Field Expandable: Supports the addition of snap-on auxiliary contact blocks (9999D series) for secondary control circuit logic

this differential air pressure switch must be mounted with the diaphragm in a vertical plane

long-term service in the airflow stream

the SPDT contact action (Single Pole Double Throw) offers flexible wiring configurations for either opening or closing circuits upon pressure rise or fall

making it the preferred choice for tenant-controlled environments or basic residential climate oversight where ease of operation is priority

Watts 0121547 Relief Valve R-410A Field Expandable: Supports the additionFor high capacity commercial and residential hydronic heating systems, the Watts 0121547 (Series LF174A 125) serves as a critical safety component to manage thermal expansion. This 1. 5 inch lead free relief valve is specifically engineered for hot water heating boilers and domestic supply systems, featuring a bronze body construction that meets stringent lead free requirements. With a preset relief threshold of 125 PSI, this valve provides an