Date Published: 07/07/2008 [Source]
Is using the crawl space as a plenum an efficient method of heating a house?
When a crawl-space area is used as the plenum, the furnace fan will pressurize and heat the entire crawl space and will release the conditioned air through vents in the floors. Because the crawl space is heated, the floors will be warmer in each room. You will lose some of the heat to the soil under the home and through air leaks to the foundation.