Pentair 3-Pack Heater Safety Sensors — Flue Sensor 42002-0024S, High-Limit Switch 42001-0063S & Thermistor 42001-0053S for MasterTemp 400 / SR200 / SR333 / SR400

Complete 3-piece safety sensor kit engineered for Pentair MasterTemp 400 and compatible SR200, SR333 and SR400 heaters. This bundle replaces OEM part numbers 42002-0024S (flue sensor), 42001-0063S (high-limit switch) and 42001-0053S (thermistor) for direct fit and reliable operation. The 42002-0024S flue sensor monitors exhaust temperatures to prevent flue gas from exceeding 500°F/260°C. The 42001-0053S thermistor, protected by a reinforced stainless steel housing, supports stable performance across a -20°C~80°C range. As a fail-safe, the 42001-0063S high-limit switch automatically triggers heat exchanger activation when water temperatures reach 140°F+, helping prevent overheating and equipment damage. Parts arrive pre-calibrated with corrosion-resistant brass fittings for fast servicing—designed for tool-free installation and enabling replacement cycles in about 15 minutes using standard household tools. Purchasing this 3-pack lowers maintenance costs by 40% compared to buying components individually and includes spare units to assist with proactive system diagnostics.