Pentair 42002-0024S, 42001-0063S & 42001-0053S Pool Heater Sensor Kit, Replacement with 12 Month Warranty & USA Business

Restore critical temperature sensing and safety functions in your compatible pool or spa heater with the Wholesale Sensors Pool Spa Heater 3-Piece Repair Kit for Pentair. This convenient service kit combines three commonly used replacement components in one package: the 42002-0024S Stack Flue Sensor, 42001-0063S High Limit Switch, and 42001-0053S Thermistor.

Each component is engineered as a perfect OEM-style replacement designed to meet or exceed original functional specifications for its intended application. Instead of purchasing these commonly serviced heater components individually, this 3-piece kit provides a practical solution for pool owners, technicians, property managers, and professional pool service companies maintaining compatible Pentair MasterTemp and Sta-Rite Max-E-Therm heaters.

Includes Three Pentair Heater Replacement Parts

This kit includes replacements for the following three Pentair part numbers:

42002-0024S Stack Flue Sensor: Pentair identifies 42002-0024S as the Stack Flue Sensor in the MasterTemp heater electrical system. This sensor monitors stack or exhaust temperature as part of the heater’s operating and safety system. Pentair

42001-0063S High Limit Switch: Pentair identifies 42001-0063S as the High Limit Switch. This safety component is part of the heater’s high-temperature protection system and is designed to interrupt normal heater operation when an excessive temperature condition is detected. Pentair

42001-0053S Thermistor: Pentair identifies 42001-0053S as the heater Thermistor. The thermistor provides temperature-dependent electrical feedback that allows the heater control system to monitor water temperature and regulate heater operation. Pentair

Pentair includes all three of these components in its official heater service packages, confirming their use as service parts within compatible heater systems. Pentair

Compatible Pentair MasterTemp and Sta-Rite Max-E-Therm Heaters

This 3-piece repair kit is designed for compatible Pentair MasterTemp and Sta-Rite Max-E-Therm high-performance pool and spa heaters.

Pentair’s official replacement-parts catalog lists its heater service kits as compatible with MasterTemp and Max-E-Therm models 175, 200, 250, 300, 333, and 400. These heater families include natural gas and propane configurations, although exact component requirements should always be verified against the heater model and original part numbers before installation. Pentair

This complete 3-piece kit should not be listed as compatible with the MasterTemp 125. Pentair’s MasterTemp 125 parts documentation shows that while the 125 uses 42002-0024S for its stack flue sensor and 42001-0053S for its thermistor, it specifies 474367Z as its high limit switch instead of 42001-0063S. Pentair Flow and Filtration Solutions

That distinction is important when selecting the correct heater repair kit.

Stack Flue Temperature Monitoring

The 42002-0024S Stack Flue Sensor, sometimes abbreviated as SFS, is part of the heater’s electrical and safety system. Pentair lists this component specifically as the Stack Flue Sensor in current MasterTemp replacement-parts documentation. Pentair

The stack flue sensor monitors conditions associated with exhaust temperature. If the heater detects an abnormal condition through this circuit, the control system can prevent or interrupt heater operation depending on the condition and heater configuration.

A stack flue sensor-related problem should always be properly diagnosed. Excessive exhaust temperature or an SFS-related shutdown can be caused by conditions beyond the sensor itself, including combustion, airflow, heat exchanger, water flow, wiring, or control system problems.

High Limit Temperature Protection

The 42001-0063S High Limit Switch, commonly referred to as the HLS, is a safety component used in compatible MasterTemp and Max-E-Therm heaters. Pentair officially identifies 42001-0063S as the High Limit Switch. Pentair

The high limit circuit helps protect the heater when abnormal water temperature conditions occur. If the high limit switch is opening during heater operation, do not assume that replacing the switch alone will solve the underlying problem.

Restricted water flow, dirty filters, closed or incorrectly positioned valves, pump problems, bypass issues, scaling, heat exchanger restrictions, or other heater conditions can contribute to excessive temperature. The complete water circulation system should be inspected when troubleshooting repeated high-limit shutdowns.

Accurate Water Temperature Sensing

The third component is the 42001-0053S Thermistor, which Pentair lists as the thermistor used within the compatible heater electrical system. Pentair

A thermistor changes electrical resistance as temperature changes. The heater control system interprets that electrical response to determine water temperature and regulate heater operation.

When a thermistor becomes damaged, electrically open or shorted, or begins providing inaccurate readings, the heater may display incorrect temperatures or operate improperly. However, wiring, connectors, control boards, water flow, and other components can cause similar symptoms, so proper diagnosis is recommended before replacement.

Convenient Repair Kit for Pool and Spa Heater Service

Combining these three components into one package makes this repair kit useful for professional service technicians and pool owners who maintain compatible Pentair or Sta-Rite heaters.

Pentair itself groups 42002-0024S, 42001-0063S, and 42001-0053S among commonly used components in its heater service packages. Pentair’s current Pro Service Package for the electrical system includes the stack flue sensor, high limit switches, thermistors, and other commonly serviced electrical components. Pentair

The Wholesale Sensors kit focuses specifically on these three temperature-related components, giving technicians a convenient way to keep replacement parts available without purchasing a larger service package.

The three components perform different functions and do not necessarily need to be replaced together. Properly test and diagnose the heater before replacing components.

Installation and Troubleshooting

Before servicing a gas-fired pool or spa heater, shut off electrical power and gas according to the manufacturer’s service instructions. Allow the heater to cool completely before beginning work.

Compare each replacement component with the original part before installation. Install the 42002-0024S stack flue sensor, 42001-0063S high limit switch, and 42001-0053S thermistor only in their specified locations.

Do not bypass, jumper, or defeat the high limit switch or other heater safety circuits. Safety devices are designed to protect the heater and surrounding equipment from potentially hazardous operating conditions.

If the heater continues to shut down after replacing a confirmed failed component, inspect related systems including water flow, pump operation, filter condition, valves, bypass components, wiring, connectors, control board, combustion system, airflow, and heat exchanger.

12-Month Warranty and USA-Based Support

Wholesale Sensors specializes in dependable replacement sensors and electrical components for pool and spa equipment, commercial refrigeration, HVAC systems, appliances, automotive applications, and industrial equipment.

This Pool Spa Heater 3-Piece Repair Kit for Pentair provides replacements for 42002-0024S Stack Flue Sensor, 42001-0063S High Limit Switch, and 42001-0053S Thermistor in one convenient package. Pentair’s own documentation confirms all three as service components for compatible MasterTemp heater systems. Pentair

Every kit is backed by a strong 12-month warranty and responsive USA-based support, providing added confidence for residential pool owners, professional pool technicians, service companies, property managers, hotels, community pools, and maintenance departments servicing compatible Pentair MasterTemp and Sta-Rite Max-E-Therm pool and spa heaters.