Is it required to use all CPVC after pool heater? What about polyethylene pipe underground? Is it based on temperature? So I guess the second Jandy valve in the bypass past the heater should be CPVC? And maybe a stupid question but why not insulate the pipe that goes from the heater too the pool as heat could be lost to the earth? I know the pool is open on top, but the earth has greater mass then the air above the pool.