using waste heat from fridge

[pete c]

In the winter it helps warm the house, so no worries there, but in the summer it heats an already hot house. Has anyone every tried putting together something that would use this heat, possibly to preheat water for a water heater. I suppose if you had a hybrid water heater, you could channel the warm air from the fridge to the hybrid. But for other types how do you do it?

I had an idea of a system that uses water to do it.

For starters, make a manifold that would enclose the fridge's condenser coil. Run a line to the storage tank near the water heater and back. Install a low flow pump in this line. Insulate all of this. Now run the water heater feed through a copper coil in this tank.

I see one issue with this system. Let's say you go away for a weekend. You use no hot water, but the fridge is still running. Eventually that tank is going to get too hot to accept anymore heat. I guess you could have another coil outside the tank which you could pump water through to radiate enough of the heat.

The question is can this be done cheaply enough to be practical?