420010053S Heater Thermistor — directfit replacement for pool and spa heater electrical systems. Designed for indoor or outdoor installations, this thermistor restores accurate temperature sensing for reliable heater operation. Key benefits Direct fit and easy replacement: Designed to match original form and connectors for a quick swap during repairs or maintenance. Broad compatibility: Works with a range of pool and spa heater electrical systems. Replaces part numbers 420010063S, STA1516255, 420020025S, 420010064S, HMXHLI2932, and HAXHLI1930. Durable construction: Stainless steel, rust resistant housing for long service life in wet environments. Wide operating range: Rated for operation from 20C to 80C to handle typical pool and spa conditions. Time saving installation: Simple to install in minutes when replacing a faulty sensor. Follow basic safety steps such as disconnecting power and wearing gloves. Compatibility notes Compatible with Pentair MasterTemp models 250, 300, and 400 (Natural Gas and Propane) and Pentair StaRite MaxETherm models 200, 333, and 400 (Natural Gas and Propane). Use as a direct electrical system thermistor replacement for these heaters. Typical applications a failed thermistor in a pool heater electrical system to restore accurate temperature sensing and proper heater cycling. Install during routine heater maintenance to renew the temperature sensor and reduce service calls. Use in both indoor and outdoor pool and spa heater installations where the listed part numbers or compatible models are used. Installation tips Turn off power to the heater before beginning work. Remove the old thermistor, install the 420010053S in the same location, and reconnect wiring securely. Consult an online replacement guide or a service manual for stepbystep guidance if needed. Specifications Part number: 420010053S Replacement for: 420010063S, STA1516255, 420020025S, 420010064S, HMXHLI2932, HAXHLI1930 Material: Stainless steel, rust resistant Operating temperature: 20C to 80C Application: Pool and spa heater electrical systems, indoor or outdoor installations This thermistor provides a straightforward solution for restoring temperature sensing in compatible pool and spa heaters, combining durable materials, broad compatibility, and simple installation.