Gas Water Heater Replacement Cost

Gas water heaters heat water faster than electric tanks and usually cost less to run, but the installation involves a gas connection and venting. Angi puts a gas tank replacement at $700 to $2,700 installed.

Costs at a glance

Venting

Gas water heaters must vent exhaust outdoors. A straight replacement can often reuse the existing vent, which keeps venting costs at $100 to $600 (HomeGuide). A first-time installation needs new venting at $500 to $1,500. Power-vented units, which use a fan, cost $350 to $500 more than direct-vent models, and Angi lists power venting at $300 to $600 plus $300 to $500 for electrical work.

Operating cost and lifespan

HomeGuide puts the annual operating cost of a gas tank at $250 to $420, compared with $530 to $600 for an electric tank. Angi gives gas tanks a lifespan of 8 to 12 years.

Switching fuels

Converting from electric to gas costs $400 to $2,000 or more (HomeGuide) because it may require a new gas line and venting. Angi lists gas line work at up to $1,500 when switching from electric to gas. Compare with electric water heater replacement cost.

Common gas water heater repairs

Before replacing, check whether a single part has failed. A thermocouple costs $100 to $325 and a gas control valve $150 to $550 (HomeGuide). See thermocouple replacement cost and gas valve replacement cost.

What the job includes

A gas water heater replacement involves shutting off the gas and water, draining the old tank, disconnecting the gas line, vent and water lines, setting the new tank, and reconnecting everything. The installer then lights the burner and checks for gas leaks and proper venting.

What changes the price

• Venting type. Atmospheric vent units use a metal flue; power-vent and direct-vent units cost more and may need new vent pipe.
• Tank size and efficiency. Larger and higher-efficiency tanks cost more.
• Code updates. A new sediment trap, gas shut-off, expansion tank, drain pan or seismic straps may be required.
• Location. Attic installs and tight closets take longer than garage swaps.
• Switching fuel. Converting from electric to gas requires a new gas line and vent, which is a much bigger job.

Venting and safety

A gas water heater burns fuel, so the flue must carry exhaust gases out of the house. A good installer checks that the vent is the right size, slopes correctly and is not damaged. Carbon monoxide detectors are a smart addition anywhere a gas appliance is installed.

Repair or replace?

Gas heaters have more serviceable parts than electric ones: thermocouples, igniters, gas valves and burners can all be replaced. A leaking tank cannot. If the tank is near the end of its typical life, replacement usually makes more sense than a major repair.

Questions to ask

1. Does the quote include the permit, haul-away and code updates?
2. Will the existing vent work with the new heater?
3. What is the warranty on the tank and on the labor?

In Texas

Many Texas homes have gas water heaters in garages, where codes typically require the burner to be raised off the floor. In attics, a drain pan with a line to the outside is an important safeguard.

What a gas replacement involves

The installer shuts off the gas at the appliance valve, turns off the water and drains the old tank. The gas line, the water lines and the vent connector are disconnected and the old tank is removed. The new tank goes in place, often on a new pan, and is leveled.

The vent connector is reattached with the correct slope and secured with screws at each joint. The gas line is reconnected with a sediment trap (drip leg) if the code requires one, and every gas joint is leak-tested. The water connections are made, the tank is filled completely, the air is bled from the hot lines, and only then is the pilot lit or the igniter started. The installer then checks that the flue is drafting properly so exhaust gases leave the house.

Atmospheric, power-vent or direct-vent

Atmospheric vent heaters use natural draft up a metal flue or chimney. They are the simplest and cheapest to replace when the existing vent is in good condition.

Power-vent models use a fan to push exhaust out through plastic pipe, often through a side wall. They need an electrical outlet and cost more, but they give more freedom in where the heater goes.

Direct-vent models draw combustion air from outside and exhaust through a concentric or two-pipe vent. They are often used in tight spaces or closets where indoor air is limited.

Switching from one type to another adds labor, so the cheapest replacement is usually the same type that is there now.

Safety items worth paying for

• A carbon monoxide detector near the heater and bedrooms if you do not already have one.
• An expansion tank, if your home has a check valve or pressure regulator on the main line.
• Seismic straps or a stand where local code requires them.
• A drain pan with a drain line in attics or upper floors, where a leak would cause damage.

How to tell if a quote is complete

Compare quotes on the same items: the tank model and size, haul-away, permit, new gas connector, new relief valve, venting changes and any code upgrades. Leaving these out is the most common reason one quote is much lower than another.

Life expectancy and timing

Gas tanks usually wear out from corrosion inside the tank, and the anode rod is what slows that down. If your heater is getting old, replacing it on your schedule lets you compare quotes and pick the model you want. Waiting until it fails usually means paying for whatever is on the truck, sometimes at an after-hours rate.

Sources

1. Angi: How Much Does Water Heater Replacement Cost? (updated Jul 20, 2026)
2. HomeGuide: How Much Does Water Heater Installation or Replacement Cost? (Jan 2, 2026)
3. HomeGuide: How Much Does a Tankless Water Heater Cost? (Jan 2, 2026)