In many athletic facilities pool heating is provided by a heat exchanger tied to the main heating boilers. While this works well enough during Winter months when additional space heating loads are present, it works poorly during those months when space heating is not required. When boilers are so large with respect to actual loads, they tend to short-cycle. Shortcycling significantly reduces fuel efficiency and causes accelerated wear-and-tear on large and expensive central plant machinery. Installing a “Summer boiler” is an old and time tested energy conservation strategy. The application of a small condensing pool heater for three season operation (together with a condensing domestic water heater) usually achieves fuel savings of 40% or more during the Summer months. This paper responds to those customers who have asked us how to do it, and introduces a new strategy for those applications where non-condensing boilers are used in this service.