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Portable Heating Thermostat With Piggyback Plug

Eventherm , TH-4-20 8PL
QC Supply Part #: 10920
Shipping: Standard
Availability: Backordered

A dependable and affordable way to maintain consistent temperatures.


Includes 8' Replaceable Cord.

This corrosion-resistant Portable Heating Thermostat can be used in all buildings. Simply plug the thermostat into an outlet and plug the heating equipment into the piggyback plug.


  • Watertight, Nema 4X rated
  • Stainless steel sensing coil
  • Calibration dial is adjustable
  • Designed to tolerate harsh environments, high humidity levels, corrosive elements
  • Used for heating
  • 1-year warranty
  • Differential: 2.5° F
  • UL listed
  • 40° F to 104° F
  • 20 Amp @ 110V; 16 Amp @ 240V
Brand Eventherm
Manufacturer Part Number TH-4-20 8PL



Manuals & Resources


Customer Reviews

  • 5 Stars

    Works great

    Review by on Nov 20, 2015

    Workss great

  • 5 Stars

    Excellent product

    Review by on Oct 24, 2015

    Fast arrival and works as described

  • 5 Stars

    Works Well!

    Review by on Jan 17, 2015

    Works well with electric heater that has bad thermostat!

  • 5 Stars

    The very best efficiency!

    Review by on Dec 27, 2014

    The thermostat appears to be very accurate and performs with consistency. The area being heated is being maintained at a comfortable 72 degrees. I feel that by using this thermostat, I am saving money and energy over the control provided by the thermostat of the heater unit itself. The heater runs less often, but the temperature is maintained. I would recommend this unit to anyone seeking a means of maintaining a uniform temperature in a given space.

  • 5 Stars

    Great product & company.

    Review by on Nov 21, 2013

    The unit is packaged well & works as advertized. It is priced right & installs easily. Would highly recommend this product & company.

  • 5 Stars

    Dead-on accurate, super quality

    Review by on Nov 10, 2013

    This is actually a waterproof unit but obviously with the power cord, the same isn't true. It's MUCH higher quality than the old-time remote bulb mechanical types--even the sensor is stainless steel. It's a fair amount of money but well worth it and, of course, QC is the quality place to buy it.

  • 5 Stars

    So Far So Good

    Review by on Nov 6, 2013

    So far it does what I want it to do, at that is keep my greenhouse from going below 45 degrees.

  • 3 Stars


    Review by on Mar 24, 2013

    not that accurate

  • 5 Stars


    Review by on Mar 9, 2013

    Great product. I used one of these on each heattape circuit (20 AMP) on the incoming water lines and outgoing sewer line in my Condominium Association. Previously, the heattape circuits were turned on from November through April. Now they only come on when necessary. A big savings in electricity.

  • 5 Stars


    Review by on Feb 13, 2013

    Works well and easy to install

  • 5 Stars

    Excellent product. Top rate dealer

    Review by on Jan 12, 2013

    I am using this product presently in the cellar of a storage building where i store potatoes thru the winter. I am very pleased with this thermostat control as it keeps room at an even temperature. I also plan to use it in my greenhouse. I very much appreciated the rapid shipping by QC.

  • 5 Stars


    Review by on Dec 26, 2012

    Bought the thermostat to keep my boat engine from freezing up in the winter. So far so good. The unit seems to be very well made and I would highly recommend it to anyone looking for a quality device that will be used outdoors or in harsh environments.

  • 5 Stars

    Good Product

    Review by on Dec 1, 2012

    I have a bathroom space heater with a bad thermostat. The manufacturer could not give me a replacement part. This product has allowed me to keep using my space heater with even better control than before! The manufacturer sent me a replacement heater since it was still under warranty, but I did not want to send the old heater to the landfill if I could still use it. The new heater is still in the box!

  • 5 Stars

    Great Unit!

    Review by on Apr 7, 2012

    Nice quality unit. Accurate & east to install. Also it is the best priced in-line thermostat I could find.

  • 5 Stars

    sturdy and accurate

    Review by on Dec 18, 2011

    Bought it to control an electric fireplace in the house so the elements aren't a concern for me but it is accurate, it holds the room at a constant as I set it. Simple to use, just plug it in. Long enough cord to get away from direct heat of the heater too.

  • 5 Stars

    This thermostat appears well made

    Review by on Feb 18, 2010

    I am using this product a area that is subject to high humidity to control a heater protecting a room from freezing.

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