Pool heater: Get a Bestway swimming pool water heater. Sensor: Water flow sensor for high-level protection Practical: A simple and effective way to warm up water in your above-ground pool. Ideal for: Use with Bestway pools measuring 15ft or smaller. How it works: Features two hose outlets, with clear water pumping into the pool heater via the filter pump before being heated and pumped back into the pool. Swimming Pool Water Heater | Living Social