Weil McLain 511-246-305 Gas Valve

The Weil McLain 511-246-305 2-Inch Manual Main Shut-Off Gas Valve is the OEM 2-inch NPT lever ball valve that sits at the front of the gas train on Weil-McLain LGB commercial gas boilers. It is a brass valve with 2-inch female NPT connections on both ends, a yellow lever handle, and a 1/8-inch NPT downstream pressure tapping on the body, closed with a brass plug, so a manometer can be connected right at the valve. In Weil-McLain’s LGB-6 through LGB-20 CSD-1 control supplement, the parts list names 511-246-305 as the manual main shut-off valve and shows it as a 2-inch Conbraco 50-703.

In that supplement, gas enters the boiler through a drip leg and reaches the manual main shut-off valve immediately after the drip leg. Weil-McLain calls for inlet pressure at this valve of at least 7 inches W.C. (5 inches W.C. on special order) and no more than 13 inches W.C.; if supply pressure can exceed 13 inches W.C., a 100% lock-up regulator goes upstream of the hand valve. The same manual has you close the valve during pressure tests below 13 inches W.C., and above that level the boiler and gas valve are disconnected from the supply entirely. The lever makes the position obvious: in line with the pipe is open, across the pipe is closed.

Replace the valve when the handle is seized or will not turn a full quarter turn, when it weeps at the stem, or when it will not hold a bubble-tight shutoff in a leak check. With the gas supply isolated upstream and the line made safe, remove the old valve, clean the pipe threads, apply gas-rated thread sealant, and install the new 511-246-305 with the pressure tapping on the downstream side. Then restore gas, leak-test every joint with approved solution, and relight the boiler by the CSD-1 operating instructions. Gas work belongs to a qualified technician following local code.

Key Benefits

• OEM Gas Train Isolation: The factory 2-inch manual main shut-off for the LGB series, positioned exactly where Weil-McLain’s piping and CSD-1 instructions expect it.
• Built-In Test Port: The 1/8-inch NPT pressure tapping lets you read gas pressure at the valve for startup, leak testing, and troubleshooting.
• Positive Quarter-Turn Shutoff: A lever ball valve shows open or closed at a glance and shuts off fully in a quarter turn.
• Clean Drop-In Swap: 2-inch NPT female ends match the original 2-inch gas inlet piping, so there is no re-piping.

Common Questions

• What boilers use it? Weil-McLain lists 511-246-305 as the 2-inch manual main shut-off valve in the LGB-6 through LGB-20 CSD-1 control supplement. Match by boiler model, size, and serial number, since inlet pipe size varies across the LGB line.
• What is the small plugged port on the body? It is a 1/8-inch NPT downstream pressure tapping for a manometer or gauge; keep the plug installed and sealed when you are not testing.
• Can I use a regular 2-inch ball valve instead? A boiler gas train should use a gas-rated manual shut-off valve specified for the application. The 511-246-305 is the factory-listed part, so the boiler’s original gas train design stays intact.

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.