem and the first time i have a split system with a unit in the attic. i am in massachusetts. i have checked out the attic...no problems,
    i have checked out the unit along with my son-in-law and its sealed good.
    my son-in-law has been in the hvac line for at least 20 years and hasn't heard about the dss problem and either have i. i have had 4 new houses so far in my time, i'm 63 yrs old. my son-in-law cleaned the coils and the system ran with no smell. the next day the smell was back. when we open the attic pull-down stair and start up the ladder you can smell the musty oder slightly.
    you talked about coating the coils...what is the coating? will any coating work?? i'm in the process of investigating so i only have to do somthing once to fix this. sounds like coating the coils works best. i did think about installing an exhaust fan....my house is new with the typical ridge and soffit vents with proper venting but coating the coils sounds like the way to go. we don't hear of this problem in my area but i'm sure its out there. you don't happen to know of any coating places around massachusetts do you??????

    thanks,

    pete

    ps,

    i'm in the design field drawing plans for commercial & residential buildings.

  2. #2
    Join Date
    Nov 2000
    Location
    Eastern PA
    Posts
    68,981
    airman1 is a deceased member of H-Talk.

    There are many others here who may be able to help.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  3. #3
    Join Date
    Nov 2000
    Location
    Eastern PA
    Posts
    68,981
    OK, read the rest of your post.

    A musty smell can be caused by several things, but usually begins with standing water. Since you are in a Norhtern climate, it is doubtful that issues that airman1 encountered are precisely the same as what you are seeing.

    I'm not sure I understand your system. Is this a hydronic coil that has hot water flowing through it from a boiler or other type of water heater? Is there a heat pump involved? Please describe "triple by-pass". Having 8 stents in my heart, triple by-pass is a scary term for me.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  4. #4
    Join Date
    Jun 2003
    Location
    Florida
    Posts
    9,548
    If the same smell is in the attic that your complaint is, that attic unit isn't sealed as good as you think. With DSS, if the coil is cleaned, the smell won't be back the next day. It will come back, just not that quick. I'd look real close at everything in that attic, including the panels on the unit. JMO.
    If everything was always done "by the book"....the book would never change.

  5. #5
    robo-teq and guys,

    my unit is a wel-mclain boiler model uo-4 series 1, 146,000btu with a becket burner, the attic evaporator unit is a first co. triple by-pass from what i'm told means the air travels over the coils 3 times before being sent thru the ducts. i can see why triple by-pass is a scary term to you robo-teq, i hope you are doing well.......i have a couple of friends with stents and they are doing real good...
    when we took the panels off the unit everything was good , the panels and the unit itself wasn't fouled up with mold.
    another idea would be to get some more air movement in the attic by installing a exhaust fan what do you think???
    the attic smell was stuffy with a very slight must odor when its hot outside.
    the local hvac suppliers have a coated unit but coated for rust and corrosion and they haven't heard of this problem altho they sell ulta-violet lights and a spray called bio-tech.
    i checked all over the attic and around the unit and i find nothing to indicate standing water or wetness.......
    i guess thats why i figured the dss was a coil thing.... i hope this info helps.

    pete,

    thanks

  6. #6
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,764
    where does drain line for a/c go to??

    could be sewer gas if it goes to a plumbing stack and trap is dry.

  7. #7
    Join Date
    Nov 2000
    Location
    Eastern PA
    Posts
    68,981
    Quote Originally Posted by t527ed View Post
    where does drain line for a/c go to??

    could be sewer gas if it goes to a plumbing stack and trap is dry.
    Definitely worth looking into. Since this is not a heat pump I don't see how any kind of growth would be occuring on the hydronic coil.

    I am assuming this First company unit has a DX coil for cooling, a blower and lastly in the air stream the hydronic coil for heating.

    A good coil cleaning just may have temporarily eliminated odors from a dry trap condensate line piped into a sewer line or sewer vent line.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  8. #8
    fellas,

    condensate line is piped to outdoors not sewer line...
    i must amend a statement i made.....when the coils were cleaned last week and the odor was not there we didn,t need a/c for 3-4 days but when turned on the odor was there. i previously said the next day but it was 3-4 days.
    my problem really sounded like the situation airman1 was talking about.
    would a coating used to inhibit rust and corrosion work like what airman1 was talking about or is the coating something special???

    pete

  9. #9
    Join Date
    Aug 2003
    Posts
    466
    Quote Originally Posted by PETE MADDOCKS View Post
    fellas,

    condensate line is piped to outdoors not sewer line...
    i must amend a statement i made.....when the coils were cleaned last week and the odor was not there we didn,t need a/c for 3-4 days but when turned on the odor was there. i previously said the next day but it was 3-4 days.
    my problem really sounded like the situation airman1 was talking about.
    would a coating used to inhibit rust and corrosion work like what airman1 was talking about or is the coating something special???

    pete
    From reading the many posts by airman1 it seems that his applications to problems are mostly localized to areas having continuous high temperatures and humidity. Airman1 also did not deal with hydronic coil heating at all, due again to his locale.

    It would seem that you should be looking for issues other then what airman1 contended with. You are in a completely different type of environment with a completely different set of issues.

    If the smell is coming from your cooling systems evaporator coil, it may be a matter of it simply not dropping to a low enough surface temperature to retard mold growth. If this is the case, you should have your HVAC technician look into possibly lowering the blower speed enough to resolve the issue. There are ways of lowering blower speeds that will not create freeze up problems. Only with an on-site inspection of your specific equipment can the proper way to lower blower speed be determined. Specific anti-freeze protection controls may also need to be installed.

  10. #10
    thanks for the input.....
    i found out this item this morning that might be interesting...
    when the coil was cleaned it was cleaned from one side because the ducts were in the way on the other side....is it possible the spray could reach the other side????i don't know stuff concerning hvac...or is it likley the build-up is on the un-seen side.......might have to cut an access in the duct???? or is it easy to take the coil out to clean both sides????

    pete

  11. #11
    Join Date
    Jun 2003
    Location
    Madison, WI/Cape Coral, FL
    Posts
    6,642
    Operating the fan in the "on" mode dries the coil/pan. Drying kills microbial growth. I operate my fan continuous "on" to eliminate musty odors. Several hours per day may prevent the build-up of biological growth in the coil and ducts. This does raise the %RH slightly. I have 90 pint dehu to maintain 50%RH throughout my home. 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"

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