H-Series FD Heater Thermistor

The FDXLTER1930 thermistor senses incoming water temperature at the manifold adapter inlet of a Hayward Universal H-Series FD heater and reports it to the control board for heating and safety shutoffs.

Key Features

• Dual internal thermistor sensors
• Cross-checks readings for fault detection

Compatibility

• H150FDN, H150FDP
• H200FDN, H200FDP
• H250FDN, H250FDP
• H300FDN, H300FDP
• H350FDN, H350FDP
• H400FDN, H400FDP
• H-Series Above Ground 135K BTU Heater
• Does not fit H-Series Low NOx heaters made 2020 or newer, or ED2 series heaters

An inlet temperature swing greater than 6°F in 60 seconds reads as a low-flow fault on the control board, not a thermistor failure, which can look like a bad sensor during diagnosis.