How Long Does a Tankless Water Heater Last? – Lifespan FAQs

Have you purchased a tankless water heating unit? If you have purchased one or have made up your mind to get one you might be wondering how long does a tankless water heater last? Overall the lifespan of a tankless unit is longer than the traditional one. They need very minimal maintenance so you don’t need to put in much time and effort. A tankless water heating unit lasts for 15 to 20 years on average. Traditional water heating lasts for about 10 years or less.

Tankless water heating units have proven to be highly effective and energy-efficient over time. If you are planning to upgrade your home appliances this year then you must consider replacing your traditional storage-type water heater with a tankless one. These units do have a high installation cost but in long run the benefits out way the initial cost. The maintenance requirements of these units are not complex and so you can easily manage this unit on your own. The annual maintenance is very important for these units.

Factors Affecting the Lifespan of Tankless Water Heater

The lifespan of a tankless water heater is affected by a multitude of factors. Let’s go through the details of each factor to know more about those factors and also how we can maximize the life expectancy of our tankless heating units.

Water Hardness

A heating element heats water passing through the pipes. If the water is hard then minerals will build up inside the system causing a blockage. This mineral when deposited on the heating element can affect its water heating capacity. The water will be lukewarm and nothing like desired. This mineral buildup needs to be descaled annually. The annual maintenance can be done by the owner himself or by a professional plumber. This is not a very expensive process so it’s easy to avail of professional help.


For average use, a unit lasts about 20 years. If you have excessive water usage the unit will last for a lesser duration. For high-demand homes, it’s always advised to install multiple units in a row. A separate water heater for separate faucets works best. Doing so reduces the load and so water is heated up to the required temperature. Separate tank-less water heaters are used for fixtures with high water usage like the shower, dishwashing, or laundry faucet. The size and capacity of a unit should be in accordance with the size and needs of your family. Choosing the right unit is a complex task for which you need to put in the time to learn about basic parts and their function.

What makes Tankless Water Heaters Last Long?

The biggest plus point of a tankless water heater is no storage tank. In a traditional water heating unit the sediment builds up on the heating element in the tank. The sediment build-up will cause tank failure. As the tank ruptures the entire unit becomes useless and needs to be replaced. A tank-less water heater is also vulnerable to mineral buildup but it’s not as serious as in the case of the traditional water heater. Moreover, a tank-less water heater can even work with a corroded heating element. A tankless water heater lasts twice as long as the traditional unit when given proper maintenance.

What Can Cause a Shorter Lifespan for a Tankless Water Heating Unit

Tankless water heating units are a great innovation. They surely are super convenient and a great addition to your home. They are supposed to last longer than the traditional ones and they do when given proper maintenance. Just like other units these tank-less water heaters are not all perfect they can sometimes stop functioning. Multiple factors can affect the functioning capacity of the water heater. They are listed next with a detailed explanation so you can make sure that your unit is taken proper care of. This helps prevent early damage and prolongs the service life of the appliance.


This is a major issue for the owners of traditional water heaters but tank-less water heaters are immune to it too. Mineral build-up can happen in a tank-less water heater too. Tank-less water heaters are small units. They are made up of multiple small electronic components. If any part of the unit leaks it will affect the electronic parts drastically. In case there is excessive leakage the heating itself might get damaged and in that case, you will need to replace the whole unit. In a gas-fueled water heater, the issue might be more severe.

The excess mineral can build up on the gas burner itself. This makes the burner unable to heat the water. The condensation can even block the gas supply partly or completely. Thus the build of hard minerals will make the water heater effective until you replace it with a new one. A water heater installed outside in case of an RV will wear out prematurely. This is due to the deposition of dirt from the environment onto the parts of the tankless water heater.

Defective Installation

The installation process of a tankless water heating unit is highly complex as compared to the traditional one. Both gas and electric tankless water heaters have complex installation processes. The installation process will cost twice as much as for a traditional storage water unit. Due to this higher installation cost, some people opt to install the unit themselves. This can result in improper installation. A water heater that was not installed correctly will have many serious issues. You must also know which is the right location to install a tankless water heater.

In a gas-fueled tankless water heater, the most common issue can be a defective gas supply line connection. Severe issues like gas leakage can occur. Those gas vapours can come in contact with the ignition flame and this will result in havoc. If you have installed an electric water heating unit then make sure that the electric supply is efficient enough to supply the needed power to the unit. In case the power runs short of demand It can result in a short circuit and thus nearby appliances can catch fire. To avoid all these devastating scenarios it is important to get the unit properly installed by a professional plumber. The process will be costly but in long run will have a budget-friendly running cost.

Repair Expense

The working of a tankless water heater involves electronic parts making the process more advanced. These parts when damaged cost a lot to repair. These electronic parts make your unit more efficient but any damage to them will put a strain on your budget. If the unit was not installed by a professional plumber and some issue arises the manufacturer won’t provide any warranty. In this case, you will have to spend a huge amount of money on the repair of your tankless water heater all by yourself.


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Tips to Increase the Life of a Tankless Water Heating Unit

Want the unit to perform for a long? When one purchases such an expensive unit it’s the aim to make the unit last longer. If you want your water heating unit to last for 20 years you need to do some work.

Descaling Regularly

The most common issue with water heaters is mineral build-up so to avoid this from happening descale your unit often. Descaling is a simple process that can be done all by yourself in no time. Substances available at home such as vinegar can be used for descaling or to make the task easier buy a descaling kit. Installing a water softener at the water inlet is another solution. This removes all the minerals from the water so the water reaching the pipes is free from calcium and other minerals that can cause a buildup on the heating element.

Descaling Process

If you want to do this job yourself we have listed all the steps so it becomes easier for you to follow them.

  • Cut off the water, gas, and electric supply to your water heater.
  • Connect one hose to the input valve and pump. Connect the second hose to the output valve and another end in a bucket.
  • Fill the bucket with descaling solution and put the pump in it.
  • Open the hot water valve and turn on the pump for 45 minutes.
  • Turn on the cold water valve and fill the bucket with it.

Disconnect the other hose too. Make all the connections again and turn on the gas water and electric supply the unit will start working like before again.

With years of experience under his belt, Adam decided to put his water heater knowledge to work. By providing high-quality content and expert guides, Adam hopes to help anyone looking for expert water heater advice.

2 thoughts on “How Long Does a Tankless Water Heater Last? – Lifespan FAQs”

  1. My 20 yr old tankless (Takagi TK-1) is not regulating the water to the factory set 120°F, its almost 140°F now. The Takagi customer service does not recommend descaling due to the age of the unit. Do you agree? Do I have another option (such as installing a thermostatic mixing valve) or is replacement the best option at this point?

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