A/c Will Not Keep up during Day

Old 06-08-10, 12:19 PM
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Unhappy A/c Will Not Keep up during Day

I know someone else posted the same but I didnt see answers that directly related. I have about 2,200 ft2 under air in SW fl., Brand new 4-ton Rheem compressor and larger air handler that when combined created 16 seer -so i'm told. I thought that my problem was poor isulation in ceilg as there was only 4" so had L-10 blown in oner entie house and garage (which has an a/c vent off handler-almost closed) equallying 16 1/4 inches. the vents are not blocked, the ducts are insulated and have been checked for leaks....I start in the morning at 74 degrees, by 12-1pm 75 degrees, by 3pm 76 degrees. Can not cool down even by 1 degress again until about 8pm. A/c techs say the system has proper freon charge and is running perfect. Graned the air is cool coming out of vents, but never the less my cool air is going somwhere...Any ideas??? I am at alodd after spendin 10k on air and insulation and being in the same place that I started!!!
Old 06-08-10, 05:40 PM
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Maybe you have an air flow problem. Check your returns. If they are flex duct, check the bends to make sure they aren't too tight. Also find out if the returns are large enough. I don't know what they should be, but maybe someone else can help you there.

What is your outside temp when this is occuring?
Old 06-09-10, 10:57 AM
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The first procedure is always to do a manual J room by room heat-gain calc with the options shown so you can do everything possible to reduce air infiltration & all sources of heat-gain & heat-loss, greatly reducing both heat & cooling BTUH equipment sizing.

Also, a possible reduction in equipment sizing will usually greatly improve the duct system performance.

The duct system airflow must be checked & be correct, before performing any charging or other procedures!

This ordered procedure must be followed to achieve an optimally charged efficient operating air conditioner.

Do not leave out any of the steps and always do these procedures in the order sequence illustrated.

First, check that there are NO air leaks in the Supply and Return Air duct system.

Before they check the refrigerant charge always check the actual air flow with an anemometer & apply the math formula.

At 50 relative humidity indoors & normal airflow the temp drop should be 18 to 20-F. A higher 16-SEER outdoor condenser temp-split rise can be as low as 14 or 15-F .

Contact me...
Old 06-09-10, 07:58 PM
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see what you do have

if the room temp is 75F, see what it is in the return plenum at the air handler. It should be 20F colder as it exits the air handler, so check it there. Now see what the temps are at the registars... if you have your 20F delta T, how much do you loose getting it to the registars... Is this in an attic where its 120F? Is the return duct insulated too?... If this was new, you likely have mismatched components... You cant take a piece of this with a piece of that and expect efficiency...Make sure both units are either R22 or R410a. What are the make and model of the air handler and condencing units? is the suction line sweating..is condensate coming out of the unit drain line??? Is the air filter new? what size is it.

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