I have a Hayward H400 IDL natural gas electronic ignition heater. My heater is about 5 yeras old and I have used it 5 times. I opened the pool this year and followed the directions to fire up the heater and it didn't work. It would start its cycle and I would hear a click then it would catch and I would feel heat from the vent and then after 3 seconds it shuts off. I had my gas company come out and they thought it was a delivery issue. I wasn't sure why now since it had worked all these years but they changed an old regulator and I recieved a greater gas flow but within the tolerance of gas supply needed to operate the unit. They checked all the limits, gas valves, cleaned the flame sensor, burners, cleaned alll the gas pipes made sure there were no obstructions and no cob webs. In the end the diagnosis was bad module controller or flame sensor or both. What do you think. These parts are expensive and I was told I could repalce them myself. help.

Pool & Spa - Hayward Pool Products - Hayward 400k Ng H Series Spa & Pool Heater