Our Aqua Hot system seems to work fine, but when I switch to the furnace setting, the air coming from the heat exchangers is warm but not hot. Shower and sink hot water all work fine. So how hot is hot at the furnace registers? All seem just warm, not hot. Thinking about taking the MH to a shop for annual AH service and see what they say. The heat exchanger fans, too, make more noise than I like. Getting picky in my old age!