Gas line work: sized by calculation, proved by pressure test

Leave the building, taking everyone with you, and do not operate light switches, appliances or garage doors on the way out: a switch contact is an ignition source. Do not use a phone inside. Once outside and clear, call the gas utility’s emergency line first; they will shut the supply. A plumber is the second call, for the repair. This is the one plumbing situation where the correct first move is to leave.

Yes. New gas piping, appliance additions and line modifications are permitted and inspected work, and the inspection includes a pressure test on the new piping. That test is the point of the process rather than a formality. It is the documented proof the system holds. Permits and inspection scheduling are handled as part of the job.

It is calculated, not guessed. Sizing depends on the appliance’s input rating in BTU, the developed length of pipe from the meter, the number of fittings, and every other appliance drawing on the same system. A line adequate for a dryer may starve a tankless water heater with three times the input. That calculation gets done properly, because an undersized line produces faults that look like appliance failures for years.

On a conversion, undersized gas supply is one of the most common causes. A tankless burner can have several times the input rating of the tank it replaced, and if the existing line was never upsized the unit is starved at full fire, presenting as ignition faults, flame loss or simply not reaching temperature. It reads like a broken heater and it is actually a fuel supply problem. See tankless service.

Yes, and it is common work here given how much of the year is spent outside. An exterior run needs the correct materials for above-ground and buried applications, protection from physical damage and corrosion, appropriate depth and sleeving where it is buried, and a shutoff at the appliance. It is sized alongside the rest of the house so adding a grill does not quietly starve the water heater.

It is an inline valve that closes automatically when it senses shaking of a defined intensity, cutting gas to the building. In earthquake country it is a genuinely sensible device: the fire risk after a significant event is largely a gas risk. Some jurisdictions and some transactions require one. It is inexpensive relative to what it protects, and it gets installed on the house side of the meter to code.

A pressure test on the isolated system establishes whether there is a leak at all and roughly how fast, which is the part that matters most. Location is then narrowed with electronic detection and solution testing at joints and fittings. Older black-iron systems most commonly leak at threaded joints, drip legs and appliance connections rather than mid-run, which is where the search starts.

It is different rather than simply better. CSST installs faster with fewer joints and routes easily through finished construction, which matters in a retrofit; it also has specific bonding and protection requirements that must be followed properly. Black iron is robust, familiar and preferred in exposed or vulnerable locations. Good installations often use both, chosen per run rather than as a policy.

Yes, and it is worth doing properly rather than leaving a capped stub behind drywall. When an appliance is removed, a wall heater, an old dryer connection, a decommissioned fireplace, the branch should be cut back and capped at a sensible point, the system pressure-tested afterwards, and the change recorded. Abandoned live branches are a recurring find in remodelled houses of this era.

A branch to a new range, dryer or heater within reasonable reach of existing piping is often a half-day to a day, including the pressure test. Longer runs, outdoor kitchens, upsizing a main run for a tankless conversion, or work through finished walls take longer. Inspection scheduling can add a day at the end, and the line is not commissioned until it passes.