How many years does a tankless water heater last?

Author: Ebba Stracke III  |  Last update: Monday, April 7, 2025

One of the most common questions asked by consumers about tankless water heaters is how long they will last. A tankless water heater can last anywhere from 15 to 20 years with proper maintenance and operation. In comparison, a standard tank water heater normally has a working life of 10 years or less.

How do you know when a tankless water heater needs to be replaced?

Common signs that it's time to replace your water heater include its age (usually 10-15 years), rusty or discolored water, strange noises, leaks or pooling water around the tank, and insufficient hot water supply.

What is the downside of a tankless water heater?

Before you commit to buying a tankless water heater, the primary drawbacks to know include: Higher upfront costs. Tankless water heaters are, on average, quite a bit more expensive to buy and install than tank water heaters. Access to fuel.

What is the life expectancy of a tankless water heater?

Tankless water heaters usually last for around 15-20 years before they need to be replaced, but they may need replacing sooner if they start to break down or lose efficiency. Some common signs your tankless water heater needs to be replaced include: Low water pressure. Water doesn't get hot.

Do tankless water heaters need to be flushed every year?

Over time, a tankless water heater may accumulate mineral build up which can erode the walls inside your tank's heating chamber. To properly maintain and clean your tankless water heater, it's important to flush those mineral deposits at least once a year.

How long does a Tankless Water Heater Last?

What is the average cost to flush a tankless water heater?

The average cost to flush a tankless water heater can vary. On average, homeowners can expect to spend between $100 and $300 for a professional flush, including any additional maintenance services required. DIY flushing costs can range from $30 to $100, depending on the flushing kit purchased.

What happens if you don't descale your tankless water heater?

What happens if I don't flush out my tankless water heater? Mineral deposits may build up. This could cause a clog within the unit and may prevent normal heating activity. Your hot water could also fluctuate and overheat the system, impacting its efficiency.

What maintenance does a tankless water heater need?

The most complicated and time-consuming tankless water heater maintenance is typically descaling and flushing out the unit. Even with the inline water filter, lime and calcium deposits can build up inside the tankless system. If you have hard water, it's a good idea to descale and flush the unit once a year.

Why don't more people use tankless water heaters?

Some people hesitate to decide on a tankless water heater because they can be a slightly higher cost; however, you get significantly more life out of one. A standard water heater tank lasts about 8-12 years. A tankless water heater can last as long as 25 years!

Can I replace my 40 gallon water heater with a tankless water heater?

Absolutely! In fact, tankless water heaters are becoming the standard for new home construction because of the energy efficiency.

Is there an IRS tax credit for a tankless water heater?

The federal tax credit for tankless water heaters can lead to significant savings for homeowners. Eligible tankless gas water heaters must have an ENERGY STAR certification and a UEF of greater than 0.95. Homeowners can claim up to $3,200 in tax credits for eligible home improvements in a single year.

Can you take a long hot shower with a tankless water heater?

While a tankless water heater will deliver an unlimited stream of hot water, they struggle to deliver a lot of hot water at one time. So while you might be able to take 100 showers in a row if you have the dishwasher, washing machine, and shower going at the same time you might have problems.

How much does it cost to replace an existing tankless water heater?

For an electric tankless water heater, the average cost is around $8,850. Replacing a gas tankless water heater costs approximately $4,700, while replacing an electric tankless water heater costs about $4,200. Factors such as fuel type, brand, labor, and home modifications can influence the overall installation cost.

How to tell if a tankless water heater is going bad?

To help you identify when you have a tankless water heater in trouble, we've listed several warning signs to watch for:
  1. A drop in hot water pressure. ...
  2. Lukewarm water. ...
  3. The water heater keeps shutting off. ...
  4. Unusual behavior from other appliances. ...
  5. Leaks.

What happens if you don't service your tankless water heater?

If you neglect maintenance on your tankless heater, it will reduce the lifespan of your investment. You could go years without performing maintenance and the heater will still function. It won't heat the water efficiently, but it will still produce hot water at a reduced flow rate.

Can multiple people shower at the same time with a tankless water heater?

A: Yes, but depending on the wattage of your unit, and the temperature you set, the pressure may go down.

What is the downfall to a tankless water heater?

A tankless water heater cannot provide hot water faster than its ability to heat the water. While a tank unit can provide hot water for multiple uses at once, a tankless unit might not be able to support simultaneous usage, such as washing dishes, taking a shower and running a washing machine all at once.

What is the life expectancy of a Rinnai tankless water heater?

The life expectancy (or useful lifespan) of a Rinnai tankless water heater is up to 20 years. Actual life is impacted by water quality, usage and proper maintenance. For comparison, a tankless water heater lasts about twice as long as a tank water heater, making them a better value in the long run.

How often should tankless water heaters be flushed?

Just like a tank unit, tankless water heaters need to be flushed once per year. Homeowners with hard water should consider flushing and cleaning the unit even more frequently, perhaps every six to nine months because of the excess amounts of magnesium and calcium found in hard water supplies.

Why avoid a tankless water heater?

Additional Installation Costs

Tankless water heaters are much more complex than traditional hot water tanks. As a result, they require professional installation. If you're switching from a hot water tank to a tankless unit, you will likely need your gas lines rerouted, as well as a larger gas supply line.

What is the expected life of a tankless water heater?

A tankless water heater can last anywhere from 15 to 20 years with proper maintenance and operation. In comparison, a standard tank water heater normally has a working life of 10 years or less.

How much does a plumber charge to descale a tankless water heater?

Flushing and descaling are important parts of that maintenance, no matter what kind of water you have. Descaling your tankless water costs between $150 and $450 on average.

Can I use vinegar to flush my tankless water heater?

To remove that calcium before it can block the tubes, and to improve the heating efficiency of the heater, we need to flush the tankless water heaters about once a year with vinegar. Vinegar is a weak acid which will dissolve the calcium.

What happens if tankless water heater is not flushed?

You need to flush a tankless water heater once a year to get rid of mineral deposits and sediment that block the water flow. If you don't, this problem can cause your tankless hot water heater to stop working. You also might void the warranty by not doing it.

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