Tankless Water Heater Repair in Nashville and La Vergne

Diagnostics, Repairs, and Maintenance for Tankless Units Across Middle Tennessee

Is your tankless water heater showing an error code, failing to ignite, or running out of hot water mid-shower?

Gold Star Plumbing (LLP #4138) diagnoses and repairs tankless water heaters for homeowners across La Vergne, Nashville, and Middle Tennessee. Our technicians work on Rinnai, Navien, Noritz, Rheem, and other major brands. We identify the problem, explain what’s causing it, and fix it.

Problems We Fix

Ignition Failures
Clogged or Blocked Exhaust
System Overload & Sizing Issues
Mineral Buildup & Scale
Error Code Diagnosis (All Brands)
Rinnai, Navien, Noritz, Rheem

(615) 290-9860

Schedule a tankless diagnosis today

Specialized Knowledge

Why Tankless Repair Requires Specialized Expertise

Tankless water heaters are fundamentally different from traditional tank units. They use electronic control boards to regulate temperature and flow. They have heat exchangers that must be maintained and diagnosed with specific tools. Gas models require precise venting (stainless steel, correct diameter, proper termination) that meets code requirements. Gas valve diagnostics require manufacturer-specific knowledge.

A general plumber can replace a thermostat on a tank water heater. Diagnosing a failing control board on a tankless unit is a different skill set. Gold Star’s technicians are equipped with the diagnostic tools and brand-specific knowledge that tankless repair demands — an accurate diagnosis the first time, not trial-and-error at your expense.

Electronic Control Board Diagnostics

Tankless units use control boards to regulate temperature and flow. Diagnosing board failures requires specific test equipment and knowledge — not available on traditional tank units.

Heat Exchanger Tools & Technique

Heat exchanger diagnosis and descaling require specialized equipment and the right procedure for each brand. Our technicians are equipped for this work at your home.

Code-Compliant Gas Venting

Gas tankless venting requires stainless steel pipe at the correct diameter with a proper termination point. We verify venting meets code on every repair and installation.

Brand-Specific Knowledge

Rinnai, Navien, Noritz, and Rheem each use different diagnostic systems. Our technicians interpret error codes and diagnose problems across all major brands — accurately, the first time.

Call Gold Star Plumbing at (615) 290-9860 to schedule a tankless water heater diagnosis at your La Vergne or Nashville home.

Common Problems

Common Tankless Water Heater Problems

Tankless water heaters are reliable, but when they fail they usually do so with a specific symptom or error code. Our technicians diagnose the actual cause — not just the symptom — and repair it correctly the first time.

Safety note: If your unit is shutting down repeatedly and you notice a gas smell or feel lightheaded, leave the area immediately. Do not attempt to reset the unit until the venting has been inspected. Call us at (615) 290-9860.

What We Diagnose & Fix

Ignition Failure

Unit clicks but doesn't light, or shuts off shortly after igniting. Can result from low gas pressure, a closed gas or water supply valve, or a failed ignition component. Our technicians test the gas supply chain, inspect the ignition system, and restore operation.

Clogged or Blocked Exhaust

Gas tankless units vent combustion gases through a dedicated exhaust pipe. If obstructed by debris, bird nests, or improper installation, the unit's safety system shuts it down. This is a safety issue — carbon monoxide from a blocked vent is dangerous.

System Overload

Running too many hot water fixtures simultaneously can exceed the unit's flow capacity, causing temperature drops or shutoff. We assess whether the problem is mechanical or capacity-related and recommend the right solution.

Mineral Buildup and Scale

Mineral deposits coat the heat exchanger over time, reducing efficiency and eventually causing overheating or shutoff. In Middle Tennessee, where hard water is common, regular descaling is essential. Our team flushes the heat exchanger and cleans inlet filters.

Error Codes

Error codes vary by manufacturer — an ignition failure on a Rinnai reads differently than on a Navien or Noritz. Our technicians read and interpret codes across all major brands, identify the underlying problem, and resolve it. Call and describe what you see — we can often tell you over the phone whether it's urgent.

(615) 290-9860

Schedule a tankless diagnosis · Same-day response

Preventative Maintenance

Tankless Maintenance: Preventing Repairs Before They Happen

The most common tankless repair calls we receive could have been prevented with annual maintenance. Descaling the heat exchanger removes mineral buildup before it restricts flow and causes overheating. Cleaning the inlet filter prevents debris from reducing water pressure to the unit. Inspecting the venting ensures safe exhaust of combustion gases. In hard water areas of Middle Tennessee, we recommend descaling every 6 to 12 months rather than waiting a full year. The cost of a maintenance visit is a fraction of the cost of a heat exchanger replacement. Tankless maintenance is also available through our preventative plumbing plans.

Descale the Heat Exchanger

Mineral deposits coat the heat exchanger and reduce efficiency. Flushing removes buildup before it causes overheating or shutoff. The single most impactful maintenance task for a tankless unit.

Clean the Inlet Filter

Debris in the inlet filter reduces water pressure reaching the unit, causing inconsistent temperature and error codes. Filter cleaning restores proper flow and prevents nuisance shutdowns.

Inspect Venting

Venting inspection confirms safe exhaust of combustion gases. Obstructions, improper connections, or corrosion in the vent pipe are identified and corrected before they become safety issues.

Every 6-12 Months in Middle TN

Hard water is common across parts of Middle Tennessee. Annual descaling is the minimum — every 6 months is better if your home has elevated mineral content. We assess at the maintenance visit.

Repair or Replace?

Can It Be Fixed, or Do You Need a New Unit?

The answer depends on the age of the unit, the nature of the problem, and how often you’ve needed service. We evaluate every unit individually and give you a direct recommendation based on what we find.

When Repair Makes Sense

When Replacement Makes Sense

Our commitment: No pressure to replace if a repair does the job. If replacement is the right answer, we explain exactly why and what it will cost. Visit our Tankless Replacement page for more on the replacement process and what to expect.

Customer Trust

Hear From Middle Tennessee Homeowners.

4.9 / 5 Stars

"They were quick and had great communication. Our hot water is great now!"

Verified Customer

Verified Customer, Nashville Area — Angi

Got Questions?

Frequently Asked Questions

Why won't my tankless water heater ignite?

Common causes include low gas pressure, closed gas or water valves, or a failed ignition component. Our team diagnoses the specific cause and fixes it at your La Vergne, Nashville, or Middle Tennessee home.

What do the error codes on my tankless unit mean?

Error codes vary by manufacturer (Rinnai, Navien, Noritz, Rheem each use different systems). Our technicians read and interpret these codes to pinpoint the problem quickly.

How often does a tankless water heater need maintenance?

Annual maintenance is recommended, including descaling to remove mineral buildup. In hard water areas common across Middle Tennessee, every 6–12 months is better.

Why does my tankless water heater run out of hot water?

This usually means the unit is overloaded: too many fixtures running at once exceeds the unit’s flow capacity. We can assess whether the issue is demand-related or mechanical.

Is it safe to keep using a tankless unit that's showing error codes?

It depends on the code. Some indicate minor issues, others signal safety concerns like exhaust blockage or gas problems. Don’t ignore error codes. Call us at (615) 290-9860 and we can tell you over the phone whether it’s urgent.

Can mineral buildup damage my tankless water heater?

Yes. Mineral scale coats the heat exchanger and reduces efficiency. Left untreated, it can cause overheating and permanent damage. Regular descaling prevents this, especially in the harder water areas of Middle Tennessee.

How do I know if my tankless water heater needs repair or replacement?

If the unit is under 10 years old and the problem is isolated, repair usually makes sense. If it’s over 15 years, requires frequent service, or has a failing heat exchanger, replacement is likely the better option. Our La Vergne team can evaluate your unit and give you an honest recommendation.

Schedule Tankless Water Heater Repair

Call Gold Star Plumbing at (615) 290-9860 to schedule a tankless water heater diagnosis at your La Vergne or Nashville home. We work on all major brands and provide upfront pricing before any repair begins. For traditional water heater services, visit our Water Heaters page.