service heater light on

[prasadkm0204]

I switched on my heater ( first time this season) and the gas heater turns on runs for a bit and turns off ( and the cycle repeats).
It takes a long time to heat up but it does reach the intended temperature but there is also significant amount of gas smell.
The water pressure is good ( hasn't been touched in a long time).

Any suggestions on how to go about troubleshooting this.

It's a pentair master temp. I can get the exact model details later when I get home.

Thanks,
Prasad

 

[ajw22]

Check the thermal regulator and bypass valve as described in Pentair MasterTemp Heaters - Further Reading