Heater Tripping Circuit Breaker


Active member
May 16, 2017
Clifton Park, NY
We just opened our pool a few days ago and turned on the heater for the first time last night. This morning we noticed the the circuit breaker had tripped. After a couple of retries to start, we confirmed that the heater is tripping the breaker. Water temperature was 55, and air temperature dropped to high 40's last night. Heater is newer, 2.5 years old. Display flashes R13 for a second, before tripping. Can't recall if that code is normal on start-up, or is indicating a problem.
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Gold Supporter
TFP Guide
Jul 21, 2013
Northern NJ
Is your CB GFCI?

At startup the MasterTemp cycles through the 888, 128, R13 . Then put your ear right next to the top of the heater (where the board is) to hear if the small relay on the board clicks (May sound more like a "tick" than a "click"), giving voltage to the blower. This click will be more subtle than the click you normally hear when the gas valve opens (you wont hear that one though if the blower never starts).

You need to check the wiring and likely the blower motor. That may have a short triping the CB.

@JamesW ideas?


TFP Expert
Mar 2, 2011
Maybe mice got in the heater and chewed the wires. Look inside for evidence of mice infestation.

Can you post some pictures of everything?