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Old 05-01-2013, 05:35 PM   #1
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Confused about AC Recommendation


We had a new complete Goodman 5 ton AC unit installed in 2010 after moving in to our new to us Dallas area 2350 sq ft home. I had a bit of a surprise last week when I had my AC serviced by the same company that did the install. The service guys asked me how the system was working and I told them okay, but it does get a bit warm August in the living area due to high (15ft) ceilings and windows. Same thing I have told the previous service guys every time the unit was serviced since it was installed. After inspection they tell me that the system needs to have additional supply vents added and a new plenum since it only is at about 1350 cfm and should be at 1600 cfm. This is also causing the suction line temp (40) and pressure (110) to be incorrect. So for $3000 they can get my system up to spec and help cool the house better. So when I ask why this wasn’t part of the install I get the “I don’t know look”. My plan is to get another AC guy out and get a second opinion as I am not sure what to think. Anything I should specifically ask or have the second guy check?

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Old 05-01-2013, 06:03 PM   #2
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Confused about AC Recommendation


manual j should be consulted to insure your system is not too big or too small.

manual d should be consulted to insure your ductwork is correctly sized.

the service guy should be able to do a delta t temp measurement and a static pressure test.

you can also ask for a flow hood for cfm into each room.

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Old 05-01-2013, 06:20 PM   #3
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Confused about AC Recommendation


5 tons x 400 cfm/ton = 2000 cfm, the minimum would be 5 tons x 350 cfm =1750 and that is with Carrier and ONLY if it is carefully balanced and setup. The service guys may be idiots or trying to upsell you something now that the economy is bad. Get another company and don't tell them anything and see what they have to say. Get a list of the readings, suction, discharge pressures and post them here along with the outdoor and indoor temps and indoor humidity and we may be able to tell you some more. Also would need the model number and SEER rating of the unit. We have a couple Texans here.
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Last edited by yuri; 05-01-2013 at 06:24 PM.
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Old 05-01-2013, 10:01 PM   #4
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Confused about AC Recommendation


Its moving more then 1350 or your coil would be freezing up.

Nothing really wrong with a suction temp of 40. Depending on the outside temp and inside temp and humidity.

You can probably do everything yourself that they are proposing to do.
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Old 05-02-2013, 01:54 AM   #5
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Confused about AC Recommendation


nothing wrong up front to consider. just a tweak.
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