# Is this acceptable HVAC performance?

My answer is that if 90 to 100 deg days are not unusual in your area, then I would not be satisfied. What happens as the temp drops later in the day? On a 100 deg day, when does it finally reach 77?
I'd also look at your attic venting. Is it adequate? Are the soffit vents open and not blocked with insulation? In areas with 100 deg days, I would also install a radiant barrier on the underside of the roof, which can help a lot. If you improve any of these, you will be saving energy costs as well.
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On Wed, 08 Aug 2007 16:45:45 -0400, snipped-for-privacy@aol.com wrote:
Reading you latest post puts a new slant on your first post.

But it was still confusing, I realize now. Your first paragraph says it's 100 out and 81 in. That's a 19 degree difference, so I didn't think that what you were referring to when you said a 20 degree drop.
If you meant the same thing, why did you up it from 19 to 20?
I said, perhaps negligently, but I'm not getting paid, that a 20 degree drop is the most you're going to gget, but that referred to 20 degrees from the input to the AC to the output, the air just before it goes in the AC to when it comes out**. IIRC, I think it was this thread where someone was explicit about hat.
Once the room is down to 90, say, a 20 degree drop will yield 70 degree output.
**But maybe measuring it as described where this footnote comes from, you only have a 15 degree drop. That might be acceptable also. Then you'll only get 75 degree air out, until the room is 85, when you should get 70 degree air out.
If your ac is big enough for the space to be cooled, you should be able to get it down to 70, but I don't think you said either how big your AC is or how big it was calculated that you need. Or how much hot air might be leaking in, through leaks or radiation, and how much the cold might be getting out. And is the attic adequately ventilated. Or how long you had been running the AC. You have never replied to any of the questions or suggestions offered, you just seem miffed that we say technical things and you're not interested in those. But we can't answer your question if you won't answer our only slightly technical questions. "How long has the AC been running" doesn't seem very technical to me, but maybe that is because I have 3 years trade school and 10 years experience in "how long". Also, I finished a certificate program in "running".
Also you shouldn't just rely on one thermometer to know the indoor temp. It could be bad, even though it is new. Surely you have another thermmometer around the house that you have reason to believe is accurate, or you can go to the store. You don't need expensive, which is almost always based on the decoration, but it should be large enough to mark every 2 degrees and to be able to read when it is between two of the markings. Then look at all the thermomters for sale like it and pick one that reads in the middle, the mode, mean, or median of what they have. They will probalby all be very close to each other, but make you don't buy one that is not. Then see if you have 81 or something closer to 77.
Also, did you try turning the stat down to 70, as somoene suggested. This is not so that you can keep your house at 70, but to see if it will go lower than 81 if the stat is set lower. Not only might the thermometer on the stat be wrong, but it could be right and the stat could be calibrated incorrectly. That's no big deal. If it is out of warranty and cools (or heats) the room to 4 degree hotter than it is set for, then one just sets it 4 degrees lower. These numbers are just there to help. They were not given by God.
So, if you've tested everything and it's all adequate and unless they sold you the wrong AC with your consent, maybe it's not acceptable. I'd like to hear the answers to everyone's questions before I can say something stronger.
And, have you pointed this out to the ac contractor? You should do it over the phone, so that he allows time and brings whatever he needs to fix it, instead of waiting and telling him when he is there and causing him to make another trip.