I currently have a series of thermostats that are connected to a window air conditioner, one is used to check room temperature the other is to trick the AC to run to a lower temperature by switching on/off a heating element connected (taped to) to the AC thermostat. The heating element that I am using is a night light bulb, which works fine except they are no longer making them (except for LEDs which don't put out enough heat) and they last about 2 or 4 months. I found on eBay "12V-220V Constant Temperature PTC Heater Element Thermostat Heating Plate Tablet" which is rated to heat to about 200C at 110V.

Voltage: AC DC 12V 12V dry burning table temperature: 80℃ / 120℃ / 220℃ ± 10 ° C

Voltage: AC DC 24V 24V dry burning table temperature: 70℃ / 110℃ / 220℃ ± 10 ° C

Voltage: AC DC 36V 36V dry burning table temperature: 220℃ ± 10 ° C

Voltage: AC DC 48V 48V dry burning table temperature: 220℃ ± 10 ° C

Voltage: AC DC 110V 110V dry burning table temperature: 230℃ ± 10℃

I only need a temperature of about 40 degrees C /100F, so is there some way I can wire in one of the thermostats with a resistor/transformer, etc. or something? I don't want to melt everything! Thanks?

  • \$\begingroup\$ Why on Earth are you doing this to your air conditioner and its thermostat? \$\endgroup\$ – Finbarr Jul 19 '20 at 21:06
  • 1
    \$\begingroup\$ Why not just use a programmable thermostat which is much more accurate and much more flexible? \$\endgroup\$ – Barry Jul 19 '20 at 22:10
  • \$\begingroup\$ I made something which makes an AC unit cool below the regular minimum temperature of about 65F and will go to 40/45F without freezing up. \$\endgroup\$ – TAP Jul 21 '20 at 1:30

You can easily substitute a power resistor for your light bulb. Just pick the resistance so that it will dissipate the same number of watts. Remember that power(watts) = Volts^2 / resistance(ohms).


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