Lochinvar & A.O. Smith 100110735 Pressure Switch

The Lochinvar & A.O. Smith 100110735 Pressure Switch is a critical safety component designed for high-efficiency commercial water heaters and furnace draft inducer systems. This OEM replacement part (replaces 9005920215 and 192761) functions as a pressure blower switch, ensuring the combustion blower is generating sufficient negative pressure before allowing the ignition sequence to proceed. For technicians troubleshooting a 3-flash error code or a unit that fails to fire despite the blower running, this switch is often the primary point of failure. It features a high-precision diaphragm that responds to specific vacuum thresholds, maintaining a safe pressure circuit and preventing the accumulation of unburned flue gases.

Built to withstand the high-cycle demands of HVAC ventilation systems, the 100110735 provides reliable continuity test results when the sensing tube is clear and the fan is at full RPM. Its robust construction resists the typical effects of condensate buildup, though professionals should always verify sensing line integrity and port cleanliness during installation. This blower assembly switch is compatible with a wide range of Lochinvar and A.O. Smith models, including the Cyclone BTH series and Copper-Fin II units, ensuring seamless integration with existing control modules and igniter circuits.

• Ensures safe operation by verifying proper venting airflow before burner ignition.
• Direct OEM replacement for Lochinvar and A.O. Smith part numbers 100110735 and 9005920215.
• Designed for prover air pressure monitoring in high-output commercial electric and gas water heaters.
• Durable diaphragm switch design reduces nuisance tripping in power vent applications.
• Maintains system AEO ranking performance by ensuring efficient combustion and exhaust.

What does it mean if my water heater shows a 3-flash error?
This usually indicates the pressure switch failed open. Check for a blocked vent, a clogged sensing tube, or a failing inducer motor before replacing the switch.

How do I test the 100110735 pressure switch?
Using a multimeter, perform a continuity test. The switch should be open when the blower is off and show closed (0 ohms) once the motor reaches full operating speed.

Will this switch fix my unit if it’s "short cycling"?
Possibly. If the switch is losing continuity due to a pinhole in the diaphragm or a weak spring, it will drop the call for heat prematurely. Always verify vacuum pressure with a manometer first.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.