Ventamatic XXFIRESTAT 10-Amp Adjustable Programmable Thermostat with Firestat for Power Attic Ventilators, Replacement

After reading every review here I was still not sure how well this unit would work to control an attic ventilation fan. So I purchased this unit and did significant testing. I performed a series of tests at these settings (90, 100, 110, 120 degrees F) for a total of 72 tests. I would not suggest anyone do these tests and remember you are dealing with 110 volts which can cause significant injury and even death. The only reason I’m writing this review is to help anyone who might wonder if this unit will work for their application. These tests were performed in my shop at an ambient temperature of 62-63 degrees F using a heat gun set on low to vary the ambient temperature and a Fluke 561 HVAC Pro Infrared thermometer to accurately determine temperature directly at the bimetal strip.This is a very simple inexpensive unit that works by using a bimetal strip to open and close two contacts to make or break the circuit. This bimetal strip bends in one direction as the temperature around it increase and bends in the opposite direction as the temperature around it decreases. The higher the temperature the more it bends. This bimetal strip has a contact point toward one end that matches a similar contact toward the end of the second strip. As the temperature increases (in the attic around the control) the bimetal strip bends toward the second strip and brings the two contact points closer together until they meet thus completing the circuit and turning on the fan. As the temperature decreases (from the fan moving cooler air past the control) that same bimetal strip bends in the opposite direction moving the two contact points apart thus breaking the circuit and turning off the fan. As you turn the temperature adjustment to the left (lower “FAN OFF TEMPERATURE”) the contacts move closer together. As you turn the adjustment to the right (higher “FAN OFF TEMPERATURE”) the contacts move further apart. The more space between the contacts the higher the temperature must be to close the contacts.Unfortunately the label on the front of the control is misleading in that it states “FAN OFF TEMPERATURE”. The degree readings are also not very accurate. That being said, keep in mind that this is an inexpensive simple control not made to be supper accurate. These controls are mass produced and may have significant variations from one unit to the next. Since this review is already long I won’t list all 72 test results. I will say that with the control on and set to 120 degrees F, I raised the temperature to 150 degrees F and it still didn’t turn off, so much for the “FAN OFF TEMPERATURE”. The important things to note on the unit I tested are as follows. The temperature variance (delta) between when the fan turns on and when it turns off are between 3 to 6 degrees. If I set this unit at 120 degree F the fan will turn on at 85 to 86 degrees F and turn off at 82 to 83 degrees F. It is also important to note that the control should be place in an area toward the center of the space and in the path of the air flow created by the fan. If not you run the risk of the control turning the fan on but not being able to turn it off because there is not sufficient air flow to lower the temperature of the control enough to turn the fan off.I will install a wall switch to feed power to the control just in case I need to turn if off manually. Attic temperatures here in central NJ can easily go above 120 degrees F in the summer. I’m not sure if this fan will be able to cool the attic enough (down to 80 degrees F) to turn the fan off. If it doesn’t I can always turn it off at the switch.

The thermostat worked as expected. When the set point is exceeded my attic exhaust fan turns on. When the attic temperature is a few degrees below the set point the fan turns off. The unit I received must be “updated” since the “Fan Off Temperature” on the label has been replaced by “Temperature Setting”. The only complaint I have is that the thermostat temperature markings are inaccurate. I had to set the unit to above 115 degrees F to have it operate at 110 degrees F. Before installing I recommend connecting the two black leads to an ohm meter, then measure the thermostat case temperature. Slowly rotate the setting to find the “ON” point by rotation from full counter-clockwise toward full clockwise and then the “OFF” point in the opposite manner. That will bracket the room temperature. Half way between these readings is a good guess at the setting for the room temperature which you can use as a “correction factor” from the markings on the unit. Even so, you might also need to use trial and error if you are unsure what setting works best in your environment.

 For this project I used 3 items together to install and set up an automated variable speed exhaust fan controlled by temperature. There are many other ways thatt this can be done but I chose to go this route simply because of the quality and efficiency of the thermostat and speed controller and variable speed fan in conjunction with one another. In the first picture you can see where I drilled a pilot hole from the exterior of the building into the interior to see exactly where I was on the inside of the building. Once I knew I simply found my center point between the studs and marked out my rough opening. After cutting through the plywood from the inside and the sheet metal siding from the outside I started to take more precise measurements of my exhaust fan louvered shell. At this point I realized the thickness of the wall was more than double what I had expected. So I took some sheet metal and fabricated a transition piece from the louvered casing , through the wall, and into the storage building. I then took some fairly heavy duty aluminum window screen type material and screened just inside the louveres to keep out bugs because it didn’t come with anything already on or with or even an add on option. I attached the motor to my transition piece and wired up the thermostat to a pigtail (extension cord cut off with male ends still attached, and also wired up the motor speed controller. I set my lowest speed setting with my speed controller so as not to harm the motor with too low of rpms. I then took some of the exact metal siding that he had leftover and cut and fit it so it would hardly be noticeable. He said he was going to paint the rivers but don’t have the updated picture. He is very pleased with the ease of use, efficiency, and the professional install. He did question why I didn’t just silicone the outside and be done with it. I simply told him that you’ll like it much more the way I’m gonna trim it out. And, boy, he was eatatic at how much better it looked at the finished product. I highly recommend all three of these products and do offer many other services if you can appreciate when things are done the right way.

A+
Muy bueno

Un peu cher
Ventilateur de serre