Although tankless water heaters have electrical components, a licensed plumber is usually the professional you should hire to repair and service them. Here are the qualifications to look for:

• Experience and expertise: Look for a plumber experienced in tankless water heater repairs, as it’s a specialized plumbing skill. Tankless units use a complex system of heat exchangers and control boards and can be more difficult to service than storage tank heaters. Read through pros’ customer reviews and ask plenty of questions to get a sense of their experience and expertise. 

• Certifications and licensing: Some plumbers obtain certifications specific to water heaters, like the AHRI Residential Water Heaters certification, in addition to their plumbing license. Though certifications may not always be required, they can indicate the plumber's knowledge and skills.

• Warranty: Find out if your plumber offers a warranty on their work in case there's an issue with the repair down the line. 

• Cost estimates: Ask a few plumbers for quotes so you can compare them and hire the pro with the fairest price. 

• Find out how long they will take: If you're dealing with a major leak or cold water temperatures, you probably want to get your water heater fixed sooner rather than later. Consider hiring a plumber who can get the job done quickly.

For more tips, visit Thumbtack’s Smart Hiring page. 

Tankless water heater repair and maintenance typically costs around $230 to $950* on average, according to Thumbtack data. Although repairing a tankless water heater might seem pricey, it’s cheaper than replacing it (costs range from around $1,870 to $2,310*).  

Tankless water heaters often last longer than traditional tank water heaters, but when something goes wrong, the repairs might be more expensive.

Here are some ways you might be able to save money on repairs:

• Maintenance: One of the best ways to reduce repair costs is to regularly flush your heater, replace the filter and have it inspected. 

• Warranty: Check your manufacturer’s warranty to see if your repairs are covered.

• Replacement: If your heater is old or malfunctions frequently, it may be cheaper in the long run to replace it entirely.

*Data on file at Thumbtack. For a personalized cost estimate, request a quote from a professional.

Here are some tips to help you decide if you should repair or replace your tankless water heater:

• Consider its age: Most tankless water heaters last around 20 years with proper maintenance. If yours is older than 20 years or hasn’t received regular maintenance, it may be time to install a new one.

• Compare the costs: If the cost to repair the issue is close to or more than the cost of a new unit, you might be better off replacing it.

• Understand its efficiency: A tankless water heater that struggles to provide enough hot water or consumes too much energy may not be as efficient as newer models. These could also be signs that the water heater is approaching the end of its life expectancy.

While there are many issues that a plumber can repair, there are some situations where it makes more sense to replace the entire unit. Contact a licensed plumber to examine your tankless water heater and make a recommendation.

Here’s what you can expect when a plumber is servicing or repairing your tankless water heater:

• Inspecting the water heater: First, the plumber will examine each part of your tankless water heater to diagnose the issue. They will likely examine your water and air inlet filters, gas burner and electrical components.

• Checking connections and sensors: The plumber will look for simple issues like loose connections and faulty sensors.

• Performing repairs: Depending on the problem, your plumber may need to replace or repair the burner or heat exchanger, especially if your water isn’t getting hot. If sediment has built up in the water filter, they may need to flush the system. Ask your plumber to explain what repairs are needed after they diagnose your water heater.

Minor tankless water heater maintenance, like flushing the water heater, might be DIY-friendly if you have some experience. However, it’s usually best to leave the repairs to a professional plumber. 

Here are some reasons to consider hiring a pro:

• Required tools: Depending on the problem, fixing a tankless water heater may require a drill, bits and burrs, a wrench, a water flushing kit, valve replacement and other new parts. A professional is typically more equipped and ready for a variety of repairs.

• Pre-work: Before making repairs, the plumber will probably need to shut off gas, water and power to the heater to inspect the sensors and exchanger. This requires specialized knowledge.

• Permits and local codes: A licensed professional should be able to get any required permits, and they can ensure the repair work is up to code.

• Avoid hazards: A professional understands the safety risks and hazards and how to prevent things like gas leaks and electrical shocks.

• Protect your warranty: In many cases, a manufacturer’s warranty can be voided if the repairs are completed by a non-professional. Check your warranty’s conditions to find out.

• Prevent costly repairs: A well-done professional job can prevent the need for future repairs, which could end up costing more money down the line. 

Here are some of the most common maintenance tasks that most tankless water heaters require:

• Water inlet filter cleaning: Check the filter every few months and clean out any debris to prevent buildup.

• Air filter cleaning: Many tankless water heaters also have a filter for air intake. Clean or replace this filter periodically according to your owner’s manual.

• System flushing: Consider using a vinegar solution or a manufacturer-recommended descaling solution to break up mineral deposits.

• Inspection: Have a licensed plumber inspect your water heater regularly to catch potential problems before they get worse.