In coach 480 we just flip on the aquahot and it keep the bays very cozy. We just came back from sub zero temps for a week.
Down to 7 Deg F today, Bays are at 67.8 Deg F and Salon and Bedroom havent gone below Thermostat set temp of 53.
All maintained on the single 220v 4600watt Aquahot electric element.
Life is good.