The engineers at Solar Hydronics Corp. worked round the clock to design the best, most efficient design for their newest branded solar pool heating system. What they developed was iSwim. The first aspect of any pool heater engineers what to improve is: “How can we make it collect more BTUs?” With a traditional gas or electric heater, engineers can just add more burners, or an additional heater coil. With solar, it takes more planning and brain power to come up with a viable solution.