This post is a copy from a community form I host. I realize there are many factors in choosing the peak effeciency system - none of with which I am familiar. I've downloaded the trial version of the calc program, but was intimidated by the many options. My question is fairly simple... Should I expect to have a new system get my house to 78 degrees?
My 1 year old, single-story, Florida spread, 2000 sqft Pulte home came equipped with a 3.5 ton Lennox AC. Since day one, it has struggled to get the temperature down to 78 degrees during the day.
In fact, I recently connected a data logger to the AC to monitor the temperature and the AC on/off cycle time. Turns out, when the AC turns off, the house rises about 3-4 degrees per hour. When it's on, it drops about 1 degree per hour - until about 79 degrees. Then, the AC simply doesn't turn off.
My questions to other homeowners (especially those in Pulte homes) are:
1) Are you able to get your home lower than 78 degrees during the hottest part of the day (with outside temps >90 degrees)?
2) If so, does your AC cycle at all, or does it stay on?
3) How long does it take for your AC to lower from, say 80F to 78F?
4) What is your ton to sqft ratio (i.e. how many sqft do you have in your home and how many tons is your ac)?
My thermostat has a runtime meter on it. On average (with temperatures above 90F) I will have between 12-14 hours of run time on my AC per day - with the house never getting below 79F until either the sun goes down, or the rains start.
Supply vs. return differential = 22F
Temperature drop w/AC on = 1 to 1.5 degrees/hr
Temperature rise w/AC off = 3-4 degrees/hr
Sqft vs. Ton = 571:1
Stall point = 79F w/temps >90 outside.
Runtime = 12-14 hrs/day
Any help would be appreciated!!!