GREAT system and I'm glad my used MH came with it as 10 years ago not sure I would have paid the extra $$$ if buying a new coach. It also gets heat from the engine so enough hot water at the end of the day for free hot showers... OK paid for from diesel burned in the engine.
Proper winterizing is critical and CANNOT be done by just blowing the water lines out with air. After blowing the hot/cold lines out you have to pump RV antifreeze into the water system until you get it coming out of a hot water outlet. It would be cheaper to take it south for the winter than to pay to repair/replace the boiler if you freeze/burst the copper lines that surround the boiler. The portion of the system that heats the coach uses a special antifreezed solution so some have learned an expensive education that the domestic hot water section is not freeze protected.
Before I stored mine inside I would leave the heat on at 40 degrees on shore power with both the electric and diesel boiler turned on so I did not have to winterize any of the water systems. Rarely did it get cold enough in the GA mountains that the diesel boil had to come on to help the electric out. There is a heat section in the basement to keep the areas with water lines from freezing.
He needs to confirm if he has one or two electric elements in it. Probably has two which means on shore power the diesel boiler will rarely come on SO, a annual service/nozzle change would be absurd. Even with only one electric element I service mine about every five years which is about 100 hours for boiler use.
