Refrigerators use a lot of electricity. A refrigerator is a heat pump. It takes the heat form inside the unit and moves it to the outside. Why not move that heat into something useful. Take that heat that is warming your house 24/7 and put it to good use. Like reducing the demand to the water heater.

If my refrigerator used 2 kWhrs a day, let’s assume then I make 10,000 BTUs a day. (my guess should be more)

Q = cmΔT

Inlet to outlet delta T is 60 degress F.

10000 = 8 x (gallons) x 60

That is 20 Gallons of free hot water. For some people that may cover all of their usage. So who is going to make it?

Update: Surfing the Internet the other day. LG has a patent on a device that supplies hot water at the refrigerator.

Since hot water is generated by the heat exchanger that has the maximized heat transfer area with the heater, hot water can be fed without installing any additional auxiliary heat source.

At least this hot water will be free. But, it is not using the wasted heat fully.