What should I consider when choosing an A/C unit installed in an attic
by
Dean
+3
We're replacing our old A/C unit. We have two units, both installed in our attic in Northern Indiana. The one in question is a 2 ton unit that cools the upstairs (672 sq. ft) where we have 3 East, 2 North, & 3 West facing windows with adequate shade. This unit developed mold on the insulation of the A coils & created an odor in our upstairs. Someone has suggested an RGF Guardian Air REME Cell. Also a 2 stage unit was suggested.
What can cause the mold? Is the Cell worth it? Is the 2 Stage worth it? Is this the right size unit?
What can cause the mold? Is the Cell worth it? Is the 2 Stage worth it? Is this the right size unit?
5 answers
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OK, first the mold. The usual cause of mold forming in or on the evaporative coil is dust accumulation and poor or blocked drainage. Evaporative coils collect water when the surface of the coil drops below the dew point of the air. Dust and dirt accumulation on the coil prevents the coil from draining properly. A block or restricted drain will allow water to stay in the unit. When the unit isn't operating the warm air and the moisture create the perfect breeding ground for mold. If the mold is on the exterior then it needs to be sealed and protected from air getting to any exterior sheet metal. I'm not familiar with the RGF but I'm not sold on any 2 stage unit. First off a 2 stage unit runs almost continuously. On low or stage 1 it operates to maintain a temperature on the evap coil to remove excess humidity from the air. At stage 2 it operates to cool the air in the house which also reduces humidity. In energy efficiency ratings a 2 stage unit gets low marks and will cost more to operate. I personally would opt for the highest SEER rating (single speed) 2 ton unit I could afford. SEER rating is simply a numeric rating attributed to the cost of operation of the unit. The higher the SEER rating, the lower the amount of power (electricity) required to achieve a specific amount of cooling. A 2 ton unit does seem right for this size of area but there are a lot of factors involved in doing a proper calculation; total area volume, ceiling and roof insulation, sun exposure, window exposure and so on.
D & K
on Mar 22, 2015
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Attics are the worst place imaginable for blower coils...you have a cold metal box in a hot humid space, mold is growing and thriving on the condensation...
Pete Wells
on Mar 23, 2015
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Personally, I would talk with another HVAC person. An air conditioner in the attic sounds horrible to me. Good luck!
9530106
on Mar 23, 2015
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A family member living in GA rented a house that had an AC as you are considering. The upstairs in the summer was so cold while the downstairs was like an oven, The thermostat had to be turned down so low but no matter how low the downstairs was too hot. Even ceiling fans didn't have.
Colimbia1
on Mar 23, 2015
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AC blower coils in attics are great if you like brown water stains on your ceiling..
Pete Wells
on Mar 24, 2015
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