On my previous AS (96 21' Sovereign) I changed from a LP to a gas/elec water heater. The mechanical change out was not difficult. I had to use PEX to replace some of the grey plastic lines. The biggest problem was the electric. I could not find if AS had installed a separate power line that ran to the swith in the bathroom. The heater needs 12v
and 120v lines. I tapped into the 12v
line behind the fridge and into an outlet under the bed for the 120v. I then put two switches on the side of the bed frame, one for 12v
and one for 120v. Both switches had to be on for the water heater to work but it worked well. I did use one of those switches that have an indicator light for the 120v as a reminder that it was on.