Resideo Gas pressure switch 45900438-209B

The Resideo Gas pressure switch 45900438-209B is a safety component for gas-fired heating systems, monitoring gas pressure in the supply line. It operates at a supply voltage of 220 V and has a nominal pressure of 1.5 bar, with a maximum working pressure of 3 bar. The switch provides measurement accuracy of ±0.1 bar and can handle a maximum current of 1 A. It is designed to prevent boiler instability and accidents by ensuring gas pressure remains within safe limits.

When selecting a gas pressure switch of this type, verify the medium (gas), the required switching range and differential, the connection type (thread or hose spigot), the contact rating, and the approval class for the application. The switch is typically installed in the gas train between the filter or regulator and the gas valve, using an impulse line connected to the upstream side. Before ordering, measure the actual minimum and maximum pressures of the installation to ensure the setpoint can be adjusted accordingly.

Common failures of gas pressure switches include a torn diaphragm, a blocked impulse tube, or a drifted setpoint after thermal cycling. These issues often present as burner lockouts that resemble ignition problems, because the burner control receives no permission to open the gas valve. When diagnosing a lockout, confirm the switch changes state when gas pressure is present, and clean or replace the impulse line before condemning the switch.