be80be:
If you post what brand of window AC model number It would be easy to fix this for flowers
Yes that would be useful.
For a 8x8 room insulated to 100mm AND HERMETICALLY SEALED a 1 KW unit should suffice to get your target temp.
Any air leakage around the door or poorer insulation you may need triple that power.
I'm actually going 200mph.
The tires on the Bugatti Veyron cost $12,000/EACH (x4=$48,000) and last only 12 minutes at 253 mph. (that;s $4000/minute)
raschemmel:
The tires on the Bugatti Veyron cost $12,000/EACH and last only 12 minutes at 253 mph. (that;s $1000/minute)
I do, in fact, drive a Bugatti sibling
cough it's a VW cough
I do, in fact, drive a Bugatti sibling
So what do you call that "a cheap sister " ? ;D
What the the poster wants is easily done but as boardburner pointed out you are totally removing the controller out of the picture that came with it.
Then fix the fan on all the time works the best get a refrigeration thermostat and let that turn the compresser on
Off topic:
If you own a Bugatti Veyron and are able to drive it at 250mph... I doubt tire replacement cost is much of a concern for you. You probably light your cigars with $100 bills. If you live in a world with a worldview divorced from reality, you tend to only think in terms of what it says about you... not what it costs.
I would have to agree but I would think the Italians and French and Germans have more class than to light their cigars with $100 bills. I think they don't feel a need to do that.
Back in my day....
(I hate that I can say that).
When the X-10 was IOT before the I, this is exactly how an A/C thermostat was controlled remotely.
It's "Back in the day..."
Paulcs:
If small, buy a stand alone freezer, and cut 2 holes in it for air-in and air-out. Put a fan and a movable damper of the holes for automatic closing when you hit 7C.
That wouldn't work as the heat extracted from inside the box would be released straight back into the room at the back, plus the heat from the compressor, it would warm the room up, not cool it.
Hey man you're crazy ) you want to live in a refrigerator or what ? or you training for a nuclear winter? Never met people so loving the cold in that case you'd better move to Alaska where you don't need air conditioning and the question will disappear by itself)) ok ok I'm just kidding, if to speak seriously then such in principle possible. I have a friend who works at https://www.socool.sg/ and he was telling me about the different possibilities of air conditioning. From his words it turns out that your idea is feasible. So try to find an aircon company that can do it.
allanhurst:
Even some of the old mechanical thermostats had a heating resistor in them to add hysteresis to the system..regards
Allan.
Then someone worked out its easy to add hysteresis mechanically.
allanhurst:
Even some of the old mechanical thermostats had a heating resistor in them to add hysteresis to the system..regards
Allan.
Actually they didn't.
I mean, they had the heating resistor but it was not to add hysteresis. Mechanical thermostats have hysteresis as a result of their construction with a bi-metallic strip and a spring arrangement. The heater, which comes on when the thermostat is calling for heat, makes the thermostat into a thermo-mechanical PWM controller with a cycle time of about 10 minutes.
azzabcd:
Hi, I have a little experience with Arduino and electronic in general but I'm not too sure how to achieve this. My air conditioner thermostat can only go down to 17 degree Celsius. I'd like to reach 7 degree Celsius.To do so, I'm planning to build a controller to take the ambient temperature of a room and to attach something (possibly a resistor) to the air conditioner temperature sensor. This "something" should generate enough heat (let say 20 degree Celsius) so the air conditioner will keep on running until the new temperature sensor reach the desired temperature and shut off the heat. Then the air conditioner will stop by itself.
Doing it this way will allow me to put that controller to any air conditioner without having to do any modification to the unit. I've already build something else dealing with one wire temperature sensor so the only problem I have right now is how can I generate that heat.
I thought of using a small bulb light, but I'm sure somebody can suggest me a more elegant way...
Thanks
A small (2 watt) resistor of the proper value would be a small, safe and inexpensive heat source to "trick" a thermostat.
Just use a resistor that will dissipate 2 watts (or whatever power yours is rated for at the voltage you use).
raschemmel:
I think you have overlooked the fact that all air conditioners have a physical limit to how much heat they can remove from a room. It is pointless to have a thermostat that allows you to set a temperature that is beyond the air conditioner's capacity to remove heat. It is , after all, only a heat remover , (NOT a cold injector).
Ha! My mother always yelled at me to close the refrigerator door so the "cold wouldn't get out".
When I told her that there was no such thing as "cold" and that closing the door kept the heat out, she called me a smarta$$ and said to shut up. 
