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

How do I test this sensor in the field

optimized for thermal protection and corrosion resistance in condensing and non-condensing heating environments

Engineered for OEM compatibility

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

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"