[dmharris]

I had a certified HVAC contractor install an Amana 2-ton heat pump system ASPF183016(Indoor) and SSZ140241(Outdoor) using 410A refrigerant on 4-28-10. I live in Middle Georgia. I notice on 6-12-10 that the system was not cooling in the early afternoons around 1:30pm. Until 11:00pm. The thermostat would be set to 75 degrees yet it would be 80 degrees in the house. I set the thermostat to 72 degrees and still nothing. It would cool from 11:00pm to 1:30pm holding the temperature set. I called the contractor and he told me it was the 90-day air filter that I was using and to change to a 30-day. Needless to say that didn't work. He came out and determined it was because the air return area was not insulated. So he purchase polyshield to put in that area. This didn't work either. Now he won't return my calls. I have reported him to the Better Business Bureau. I have had two other certified contractors come out and one said it was an insulation problem in the attic. So I called an insulation contractor and he said it was more than enough insulation in the attic. The second HVAC contractor told me it's just hot out(temperature that day was 97degrees). I am so frustrated and feel that I am being taken advantage of because I am a single female and first-time homeowner. Can someone PLEASE advise as to what the problem maybe.

[hvac1000]

The unit could be to small for your home. Did the contractor do a manual J to calculate the size needed?

[dmharris]

No, he just provided a quote for three systems and then installed the unit. The unit is actually 2.5 ton and my home is 991 sq. ft. with vaulted ceilings.

[dmharris]

The unit could be to small for your home. Did the contractor do a manual J to calculate the size needed?

No, he just provided a quote for three systems and then installed the unit. The unit is actually 2.5 ton and my home is 991 sq. ft. with vaulted ceilings.

[KISS]

A general quick test of the AC system is the temperature difference across the coil in the air handler. 15-20 degrees depending on humidity. This is a basic performace test.

If the house never had AC then a manual J (heat loss) should have been done. HVAC Software, HVAC-Calc for Heat Loss, Heat Load Calculations sells software where a homeowner can do it herself. This will tell the installer what size AC or heating unit that needed. It is based also on an anticipated exterior temperature and home construction and LOTS of other variables. It may not have been sized for the higher outdoor temperatures.

Manual D has to do with duct design and you need the Manual J calcs to proceed. AC requires higher velocities.
You should notice a difference in fan speed for heating and cooling.

Is there a decent return air system in the house?

A significant way of improving performance is to add both hot and cold air returns. Generally you can replace the lower (cold air) return with one that can be shut off. You then add another return above since the stud space is the return space that also can be turned on and off. You flip which one is on based on the heating or colling season.

Ceiling fans can help the spaces with vaulted ceilings.

To also get better efficiencies, drapes and shades generally should be opened at night and closed during the day. People, don't like that, however.

[dmharris]

A general quick test of the AC system is the temperature difference across the coil in the air handler. 15-20 degrees depending on humidity. This is a basic performace test.

If the house never had AC then a manual J (heat loss) should have been done. HVAC Software, HVAC-Calc for Heat Loss, Heat Load Calculations sells software where a homeowner can do it herself. This will tell the installer what size AC or heating unit that needed. It is based also on an anticipated exterior temperature and home construction and LOTS of other variables. It may not have been sized for the higher outdoor temperatures.

Manual D has to do with duct design and you need the Manual J calcs to proceed. AC requires higher velocities.
You should notice a difference in fan speed for heating and cooling.

Is there a decent return air system in the house?

A significant way of improving performance is to add both hot and cold air returns. Generally you can replace the lower (cold air) return with one that can be shut off. You then add another return above since the stud space is the return space that also can be turned on and off. You flip which one is on based on the heating or colling season.

Ceiling fans can help the spaces with vaulted ceilings.

To also get better efficiencies, drapes and shades generally should be opened at night and closed during the day. People, don't like that, however.

The contractor that came out on Monday gave the following readings: Air from vents was 69 degrees; Return 75 degrees and wall where thermostat was 82 degrees. The thermostat was set at 72 degrees(all day).