I have a Raypak R406 Pool Heater that is fires up and starts heating for about 10 - 15 minutes then shuts down trying to start again. It shows CFH and SPK and you can hear it trying to light again but it doesn't. The pool guy said it was probably a PC Board since there were no codes displayed but I am just not confident with that. Water flow and pool level are good. Has anyone had a similar problem? Thanks,