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CAT # THM-4 4.5 out of 5 stars(7 Reviews) Write a Review

$ 6.00
$6.00 each
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Product Description
Digital module can be programmed to turn equipment on or off at specific, pre-set temperatures. Also has hysteresis setting, delay setting, upper-limit setting and upper limit alarm setting. Displays temperature in Celsius on 3-digit LED display. On-board 20A relay. Waterproof temperature sensor. Three buttons for navigating temperature parameters and other functions. Operating voltage 12 Vdc. Overall dimensions 48mm x 40mm x 14mm. Clear plastic case available, see our CAT# THM-4B.
Spec sheet available in PDF format.
WARNING: May cause cancer or reproductive harm.
California Prop. 65
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Customer Reviews 4.5 out of 5 stars(7 Reviews)

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Capable package, great price 5 out of 5 stars

Reviewer: from Hampton Bays, NY

Good capability for the price, but here are some considerations:

- Can only display in degrees C.
- Maximum temperature is 110 C both for setpoint and alarm.
- Minimum temp. is -39 C.
- Total sensor length is about 12 inches, but could be extended.
- Can be configured for heating (relay contacts open on reaching temp.) or cooling (contacts close).
- Relay contacts Normally Open when unit is unpowered.
- Relay case shows contact rating of 20 Amp. at either 14 VDC or 125 VAC, although I would use
it to operate a heavier duty mechanical or Solid State Relay for continuous currents that high.
- Comes with a single page of instructions that are easy to follow.

57 of 57 people found this review helpful. Do you? Yes No  Certified buyer

Device Looks Good, A Little Tough to Program 5 out of 5 stars

Reviewer: from USA

I bought 8 of the THM-4s to replace defective thermostats in electric space heaters. The THM-4 needs 12VDC, but they don't tell you what voltage range it can use. Powered by 12.0 VDC it draws 30mA when the relay is not engaged and 80 mA when relay pulls in.
When being programmed, the device will switch back to "idle" mode if you stop pressing the buttons for more than a few seconds. Best to have a list of the parameters and values you want to program before you start.
Press and release SET button to program the temperature set point (press + and - buttons to change value).
Press and hold SET for 5 seconds to access parameters P0 through P6. After "P0" appears in the display, use + and - buttons to select the parameter you want. Then press SET again to access the parameter value. Use + and - buttons to get the value you want. Press SET again to go back to the list of parameters to select another.
The display shows "LLL" if the temperature sensor is unplugged.
I have not used the THM-4 enough to know how the relay will stand up to a 13amp/120VAC heater load switching maybe several times an hour 24/7. I am prepared to use 40A solid-state relay if the on-board relay can not take it.

32 of 32 people found this review helpful. Do you? Yes No  Certified buyer

Great deal! 5 out of 5 stars

Reviewer: from Chester, Ca

Very accurate. Easy to program. For heating AND cooling. Buy an extra and you will find a use for it.

19 of 19 people found this review helpful. Do you? Yes No  Certified buyer

Great thermostat 5 out of 5 stars

Reviewer: from USA

This is a great thermostat, it works very well. You can not only set the temperature but also the hysteresis and whether you want it to control a heater or a cooler/AC. The instructions that come with it explain all the settings very well. You will need an external 12VDC power supply. The only two caveats I found with this board is it only reads in centigrade (if anyone figures out how to make it read in normal degrees, please post it here) and when the relay engages or disengages there is some kind of transient that makes the temperature reading jump by approx 0.2 degrees, but it quickly settles back down after a second or two.

14 of 14 people found this review helpful. Do you? Yes No  Certified buyer

Great Thermostatic Control Module 5 out of 5 stars

Reviewer: from Jacksonville, Florida

I used this module as a temperature control unit for a steel solar battery box on my fishing dock. This module controls 2- 3 inch computer fans which draws only .57 amp each. Each fan moves 235 CFM of air. One fan pulls outside air in and the other expels hot air out extending the life of my batteries.Going to buy 4 more of these. 2 of them to control my 12 volt attic ventilating fans in my house operating on solar panels and 2 of them in my shed for ventilation to also work with my battery solar power system. This module works well and an instruction paper tells how to program the unit HOWEVER it does not come with instructions on how to connect the unit. BUT it is very simple once I looked at the circuitry. On the PC board it is marked for positive and negative battery input But the other 2 lugs are labeled as K0 and K1 . K0 and K1 are relay switch connections. So it's really simple.

8 of 8 people found this review helpful. Do you? Yes No  Certified buyer
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