Tankless water heater installation and service in Orange County

By William Jay Horsky Jr., Owner, Professional Plumbing, Inc. · Published July 12, 2026

Tankless water heater installation in Orange County is the work of converting a home to, or replacing, an on-demand water heater that heats water as it flows instead of storing it in a tank. Done right, it means a properly sized gas line, the correct venting, a dedicated electrical circuit, and every code upgrade the swap triggers. The unit on the wall is the easy part. Behind it is where the job is won or lost, and it is the part some companies cut corners on.

What a tankless installation really involves

The tankless conversion is the biggest project in the water heater category, and four things behind the wall decide whether it is done right.

Gas line sizing

Some companies will install a tankless on the existing half-inch gas line, because that is cheaper than running a new line. It can be done. It should not be. When a tankless burner starves for gas at full flame, combustion goes incomplete and the unit puts out soot. On a condensing tankless, which most modern units are, the heat exchanger runs wet and slightly acidic, so the soot bonds to the wet metal, the acidic film eats into the copper, and the heat exchanger fails. Worse, the manufacturer can see the soot when the unit comes in for warranty service, and at that point the warranty is voided. The right install runs a properly sized gas line back to the meter.

Venting

Older steel atmospheric vents from a tank water heater cannot be reused for a condensing tankless. Tankless units produce wet flue gases that destroy steel from the inside, so manufacturers require either certified plastic vent (PVC, CPVC, or polypropylene depending on the unit) or stainless. Over time the trade moved largely to plastic on condensing units. A non-condensing unit runs hotter and needs stainless Category III venting, which is expensive, and it is one reason we usually steer homeowners toward a condensing unit.

The outdoor-relocation pattern

Here is a common Orange County install pattern. The existing tank sits in the garage near an exterior wall, so we move the new tankless to the outside of that wall. That removes the venting question entirely, because the unit is now outdoors, the water line move is short, and the gas tie-in runs straight from the meter, which in Orange County homes is usually near the garage. As a bonus, the garage gets floor space back. Two conditions have to be met: there cannot be a window directly above the unit, for combustion-air clearance, and the unit needs a small concrete pad or a wall bracket per the manufacturer instructions.

Install timelines

• Tankless-to-tankless swap of the same size and brand: about 2 hours.
• New tankless install, first time on the home: 6 to 8 hours, plus extra if the gas line has a long run.
• The gas line and venting are what add the time, not the unit itself.

Is tankless right for your home?

Tankless is not automatically the right answer for every home, and we will tell you when a tank is the better call. Tankless makes the most sense in a few situations. It fits larger households and homes where several showers run back to back, because it never runs out of hot water within its flow rate. It fits long-term owners, because the U.S. Department of Energy puts a tankless unit’s life expectancy at more than 20 years, against 8 to 10 for a tank (U.S. Department of Energy). And it fits vacation or part-time homes, because the unit heats only on demand instead of holding 40 or 50 gallons hot around the clock for nobody to use.

Where it fits less well is a home on the existing half-inch gas line with a long run to the meter and no easy exterior wall, because the gas and vent work then drives the cost up. That is exactly the kind of thing we price on site, honestly, before you commit.

Our install process

Every tankless installation follows the same path. First, an on-site evaluation: we look at the gas meter and line size, the run to the unit location, the electrical, the venting path or the exterior-wall option, and the code items the swap will trigger. Then a written estimate, with each variable and its price listed, before any work begins. On install day we run the correctly sized gas line, set the unit, install the venting or mount it outdoors, make the water and electrical connections, and complete the code work. Finally we commission the unit, check the gas pressure under full fire, and walk you through the controls and the yearly flush.

Sizing and which unit

A tankless unit removes the gallon question and replaces it with a flow-rate question: how many fixtures can run hot at once. We size the unit to the number of simultaneous fixtures your household actually uses, at the temperature rise for Orange County water, not to a tank-equivalent number. Guess low and the unit cannot keep up when two showers run together; guess high and you pay for capacity you never use.

To see which specific models fit your home, and to compare them side by side, use our tankless water heater tool, and read the tankless water heater guide for how to choose. Noritz is our preferred tankless brand, and we also install Rinnai and Navien. We match the unit to the home on the estimate.

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What a tankless installation costs

We do not publish dollar amounts, because the price of a tankless installation in Orange County depends almost entirely on the work behind the wall. What is consistent is what drives the number, so you can read any quote, ours or a competitor’s, and understand it:

• Whether it is a swap or a first-time conversion. A tankless-to-tankless swap is the lowest. A first conversion with new gas and vent work is meaningfully higher.
• Gas line size and the run to the meter. A short run from a nearby meter is straightforward. A long run from a meter on the far side of the home adds material and labor.
• Venting, or the exterior-wall option. New venting adds cost; relocating the unit outdoors can remove it.
• Code upgrades the swap triggers, and whether the electrical circuit is already in place.
• The unit itself, condensing versus non-condensing, and any recirculation.

Every estimate lists the variables that apply and the price for each, in writing before any repair work begins. Tankless quotes often differ by hundreds or thousands of dollars between companies, usually because one company sized the gas line correctly and another did not. If you have gotten a quote for a job of $2,500 or more and would like a second opinion, we do them for free. The customer needs to have a written estimate from the other company. Call or ask for details.

Check for rebates before you buy. SoCalGas offers rebates on qualifying high-efficiency tankless water heaters — we’ll help you find the current program that fits the unit you choose.

Tankless maintenance

A tankless unit should be flushed once a year to keep scale out of the heat exchanger. Orange County water runs 8 to 19 grains per gallon, so mineral scale forms inside the tube bundle faster than most homeowners realize, and without a yearly flush the unit eventually fails to hold temperature or throws a fault code. The flush takes 45 minutes to an hour and meaningfully extends the unit’s life. For installs we did, we offer a discounted prepaid flush scheduled about a year out, so it does not get forgotten.

Tankless water heater FAQ

Tankless service across all of Orange County

We install and service tankless water heaters throughout Orange County. Pick the office or service area nearest you:

• Anaheim
• Costa Mesa
• Fountain Valley
• Garden Grove
• Huntington Beach
• Irvine
• Newport Beach

What happens when you call us

If you would like us to come out and take a look, we are available 24 hours a day, every day of the year. Estimates are free during normal business hours, Monday through Saturday, for work we can see and price on site. After hours and on Sundays, the visit is at overtime rates. We give a two-hour window and call when the truck is on the way. If a tankless is the right call for your home, we will size it correctly and price the gas and vent work honestly. If a tank is the better answer for your situation, we will tell you that too.

More of what we do

A tankless water heater is one system in a house full of plumbing. We also handle standard water heater service, gas lines, drains and sewers, and slab leak repair. When you are ready, request a quote or contact us.

About the author

William Jay Horsky Jr. owns Professional Plumbing, Inc. He founded the company in Orange County in 1985 and has run more than 36,900 plumbing jobs across the area since then. The company has been licensed by the California Contractors State License Board since 1987 (CSLB license number 517514, classification C-36, current and active), incorporated as Professional Plumbing, Inc. in 2001, and is a 2026 BBB Torch Awards for Ethics finalist. It operates from offices in Fountain Valley, Garden Grove, Huntington Beach, Costa Mesa, and Newport Beach, and serves homeowners and businesses across Orange County.

Serving Orange County since 1985.

Call (714) 964-3519 · Free tankless estimate