Hayward CZ/HM/HM2 Thermostat w/o Knob (CHXTST1930) grasslin Confirm the pump model and

Confirm the pump model and part number C1-274P before ordering

A properly selected Viton O-ring helps support cleaner groove fill and contributes to more dependable sealing performance where both size and compound matter

Installing a fresh body O-ring can help restore the pump assembly without forcing replacement of larger body components

Key identifiers and configuration details include 1

Hayward CZ/HM/HM2 Thermostat w/o Knob (CHXTST1930) grasslin Confirm the pump model andThis thermostat is used on compatible Hayward CZ, HM, and HM2 heater systems where temperature regulation hardware needs replacement but the control knob is not required. It is a practical service part for restoring proper heater response when the existing thermostat is worn, inconsistent, or no longer controlling the system correctly. For pool and spa heaters, small control components can make a noticeable difference in comfort and reliability.