Jandy JXi™ JXI200PK Liquid Propane Low-NOx Pool and Spa Heater with VersaFlo™ with Poly Heaters 200K BTU. The JXi heater sets the standard in pool and spa heating technology with its ultra-compact size, lightweight design and installation flexibility — making it a top choice for pool professionals and pool owners everywhere. The high-efficiency, low-NOx JXi is available in three BTU sizes, 200K, 260K, 399K, and offered in both natural and propane gas models. VersaFlo Integrated Bypass technology for JXi available installed from the factory (select models) or as an easy retrofit to any JXi on site.