What is a sediment trap (gas line)?
A short capped nipple installed at the gas line inlet of furnaces and water heaters to collect debris and condensation before fuel enters the appliance.
A sediment trap is a short vertical pipe nipple, typically capped or plugged, that sits between the main gas line and a gas appliance such as a furnace or water heater. As natural gas and liquefied petroleum gas flow through supply lines, they can carry small particles of dirt, pipe scale, and moisture. The sediment trap catches these contaminants in its dead-end chamber before they reach the appliance burner or control valve.
In Greater Hartford, building inspectors require sediment traps on gas-fired furnaces and water heaters as part of the Connecticut plumbing and mechanical codes. This requirement protects the appliance's ignition system and gas control components from clogging or corrosion. Without a trap, debris can restrict gas flow or damage sensitive pilot light assemblies and regulators, leading to equipment failure or safety hazards.
The trap is installed horizontally or vertically, depending on the gas line configuration, and must be accessible for cleaning or replacement. Plumbers typically size the nipple to match the gas line diameter (often 1/2 inch) and cap it with a removable plug. Over time, sediment can accumulate in the trap, so periodic inspection or flushing may be necessary, especially in older buildings with corroded supply lines.
When hiring a contractor for furnace or water heater installation or repair, ensure they include a compliant sediment trap and understand local code requirements. Gas line service providers in the area are familiar with these standards.