Gas Line Installation in Longmont: Appliance Hookups, Permits and Leaks

Smell gas first: the steps before any repair call

Natural gas has an additive that smells like rotten eggs, and a leak can also sound like a hiss or blowing noise. If either shows up, the repair question comes second. Safety comes first.

1. Leave the building at once with everyone inside, and leave doors open if you can do so without delay.
2. Do not switch lights on or off, use a lighter, start a car in the garage or run any electrical device while you are still inside.
3. From outdoors, at a distance, phone 911.
4. Report the leak to Xcel Energy at 800-895-2999 after 911, as the utility told Denver-area customers.
5. Stay out until responders say the building is safe, then have a plumber check the piping before any appliance is relit.

Once the building is cleared, a plumber serving your area can find the failed joint, valve or connector and repair it. The leak detection page covers water, which is a separate case from gas.

Pipe size comes from the load and the distance

Gas pipe is sized with a table, not a guess. The method used in code guides is the longest length method: measure from the gas meter to the farthest appliance, add up the BTU input of the appliances on each section, and read the pipe diameter from the table for that length and load. Fittings count as added length, and a common shortcut adds half again to the straight run.

Natural gas and propane have separate tables, since the two fuels carry different loads at the same pipe size. Common appliance inputs run from about 40,000 BTU per hour for a storage water heater to about 100,000 for a furnace, and a tankless unit can draw far more than either.

This is why a plumber will ask what else is on the line before adding anything. A branch that works for one dryer can fail once a fireplace and a tankless heater share the same trunk. The tankless heater page shows how that comes up in a conversion.

Repairing a gas leak: valves, connectors and joints

Most leaks come from a few places: an old flexible connector, a worn shutoff valve stem, a threaded joint that has loosened or a corroded section of steel pipe. Plumbers find them with a gas detector and a leak-check solution that bubbles at the spot, not by sniffing alone.

• Connector leak: replace the connector. Reusing an old one is discouraged, since connectors are listed for one installation.
• Valve stem seep: replace the valve, not just tighten the packing.
• Joint leak: disassemble, clean, reseal with a gas-rated compound and retest.
• Corroded pipe: cut out the section and replace it with new pipe or tubing.
• Appliance leak: the appliance itself may need service from its maker or a servicer who handles that appliance type.

Pipe replacement depends on the material. House gas piping is usually black iron steel pipe or corrugated stainless steel tubing, called CSST. Rusty or corroded black iron is cut out and replaced, and CSST follows the maker's installation rules. Ask which material the plumber plans to use and why.

Once the work is finished, the plumber tests it and checks nearby appliances before leaving. Ask to see the test, and have the appliance relit only after it passes.