Gas lines: new runs, repairs, and the test that has to happen at the end

If you can smell gas right now

Do this first and read the rest later. Leave the building and take everyone with you. Do not operate light switches, appliances or garage door openers, and do not use anything that sparks. If the smell is strong or you hear hissing, leave doors open behind you and get well clear before using a phone. Call your gas utility’s emergency line, they respond to suspected leaks at no charge and they will make the property safe at the meter.

Once the utility has isolated the problem, the repair on the house side of the meter is plumbing work, and that is where we come in. The order matters: utility first for safety and isolation, then a plumber for the repair, test and reinstatement of the appliances.

If the smell is faint and intermittent, that still deserves investigation rather than tolerance. Small leaks at fittings, at flexible appliance connectors and at old shutoff valves are common, and they do not improve on their own.

The runs people actually ask for

Most residential gas work in Arizona is one of a handful of jobs.

A range or cooktop conversion. Moving from electric to gas cooking means a new branch to the kitchen, an appliance shutoff at the connection, and a check that the existing system has the capacity to carry it. It is the single most requested gas job, and the run is usually the easy part, the route matters more than the length.

A dryer connection. Similar work, often shorter, and frequently in a laundry that already has a capped stub from the original build.

An outdoor grill or fire feature. A permanent line to a built-in grill, fire pit or fire table replaces the propane bottle routine. Outdoor runs bring their own requirements, approved materials, protection where the line is exposed, correct depth where buried, and a shutoff you can actually reach.

A pool or spa heater. The biggest load in most homes by a wide margin, and the job most often undersized. A pool heater added to a line that was adequate for a range and a water heater will starve everything on the system, including itself.

A tankless water heater. High-demand units frequently need a larger gas line than the tank heater they replace, which is a recurring surprise in retrofit quotes, see tankless water heater installation.

Generators, patio heaters and casita extensions. Less common, same principles: load, route, protection, test.

Sizing: the part that gets skipped

This is the technical heart of gas work and the thing that separates a competent job from a cheap one.

A gas system has to deliver enough volume to every appliance running at once, at the pressure each one needs. That depends on the total connected load, the length of each run, the number of fittings and turns, and the diameter of the pipe. Undersize it and the symptoms are subtle rather than dramatic: a range that does not reach full output when the pool heater is running, a tankless heater that cannot hold temperature at high draw, a furnace that short-cycles, appliances that never quite perform as specified.

The right process before any pipe is bought is to total the demand of every existing appliance, add the new one, and calculate the required diameter over the actual route. Sometimes the answer is that the existing line will carry it. Sometimes the answer is that the branch is fine but the trunk from the meter needs upgrading. Occasionally the answer is that the meter itself is undersized for what you are asking, and that is a conversation with the utility rather than with a plumber.

It is entirely reasonable to ask whoever quotes your job what the calculated load is and what diameter they arrived at. A plumber who has done the sums will tell you readily.

Materials, and where each one belongs

Several materials are legitimate for residential gas, and each has a proper place.

Black iron pipe is the traditional choice for interior runs: threaded steel, robust, and unambiguous to inspect. It is heavier to work with and every joint is a threaded connection, which is precisely why it is tested at the end.

Corrugated stainless steel tubing routes through framing and around obstacles far more easily, which makes retrofits through finished spaces much less destructive. It has to be installed by someone trained in the specific system, correctly bonded, and protected wherever it could be struck, the protection detail is where poor installations show up.

Coated or wrapped steel and approved plastic have roles underground, with the material, depth and tracer requirements that go with buried work. Uncoated steel in Arizona soil is a corrosion problem waiting to happen, and caliche makes any burial slower than the drawing suggests, the same ground conditions that complicate main water line repair.

Flexible appliance connectors are for the final connection only, never as a substitute for a fixed run, never routed through a wall or cabinet penetration, and never reused from an old appliance. They perish, and an old connector behind a range is a genuinely common leak source.

Two details that get missed on otherwise tidy work: an accessible shutoff valve at each appliance, and a sediment trap where the appliance requires one. Both are small, both matter, and both are easy to check yourself.

Finding and fixing a leak

Once the property is safe, locating a leak is methodical work.

A combustible gas detector sweeps the run and narrows the area quickly. Bubble solution on suspect joints confirms it visually. Where the location is unclear, a pressure test on an isolated section proves whether that section holds, and sectional testing brackets the fault. Buried lines are harder and sometimes need excavation at the most likely point rather than the whole route.

The usual culprits, in rough order: aged flexible connectors at appliances, threaded joints that have been disturbed or badly dressed, corroded shutoff valves, corrosion on buried or exposed steel, and physical damage, a line clipped by landscaping equipment, a fence post, or a trench dug for something else.

Repair strategy depends on cause. A single bad fitting is a fitting. Corrosion along a length of buried steel is a section replacement, because the rest of that run is the same age in the same soil. And a system with multiple failing joints on old pipe is a case for replacing the run rather than chasing leaks one at a time, the same logic that applies to a house on failing supply pipe.

Every gas repair ends with a pressure test. Not a sniff and a shrug, a documented test that holds.

Permits, tests and inspection

Gas is permitted work in Arizona jurisdictions, and the requirement varies by city, county and utility. New runs and extensions generally require a permit and an inspection; like-for-like appliance connections often do not. The safe assumption is that a new line needs one.

What a permitted job looks like from your side: the work is done, the line is pressure tested and left under test, an inspector verifies materials, support, protection, sizing and the test result, and the utility or the plumber then relights and checks the appliances. That sequence exists for good reason, and the paperwork is worth having, unpermitted gas work is a real problem at resale, and a real problem with an insurer after an incident.

Two things to ask for and keep: the permit number, and the pressure test result. If a quote is notably cheap and does not mention either, that is usually why.

One point specific to this state: the mix of municipal utilities, private providers and rural propane means the requirements genuinely differ from address to address. Nobody should be telling you what your jurisdiction requires without checking it.

Outdoor kitchens, pools and fire features

Outdoor gas is where Arizona homes concentrate their demand, and the desert setting adds requirements.

Anything built into masonry, a grill in a block surround, a fire pit in a hardscape, needs the shutoff accessible after construction, and it needs to be established before the mason arrives. Retrofitting access into finished stonework is expensive and avoidable.

Buried runs to a distant feature need the correct material and depth, and in caliche the trench is the cost. Where a run crosses a driveway or hardscape, sleeving matters. Where a line emerges above grade, it needs protection and a corrosion-resistant finish, because exposed steel in this climate takes a beating from UV, irrigation overspray and the heat cycling of a surface that hits extreme temperatures.

Pool heaters deserve their own note. They are the largest gas load in a typical home, and adding one to an existing system without recalculating is the most common capacity mistake we see. Combining a pool heater with a tankless water heater on an unmodified line is a reliable way to make both of them disappoint you.

Propane and off-grid Arizona

A large part of the state is not on natural gas at all. Across the high country, the western corridor and rural Pinal, propane from a tank is normal, and the differences are practical rather than academic.

Propane operates at different pressures and delivers different energy per unit volume, so appliances are configured for one gas or the other and orifices must match. Sizing calculations differ. Tank placement, distances from structures and openings, and regulator arrangement are all governed. And because propane is heavier than air, it pools low rather than dispersing upward, which changes how leaks behave and where detectors belong.

If you are moving to a property that runs on propane, or converting an appliance between fuels, say so at the outset. It is not a footnote to a natural gas job; it is a different specification, and appliances converted casually are a real hazard.

What we do not do

Worth being plain about the boundaries.

We do not respond to suspected leaks in place of your gas utility, they are the emergency service for that, they are free, and they can isolate at the meter. We do not work on the utility’s side of the meter, or on the meter itself. We do not carry out utility service upgrades, though we will tell you when your meter rather than your pipework is the constraint.

We also do not service the appliances themselves beyond connection and safe reinstatement, a furnace fault, a pool heater control board or a range igniter is appliance service work. And in propane country, tank installation and filling belong to your propane supplier; the house-side piping is ours.

What we do is the piping between the meter or tank and the appliance shutoff: sized, in the right material, protected, permitted where required, and pressure tested at the end.