Tankless Water Heater Repair in Houston, TX

Error code on the display, water cycling hot and cold, or no hot water at all: when a tankless unit acts up, it tells you what is wrong if you know how to read it. Tankless water heater repair is diagnostic work first, and our licensed plumbers service Navien, Rinnai, and Rheem units every week, so we arrive knowing what the code means and what usually causes it in Houston homes. Upfront pricing on the fix before any work starts.

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Why Tankless Water Heaters Fail in Houston

Most tankless failures here trace back to one culprit: scale. Houston’s hard water coats the heat exchanger until the unit overheats against its own deposits, and that is when the error codes start: overheat faults, flow sensor errors, ignition failures that are really flow problems in disguise. The rest of the repair calls we run are flame rod corrosion from Gulf Coast humidity, clogged inlet filters and condensate lines, failed flow sensors, and venting faults.

The good news inside that list: a large share of “broken” tankless units are not broken, they are scaled, and a deep descale is the repair. That is a few hundred dollars, not a few thousand. It is also why the honest first question on every call is whether you need a repair at all or whether tankless water heater maintenance would have the unit running like new. We tell you which before you commit to either.

Fast, Honest Diagnosis

What to Expect From a Tankless Water Heater Repair Visit

Every repair visit starts with reading the unit, not replacing parts on a guess: error code history, inlet filter, flame rod, flow sensor, and scale condition, in that order.

What you get on every tankless water heater repair call:

Read the Code

Common Tankless Error Codes We Repair

The display is telling you what hurts. These are the codes we see most in Houston homes, and what they usually mean here, where scale is behind more faults than the manuals admit. Whatever your unit is showing, tell us the code when you call and we arrive with the likely parts on the truck.

Navien: E003, E012, E407

– Ignition and flame loss codes (E003, E012) often trace to gas supply or a corroded flame rod; E407 and the 400-series overheat faults are almost always scale in the heat exchanger

Rinnai: 10, 11, 12

– Code 10 is venting or air supply blockage, 11 is ignition failure, 12 is flame loss; on older units the fix is frequently the flame rod, on scaled units the burner is starving through restricted flow

Rheem: 11, 13, 29

– Ignition and combustion codes (11, 13) parallel Rinnai’s; 29 is a condensate drain fault, common here when the neutralizer or drain line clogs

BRAND-SPECIFIC TANKLESS REPAIR: NAVIEN, RINNAI & RHEEM

Navien

Navien repairs we run weekly: heat exchanger descaling for the 400-series overheat codes, flame rod and igniter replacement for E003 and E012, condensate trap clearing (they clog faster in our hard water than the service schedule assumes), and recirculation pump faults on ComfortFlow models. We stock the common NPE-series parts, so most repairs finish in one visit.

Rinnai & Rheem

Rinnai and Rheem each fail in their own ways. Rinnai’s codes 11 and 12 usually come down to the flame rod, which corrodes early in Gulf Coast humidity, and SENSEI condensing units add neutralizer and condensate faults to the list. Rheem repairs run the same territory, with parts available at every supply house in Houston when something uncommon fails. Both brands get the same rule: diagnosis first, price approved before parts go in.

How a Repair Visit Works

Tell us the error code and the brand when you call, and we arrive with the likely parts. On site, the diagnosis runs the same order every time: code history, gas and water supply, inlet filter, flame rod, flow sensor, scale condition. Then you get one price for the fix, approved before any work starts. Most repairs, including deep descales and flame rod replacements, finish the same visit, and every repair is verified at temperature before we leave.

Before You Call

How Much Does Tankless Water Heater Repair Cost in Houston?

Repair pricing depends on what the diagnosis finds, but typical Houston ranges look like this, and your exact price is approved before any work starts:

Repair	Typical Houston Price
Deep descale when scale is the fault (the most common "repair")	$250 - $350
Flame rod, igniter, or sensor replacement	$250 - $600
Major component repair (fan, control board, gas valve)	$500 - $1,200
Your unit's exact number	Free quote before any work

The repair-or-replace math, shown honestly: when a repair quote passes half the cost of a new unit on a heater past year 12, replacement usually wins, and we will say so. A new tankless water heater installation starts around $4,000, and repairs on a unit that old buy years, not decades. Under warranty? Parts may be covered, and the written diagnosis we provide supports the claim.

Every tankless water heater repair is quoted before we start, with no trip charge and no hidden fees. Call (832) 662-4288 with your error code or schedule online.

No Hot Water? Run Through This First

Some “failures” are five-minute fixes, and we would rather you find them than pay us to flip a breaker. Run this list before you call, and if the unit is still down at the end, you have already gathered everything we need to diagnose it fast.

Check the display for an error code and write it down, even if it clears. The code history is the fastest path to the cause.
Confirm power and gas: breaker not tripped, unit display lit, and the gas shutoff valve on the supply line fully open.
Test cold water flow at a nearby faucet. No cold water means a supply problem, not a water heater problem.
Open a hot tap fully. Tankless units need minimum flow to fire; a barely open tap or a clogged aerator can keep the burner from ever igniting.
Check the cold inlet filter at the bottom of the unit if you are comfortable doing so: shut the isolation valve, remove, rinse, reinstall. A clogged filter mimics half a dozen bigger failures.
Power cycle the unit once: off for 30 seconds, back on. If the code returns or the water is still cold, stop there and call with the code: (832) 662-4288.

What not to do: do not open the unit’s cover, do not work on gas connections, and do not keep power cycling past one attempt, because repeated resets can mask the code history that tells us what is actually failing. If the checklist above did not bring the hot water back, the fault is real, and it is usually the flame rod, the flow sensor, or scale.

One more honest note: if the unit runs but the water cycles hot and cold, that is the classic scale symptom, and the fix is usually a deep descale rather than parts. Our tankless water heater maintenance page covers what that visit includes.

Testimonials

What our clients Say about us

“Matthew was very polite and informative. He explained and showed me what the problem was and how he was going to fix it. He came out to my house and stayed till the job was complete. Would recommend 10/10.”

U.R.

“My go-to plumber! I look for someone who is reliable, stands behind their work, and doesn’t try to price gouge you! Was a great experience and will use him again!”

Timothy P.

“Repipe Solutions did an excellent job re-piping my 2-story house built in the 1940’s. They used legitimate Uponor PEX-A, completed the job in the time frame promised, and offered the best price.”

Jose H.

Frequently Asked Questions

How much does tankless water heater repair cost in Houston?

Typical Houston ranges: $250 to $350 when a deep descale is the fix, $250 to $600 for flame rods, igniters, and sensors, and $500 to $1,200 for major components. Diagnosis comes first and your exact price is approved before any work starts, with no trip charge.

Why is my tankless water heater not heating water?

The usual causes in Houston, in order: scale in the heat exchanger, a clogged inlet filter, a corroded flame rod, insufficient flow to trigger ignition, or a gas supply problem. Run the checklist on this page first; if the unit is still down, call with the error code and we diagnose from there.

What does the error code on my tankless unit mean?

It depends on brand: Navien’s 400-series faults are usually scale, Rinnai’s 11 and 12 point to ignition and flame loss, and Rheem’s 29 is a condensate fault. The section above covers the codes we see most. Whatever yours shows, note it before power cycling, because the code history speeds up diagnosis.

Can you repair my tankless unit the same day?

In most cases, yes. We stock the common Navien, Rinnai, and Rheem parts, and calling with your error code means we arrive with the likely fix on the truck. Major component orders occasionally need a second visit, and we tell you that before you commit.

Is my tankless repair covered under warranty?

Possibly. Navien, Rinnai, and Rheem heat exchanger warranties run 10 to 15 years and parts warranties around 5, but scale damage on an unmaintained unit is excluded. We tell you during diagnosis whether your failure looks like a warranty claim, and our written diagnosis supports it if so.

Should I repair or replace my tankless water heater?

The honest math: repair when the unit is under 12 years old and the fix is under half the cost of replacement, and replace when it is older and the quote crosses that line. A new install starts around $4,000, so most single-part repairs are clearly worth it. We show you the numbers either way.

Is it a repair problem or a maintenance problem?

If the unit runs but cycles hot and cold, delivers less flow than it used to, or throws overheat codes, that is scale, and a deep descale usually fixes it. Our tankless water heater maintenance page covers the annual visit that keeps it from coming back. Dead unit, ignition failures, or persistent codes after a descale are repair territory, which is what this page is for.