Many people and businesses use SensorPush to monitor their fridge or freezer, or even commercial walk-in coolers.
There are some important things to keep in mind, however.
First, signal strength / range will be less, because the signal has to travel through the walls of the equipment. Generally this is pretty easy to work around, as long as you know what to expect. In a normal refrigerator or freezer, you'll still likely get a good signal in the same room or even in adjacent or nearby rooms, but the range won't be as long as it would be if the sensor wasn't inside. Particularly when placing a G1 WiFi gateway, this is important to keep in mind. You'll want to have the gateway relatively close to the refrigeration equipment, and if for other reasons you need it to be a bit farther away, a little trial and error may be required to make sure you have a reliable connection.
Another important thing to understand about signal strength that is particularly important in food refrigeration equipment is that water is a very effective absorber of Bluetooth signals. Since virtually all food products contain a large percentage of water, this is important to keep in mind. The usable range can vary significantly based upon how the sensor is placed within the equipment.
Learn more about signal strength and SensorPush devices in these articles:
Signal Range and SensorPush Products
What is the Wireless Range of SensorPush Sensors?
Secondly, batteries are less efficient at cold temperatures, so battery life will be somewhat less. In a refrigerator, this effect is relatively minor, but in very cold freezers, you might need to change the battery more often, like perhaps every 6-12 months instead of the usual 2+ year interval.
Learn more about battery life and changing batteries here:
How Long Will the Battery Last? And How Do I Change the Battery?
Finally, for best results with sensitive applications like these, combining the sensors with a G1 WiFi Gateway is recommended for best results. Particularly since the range is reduced from inside refrigeration equipment, the best way to be sure you're always up to date and alerted when things go wrong is with the SensorPush Cloud and the G1 WiFi Gateway.
Learn more about the SensorPush Cloud and G1 WiFI Gateway here:
Do I need a SensorPush G1 WiFi Gateway?