Greetings !

I just purchased an Atwood GEH9-EXT Gas and Electric with Heat Exchanger XT 6 Gallon DSI Water Heater (90068).

http:// www.amazon.com/Atwood-GEH9-EXT-Electric-Exchanger-Gallon/dp/B00CLSUIU6/ref=sr_1_1?s=automotive&ie=UTF8&qid=1453472812&sr=1-1&keywords= Atwood+GEH9-EXT+Gas+and+Electric+with+Heat+Exchanger+XT+6+Gallon+DSI+Water+Heater+90068

It seems to be a pretty nice unit... it superheats the 6 gallons and then dispenses it through a thermostatically controlled mixing valve (mixes with cold stream) yielding 9 gallons of hot water.

I'm aware of the "T" fitting on the rear of the engine on the passenger side to get hot engine coolant... I'll run a line from there to the water heater.

But where should I plumb in the return ?? Another "T" in the heater hot water return line ??

I've also installed a ball valve to block flow to the firewall mounted heater / AC unit. When that valve is closed - will that also block flow to the water heater ?

I'd prefer not to reinvent something here... Could anyone please share a quick description of how the "factory" heat exchanging water heaters were plumbed ??

As always, THANK YOU ALL for the wealth of information shared here.

Steve W
1973 23'
Southern California