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Tankless Water Heater Repair Across Hawaii

Fast, reliable service, done right the first time.

No hot water, lukewarm water or a unit that shuts off? We repair gas and electric tankless units on Oahu, Maui and the Big Island.

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When a tankless water heater flashes an error code, runs lukewarm or quits in the middle of a shower, the cause is usually one specific fault that can be fixed. A failed sensor, scale on the heat exchanger, an ignition problem or a restricted vent does not mean the whole unit has to go. All Aloha Plumbing repairs gas and electric tankless water heaters on Oahu, Maui and the Big Island, and we find the actual fault before we quote a repair.

Signs Your Tankless Unit Needs Service

  • An error code on the display or a unit that shuts down and needs a reset.
  • Water that swings between hot and cold, or never gets fully hot.
  • Hot water that stops partway through use.
  • A noticeable drop in flow when the hot side is running.
  • Rumbling, whining or clicking from the unit.
  • A gas burner that struggles to ignite or will not stay lit.

Why Scale Is a Common Cause

Every gallon of hot water passes through the unit’s heat exchanger, where it is heated quickly. Dissolved minerals in the water can come out of solution during that fast heating and build up as scale on the exchanger. Scale slows heat transfer, restricts flow and can trigger temperature and flow error codes. Left alone, heavy scaling shortens the life of the unit.

That is why many of our tankless repairs include a descale and flush. Clearing the error code without treating the scale often means the same fault returns. After the repair, we recommend a flushing interval that fits your water and your usage.

How We Repair a Tankless Water Heater

Each manufacturer has its own error code list, and a code points to where the unit detected a problem, not always to the part that failed. We read the code and the fault history, test the sensors, igniter, flow components and venting, and confirm the cause. You get upfront pricing to approve before the repair begins. After the work, we test that the unit fires, heats and holds temperature.

If a unit is very old or damaged beyond an economical repair, we will say so and explain replacement options.

Tankless Repair by Island

  • Oahu: Condo units in Honolulu often have tankless heaters in tight closets with shared venting, while homes in Ewa Beach, Mililani and Kailua have more space to work. See tankless water heater repair on Oahu.
  • Maui: Vacation rentals in Kihei, Wailea and Lahaina cannot wait days for hot water, and salt air near the coast speeds corrosion on exterior-mounted units and vents. Visit tankless water heater repair on Maui.
  • Big Island: From Kailua-Kona to Hilo and Waimea, we work on units fed by county water and by rainwater catchment, which can affect filters and flow. Read about tankless water heater repair on the Big Island.

Why Call All Aloha Plumbing

We are family-owned, licensed and insured under Hawaii contractor license CT-36812. We treat the cause of a fault, not just the code, and we explain what we found in plain terms. We offer $50 off any plumbing service, senior and military discounts, and financing if a replacement turns out to be the better option.

Get Your Hot Water Back

Start with your island page for Oahu, Maui or the Big Island. If you have no hot water or smell gas near the unit, call the number at the top of this page. A real plumber answers 24/7.

Need Tankless Water Heater Repair on Hawaii?

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Quick Answers

Good To Know

Do you repair tankless water heaters on all three islands?

Yes. All Aloha Plumbing repairs gas and electric tankless water heaters on Oahu, Maui and the Big Island. Our Oahu team is based in Waipahu and our Maui team is based in Makawao. On the Big Island we serve areas including Kailua-Kona, Hilo, Waimea and Waikoloa, with arrival windows based on location.

What does a tankless error code actually tell me?

An error code tells you what kind of fault the unit detected, such as an ignition failure, a flow problem or a temperature sensor reading out of range. It does not always identify the failed part. Codes also differ by brand. We read the code and the fault history, then test components to confirm the real cause.

Why does my tankless water heater go lukewarm in the shower?

Lukewarm or fluctuating water usually points to scale on the heat exchanger, a flow or temperature sensor that is misreading, low gas supply, or a burner that is not staying lit. Sometimes a clogged inlet filter restricts flow enough to cause it. We test the unit to find which one it is before quoting a repair.

How often should a tankless unit be flushed?

It depends on your water and how much hot water your household uses. Homes with more mineral content or heavy use need flushing more often. Rather than apply one interval to every home, we look at your unit and water source, including catchment systems on the Big Island and rural Maui, and recommend a schedule.

Is it safe to keep resetting my tankless water heater?

One reset is reasonable. If the unit faults again, stop resetting it. Repeated shutdowns mean the unit is protecting itself from a condition that has not been fixed, such as scale, a blocked vent or air intake, a gas supply problem or a failing sensor. Never bypass a safety device, and call us if you suspect blocked venting.

Should I repair or replace my tankless water heater?

Most tankless faults, including scaling, ignition problems and failed sensors, are worth repairing because the units are built for a long service life with maintenance. Replacement makes sense when a unit is very old, the heat exchanger has failed, or the repair cost approaches the cost of a new unit. We give you upfront pricing for both.

Real Customers • Real Stories

What Our Ohana Says

5 star rating quote

“All Aloha came out super fast and fixed our leak the same day. Excellent service! These guys are real pros and treated my home with respect.”

HBM

Hawaii Bottle Man

Honolulu, Oahu

5 star rating quote

“They replaced our water heater quickly and left everything spotless. The crew showed up exactly when they said they would. Couldn’t ask for better.”

RC

Ray Cabanting

Kailua, Oahu

5 star rating quote

“Called at midnight with a burst pipe. They were here in 25 minutes and had it contained before the ceiling came down.”

TT

Thai Tran

Kapolei, Oahu

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Three Islands. One Family.

From the North Shore to Hilo, we’re proud to bring honest plumbing with aloha to homes across Hawaii.

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