Coax a little more heat out of cast-iron radiators with this Radiator Booster. The long, thin tube is made of recyclable polycarbonate. Internal fans are thermostatically controlled and designed to turn on at 86 degrees.
The device redirects heat away from the wall and into the living space. That in turn keeps the furnace from cycling on as frequently, saving on fuel.
It can be used atop radiator covers, but will not be as efficient. You'll need an electrical outlet, and the booster cannot be used in humid areas such as bathrooms.