the Nordyne 661055R is frequently utilized in natural gas applications or specialized high-altitude conversion kits where a #55 drill size is specified for derating

The Ranco O16-624 is a commercially rated low pressure control designed for comprehensive system protection and compressor cycling in HVACR applications

this is a direct-acting solenoid

cycling the thermostat or main power supply will reset the internal logic once the pressure fault has cleared

Note that this updated model utilizes brazed stub tube connections (7/8” suction and 1/2” discharge) rather than the older rotolock style

Rheem-Ruud 42-100491-54 Start Relay L99H008 the Nordyne 661055R is frequentlyStart Relay