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Community and Q&A

HVAC system to large for home

Pigluvswtz | Posted in GBA Pro Help on

Help! Approximately 2 years ago our HVAC system was replaced. The salesman was fired for selling oversized units and then shortly after that the company was sold to another. I have hated the system since day one because the humidity level is high causing mold and mildew in the house and ductwork. Also the unit cycles all the time at just a few minutes each time.The company that purchased the old company refuses to acknowledge that the problems are due to the size being incorrect. They won’t even let me see the load calculations. Their answer is to replace the ductwork with larger ductwork and add a return.
i have had 3 other companies come in and evaluate the situation and all three have calculated (and shown me the calculations) and advised that the unit is too large and by sealing the ductwork it would enhance the problem rather than correct it. Not one of those 3 will do anything because they said the only true fix is decrease the size of the unit.
i am so frustrated and don’t know where to turn. It’s miserable in the house and I don’t want to spend an additional $16,000 for it to be worse.

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  1. user-6623302 | | #1

    Some information about the specifics of the system would help move the discussion forward.

  2. Jon_R | | #2

    > advised that the unit is too large

    By how much? Contrary to popular opinion, over-sizing often has little effect on humidity. Use dehumidifiers to get comfortable and then evaluate if it makes sense to improve things from there.

    Also make sure that your thermostat has the highest dead-band/hysteresis that is adequately comfortable (this could easily double run-times at very low cost).

  3. _Stephen_ | | #3

    Only thing I've seen cause massive humidity problems, is if it short cycles, and then also doesn't turn the fan off, re-evaporating all the water on the coil.

  4. creativedestruction | | #4

    Short term, run a dehumidifier to get ahead of the problem. Long-term you can make the investment in a smaller system with a better HVAC installation company, or threaten legal action against the previous to see if they will pony up.

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