Originally Posted by TouringDan
You can buy a single remote thermometer at Walmart for under $10. You don't really need dual, just the fridge section. I have details in a thread in the fridge area titled "monitoring fridge performance. Just as an alternative FYI.
If you want to monitor freezer performance as well as the fridge, all you need is a penny and a small plastic cup half full of water. Put the water in the freezer. After the water in the cup freezes, place the penny on top. Then let it sit for as long as you use the freezer. As long as that penny is on top
of the ice, no problem. If the penny is ever inside
the ice, that means your freezer has thawed and refrozen and it's time to throw out your frozen foods.
This is a trick that I've used here in the New Orleans area for every storm-related power outage in the past couple of decades. When a storm comes through, a power outage is almost guaranteed; the only question is, how long it lasts. With the penny trick, I can tell if it was long enough to thaw anything important.