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Community and Q&A

Can ceiling-mounted canned lights and speakers cause noticeable problems for my air conditioning system?

jgodd | Posted in Energy Efficiency and Durability on

The home I recently moved into has many can lights and audio speakers mounted into the ceilings throughout both levels of this 2000 sf, 15 year old, south florida house. The second level is topped by an attic with the HVAC ducts. I have a split air conditioning system with the air handler in a closet in the unairconditioned attached garage. I am having difficultly identifying from where a “musty” odor throughout the house is originating. I have had HVAC techs check out duct work seals & insulation, house humidity level, air temperature match to thermostat setting, air handler “cleanliness”, and compressor freon, all of which they say are in fine shape. Leaks and/or seeps from lights and speakers probably seems far fetched but I am at a loss where to look next.

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  1. GBA Editor
    Martin Holladay | | #1

    It's going to be impossible to diagnose this problem on the internet. The first diagnostic test I would recommend would be to use a manometer to check the pressure difference between the indoors and the outdoors when the air handler is operating. This test should be performed in each room. If the room has a door that is sometimes closed, you should perform the test with the door closed.

    There's a good chance that the operation of your air handler is causing portions of your house to be depressurized, and that air from a musty source is entering your home through cracks whenever the house is depressurized.

    Penetrations in your ceiling are probably not well sealed. If they represent holes in your home's air barrier -- and I imagine they do -- then each penetration needs to be sealed.

    Another possible solution is to convert your vented unconditioned attic into an unvented conditioned attic, thereby moving the air barrier to the roofline. This might help two of your problems, but it's an expensive remedy.

  2. GBA Editor
    Martin Holladay | | #2

    In general, you don't want to locate an air handler in a garage. Small cracks in the plenum or ductwork might be introducing air from your garage into your house.

    In short, your house has several major problems. One possible remedy is to abandon your HVAC system and replace it with a few ductless minisplits.

  3. jgodd | | #3

    Thanks for such thoughtful answers Martin. I will have have someone come back out to look at the issues you described. Unfortunately, now I feel worse than ever about what to expect.
    I have not had luck with the 3 HVAC co's I called. What type of individual or company undertakes these types of diagnostics?

  4. GBA Editor
    Martin Holladay | | #4

    You want a home performance contractor, a blower-door expert, or a home energy rater. Ask the contractor whether they own a manometer, and whether they can measure the difference in pressure between an indoor space and the outdoors.

    For more information, see An Introduction to Pressure Diagnostics.

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