I just bought a 1979 Catalina 30 with little documentation. It has a "fuel" cap and a "gas" cap, I was told that the fuel is for the motor, and the gas is for the heater? The old owner said there was some sort of heater that he never used. Also, there is some type refrig unit, again, the old owner never used it? Any ideas how to use this? Any and all help is appreciated!