I have a big problem with my air conditioning not keeping up in my
condominium. Outdoor unit is a Tempstar 2.5 ton 12 seer, indoor unit is a
Goodman GMP075-3. Stat is at 68. If the outdoor temp stays below 75, indoor
temp stays around 68-72. If the outdoor temp is above 75, the indoor temp
rises, faster or slower depending on the outside temp. If we get a heat wave
and it's above 90, the inside temp will rise to 80 and stay there until the
outside temp falls below 75.
Called the company that replaced the company that installed the systems when
the condo was built. A tech came and looked out the outdoor unit... good
pressure, no leaks, working great. They looked at the indoor unit...
everything looks good. They can't figure it out. The think there may be
issues with the thermostat, so they start by replacing it. After several
days, it makes no difference.
The owner then came out. Came to the same conclusions, the indoor and
outdoor are working good. He said that the original company that installed
the ductwork made it a bit more complicated than it should be, and basically
the air has to travel farther. Due to some complaints from other residents,
the builder asked this new company to come up with a better ductwork design.
They now do it a lot different than the previous company. He says he feels
that replacing the air handler (the Goodman GMP075-3 is a forced air furnace
with a 1/3 HP blower motor) with a higher efficiency unit with a DC Drive
motor will overcome the ductwork issues. However, when checking all the
registers, he was very surprised to find good flow out of all of them.
He was at a complete loss. He said he wanted to call in a engineering team.
Three guys came out, one was the boss. He looked at everything. The outdoor
unit is in top shape. The air handler has 71 degrees from the return air,
and 51 degrees from the outgoing air. He says he normally expects to see a
best case scenario of a 16 degree drop. I'm getting 20, which he says is a
"pipe dream." He then checked the air flow through the unit. It was more
than optimal. He checked air flow out of all the registers, taking the size
of the condo into consideration, it was again more than optimal. The
temperature out of the registers was about 60 degrees. He ruled out any open
headers in the ducts, as the flow out of every register--even the ones
farthest from the air handler--was good.
Yet, the day the team took all these readings, it was 70 degrees outside,
and still 75 degrees inside (it was 93 degrees the previous day and the
temperature was still slooowly falling inside.)
He checked the insulation in the house. It was perfect. Which didn't
surprise me... I hardly ever have to turn my heat on in the winter, the
condo insulates so well.
He spent a good hour scratching his head. He left saying, "this is the first
time in my 22 years as an engineer that I've seen anything like this. You
have a system that is above optimal. If it's 90 degrees outside, your system
should drop your inside temp down to 70 quite quickly with no issues. Yet
right now, every aspect of the system is working more than perfectly, and
it's colder outside than it is in your house. It's official... I now know
nothing about HVAC." He said he is going to have to do an intensive case
study to figure out what the hell is going on.
About 12 hours after he's gone, it's now 60 degrees outside and still 71
degrees inside (again the stat is at 68).
Has anyone ever heard of a similar story?