McDonnell & Miller 317353 Valve R-410A Unlike a Temperature and Pressure

Unlike a Temperature and Pressure (T&P) valve used on water heaters

For service technicians handling residential and light commercial HVAC repairs

This OEM replacement part is factory-calibrated to a

Durable Construction: Built with moisture-resistant materials to withstand the harsh conditions of outdoor condenser sections

Thermal Protection: Internal overload protection prevents winding failure during restricted airflow or high ambient conditions

McDonnell & Miller 317353 Valve R-410A Unlike a Temperature and PressureThe McDonnell & Miller 317353, specifically the Model TC L Test N Check Lower Valve, is a critical component for contractors maintaining hydronic systems. Designed for hot water boilers, this 1" NPT valve is engineered to simplify ASME CSD 1 code mandated testing of low water cut offs (LWCO). By replacing standard 1" crosses in the equalizing lines, the TC L allows for the isolation of the float chamber during blow down procedures without requiring a