I have a 6 year old Hayward Pool Heater which I use a few times a month to heat up the hot tub. It overheated badly one day, as it had gotten terribly sooted up. I took the whole thing apart and brushed off the soot from the heat exchanger. I put the thing back together and it starts up fine, however...
After about 2 mins, it shuts off. The fan blowing, but the flame goes on and off at fairly rapid frequency. It sounds like a sad donkey which keeps on puffing and puffing. There are no error codes and although heating very intermittently, the hot tub doesn't get any warmer.
I called Hayward and they said that I should have it checked out.
Do you know how I can diagnose this myself? Thanks in advance.