Use the same foam seal material as the access door has available any hardware store as a stick on @1/2 inch wide.It is not easy to R&R the heater , but I have done a few alone with a bad back. My Rampy has gas heater.If you drive in the fall around central NY , you really enjoy the gas heat!regards, Tim Colson C N Y C C. http://corvair.de/n2vzd/ gas heater pics