firstname.lastname@example.org (Doug Miller) wrote in
The do nothing maintenance people took the cover off so it is difficult
to determine what setting is low. In any case the blower is on
continuously when I am gone. Does the blower itself use that much power
or is the main power drain due to the compressor/cooling? I would like
to be able to shut the whole damn thing off over a 10 degree spread in
temperature, but maybe your right, that this would lead to an early
demise in the entire unit.
Main power drain is the compressor. Tell your maintenance
people to fix it so you can set it correctly or pay your
additional cooling bills.
Almost all HVAC systems will do what you are asking for yours
to do without any additional equipment. Get your maintenance
people to explain your system to you and instruct you on how
to set it to achieve the desired result.
Chilled water, as in the apartment complex puts a big central unit in
someplace (maybe the roof) and pipes chilled water to all the apartment
units. Then the apartment units each have a simple device with a coil
and a blower motor.
The central unit that chills the water could either be a larger scale
conventional compressor/refrigerant thing or a cooling tower (that uses
The reason I mention this is that there is one apartment complex here
in town where I live that has a system like this. The complex is built
so that there just a few buildings, and each building is a big long
rectangle, which made it easy to run plumbing to every unit. Summers
are hot here, and people who live there (of which I've known several)
have loved that you can crank the A/C down as low as you want with
paying a cent more (and same with heat in the winter). The negative
side is that the entire system can either cool or heat, so the
management has to make a decision about when to switch the entire
complex from hot to cold as the seasons change, and residents have
no control over that.
I think it wouldn't be hard to do. Lowest is at one end or the other.
Put the knob in the middle. Let it run until the compressor turns
off, wait 3 or 4 minutes because it's not good to restart an AC right
after it turns off, then turn the know CW and see if the compressor
comes back on. If it does, that direction is for greater cooling,
lower temp. If not, turn the knob CCW and see if it comes on. it
will only come on in one direction.
If that doesn't work, go to the store adn see which direction is cold
on the AC's they sell there. I think they are all the same. Look at
several brands to find out. Look at your brand. Within one brand,
it is are almost certainly all the same.
Why don't you just turn the whole AC off when you are gone, and turn
if on when you get home? You can do something outside until it cooles
Someone in mcfl must have said that. I don't agree, except maybe to a
small degree. If you have 15 more years left on the AC, you might
lose 3 months in my opinion.
I rewired my room AC so that when the compressor turned off the fan
did too, and vice versa. I did this mostly because the noise of the
fan annoyed me, especially later at night when I didn't need AC at
all, or the fan. If this was 2 in the morning, I would have had to
listen to the fan in my sleep for another 5 hours for no good reason.
Rewriing didn't require any cutting, soldering, unscrewing or
screwing. But it did require thinking. All the connections in most
of these things are made with slide on connectors, that slide on to
spade lugs. Unless things have changed recently. In other words,
things that go on both side of other things that are flat.
Power Cord --- On/Off ---|-----thermostat-----compressor motor-
A |---- fan motor---
Each of these two things on the right are connected to the other side
of the power cord.
Plan this totally before starting. Make a clear drawing of how it was,
including wire colors and sketches of the connector, in case you have
to put things back the way they were.
Unplug the AC.
Pull the wire from the ON-OFF to the fan motor off at one end or the
other, B or A, probably B. Connect the end of the wire to C, so
that both the thermostat and the compressor motor are controlled by
There were 3 steps when I did it, because I had to move around a wire
that had connectors on both ends.
That should do it. I slept a lot better after I did this.
Well, the second one doesn't control the temp because the first one
does. You have either a two-speed or three-speed fan.
The AC may also do heating, expecially if it came from a motel, where
they often have an AC do double duty as a room heater. If that is the
case, the center position is usually off, and one notch on either side
is usually low-speed fan and AC or heat. TWo notches on either side
is usually high-speed fan and AC or heat. You can tell by listening
what position runs the fan at a higher speed.
More likely is that there is no heat, but there are two speeds for
ventilation only, with no AC. That would also use a five position
They could make, if they wished, room AC's with 3 speed fans but I
don't know that anyone does.
Again, you can learn more about these controls by going to a store and
seeing what sort of controls are present on other room ACs.
There might not be one you can find. OTOH, there is often a black and
silver plate right under the cover panel that says the model number
and how many amps it uses, etc. and that probably gives the brand.
I wouldn't take the AC out of the wall to learn the brand, because
most breands do things the same way. In addition, even if somehow you
draw the wrong conclusions about how the controls work, you'll realize
it doesn't work that way eventually, and you can refine your
There are usually 2 or 3 "Cool" settings (adjusting fan/blower speed
to Low/High, possibly medium, without directly affecting how often the
compressor cycles on -- the Temperature adjustment does that), with an
equal number of "Fan Only" modes which inhibit the compressor from
coming on at all.
Some window units have a heating mode as well, but with only 4-5 dial
settings, yours probably doesn't.
Here are some measurements from a small (5200 BTU/hr) 120V, Frigidaire
window AC using a Kill-a-Watt meter, taken while outside temperature
was about 10F warmer than inside.
Fan only (low) 58W
Fan only (med) 70W
Fan only (high) 95W
Compressor running, with fan on Low:
starting surge 500W
running 322W-433W (gradually increasing until compressor
So, subtracting 58W for the fan/blower, and neglecting that very brief
startup surge, with this small AC the compressor itself consumes an
average of ~320W, 5.5 times what the fan/blower pulls on Low. If it's
very hot outside, the compressor can draw more power.
Your 220V window unit is probably at least double the cooling capacity
and power consumption of this small one, but its fan vs. compressor
wattage ratio is probably similar.
I've never seen this for sale as an all-in-one unit. It wouldn't be
difficult to create one, using some contactors and a simple central-AC
thermostat, without modifying the window unit itself, but perhaps not
worth the trouble.
There are X10 power-control modules available for 220V sockets,
though. I used one with a window AC at my old apartment, to let a
nearby computer control it via power-line commands. One X10 tabletop
controller has a timer feature built in, but I don't know of a simple
one that can send commands based on temperature. You might want to
try asking on the "comp.home.automation" newsgroup.
It controls the power, modulewise.
Sorry, I couldn't resist.
It turns the power on and off. X-10 things are connected by radio
waves and are somewhat more expensive because of that. Also because
in this case, you would need, iiu x-10 c, an X-10 contol-unit to
control the power control module. (I wasn't even trying here.)
Interesting. That has a British plug on it, which could be a problem
if the original poster is from the US or Canada, but might work OK
with adapters on either side (unless it cares about 60 vs 50 Hz).
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