Installing Atwood Water Heater

[55AS]

My 55 FC came with a non-functioning 3 gallon electric water heater under the rear bed. In order to get camping sooner I simply replaced it with a new 6 gallon electric heater of similar size. Works great.
Now that we are camping I prefer to have a propane heater and have pretty well settled on the Atwood 6 gallon DSI unit. I will have to run LP to the rear of the trailer and connect the plumbing - no problem. My fear is cutting into the outer shell. The logical location is under the bed on the street side just behind the bathroom. The shell is only slightly curved here and I have seen other 55's with the heater in this location. I will remove the inner skin or just cut the appropriate size hole there in between ribs and do the same on the outer shell. I have done a huge amount of renovation work myself but this task is intimidating me for some reason.
Anyone else done this or have an Atwood installed in this location? Pics would be great. RV-550 seemed like a viable (though expensive) option since it vents through the bottom but it is too tall to fit under the bed.

[55AS]

Not sure the Atwood will fit. For one thing, the water lines run along the shell behind the bathroom wall and will interfere with the heater unless I mount it further back, which then runs into a rib as the trailer starts to curve. How have others done this?
All advice is appreciated at this point.

Thanks!

[calais66]

You could just re-route the lines above the tank by splicing in some PEX, no? Or, if the lines are running along the bottom of the shell, maybe mount the tank on a slightly elevated riser so its vent door sits above the water lines.

[55AS]

Not so easy to do and I think my explanation was a bit unclear. Lines are PEX and penetrate the wall/bulkhead right where I want to put the water heater (see pic). I plan to add elbows as close to the bulkhead as possible and mount the water heater as close as I can.

[Shacksman]

We put a 6 gallon Suburban water heater in a 55 airstream. It fits easier as it's just over 12" square.

[55AS]

Great advice, thanks!
Which type door did you use?
Any pics?

[55AS]

Great advice. Suburban fits nicely under the bed. Bracing myself to cut the shell. Does anyone know how wide the "rib" stiffener is and how far it extends from the panel edge? Need to decide where to start cutting...

[55AS]

OK, it is done.
After lightly sanding the white painted door and door frame I used RustOleum metallic paint to try to match the AS skin.
After repeated measurements and two small test holes, I got up the courage to cut the opening through the shell. I had to trim off the bottom of the door frame to avoid overlapping the beltline trim piece. The heater ended up nearly two inches above the floor inside and barely below the bed decking, but it fits. I also drilled through the floor and belly pan to run the copper gas line.
Aside from a tiny water leak, everything works!

[Shacksman]

Originally Posted by BambiTex

OK, it is done.
After lightly sanding the white painted door and door frame I used RustOleum metallic paint to try to match the AS skin.
After repeated measurements and two small test holes, I got up the courage to cut the opening through the shell. I had to trim off the bottom of the door frame to avoid overlapping the beltline trim piece. The heater ended up nearly two inches above the floor inside and barely below the bed decking, but it fits. I also drilled through the floor and belly pan to run the copper gas line.
Aside from a tiny water leak, everything works!

Good job, it fits and looks good!

[55AS]

After an extended camping trip I am happy to report the heater works perfectly. Amazingly fast recovery time and very quiet when running. People think it is an OEM installation :-)