Energy Waste?

Question

Give an example in your home where waste heat could be reused.

Answer 1

Ducts with fins can be installed to carry waste heat from a clothes drier to assist in room heating.

I am not sure you would think of the heat in an attic is waste heat, but I utilize it. Two fans in the attic. One blows attic air into one end of the house. The other takes air out of a bedroom in the back. A thermostat in the house closes when the room temperature is below 70 degrees F. A thermostat in the attic closes when attic temperature is above 73 degrees F. When both contacts are closed, both fans run. Attic air circulates through the house. On a mild winter day, with plent of sun, the arrangment runs for several hours.

A manually controlled switch disables the fan that pumps air into the house. When this switch is open, only the exhaust fan runs. I use it on summer evenings to draw hot air from the house, into the attic. This cools both the house and the attic.

Answer 2

The air conditioner compressor outside puts out hot air when the air conditioner is running. If that heat could be used to preheat the water going to the hot water heater, that would prevent some heat waste.