On Wed, 08 Aug 2007 16:45:45 -0400, wrote:

Reading you latest post puts a new slant on your first post.

I just had a new HVAC system installed in a new house and have not paid for
it yet. Today the temperature is 100 outside. I have my thermostat set to
77 and the actual temperature is 81. (This is upstairs, downstairs a
separate system is maintaining the selected temperature.)

I am getting about a 20 degree drop. Is that acceptable or should the
system be doing better?

You are asking here, it seems, about the 20 degree drop.

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.

Thanks for any help!