Licensed diagnosis, repair, and descaling for every major brand
Tankless unit repair Katy TX done right the first time
When your tankless unit quits, you want hot water back today, not next week. Our tankless unit repair Katy TX service covers no hot water, error codes, scale lockouts, and failed ignitions on Rheem, Rinnai, Navien, and Noritz systems. We stock common parts on the truck, test the unit under real flow, and leave you with a straight answer on what failed and why. Same-day and 24/7 emergency calls available across Katy and Waller County.
Live dispatcherUpfront optionsBacked workmanship
What's included
What our tankless unit repair includes
Every tankless unit repair Katy TX visit covers full diagnosis, the repair itself, and a functional test under real household demand. Parts and labor are quoted upfront. Descaling is included when the heat exchanger shows scale. We also check the surrounding connections so a small issue does not become next month's call.
Full diagnostic and error code read
We pull the fault code, test gas pressure with a pressure gauge, measure flow rate, and inspect the inlet filter, igniter, flame sensor, and thermistor. Thirty to forty-five minutes of testing before any part is quoted.
Failed part replacement
Igniters, thermistors, flow sensors, gas valves, and inlet filters get replaced with manufacturer-spec parts. We carry common components for Rheem, Rinnai, Navien, Noritz, and A.O. Smith so most repairs finish on the first visit.
Heat exchanger descaling
When scale is present, we circulate descaling solution through the heat exchanger with a descaling pump until flow returns to rated capacity. This is the step that fixes most low-temperature and lockout complaints in Katy's hard water.
Safety and code checks
We verify the T&P relief valve with a T&P valve tester, inspect the flex connector and dielectric unions, and confirm venting meets Uniform Plumbing Code and International Plumbing Code requirements before we call the job done.
Full-demand performance test
We run two showers plus a kitchen sink and watch outlet temperature hold within 2 degrees of setpoint. No error codes, no cold spikes. You get the failed part and a written summary of what we found and fixed.
Service overview
What tankless unit repair Katy TX actually involves
Tankless unit repair Katy TX is the diagnostic and mechanical work that restores a tankless water heater to full output without replacing the whole unit. We open the cabinet, read the error code, and test incoming gas pressure, water flow rate, and the inlet filter before we touch a part. From there we check the igniter, flame sensor, thermistor, and heat exchanger for scale or soot. Most failures trace back to three things: hard water scale, a clogged inlet filter, or a failed igniter assembly. We fix the cause, not just the symptom.
Katy sits on some of the hardest water in the Houston metro, and that calcium load punishes tankless heat exchangers. A unit rated for 9 gallons per minute can drop to 4 or 5 within a couple of seasons once scale builds inside the coils. Homeowners in Cinco Ranch and Firethorne often call us when the shower goes cold mid-lather or the display throws an error code. If you need tankless water heater repair Katy, we can usually get eyes on the unit the same day and tell you whether it is a repair or a flush-and-descale job.
How we workWe verify the cause, compare realistic options, and confirm the repair before we leave.
The service timeline
How our tankless repair process works
The process flexes to the condition, but these checkpoints keep decisions clear.
Phone triage
Call (281) 326-6032 and describe what the unit is doing. Error code, no hot water, cold showers, or a leak. We ask the model and roughly how old it is. That five-minute call tells us which parts to load and whether this is a same-day fix or a next-morning job.
On-site diagnosis
We pull the front cover, read the fault code, and test gas pressure with a pressure gauge and water flow with a flow meter. We check the inlet filter, flame sensor, igniter, and thermistor with a multimeter and thermocouple tester. Diagnosis takes 30 to 45 minutes and you get the finding in plain language.
Upfront price
You get one number before we start the repair. Parts, labor, and any descaling included. No surprise line items after the fact. If the unit is not worth repairing, we tell you that straight and quote replacement instead, with no pressure either way.
Repair and descale
We replace the failed part, then run a full descale with a descaling pump and solution if the heat exchanger shows scale. We flush the inlet filter, check the T&P relief valve with a T&P valve tester, and verify gas connections with a pressure gauge. Most jobs finish in two to four hours.
Test under real flow
Before we pack up, we run the unit at full demand. Two showers plus a kitchen sink. We watch outlet temperature hold steady within 2 degrees of setpoint, confirm no error codes return, and walk you through what failed. You get the old part and a written summary.
Tools & methods
Tools and methods we use
Purpose-built equipment, used by trained technicians, so the job is done accurately the first time.
Multimeter and thermocouple tester
Used to test thermistors, heating elements, flame sensors, and thermocouples for resistance and voltage. This is how we confirm a failed part instead of replacing components on a hunch.
Descaling pump and water heater flush kit
Circulates descaling solution through the heat exchanger to dissolve calcium and magnesium scale. Essential for Katy's hard water, where scale is the leading cause of reduced output and lockouts.
Pressure gauge
Checks incoming gas pressure and water pressure at the unit. Low gas pressure causes ignition failures that look like electrical problems, so we verify supply before replacing parts.
Pipe wrench, tube cutter, and soldering torch
Used for water line repairs, valve replacement, and fitting work around the unit. We keep dielectric unions and flex connectors on hand to isolate dissimilar metals and prevent corrosion.
T&P valve tester
Verifies the temperature and pressure relief valve opens at the correct setpoint. A stuck T&P valve is a safety issue, and we check it on every repair visit.
Element wrench
Removes and installs heating elements on electric tankless and hybrid units without damaging the tank fitting. Paired with a multimeter to confirm the new element reads within spec.
Use cases
When to call for tankless repair
These examples show how the service framework adapts rather than forcing every call through one repair.
Navien lockout fixed with igniter swap
A Navien unit in Firethorne fired for three seconds and shut off, throwing an ignition fault. The homeowner had no hot water for two days and had already been told the control board needed replacing at $700. → We tested the igniter and flame sensor with a multimeter and found the igniter out of spec. A $210 igniter replacement plus a gas pressure check restored normal operation. The unit has run without a fault code since.
Emergency leak stopped in Falcon Landing
Water was pooling under a tankless cabinet in Falcon Landing at 9 p.m. The homeowner shut off the water supply and called. The leak traced to a cracked condensate trap and a loose dielectric union on the cold inlet. → We replaced the condensate trap, reseated the dielectric union, and pressure-tested the water path. The cabinet was dry, and the unit passed a full-demand test with no drips. Repair finished in under two hours.
Problems we solve
Tankless problems we fix in Katy
Most tankless calls fall into a handful of failure patterns. Here is what we see and how we handle each one.
No hot water and an error code on the display
We read the code, test gas pressure and water flow, and isolate the failed component. Most lockouts trace to scale, a clogged inlet filter, or a weak igniter. We repair the cause, descale if needed, and reset the unit to normal operation.
Water goes cold mid-shower
We measure flow rate and outlet temperature rise, then descale the heat exchanger and test the flow sensor. Restoring rated flow typically brings back steady hot water the same day for $220 to $480.
Unit fires then shuts off within seconds
We clean or replace the flame sensor and igniter, verify gas pressure at the inlet with a pressure gauge, and confirm the burner holds a steady flame through a full-demand test before we leave.
Water dripping from the cabinet or fittings
We pressure-test the water path, replace the failed O-ring, trap, or union, and dry-test the repair. If the leak reached the control board, we assess whether the board is salvageable or needs replacement.
Pricing process
What tankless unit repair costs
$180 - $650 depending on scope
Failed component type
An igniter or thermistor is a quick, low-cost swap. A gas valve, flow sensor, or control board costs more in parts and labor. We quote the specific part before starting work.
Scale severity
Light scale adds a short descale to the visit. Heavy scale that has restricted flow for months takes longer to clear and may require a second flush to restore rated capacity.
Access and venting
Units in tight mechanical closets or with long vent runs take more time to service. We check venting against Uniform Plumbing Code requirements as part of every repair.
Customer reviews
What Katy homeowners say
★★★★★
“Our Rinnai threw an error code and we had no hot water for two days. They came out same afternoon, found the inlet filter packed with scale, and descaled the whole unit. Two hours and $420 later we had hot water and a maintenance plan. Straight talk, no upsell on a new unit.”
★★★★★
“Navien unit kept shutting off mid-shower. The tech tested gas pressure and flow, replaced a thermistor, and showed me the old part. Explained why Katy water causes this and set us up on annual descaling. Third plumber we called and the only one who actually diagnosed it.”
★★★★★
“Called at 9 p.m. with water pooling under the tankless cabinet. They walked me through shutting off the water, then had a tech out first thing. Cracked condensate trap, fixed in under two hours. Fair emergency pricing and a 90-day warranty. Saved my flooring.”
Why is my tankless water heater not working in Katy TX?
The most common cause in Katy is hard-water scale blocking the heat exchanger, followed by a clogged inlet filter or a failed igniter. Scale forces the unit to overheat and trip a safety lockout, so you get cold water and an error code. We test flow rate, gas pressure, and the igniter circuit to confirm which one it is. Most of these fix in two to four hours for $180 to $650.
How much does tankless unit repair cost in Katy?
Typical 2026 pricing in this area runs $180 to $650 depending on the failed part and whether descaling is needed. A thermistor or igniter swap sits at the low end. A heat exchanger descale plus a flow sensor replacement lands higher. You get one upfront number before we start, and repairs carry a 90-day parts and labor warranty.
Can a tankless water heater be repaired in Katy Texas?
Yes. Most tankless failures are component-level repairs, not unit replacements. Igniters, thermistors, flow sensors, gas valves, and inlet filters are all serviceable, and descaling restores lost capacity from hard-water scale. We repair Rheem, Rinnai, Navien, Noritz, and Bosch units across Katy. Replacement only makes sense when the heat exchanger itself has cracked or corroded through.
Who repairs tankless water heaters near me in Katy?
We do. Katy Water Heater Repair handles tankless unit troubleshooting Katy Texas and full repairs across Cinco Ranch, Falcon Landing, Seven Meadows, Firethorne, and the surrounding ZIP codes 77493, 77494, and 77491. Call (281) 326-6032 for same-day or 24/7 emergency service. We stock common parts, so most jobs finish on the first visit.
Related services
Related Services
Leaking Tank Repair
A tankless unit that drips from the cabinet or a fitting is often a failed O-ring, a cracked condensate trap, or a loose dielectric union. We pressure-test the water path and seal or replace the failed connection before it reaches your floor.
Tankless Flush and Descaling
Katy's hard water coats heat exchangers in calcium. Our descaling pump and solution flush restores lost flow and temperature rise. Annual service keeps a Navien or Rinnai unit running at rated capacity and prevents the lockouts that look like a repair call.
No Hot Water Diagnosis
Cold water at every tap points to a tankless unit in lockout, a failed igniter, or a gas supply issue. We read the error code, test gas pressure and flow, and tell you exactly which component failed. Diagnosis takes 30 to 45 minutes.Ready when you are
Get tankless unit repair Katy TX today
Cold showers do not wait, and neither do we. Call (281) 326-6032 for same-day or 24/7 emergency service. Licensed, insured, and warrantied on every repair. One upfront price before we start.
Talk with the local team
Request Tankless Unit Repair
Phone is the fastest way to reach us. Call (281) 326-6032 and you will talk to a person who knows water heaters, not a call center. We answer 24/7 for emergencies and schedule standard repairs Monday through Friday, 8 a.m. to 6 p.m. Most calls in Katy get a same-day window.