Weil McLain 511-624-542 Pressure Switch

The Weil McLain 511-624-542 Air Pressure Switch is a 1.53 inch W.C. SPDT differential air pressure switch for gas-fired Weil McLain boilers. It works as the combustion air proving switch: it senses the pressure difference created when the draft inducer is running and tells the ignition control that air is actually moving through the burner and vent path before the burner is allowed to light. The switch comes mounted on a metal bracket, and its set point is 1.53 inch W.C.

The manufacturer's own CGt manual addendum lists an air pressure switch rated 1.53 inch W.C. under this part number in its replacement parts table, so 511-624-542 is the factory part number and not a universal cross-reference. Set point is the specification that matters most on a switch like this. A switch with a lower set point can prove airflow that is weaker than the boiler was designed for, and a switch with a higher set point can cause nuisance lockouts, so the replacement should always match the original set point.

SPDT means single pole, double throw: a common terminal that connects to either a normally open or a normally closed terminal depending on whether the pressure difference has reached the set point. Match the wiring terminal for terminal when you swap it in. Never jump out or bypass an air pressure switch to get a boiler running. If the switch does not prove, the cause is usually a blocked vent, a blocked or kinked sensing hose, or a draft inducer that is not up to speed, and those are the items to check first.

Key Benefits

• Factory 1.53 Inch W.C. Set Point: Matches the 1.53 inch W.C. air pressure switch Weil McLain lists in its CGt manual addendum, so the proving point is the one the boiler control expects.
• SPDT Contact Arrangement: One common terminal with normally open and normally closed positions gives the control the signal it needs to confirm airflow before ignition.
• Bracket Mounted: Arrives on a metal bracket, so it mounts the way the original did instead of needing a separate bracket sourced on the side.
• Manufacturer Part Number: 511-624-542 is the number shown in the Weil McLain CGt manual addendum for the 1.53 inch W.C. switch, which takes the guesswork out of ordering.

Common Questions

• What set point does the 511-624-542 have? It is a 1.53 inch W.C. air pressure switch with SPDT contacts. Do not substitute a switch with a different set point.
• Which boiler does it fit? Weil McLain's CGt manual addendum lists the 1.53 inch W.C. air pressure switch as 511-624-542. The addendum does not break the table out by size, so please send us the boiler model and serial number and our team will confirm fit before you buy.
• Can I bypass the switch to test the boiler? No. The air pressure switch is a safety device that proves venting and combustion airflow. If it is not closing, check the vent, the sensing hoses and the draft inducer rather than jumping the switch.

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.