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smart window thermostat Answered

Wanted:
circuit to open window at night when it is cooler outside than in.
Close it when hotter outside in morn.
Probably add something to prevent it from opening and closing several times in the eve and morn with random fluctuations.
Prefer 2 thermostats, 1 outside, one in, rather than a timer.

I've a vague recollection of a circuit with 2 potentiometers, one on the motor, one on the control panel, such that turning the control pot will activate the motor until its pot is at the same position as ctrl pot.. Could a circuit something  like this control my window? But most thermostats are on/off, not continuous variable.  

It would be simple to do a switch logic thing like:  “IF thermo ‘I’ is above 70 AND thermo ‘O’ is below 70, THEN OPEN “  but that only works at 1 temp.

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Downunder35m

3 years ago

Power supply - thermostats - endstops - motor(s).
If the thermostat says "open" the motor opens until the endstops cuts the power to it.
If the other thermostat says "close" same with the other motor/direction.
Basically the same as a gate opener just with thermostats instead of switches....

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Toga_DanDownunder35m

Reply 3 years ago

perhaps I wasn't clear.

If it is 85F inside and 80F outside, open.

If. It is. 70F inside, and 65F outside, open.

If it is 70F inside, and 75 outside, closed.

See the complexity? It's a comparison of TWO thermostats.

Hotter inside than outside? Open.

Hotter outside than insi? Closed.

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Downunder35mToga_Dan

Reply 3 years ago

Ok, makes much more sense now, sorry my crystal ball just came back and must be cloudy from the transport ;)
Well, in such a case I would opt for a microcontroller like Arduino.
If you check in the 3D printing department everything is done by PID control and temp sensors.
Should be possible to get the reference tables for some common temp sensors.
With that you take the inputs of both sensors to get the real temp instead of just a sensor value.
Compare both and if inside is 5° degree warmer than outside for more than 5 minutes or so activate the motor to open.
If inside is 5° colder than outside let the motor close.

But a dual temp controller like the Rex 100 with two thermocouples should work too.
Still requires endstops for the motor though.