Have you ever considered home performance testing and repairs? If the home requires air sealing then leakage areas can be repaired or sealed with spray foam. Duct leakage testing is always recommended as it plays an important part on your home's ability to save on utility bills. You wouldn't want to just heat under the home and outside? Results vary for each home, but some may only require duct sealing with products like Duct Mastic. While others need partial duct repairs or full ductwork system replacement.