also known by its identical counterpart Q90DD-1C and part number J993HHW-6221

How do I test this sensor in the field

Adjustable Low-Side Differential: Fine-tune the 10 to 40 PSI differential to prevent short-cycling and ensure precise compressor operation

Common Questions: What models are compatible with the S1-031-09170-000

Engineered for OEM compatibility

Lochinvar & A.O. Smith 100110820 Pressure Switch 321894-708 also known by its identicalThe Lochinvar & A. O. Smith 100110820 Pressure Switch is a critical safety component designed for high efficiency gas fired boiler and water heater systems. This 1. 42" air pressure switch (1. 42 in. WC) functions as a differential pressure switch, ensuring the combustion blower is generating sufficient airflow before allowing the ignition sequence to proceed. As a veteran technician knows, a failing HVAC pressure switch often results in a "no heat"