Install

Install

QUESTION:

I have a few concerns with my current unit and plan on replacing it in the near future.
It is an Achiever 9 but I am unsure of the size, model is UAFD-042-JBS built in 1991. Is this a 9 SEER?
My house is 1500 square feet with vaulted ceilings throughout and the AC unit seems to have a hard time keeping up with the heat (100-105) here in Southern Cal. lately. If I set the thermostat (good digital) at 80 the unit seems to keep up okay but if I try to cool it to 77-78 it will run continuously during the mid day heat. It has been this way for as long as I owned the house, I bought it new, so I am assuming the unit is too small. The charge in the unit is fine and the air temp at the vents is 20 degrees cooler than the return air. I always clean the furnace filter and burner area and last year I cleaned the evap coil and noticed the drain pan was pretty corroded due to the installer not having the drain at the lowest point. Also since new the compressor seems to be very loud. To top it all off the furnace electronic ignition module goes out about every 2- 3 years at $150.00 a pop.
I would like to install the unit myself and pay someone to evacuate and charge it but I am not sure if there is anyone local who would sell to a non contractor type like me.
How much would a 13 or 14 SEER save over a 9 seer?
If I go with a unit that is 1/2 to 1 ton larger what would this do to the energy usage? Use more amps but cycle less? Save money?

ANSWER:

Vaulted ceilings are are real added heat load problem. I would say at 100 to 105 F, 80 degrees is doing okay especially considering the vaulted ceilings. In Oklahoma techs would say 15 degrees under the outside temperature when it's really hot is doing okay. You are getting 20 to 25 degrees under, so be thankful, it is big enough!
Figure out ways to reduce the radiant, conduction and infiltration heat loads, that will save money, notwithstanding the SEER rating. If you install it in you may get less cooling with the bigger unit and gain nothing Additionally, if everything is not done properly you'll lose the unit prematurely!
Wear shorts and go bare foot and with an added floor or small fans directed on you, you should be in the comfortable zone.
Try not to disturb the air above the 7 foot level as you don't want all that hot air in the vaulted ceiling area going through the evaporator coil. Do some studying and then call a good tech to evaluate your entire situation! Don't make a huge mistake!

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