On Wed 22 Jul 2009 11:36:15p, The Daring Dufas told us...

Wayne Boatwright wrote:
On Wed 22 Jul 2009 10:47:40p, The Daring Dufas told us...

Smitty Two wrote:
In article ,
"SteveB" wrote:

"Wayne Boatwright" wrote in
message 5.247...
...anticipate the time it takes to reach a certain temperature by a
certain time?

For example, during the day while no one is home but the cats, we
keep the temperature set at 80°F. I arrive home at 5:00 p.m. and
would like to have the temperature at 75°F. when I arrive.

Rather than my having to "guess" how long it might take to reduce
the temperature by 5 degrees, is there a thermostat capable of
figuring that out?

TIA

--
Wayne Boatwright
I had two programmable thermostats removed, and cheepos put in their
place. Unless you are homebound and have the exact same schedule
week to week, there is always times when the units are running and
no one's home, or it's too hot or too cold. Saved a lot of money.
We live in hell. Couple of days ago, it was 113. We leave the
windows open during the day, as leaving on the AC is just a waste.
From the time we get home, it takes only about fifteen minutes to
cool down the house. Then at about ten, we open it up again, as the
night time temps are very cool. I don't think fifteen minutes is a
long time to wait, when given the choice of $$$$$ more each month.

Steve
So your A/C cools the house from 113 to habitable in fifteen minutes?
It may be possible in a low humidity environment but not
here in Alabamastan. It would take more like 15 hours
with the humidity we have. I spent some time in the
country of Californiastan about 20 years ago and were
I was working, the dry wind was blowing off the desert
and the air temp was 105. My shirt was dry, even my
under arms. When the temperature hits 105 here at home, my shoes are
wet, every stitch of clothing is soaked with sweat which drips off my
elbows like a leaking faucet. If it weren't for air conditioning those
Damn Yankees would fly home every summer. *snicker*

TDD


An improperly oversized unit can certainly produce those kinds of
results, however it's an impractical solution. Here in Arizona where
our summer temperatures can easily run as high as 115-118 degrees, the
humidity is typically low except during our monsoon season. In spite
of that, dropping a temperature by 40 degrees is near nigh impossible
with a properly sized unit. A properly designed unit simply isn't
designed to do that.

When an AC system is properly designed and sized for the space, it
should actually be running more than it is off. One of the main
reasons is to allow the unit to remove as much humidity as possible.
An oversized unit will cycle on briefly and reduce the temperature, but
fail to remove the maximum amount of humidity, so the atmosphere
becomes cool and damp.


Well, I know a little about refrigeration and air conditioning.
The last big one I worked on was a four thousand ton Carrier
centrifugal chiller and Sunday I helped a friend swap out a
1&1/2 ton compressor at his home. The line set on the ton and
a half was a little smaller than that on the 4K ton unit. *snicker*

TDD


Yes, I imagine it would be. :-) My dad was an HVAC engineer with the York
Corp. for many years. Primarily he designed various climate control
systems for very large scale installations, although occasionally piddled
with residential appliations. I absorbed quite a bit from him while I was
growing up and surrounded by his work, as he did a lot of work at home.

--
Wayne Boatwright
------------------------------------------------------------------------
Most of the food allergies die under garlic and onion. Martin H.
Fischer