Bob: I think it is going to be a big problem bleeding the system of air. Normally the radiator cap is the highest point in the system and the air goes to the top and out the cap. You would have to come up with some sort of bleeding valve on the heater. I think it would be easier to duct the air into the cabin and mount the heater below the top of the engine. Frank > >I own a trawler with 120 Lehman power (single). I am thinking about >installing a heater flush mount on the floor that will use the FW water from >the engine cooling system. The radiator style heater (Red Dot) will be >slightly higher then the motor. Will this pose any problems with the engines >cooling system? > >Thanks > >Bob Mihailov >38' Inside Passage >Bellevue, WA