Air Con Units On Hot Walls

[Nekton]

I have three new air con units (one Central Air 24,000BTU and two Daikin 12,000BTU) in my apartment. They work great but there is one problem. The thermostats just completely do not work during the day.

The blower units are mounted on an outside wall which gets direct sun for much of the day. This wall gets seriously hot! They are also mounted directly above sliding glass doors with heavy curtains. The curtains are about 3-4 inches off the wall, and this produces a nice place for hot air to flow upwards. I am considering trying to block this or seal it up some way but haven’t tried yet. So the thermostats which are housed in the unit are being subjected to temps much higher than the room. This all results in having to run the temp control way up or even just shutting the unit off to keep the compressor from running nonstop. I am sure this is not efficient and I know it is not comfortable.

Is there any way to mount an outside temperature sensor or thermostat away from the unit and the hot wall? What would this entail? Any other ideas or suggestions?

Thanks!

[Naam]

Is there any way to mount an outside temperature sensor or thermostat away from the unit and the hot wall?

unfortunately that is not possible as the sensor of modern units is integrated in an electronic block and therefore can't be separated. i was interested in removing the sensor of one unit for a different reason than yours but did not succeed.

it was a piece of cake doing that with old units where the sensor was a capillary tube that triggered by pressure mechanically a compressor off/on switch. but that was many rainy seasons ago.

[kwonitoy]

I was under the belief that there is a temperature sensor in the remote control unit.

When the temperature in the room at the remote is reached the air con should shut down?

My bedroom aircon is on a wall that gets direct sun all afternoon and will shut down when the temp on the remote setting is reached

A six year old Daiken model

Edited May 3, 2012 by kwonitoy

[bankruatsteve]

I don't think the remote has temp sensor - at least my unit doesn't. But OP, is the problem you get too cold? If it's just a daytime event, why not try opening up for venting during the day - keeping the drapes closed to the sun side. Just use the A/C at night (as perhaps most of us who live here do).

[Naam]

remotes do not have sensors.

[Nekton]

unfortunately that is not possible as the sensor of modern units is integrated in an electronic block and therefore can't be separated.

Thanks Naam, that is what I wanted to know, I guess the only way to go about this is to try and isolate the sensor from the heat coming from the wall and door.

[Nekton]

I don't think the remote has temp sensor - at least my unit doesn't. But OP, is the problem you get too cold? If it's just a daytime event, why not try opening up for venting during the day - keeping the drapes closed to the sun side. Just use the A/C at night (as perhaps most of us who live here do).

The problem is that the thermostat is being subjected to much higher temperatures then the actual room temperature causing the compressor to run constantly. The apartment is occupied during the day and 40 degree heat is unacceptable, so the AC must be used. I am not sure most people do spend their days without AC, I witnessed a great deal of people loitering in the malls today, sitting around the food courts soaking up the free AC.

[Naam]

unfortunately that is not possible as the sensor of modern units is integrated in an electronic block and therefore can't be separated.

Thanks Naam, that is what I wanted to know, I guess the only way to go about this is to try and isolate the sensor from the heat coming from the wall and door.

that IS the problem which i could not solve Nekton. the sensor is exposed to the air intake temperature sensor and there is no way to insulate it. i was trying to do that but to achieve the opposite, meaning i wanted to go 2º-3º below the usual +18ºC when the sensor switches off the compressor to prevent ice forming on the evaporator coils.

to solve your but not my problem, a most tedious piece of "surgery" would required, namely to remove the whole electronic block, move it a few meters (down or away), attach wiring by soldering to a dozen or more contacts a dozen and then connect the wiring to the unit = an undertaking fit as punishment for somebody who killed his parents with an axe (german saying).

[Naam]

remotes do not have sensors...

...because if that was the case Nekton's and my problem could be solved with a fingers snap.

[JAS21]

A pelmet for the curtains would help considerably, easy to make and put up ... you would just have to try and cover it with some sort of material that matches the curtains. You could even use say half inch thick polystyrene on top of the pelmet.

As Naam says the temp sensor is on the air inlet, usually very close to the fins, so maybe also think about some insulation on the wall above the air intake, but I think your main problem is convected heat from the windows below. A window film would also help ... expensive if a large area though.

[tutsiwarrior]

I have a temperature gauge in the bedroom near the AC outlet to measure the room temperature during AC operation...simply adjust with the AC control when the room temp rises...'steam operated' but does the trick...

[Kwasaki]

You say apartment but is there anyway to shield the units from the sun with a canopy roof.?

[Khun Jean]

A design flaw unfortunately and it seems to be like that with all of the aircon units i have seen.

Maybe you could use a timer to switch on/off the airconditioner. Experiment with on/off durations to get the right temp.

Maybe add a fan to bridge the off cycle.

[HerbalEd]

I've never seen nor heard of a thermostat being a part of the outside air-conditioning unit. I've only seen the thermostat mounted inside the room/area to be air-conditioned. Does't make sense to mount it outside which when hot would run the air-conditioner continuously.

[Pib]

Yea, I'm somewhat confused also about all this temperature sensor location talk. I thought the only temperature sensor was located right behind the split air evaporator control/filter panel (i.e., the unit inside your house; not the outside air compressor unit). The sensor unit is mounted on the evaporator core but the sensor itself is not touching the evap coils which are very cold...this sensor is measuring the air coming into the unit to determine room temperature. A sensor for a window air con is pretty much in the same location. Now for a central air con the sensor is located on the wall. I'm confused...but that's OK because I'm use to it.

[Naam]

Yea, I'm somewhat confused also about all this temperature sensor location talk. I thought the only temperature sensor was located right behind the split air evaporator control/filter panel (i.e., the unit inside your house; not the outside air compressor unit). The sensor unit is mounted on the evaporator core but the sensor itself is not touching the evap coils which are very cold...this sensor is measuring the air coming into the unit to determine room temperature. A sensor for a window air con is pretty much in the same location. Now for a central air con the sensor is located on the wall. I'm confused...but that's OK because I'm use to it.

with central aircon there are two ways:

-wall unit temperature selector and sensor. unit switches compressor according to the temperature at its location.

-wall unit with temperature selector but sensor located in return air. compressor is switched on/of according to temperature of return air which is preferable.