Magnetic Thermostat Switch

This thermo switch was delivered in 2 days & got my fireplace fan working again - another spree of 20 degree nights -- Magnet is quite strong and product has plenty of prior positive reviews Thanks !!!

Worked perfectly. Been three years. Happy with my buy.

I bought this to use in conjunction with my woodstove fan. I had to wire it in myself but that was easy enough.. once I figured out what I was doing. I found the perfect spot to attach it (strong magnet) and it works great, turning the fan on and off when then the stove reaches temperature

My search for a heat activated switch needed for my project found this. The pros: + Low price of $7.99 with free Amazon shipping! ◄ This is a very good price! + Pretty good customer product reviews. + Sensor rated - 10 A, 125 VAC, 50°C ◄ See my the first attached picture. + Advertised - magnetic mount thermostat switch for fireplace stove blower. + Advertised - strong magnet, easy and simple to place ◄ Very handy, worked perfectly on my project! + Advertised - temperature switch closes (turn on) at approximately 120°F, opens (shut off) at approximately 90°F (+/- 5°F tolerance). + Advertised - measures 2 1/2-inches in length by 1-3/4-inches in width. + Advertised - 2-year limit warranty. The cons: - The wiring terminals are exposed, which can be a shock hazard when used with 120 VAC line voltage. ◄ I covered the the terminal with shrink tubing, but parts of the terminal still remain exposed. - No documentation or wiring is included! You will only receive a thermostat sensor mounted on a magnetic bracket. - The heat has to transfer... pass thru the metal mounting to reach the sensor. ◄ I removed the sensor, applied computer heat sink compound on the sensor button & reattached it to the mounting bracket with screws. This promotes faster operation, as the heat is transferred to the sensor sooner! See my second attached picture. If you opt to do this, consider using flat head screws & countersinking the bracket, so the bracket will mount flush with the heated surface. This wasn't necessary in my application. - No country of origin. ◄ I'm going to say this is made in China, for those that prefer to buy products made in the USA. The problem - what this device helped to resolve: We have 4 attic storage area exhaust fans installed to keep the garage & attic storage area cool during the summer. 4 fans, each rated at 210 CFM, so 4 fans = 840 CFM of air flow! That much exhaust causes outside air to be drawn down the 4" natural gas water heater flue... B-vent pipe chimney, when it's cold... not in use. When the natural gas water heater starts heating, burner on full, the B-vent pipe chimney is cold, so there's no flue gases draw up the B-vent chimney pipe. The natural draw up the B-vent pipe doesn't occur until the B-vent pipe chimney liner is heated by the hot flue gases. When the attic storage area fans are operating, the outside cold air is drawn down the B-vent pipe chimney into the garage. This prevents the hot flue gases from going up the B-vent pipe chimney to heat it up the pipe to create a natural draw. Instead of going up the B-vent pipe chimney, the hot flue gases are pulled into the garage, which is unsafe! The solution: The solution to this problem is simple. Detect the hot flue gases being sucked into the garage & switch off the attic exhaust fans! Theory of operation: The Thermostat sensor is heated by the natural gas water heater hot flue gases being pulled past the sensor. Refer to the third & forth attached pictures to see how the Thermostat sensor is positioned on the natural gas water heater flue hood. Once the sensor reaches around 120°F, it operates, which in turn operates a 12 VDC relay that turns off the attic storage area exhaust fans. A note on the relay: The attic storage area exhaust fans operate thru the relay NC - normally closed contact, so when the relay operates, the attic storage area fans are turned off. When the relay is off, not operated, the attic area exhaust fans are on. Of course that's assuming they were on... operating via the attic temperature sensor switch or manually turned on. Theory of operation, continued: When the thermostat sensor drops to around 90°F, the thermostat sensor turns off. This opens the 12 VDC relay circuit, which switches the attic storage area fans back on. Once the natural gas water heater B-vent chimney pipe is hot, the draw is strong enough to where it will continue, even with the attic area storage exhaust fans are operating. This review focuses on this thermostat sensor switch, so it doesn't show the exhaust fan side, where the 12 VDC relay & power supply are located. If you're interested, I did do customer product reviews on the 12 VDC relay, the project boxes & even the magnets I used on the project box to attach it to the metal water heater. Closing remarks: ▪ Thus far, this thermostat sensor switch has been working perfectly! If it continues to work as it is now, I'll consider upping the product rating.

Placed on the back outer plate of the fireplace insert and has worked great for the last 2 days cutting off the insert when the temperature drops. Cuts on at 120* and off at 90*. Only time will tell the long term of any new product, but good so far.

After using this thermal switch for a few weeks I can tell you that it is working as expected and as I wanted it to. I leave the fan switch on all the time and with this thermal switch in series, the fan only runs when the stove is hot. The thermal switch is open until the stove is just above room temperature (I have a fire started). Once it turns on it stays on until the stove cools down to just above room temperature.

The blower motor on my gas fireplace stopped turning on and off like it used. I found that the temperature sensor switch had disintegrated because it had overheated. The local fireplace repair company wanted $196 to replace the sensor (the cost of the service call plus parts.) This switch cost less than $10 and took about 10 minutes to install. You might have to search on the internet for installation instructions, but it is really simple to do. You just remove the two wires going to the old switch, put them on the new switch, and use the magnet to attach it to the metal bottom of the firebox, It works great.

This is the second time I've purchased this. First one is still on my wood furnace and still working after 6 years. Second one is going on our regular wood stove to replace a failed one from a different company that didn't make it two years.