Tankless Water Heater Repair: What You Need to Know

Tankless water heaters are a smart investment for homeowners and businesses looking for energy-efficient hot water solutions. They save space, offer on-demand heating, and generally require less maintenance than traditional water heaters. But like any appliance, tankless systems can run into issues that demand timely repairs.

In this guide, we’ll walk through the most common tankless water heater problems, how to spot them, and why professional help is often the best course of action.

Common Signs Your Tankless Water Heater Needs Repair

Many homeowners ignore early signs of trouble until the unit stops working entirely. Catching issues early can save you from costly replacements.

Look out for these warning signs:

• Fluctuating Water Temperature: If the water switches between hot and cold frequently, it could be a mineral buildup or a malfunctioning sensor.

• No Hot Water at All: This might point to a gas supply issue, faulty ignitor, or electrical failure.

• Unusual Noises: Humming, banging, or screeching could mean there's debris or scale buildup inside the system.

• Error Codes Displayed: Most modern units show error codes when something’s wrong. Refer to your manual or call a technician for diagnostics.

• Reduced Water Pressure: A clogged filter or internal scale buildup may be restricting water flow.

What Causes Tankless Water Heaters to Malfunction?

Understanding the root causes can help you take preventive action or better explain the issue when you call a technician.

The most common causes include:

• Hard Water Buildup: Over time, minerals from hard water can accumulate inside the unit, leading to reduced efficiency or failure.

• Improper Installation: If the heater wasn’t sized or installed correctly, it might not meet your household’s demand.

• Lack of Maintenance: Tankless heaters still need periodic flushing and filter cleaning to prevent long-term damage.

• Power Supply Issues: Gas units may face pilot or ignition problems, while electric ones can suffer from tripped breakers or worn-out components.

• Blocked Venting: Proper ventilation is critical. Blockages can trigger safety shutdowns or prevent the system from firing up.

Residential vs. Commercial Tankless Water Heater Repair

Though the core technology is the same, residential and commercial systems serve different purposes—and their repair needs can vary significantly.

Residential Repairs

For homeowners, problems often surface when demand increases or maintenance is skipped.

Typical residential repair tasks include:

• Cleaning or replacing filters

• Descaling the unit to remove mineral buildup

• Replacing ignitors or sensors

• Fixing water pressure issues

• Updating software or resetting the system

Commercial Repairs

In businesses, the systems are usually larger, sometimes working around the clock. Breakdowns can mean downtime and lost revenue.

Commercial systems may require:

• Multiple unit diagnostics (if systems are installed in series)

• Heavy-duty descaling

• Gas line inspections for large-capacity setups

• Monitoring and adjusting flow rates for consistent delivery

• Regular inspections as part of preventive maintenance plans

Because the scale of commercial systems is more complex, even a minor issue can ripple through the entire operation. It’s crucial to get regular checks and repairs done by experienced professionals.

DIY Fixes vs. Professional Help

We all like to save a buck where we can, and a quick YouTube video might make a fix look simple. But not every tankless water heater problem can—or should—be tackled on your own.

What you can safely try yourself:

• Check the Power Supply: Make sure the breaker hasn't tripped or the gas valve isn’t shut off.

• Clean the Filter: Most units have a filter you can access and rinse out.

• Reset the Unit: Sometimes, a simple reset can clear minor glitches.

When to call a professional:

• You're getting error codes you don’t understand.

• The unit keeps shutting off during use.

• There are strange sounds or leaks coming from the system.

• Your unit is still under warranty (DIY fixes might void it).

• You’ve tried troubleshooting but the problem keeps returning.

Why You Shouldn’t Wait to Schedule Repairs

Waiting too long to address an issue can turn a manageable repair into a full replacement. A malfunctioning unit also consumes more energy and may compromise safety—especially with gas-powered models.

Timely repair can:

• Extend the life of your unit

• Maintain energy efficiency

• Keep your hot water supply consistent

• Reduce the risk of costly emergencies

• Protect your property from potential water damage

Calling a professional before it’s too late is not just a matter of convenience. It’s a matter of safety and long-term savings.

FAQs About Tankless Water Heater Repair

1. How often should I service my tankless water heater?

 Once a year is ideal, especially if you have hard water. Regular descaling and cleaning can prevent most issues.

2. How long do tankless water heaters last?

 With proper maintenance, most units last 15–20 years. Neglected ones may start failing after 8–10.

3. Is it better to repair or replace a malfunctioning unit?

 If your unit is under 10 years old and the issue is isolated, a repair usually makes more sense. If problems are frequent or the unit is older, replacement might be the smarter option.

4. What’s the average repair cost?

 Residential repairs can range from $100 to $500, depending on the issue. Commercial systems might cost more due to their complexity.

Emergency Plumbing Help You Can Count On

When hot water stops flowing, the last thing you want is to wait for hours—or days—for a technician to show up. That’s where Mr. Pipey Plumbing steps in.

We offer 24/7 emergency plumbing services across Metro Detroit and nearby areas. Whether you're dealing with a malfunctioning tankless water heater at home or a critical issue in your commercial facility, our team of licensed plumbers is ready to help.

Services we provide include:

• Tankless and traditional water heater repairs

• Leak detection and pipe repair

• Clogged drain solutions

• Sewer and gas line inspections

• Routine maintenance plan

Final Thoughts

Tankless water heaters are efficient, but they’re not immune to problems. If you’re experiencing inconsistent hot water, error codes, or strange noises, don’t wait until the problem escalates. Knowing when to handle it yourself and when to call in the pros can make all the difference.