A tankless water heater repair starts with a simple question: what is the unit doing right now? No hot water at all, water that goes lukewarm halfway through a shower, a code flashing on the display, or water pooling under the unit — each one points at a different fault, and each one has a different fix. This site exists for the moment the hot water stops. Call (877) 418-1589, describe what is happening, and an independent local provider in your city takes it from there.
A tankless unit is not a tank. There is no stored hot water to fall back on. When it works, it heats water the moment a tap opens and stops the moment the tap closes. When it fails, the failure is immediate and obvious — cold water, or water that never reaches the temperature you set. That is why the repair matters the same day, and why the phone is the way to reach us. There is no contact form on this site. The call is the service.
What usually goes wrong
Most tankless failures fall into five groups. Knowing which one you have helps the provider bring the right parts and ask the right questions on the call.
No hot water at all
The unit does not fire. On a gas unit this is usually ignition, gas supply or a flame sensor. On an electric unit it is usually an element, a thermostat, or a tripped breaker. The first check is always the simple one: gas on, water on, power on.
An error code on the display
Rinnai, Navien, Noritz and Rheem units all show codes when something is wrong — ignition failure, flame loss, overheating, a blocked vent, a clogged filter. The code is the unit's way of telling you where to look. Our error-code page lists the common ones and what each means.
Lukewarm water
Water that starts hot and fades, or never gets properly hot, is the classic sign of scale inside the heat exchanger. In hard-water cities this is the most common tankless problem of all. A flush and descale usually brings the temperature back.
A leaking unit
Water under a tankless unit can come from a fitting, a valve, the relief valve, or the heat exchanger itself. A fitting leak is a repair. A heat-exchanger leak usually means the part has to be replaced — and an honest provider will say so rather than patch it.
Scale-clogged exchanger
Every gallon of hard water leaves a little mineral behind. Inside a tankless heat exchanger, that mineral becomes a layer of scale that insulates the water from the heat. The unit works harder, the water gets cooler, and eventually the unit overheats and shuts down.
It works — then it stops
Some units run fine for a few minutes and then cut out. That pattern usually means a sensor is tripping: over-temperature, a flow sensor that cannot read, or a venting fault that only shows up once the unit is hot. It is a fault that needs a look, not a reset.
How a repair visit works
There is no mystery to it, and no reason to dress it up. A repair visit follows the same five steps in every city we serve.
- The call. You describe what the unit is doing — the symptom, the code on the display if there is one, the brand if you know it. That is enough to send the right provider.
- The check. The provider looks at the unit, the gas and water supply, the venting and the error history. The diagnosis comes before any part is touched.
- The plain answer. What is wrong, what it takes to fix it, and whether a flush, a part, or a replacement is the honest answer. If a repair is not worth it, you hear that too.
- The fix. The part is replaced, the exchanger is flushed, the sensor is cleaned, or the venting is corrected — whatever the diagnosis called for.
- The test. The unit runs through a full hot-water cycle before the provider leaves, so you see the temperature hold instead of taking it on trust.
What we fix
Seven services cover the whole life of a tankless unit, from the first error code to a new install.
Tankless Water Heater Repair
Diagnosis and repair for gas and electric tankless units: no hot water, lukewarm water, ignition failure and scale-clogged heat exchangers.
Gas Tankless Water Heater Repair
Ignition failure, gas valve and flame sensor faults, venting problems and gas-smell safety checks for gas tankless units.
Electric Tankless Water Heater Repair
Heating elements, thermostats, breakers and wiring faults on electric tankless units — including the ones that trip the breaker.
Leaking Tankless Water Heater Repair
Heat-exchanger leaks, fitting and valve leaks, relief-valve discharge and condensate leaks — diagnosed honestly, including when replacement is the right answer.
Tankless Water Heater Flush & Descale
A flush removes the scale that makes water run lukewarm and wears out the heat exchanger. The most-requested service on this site.
Tankless Water Heater Error Code Diagnosis
Rinnai, Navien, Noritz and Rheem error codes explained: what each code means, what to check first, and when to call.
Tankless Water Heater Installation
New installs and tank-to-tankless conversion: sizing, venting, gas and electrical work, and the permits that come with them.
Why tankless units fail — and why it differs by city
A tankless water heater fails for local reasons as much as for mechanical ones. The water in Casper, Wyoming runs about 19 grains per gallon of hardness — very hard — and scale is the first thing a technician checks there. The water in Medford, Oregon runs 20 to 40 parts per million — soft — and scale is barely a factor; a Medford failure is almost always ignition, flow or a sensor. Longview, Texas is soft to moderately hard at 55 to 68 milligrams per liter, while Janesville, Wisconsin runs about 350 milligrams per liter. Same kind of unit, completely different wear pattern.
Climate matters too. In Casper and Great Falls, Montana, the winters are cold enough that freeze protection is not optional — a cracked heat exchanger from a freeze is one of the few tankless failures that is not worth repairing. In the Texas cities, the risk is the opposite: long hot summers and the occasional hard freeze that catches an exterior-mounted unit off guard. In Waukesha, Wisconsin, the water changed in October 2023, when the city switched from deep wells at about 21 grains per gallon to Lake Michigan water at about 8 — better, but still hard.
That is why every city page on this site carries its own local facts: the county, the water hardness where it is published, the climate, and the landmarks that make the place what it is. A repair in Boise is not the same job as a repair in Laredo, and the page for each city says why.
Where we serve
Thirty cities, one phone number. Choose your city for the local page — water hardness, climate, landmarks, and what usually fails there.
Questions people ask
How fast can someone come out for a tankless water heater repair?
Call (877) 418-1589 and describe what the unit is doing — no hot water, an error code, lukewarm water, or a leak. An independent local provider in your city takes the call from there and arranges the visit. The phone call is how the job starts; there is no online form to wait on.
How much does a tankless water heater repair cost?
It depends on the part, the brand, how bad the scale is, and whether the unit is gas or electric. A flush costs less than a part replacement, and a part replacement costs less than a new unit. The honest answer is that the price is set once the unit has been looked at — this site does not publish prices because no two repairs are the same.
My tankless water heater shows an error code. What should I do first?
Write down the exact code, then check the simple things: gas supply on, water supply on, the inlet filter clean, and nothing blocking the vent. Do not keep resetting the unit — a code that comes back is the unit telling you something is wrong. Our error-code page lists the common Rinnai, Navien, Noritz and Rheem codes and what each one means.
How often should a tankless water heater be flushed?
In hard-water cities, once a year is the usual rhythm; in soft-water cities, every two years is often enough. The maintenance reminder on many units — Navien's W003, for example — is the unit asking for a flush. A flush removes the scale that makes water run lukewarm and shortens the life of the heat exchanger.
Gas or electric — does it matter which kind I have?
Yes, because the faults are different. A gas unit fails at ignition, the gas valve, the flame sensor or the venting. An electric unit fails at the heating elements, the thermostats, the wiring or the breaker. The repair visit starts by identifying which kind of unit you have, and the fix follows from that.
Do you serve my city?
We serve 30 cities across the United States — from Boise, Idaho to Laredo, Texas. The full list is on this page. If your city is listed, call (877) 418-1589 and an independent local provider in that city takes it from there.
No hot water? Call now.
One call connects you with an independent local tankless provider in your city. Describe the symptom — the rest is the visit.