Diagnosing High-Limit Trips and Millivolt Valves in Commercial Fryers

Fryers are among the most worked pieces of equipment on any line. At A/C Dr. Naz, we emphasize preventative maintenance and root-cause diagnostics to prevent catastrophic oil fires and equipment downtime.

Thermopiles vs. Thermocouples

Most commercial fryers utilize a thermopile—a group of thermocouples that produce a higher millivolt output (typically 250mV to 750mV) to power the gas valve without an external electrical source. If the fryer won’t stay lit, we test the thermopile output under load. We also investigate High-Limit Tripping. If your fryer shuts down randomly, the oil may be getting too hot, or the high-limit sensor has lost its calibration and is tripping at a lower, “nuisance” temperature.

Why does my commercial fryer keep shutting off?

The most common cause is a failed thermopile that can no longer generate enough voltage to hold the gas valve open, or a tripped high-limit thermostat triggered by poor oil circulation or a faulty temperature probe.

Expert Fryer Diagnostics

Keep your fryer line moving safely with our specialized millivolt valve service.