Raypak 53/53A/55A, Auto Reset 13-B Thermostat (600889B) sandfilters Sealing rings like this are

Sealing rings like this are important because many equipment joints depend on a small elastic seal rather than a rigid gasket

1-1/2 inch slip x 1-1/2 inch slip x 2 inch slip connection

Replacing the right board solves that problem at the point where it actually starts

or become unreliable through age or service

Raypak 53/53A/55A, Auto Reset 13-B Thermostat (600889B) sandfilters Sealing rings like this areThe Raypak auto reset 13 B thermostat is designed for compatible 53, 53A, and 55A heater applications where the supported temperature control or protective thermostat needs replacement. A thermostat like this is useful because it helps the heater respond to thermal conditions and automatically return to normal operation once the triggering condition clears. This replacement is especially useful when the original thermostat is inaccurate, worn out, or