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Alert System Type
Temperature / Humidity Alert
Sensor Type
Temperature / Freeze
Thermostat Types
110V AC
Ease of Installation
Beginner (Installs < 10 minutes)
Thermo Cube
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Avoid Weather-Related Catastrophes!
Thermo Cube TC-21 - On at 78 Degrees, Off at 70 Degrees
Thermo Cube TC-21 - On at 78 Degrees, Off at 70 Degrees
Thermo Cube TC-21 - On at 78 Degrees, Off at 70 Degrees
Item# 7144
Price: Normally $18.99 
Hot Deal $16.97
Free shipping on orders over $175 - See Details


  • Automatically turns devices on and off according to air temperature
  • Save electricity by running equipment only when necessary
  • Perfect for basic automation of weather-related devices without an intelligent controller
  • Instant installation - Just plug them in!
  • Weatherproof

Essential Info

Plug your appliance into the hot weather Thermo Cube and plug it into the wall. When the temperature rises above 78° the Thermo Cube will turn your appliance ON. When the temperature drops below 70° it will turn your appliance OFF. Each unit has two receptacles for use with more than one device. Can operate loads up to 1,800 Watts, 15 Amps, 120VAC.

Also available:
Thermo Cube TC-1 - On at 0 Degrees, Off at 10 Degrees
Thermo Cube TC-2 - On at 20 Degrees, Off at 30 Degrees
Thermo Cube TC-3 - On at 35 Degrees, Off at 45 Degrees
Thermo Cube TC-22 - On at 120 Degrees, Off at 100 Degrees

Recommended for use with GFCI outlets.


What's Included

  • 1x - Thermo Cube - 78° ON/70° OFF
  • More Info

    This hot-weather model Thermo Cube is ideal for use with window fans, exhaust fans, ventilators, attic fans or any other air-exchange devices. Automating these devices is crucial if you have plants or animals that are sensitive to heat. You can even use the Thermo Cube with a strobe light to create an "Overheating Warning" system that can be seen by neighboring homes or buildings.



    Thermo Cube, Inc. Product No.:TC-21
    Maximum Rating:1800 Watts, 15 Amps, 120VAC
    Dimensions:3-3/16" (W) x 1-5/16" (H) x 1" (D).
    Approval:UL and CSA (for Canada)
    Warranty:1 year, limited


    45 Ratings
    5 star: 40%  (18)
    4 star: 20%  (9)
    3 star: 22%  (10)
    2 star: 4%  (2)
    1 star: 13%  (6)
    Average Customer Rating
    (45 customer ratings)
    Share your thoughts with other customers
    DAVID -- forrest city, AR   5/15/2014
    Works perfectly.
    RICHARD -- homer, AK   12/22/2013
    Works great to turn on a fan above my gas wall heater for my cabin.
    KELLEEN J -- fairport, NY   7/20/2013
    I have used this product for 1 month and it seems to be working properly by turning my fan on around 78 degrees and off around 70 degrees. Great product!
    BILL -- palo alto, CA   5/31/2013
    Works great. Turns on a fan in my wife's greenhouse.
    BYRON -- mount airy, MD   1/10/2013
    Works as advertised. Would prefer weatherproof and sightly higher range (on at 87 off at 80) for barn fans.
    MICHAEL -- howell, NJ   8/8/2012
    Install was easy. Ease of use is good. Value is a little pricey buy saves labor for my chicken coop. I power a fan. I gave it 3 stars because these thing are not that accurate temp wise. This one I have used this summer. I based this review on the TC21 I am currently using. It goes off at around 63 degrees. But possibly the power from the fan heats the cord some.
    VAUGHN -- merkel, TX   10/31/2011
    They do not work. I tested them with a heater and an A/C unit in a small cabin. The test took 3 hours to perform. They did not turn off until 60 degrees, and they would not turn back on until 96 degrees.
    DAN -- cathedral city, CA   10/21/2011
    MICHAEL -- san jose, CA   10/19/2011
    My order was returned because the product description included "Maximum Rating: 15 Amps, 120VAC", but the product label stated "15A resistive, 5.6 A max inductive (motor A/C).
    Dan -- palm springs, CA   9/24/2011
    does not operate within specs. It comes on at around 78, and doesn't turn off even when I am cold until around 68 degrees. Would not even turn off with an Ice Cube on it.
    GABRIEL -- zephyrhills, FL   5/5/2011
    This product is working very good so far. I have only had it for a short period of time. My overall rating would be more accurate if the item continues to work over a long period of time without malfunctioning.I then would give it a 5 star rating, it gets a 4 for now only because of the short time I have used it.
    RAFAEL -- bristol, CT   7/26/2010
    Works really great to control an exhaust fan that keeps my chicken coop cool when it gets hot outside. Thx!
    KENNETH -- shrewsbury, MA   7/2/2010
    The unit never turns off. I have it in my attic and, even though a nearby thermometer reads less than 70 degrees, it remain on.
    MICHAEL -- colorado springs, CO   3/29/2010
    Color of unit on website was white but unit received was red, not a big deal but should be known. Works as described.
    DANA -- baton rouge, LA   1/5/2010
    Using this to operate a fan in my greenhouse. Works great.
    THOMAS -- crescent city, CA   12/17/2009
    LOREN -- westfield, MA   9/19/2009
    great product A+
    LEWIS -- oswego, NY   7/26/2009
    Awesome product.
    JIMMY -- golden valley, AZ   7/2/2009
    good service. thank you
    CHRIS -- rochester, MN   3/7/2009
    So far the Thermo Cube has been doing it's job. If you are going to use an extension cord, make sure it's a three prong. I didn't know this until the unit arrived.

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