Gas Tankless Water Heater Installation

Gas is the right fuel for whole-home tankless in Austin. A single condensing gas unit delivers the flow a family actually needs in winter, and it does it without touching your electrical panel. The catch is everything upstream of the heater: line size, meter capacity, and a vent that satisfies both the manufacturer and the inspector.

This page is about that upstream work, because it is where the price differences and the bad installs both come from.

What a gas installation involves

Gas load calculation for the whole house, not just the heater
Line sizing and upsize to 3/4-inch where the BTU rating requires it
Meter capacity check with the utility, and an upgrade request if needed
Sealed combustion venting — PVC for condensing, stainless for non-condensing
Correct clearances from windows, soffits, intakes and property lines
Condensate drain and neutralizer
Sediment trap, shutoff valve and pressure test
Permit, inspection and full combustion commissioning

Exterior vent termination and gas line connection for a gas tankless water heater

How the day goes

1

Call or send the form

Tell us the house, the fuel, and what is going wrong. Most quotes need five minutes on the phone and a photo of your current heater.

2

On-site sizing visit

We check gas line size, venting route, electrical capacity and your peak hot water demand, then put a fixed price in writing.

3

Installation day

Most changeovers take four to eight hours. Gas line or venting upgrades can add a day. We protect floors and haul the old tank away.

4

Inspection and handover

We meet the city inspector, walk you through the controller, and set your first descaling reminder.

Where gas jobs go wrong

A 199,000 BTU unit fed by an undersized half-inch line — it will run, badly, and fail early
Vent terminations too close to a window or an air intake
No sediment trap, which the inspector will fail
Condensate dumped into a drain with no neutralizer, which eats the pipe
A meter already at capacity with a furnace, range, dryer and pool heater on it
Non-condensing units vented in PVC because it was cheaper

Gas installation cost ranges

Scope of work	Typical range
Gas tankless install, existing 3/4-inch line, short vent	$3,200 - $4,200
Gas line upsize from half-inch, typical run	add $600 - $1,400
Long or two-story vent run	add $300 - $800
Meter upgrade coordination with the utility	varies by utility
Propane conversion kit and set-up	add $150 - $350
Recirculation pump and dedicated return line	add $600 - $1,800

Estimates, not quotes. Planning ranges for the Austin metro, permit included.

Gas service in the Austin area

Most of Austin proper and the older suburbs are served by Texas Gas Service; parts of Williamson County are served by other providers, and a number of newer subdivisions out west and north are propane rather than natural gas. Propane changes the orifice, the regulator and the sizing, and it is worth knowing which you have before anyone quotes you.

If your house was built before the mid-1990s, assume the line to the water heater is half-inch until we measure it. If your gas meter already feeds a furnace, a range, a dryer and a pool heater, the load calculation matters as much as the line — and that is a calculation, not a guess.

Frequently asked questions

How do I know if my gas line is big enough?

We measure it and run the load calculation for the whole house. Half-inch iron to the heater is the common finding in pre-1990s Austin homes and it will not carry a full-size tankless unit.

Can a gas tankless heater run during a power outage?

No. The controller, fan and igniter all need electricity, so a standard unit is dead in an outage. A small generator or battery backup on that circuit is the workaround, and it is worth doing here.

Condensing or non-condensing?

Condensing, in almost every Austin install. It is more efficient, it vents in PVC which gives you more placement freedom, and the price gap has narrowed to the point where non-condensing rarely wins.

Do you handle the propane version?

Yes. Propane units need the conversion kit fitted and the combustion set up for LP — it is a different commissioning, not just a different tank.