The phrase "air heat" refers to the process of heating the air. It means increasing the temperature of the air by using a heating device or system. Full definition
The forced air heat also should have a fan option for helping white out the noise. (trinidadretreats.com)
This is one example of a solar air heating collector using layers of black window screen that is inexpensive and fast to build and actually tested better than more expensive designs. (builditsolar.com)
Simple but good solar air heating collectors can be built for less than $ 4 per square foot. (builditsolar.com)