Weil McLain 511-624-520 Pressure Switch
The Weil McLain 511-624-520 Air Pressure Switch is the 1.4 in. W.C. SPST blower proving switch for the 0 to 5,500 ft elevation range on the Weil-McLain GV gas boiler. The GV Series 1 and 2 parts list (Fig. 5) describes it as a "Pressure Switch (0 to 5,500 ft. Elevation) 1.4" W.C." with a Honeywell IS20292-5426 reference, and the GV Series 3 (Fig. 3/4) and GV Series 4 (Fig. 3) parts lists show it as an "Air Pressure Switch (0-5500' Elevation)" with a Tridelta FS6330-527 reference. The switch has dual 1/4 in. barb connections and comes with an L-shaped bracket, and the beige and gray body is molded ORIGINAL USA with a P2 marking.
An air pressure switch is a safety proving device. The blower creates a pressure differential, and when that pressure reaches the 1.4 in. W.C. set point the single-pole, single-throw (SPST) contacts close and tell the control module that airflow is established. If the switch does not close, the boiler will not fire. If the vent or air intake is blocked, the pressure drops and the switch opens, which shuts the burner down. It is a safety control, so it should be replaced with the correct number and never bypassed or jumpered.
Elevation matters with this part. The 511-624-520 is the 0 to 5,500 ft switch, and the GV Series 1 and 2 parts list shows a separate kit, 382-200-317, for 5,500 to 10,000 ft, so confirm your installation altitude before you order. If a GV boiler locks out on a pressure switch fault, check the blower wheel, the vent and air intake, and the sense line for cracks, water or a pinched section before you replace the switch. Condensate in the sense line is a common false fault. Once the lines are clear, a switch that still will not close at the correct pressure is ready for replacement.
Key Benefits
- 1.4 In. W.C. Set Point: The set point shown on the Weil-McLain GV Series 1 and 2 parts list for the 0 to 5,500 ft switch.
- Listed Across GV Series 1 to 4: Shown on the GV Series 1 and 2, GV Series 3 and GV Series 4 parts lists.
- Dual Barb Connections and Bracket: Dual 1/4 in. barb ports and an L-shaped bracket come with the switch, ready to mount at the blower.
- SPST Safety Contacts: SPST contacts prove blower airflow to the control module before the boiler is allowed to fire.
Common Questions
- What elevation is the 511-624-520 for? 0 to 5,500 ft. For 5,500 to 10,000 ft the GV Series 1 and 2 parts list shows the 382-200-317 kit.
- Which GV boilers list this switch? The Weil-McLain GV Series 1 and 2, GV Series 3 and GV Series 4 parts lists.
- Can I bypass the switch to test the boiler? No. It is a safety proving control. Check the blower, vent, air intake and sense line, then replace the switch if it still will not close.