How much does it cost to repair a tankless water heater?

Reviewed by Adam Graham remodeling expert. Written by Fixr.com.

Tankless water heaters are becoming increasingly popular in homes around the world. These systems do not feature a water tank, so they do not take up as much space inside the home. They heat the water directly rather than heating and storing it for later. They tend to be low-maintenance, but issues can still arise with tankless water heaters, such as pilot light, thermostat, and valve problems. When this happens, you need your heater repaired.

The national average for tankless water heater repair costs are between $100 and $650, with most homeowners paying $375 to fix a heater that makes loud rumbling sounds. This project’s low cost is $50 to tighten a loose valve. The high cost is $1,000 to install a high-end mini tank heater to deal with a cold water sandwich.

Cost to Repair a Tankless Water Heater

Tankless Water Heater Repair Cost by Fueling Method

There are various fueling methods for tankless water heaters. Some are powered by electricity, while others use gas. There are also other kinds, such as solar and oil-powered heaters, and repair costs vary between these types because some have more complex and expensive parts.

Electric Tankless Water Heater Repair

The average cost of electric tankless water heater repairs is between $100 and $600. Electric heaters tend to be the cheapest to repair but can still have a wide range of technical problems, including issues with the wiring, thermostat problems, and damage to the heating element.

Tankless Gas Water Heater Repair

Homeowners spend between $150 and $650 on tankless gas water heaters repairs. Gas units are one of the most common varieties, and they can suffer from a range of problems that require professional repairs, including pilot light and burner issues, gas control valve problems, and piping issues.

Propane Tankless Water Heater Repair

To repair a propane tankless water heater, expect to pay between $150 and $650. They are a specific gas heater powered by propane. They can suffer from the same issues as other gas tankless heaters, such as burner problems, pipe damages, and thermostat issues.

Repair an Oil Tankless Water Heater

The cost to repair an oil tankless water heater averages $150 to $650. Oil-fired heaters have much in common with gas and propane systems, except they use oil. Possible issues you might encounter with this type include burner issues, valve repairs, and pipe problems.

Solar Tankless Water Heater Repair

Homeowners pay between $200 and $700 for solar tankless water heater repairs. Most solar systems include tanks, but you can power a tankless unit with solar power. You may have to deal with repairs to the solar panels and collectors, which can be costly compared to other tankless heaters.

Tankless Water Heater Repair Cost by Type of Repair

Various problems can arise with a tankless water heater, including blown fuses, pilot light issues, and thermostat problems. Some problems are cheaper and simpler to resolve than others, so the cost of your repairs depends on the problem. The table below shows common examples and average costs to fix each.

Fuse Repair

The average cost of fuse repair in tankless water heaters is between $50 and $75. Typically, you cannot repair fuses because they are very small and delicate. So, they must be replaced if something goes wrong. The only exception is if a fuse has fallen out of position and needs to be readjusted to get the system working.

Tankless Water Heater Vent Repair

For tankless water heater vent repairs, expect to spend between $50 and $125. Any unit that uses gas or propane needs a ventilation system to take dangerous byproducts away from the home, but vents may need to be patched if they are cracked or damaged.

Tankless Water Heater Pilot Light Repair

Homeowners spend between $75 and $150 on pilot light repairs in tankless heaters. The pilot light is a component found in gas models. It is a small flame that lights the heater’s burner to heat the water. If it goes out, the assembly around the light might need to be readjusted or the light re-lit by a professional.

Repair a Tankless Water Heater Thermostat

To repair a tankless heater thermostat, expect to pay between $75 and $150. The thermostat is a very important component in any heating system because it detects and controls the water temperature. Broken thermostats may cause the water to become scalding hot or not heat at all. A damaged thermostat could be rewired or readjusted if it is in the wrong position.

Pressure Relief Valve Repair

Pressure relief valve repairs for tankless water heaters average $75 to $150. The pressure relief valve relieves excess pressure in the heating system, so keeping this valve in working order is important. It might become loose, cracked, or damaged, so it may require tightening, patching, or readjusting.

Repair a Tankless Water Heater Pipe

Homeowners spend between $100 and $350 to repair pipes. The price depends on how accessible the pipe is, the material, and how much piping must be repaired. Various issues can arise with pipes, such as cracks, holes, rust, and other damages that may need patching.

Tankless Water Heater Repair Cost by Type of Replacement

If parts of your tankless water heater break down or become damaged, it might not be possible to repair them. Instead, they may need to be replaced with new parts. The cost of replacement parts varies because some parts are smaller, simpler, and cheaper than others. The table below shows common replacement parts for tankless heaters and average costs, including parts and labor.

Fuse Replacement

Homeowners spend between $50 and $75 on fuse replacements in tankless heaters. A fuse might blow if the circuit powering the system becomes overloaded or a short circuit occurs. Either way, blown fuses must be replaced. New fuses are inexpensive and easy to install.

Tankless Water Heater Flow Switch Replacement

The average cost of replacement flow switches in tankless heaters ranges from $75 to $150. The flow switch is a key component in a tankless system and used to detect water flow and automatically turn on the system and start heating. If the switch is not working correctly, you may not have hot water or the flow may be intermittent.

Tankless Water Heater Vent Replacement

The average cost to replace vents for tankless heating systems averages $75 to $250. The price depends on the vent size and type and how accessible the area is. Small and easy-to-access vents are cheaper to replace. You may need vent replacement if your existing vents are excessively clogged or seriously damaged.

Pilot Light Replacement

Pilot light replacements in tankless heaters cost between $100 and $175. Pilot light assemblies do not usually need to be replaced. A plumber first tries to reignite or adjust a pilot light that has gone out. But the assembly or thermocouple may need to be replaced if the light does not come back on.

Replace a Tankless Water Heater Thermostat

Thermostat replacements in tankless heaters average $100 to $250. If your heater is not heating up correctly or getting too hot, you may have a broken thermostat that needs to be replaced. The price for this replacement depends on which thermostat you need and your heater brand because some thermostats are more complex and expensive than others.

Tankless Water Heater Pressure Relief Valve Replacement

Homeowners spend between $100 and $250 on pressure relief valve replacements in tankless heaters. The pressure relief valve is one of the most important valves on any system because it controls the pressure. You may need a new valve if yours has been seriously damaged or you are having pressure problems.

Valve Replacement

The average cost of valve replacement in tankless heaters ranges from $100 to $300. A range of valves might be found around your system, including drain valves, shut-off valves, pressure relief valves, and gas valves. All these valves can become damaged or stop working, so they may need replacing.

Replace a Tankless Water Heater Pipe

The average cost of pipe replacement in tankless heaters is between $150 and $800. The total repair cost varies based on the pipe size and material that needs replacing. Pipes may need replacing if they are rusty or excessively damaged with cracks or holes too big or dangerous to fix.

Tankless Coil Replacement

The cost of coil replacement in tankless heaters averages $200 to $750. Coils are found in electric heaters and some solar-powered models. They are used to heat the water, and if they are not working correctly, you may find no hot water coming from your faucets or shower.

Tankless Water Heater Element Replacement

Homeowners spend between $200 and $750 on heater element replacements in tankless heating sytems. The heating element is essentially the same as the coil. It is a part of an electric heater directly responsible for heating the water. If you have no hot water or your unit does not seem to be working, you may need a new heating element.

Tankless Water Heater Repair Cost by Problem

The cost of your tankless water heater repairs varies greatly, depending on the problem. For example, fixing a leak is different than dealing with rust in your system or a low-pressure problem with your heating system. The table below shows common problems with these types of heater and the average costs to fix each.

Tankless Water Heater Shuts Off During a Shower

If your heater randomly shuts off while taking a shower, expect to pay between $50 and $500 to repair it. There are various reasons for a heater to shut off randomly. It could be a blown fuse that must be replaced or an issue with another component like a valve, flow switch, pilot light, or wiring.

Leaking

Repairing leaks in tankless heating systems averages $50 to $600. This wide price range is because some leaks are much simpler to fix than others. Your leak could be caused by a loose valve that needs tightening, or it might be caused by a burst pipe, raising costs.

Low Pressure

Homeowners pay between $75 and $500 to fix low-pressure problems in tankless models. Low pressure in this type of units is commonly caused by an issue with the valves or pressure regulator, which may need minor adjustments. It could also be caused by problems with the pipes or mineral buildups in the system, which needs flushing out.

Ignition Failure

The average cost to fix ignition failure problems in a tankless heater ranges from $100 to $300. Your heater might not ignite for several reasons. It could be caused by an issue with your gas or propane supply or a valve problem. The valves might need to be adjusted or replaced.

Tankless Water Heater Makes a Loud Rumbling Noise

The average cost to fix a tankless heating system making loud rumbling noises is between $100 and $650. Your unit could be making noise for a few reasons. One of the most common issues is sediment buildup. There might also be an issue with your heating element or problems with loose or damaged piping. Depending on the problem, different repair methods may be needed, such as replacing the heating element or flushing the system.

Mineral Buildup

If you have a mineral buildup causing a clog in your tankless heating system, expect to spend between $150 and $400 to repair it. Mineral buildups most commonly occur in homes with hard water supplies, but mineral buildups and clogs can accumulate even in areas with soft water. To deal with this, a plumber must locate and flush the clog.

Scaling

Scaling problems in tankless heating systems cost between $150 and $450 to repair. Scaling is when mineral deposits and limescale form inside the pipes and other parts of your system. Your system is at an above-average risk of scaling if you live in a hard water zone. Flushing and cleaning the system can help with this problem and remove scale deposits.

Frozen Pipes

If you have frozen pipes in your tankless heating system, costs range from $200 to $550 to have them repaired. You may encounter this problem if you live in an area with cold winters and freezing temperatures. If the pipes freeze, the water supply must be turned off while a plumber carefully thaws the frozen sections. They may also recommend installing insulation to prevent future freezing issues.

Tankless Water Heater Smells Like Rotten Eggs

If your tankless heater emits a smell like rotten eggs, expect to pay between $200 and $600 to have it fixed. A rotten egg smell is usually a sign of hydrogen sulfide, which indicates corrosion or a buildup of bacteria. In either case, the source of the problem must be identified, and the system needs to be flushed and cleaned.

Rusted Heater

If your tankless heater has rust problems, expect costs of between $200 and $800 to have it repaired. Rust can be a serious problem, and if it builds too much, the heater may be beyond repair. You need a new heater in this case, which can be very expensive. It is best to deal with rust as soon as you spot it. Any rusty sections of pipes or vents may be cleaned, sanded, or replaced.

Cold Water Sandwich

When dealing with a “cold water sandwich” problem in your tankless heating system, expect to spend between $300 and $1,000 to fix this issue. The usual repair method for this problem is the installation of a mini tank heating tank. This problem happens when the shower temperature randomly changes, going from hot to cold and then back to hot, usually while taking a shower. This often happens because of trapped water in the pipes. A mini tank water heater helps prevent the sudden blast of cold water.

Tankless Water Heater Repair Cost by Brand

There are various brands of tankless water heaters, including Rheem, Noritz, Bosch, and EcoSmart. The heater brand directly affects the cost of your repairs because some brands have more expensive parts and more complex systems than others. The table below shows common brands and the average costs to fix a tankless water heater for each.

​​Bosch Tankless Water Heater Repair

The average cost to repair a Bosch tankless heater is between $100 and $600 for electric models and $125 and $625 for gas models. Bosch is a German brand founded in 1886, which produces and sells a wide range of electrical appliances, including tankless heaters. This brand offers affordable models that are relatively inexpensive to fix.

Rheem Tankless Water Heater Repair

Repairing a Rheem tankless heater averages $125 to $625 for electric units and $150 to $650 for gas models. Rheem is a U.S. brand based in California. It is the largest water heating manufacturer in the world, offering a wide range of tankless models in many styles and sizes to suit different households. Repairs for Rheem heaters may include thermostat replacements and valve repairs.

EcoSmart Tankless Water Heater Repair

The average cost to fix an EcoSmart tankless heater is between $150 and $650 for electrical units and $175 to $675 for gas-powered models. EcoSmart is a brand specializing in eco-friendly heaters, including solar-powered models. Heaters from this brand tend to be advanced, and certain replacement parts may be priced slightly higher than average.

Takagi Tankless Water Heater Repair

Homeowners spend between $175 and $675 on repairs for Takagi tankless gas heaters. Takagi is a brand specializing exclusively in gas-powered heaters. They usually do not have advanced smart features like Wi-Fi connectivity or mobile controls, but they are known for being reliable and sturdy. Like other heaters, they can break down and require repair.

Noritz Tankless Water Heater Repair

Repairing a Noritz tankless gas heater averages $200 to $700. Noritz is one of the more high-end brands, offering a range of gas and propane tankless models. Like Takagi, Noritz-branded products are famed for being strong and reliable, so they should not break down much in the first years. However, they can still suffer wear and tear.

Navien Tankless Water Heater Repair

The cost to repair a Navien tankless gas heater ranges from $200 to $700. Navien is a Japanese company founded in 1978 and has become one of the leading brands of tankless heaters. New models purchased from this brand come with 15-year warranties and are some of the most reliable around. But you may still encounter issues with parts like the thermostat and pilot light.

Rinnai Tankless Water Heater Repair

Homeowners spend between $200 and $700 on repairs for Rinnai tankless gas water heaters. Rinnai is a leading producer of high-end tankless heaters, specializing in gas-powered models that often feature smart connectivity and Wi-Fi controls. Rinnai heaters are also very efficient, ideal for people who want to waste less energy. Like any heater, they can suffer from damaged parts, such as valves, thermostats, and pilot light assemblies.

Labor Cost to Repair a Tankless Water Heater

Plumbers and water heater repair specialists charge anywhere from $50 to $150 per hour for their services. Some charge by the hour, while others have set fees. The price may also be influenced by your location, the amount of competition among plumbers in the area, and the plumber’s experience. You may pay extra for emergency repairs or an extra fee if you live in a remote location and the plumber has to travel a long distance to get to your home.

Tankless Water Heater Maintenance Cost

The average cost of professional tankless water heater maintenance is between $50 and $400 per visit. You can do maintenance on your own to save money. In general, homeowners cannot do much for tankless water heater maintenance, but there are some small tasks you can carry out regularly to keep your heater in good condition. First, inspect the heater regularly to look for warning signs, such as rust, leaks, loose valves, or warning messages on the heater’s display. It is also recommended to descale your heater once a year. This helps prevent mineral buildups in the system.

Flush a Tankless Water Heater

The average cost to flush a tankless water heater ranges from $100 to $200. Flushing is a useful technique recommended to be done annually to keep your unit in the best condition. It involves flushing water through the system to eliminate buildups of calcium and other minerals. Some models have a warning light when they need flushing.

Repair vs Replace Tankless Water Heater

You may have to decide between having your tankless water heater repaired or replacing it with a new one. There are a couple of factors to consider, and the most important one for most homeowners is the price. Costs average $600 to $6,000 to install a new tankless water heater. If you have high repair bills for your current heater, it may be better to purchase a new one. Think about the age and condition of your current heater. These units have an estimated lifespan of around 20 years and usually start to break down more as they get older, leading to repeated repair costs. If your heater is old, it might make sense for you to buy a new one rather than worrying about more repair bills and problems.

Enhancement and Improvement Costs

Earthquake Straps for a Water Heater

Having earthquake straps fitted to your heater ranges from $100 to $200. Having earthquake straps is an obligation in certain states with a high risk of earthquakes. If an earthquake happens, the heater can be damaged and cause leaks and flooding. The straps prevent this. You may save money by buying and fitting earthquake strap kits yourself.

Sediment Trap Water Heater

Homeowners spend between $50 and $100 on sediment traps for water heaters. A sediment trap, also known as a dirt trap, is fitted to gas heaters to trap sediment and debris, protecting the system from damage. You can save money by buying and installing your own sediment trap kit, but it may be best to leave this job to a professional if you do not have much experience.

Freeze Protection

The average cost of freeze protection for a tankless water heater is between $100 and $350. Many modern tankless heaters come with built-in freeze protection, but you can add additional protection with heating cables or pipe wrap insulation to help prevent freezing issues in the pipes. Freeze protection solenoid valves may also be added. Costs vary, depending on how much protection you want or need.

Water Tank Heater

Installing a new water tank with your tankless system costs between $600 and $2,000. Even though a tankless system does not need a tank to operate, it can be worth having a tank to store hot water. This can be useful when there is pressure on the system, such as when multiple people are taking simultaneous showers.

Additional Considerations and Costs

• Warranty. Check the warranty policy of your tankless water heater. If the policy is still valid, you may get certain repairs and replacement parts free of charge.
• Old unit removal and disposal. When having a new tankless water heater installed to replace an existing one, you may need to pay a fee of around $50 to $125 for the removal and disposal of the previous unit.
• Lifespan. On average, tankless water heaters last around 20 years. Regular maintenance can help your system last longer, while poorly maintained units might break down within 10 to 15 years.
• Permit. Building codes for these appliances vary from place to place, and you might need a permit when having certain repairs or replacements.
• Troubleshooting. If your heater is not working, try a few troubleshooting steps to find out what is wrong. Turn off taps or appliances using the water to see if the system has been overloaded, and check vents and air intake channels for blockages. You can also check filters and reset your heater’s thermostat.