I have an 1980's model camp trailer. It has an Atwood G6A-7, gas only, hot water heater that needs replaced. I have had problems finding an exact replacement. I purchased a Dometic WH-6GA Water Heater #94001BP which is gas only with an electric ignition. How do I install a circuit for it? What size fuse? Can I use the existing thermostat? Who can help me?