Aqua Hot not only provides the hot water heating it provides all coach heating via an electric element or diesel. Coach heating is via small radiators located throughout the coach that the AQ system pumps heated antifreeze to. Small fans then blow the heated air. There are usually three zones in addition to an engine preheat system. Wonderful system, expensive to buy and expensive to repair. Most get damaged when not properly winterized and the coils within the heating unit burst from freezing. If the dealer is not a certified AQ dealer, demand that it be inspected by one before purchase and get a warranty that covers it.