How Often Do Tankless Water Heaters Need Maintenance?

2017 Nov 02
Posted in: Plumbing

Tankless water heaters should be maintained by a professional at least once a year.

But, you may need to get your water heater twice a year if…

  1. The area you live in has hard water
  2. Your water heater is set to a high temperature

We’ll go into more detail about these 2 points later and why tankless water heaters need maintenance in the first place. But first, let’s quickly look at how tankless water heaters work.

How tankless water heaters work

Tankless water heaters don’t use a storage tank. Instead, they heat water directly as it comes in from your home’s cold water line. So when you turn on your hot water faucet, you essentially activate the tankless water heater. 

Tankless water heaters heat water using heating elements, commonly referred to as a heat exchanger. The heat exchanger is either powered by gas (most common) or electricity.

Now that we’ve given a brief overview of how tankless water heaters work, let’s dive into why they need maintenance...

Why tankless water heaters need maintenance

Tankless water heaters can last 20+ years—but only if they’re properly maintained. 

Unfortunately, tankless water heaters are often inaccurately marketed as “low-maintenance” devices compared to regular tank water heaters.

But that’s not the case. Really, there’s not a lot of difference when it comes to how much maintenance both units require. Here’s why: hard water affects both types of water heaters.

Hard water means that the water in your area carries lots of minerals in it, primarily calcium and magnesium. In a tankless water heater, these minerals can build up within the heat exchanger, over time plugging up the passages where water can no longer flow. This causes your water heater to work overtime to heat your water.

Over time, this will shorten the water heater’s lifespan and raise your energy bills (water heater has to work longer, using more energy to heat the water). Plus, this mineral buildup on the heat exchanger can cause irreparable damage, requiring the heat exchanger to be replaced or the entire unit to be replaced. This type of damage is not covered under the manufacturer’s warranty.  

During a regular maintenance visit, a professional will descale, also called delime, your tankless water heater to make sure there’s no buildup around the heating elements.

A professional should descale your water heater at least once a year. BUT there are 2 specific instances in which you might need to get maintenance more than once a year...

You may need maintenance more than once a year IF...

#1: The area you live in has really hard water

No matter where you live, the water entering your water heater carries some amount of minerals in it. However, in certain areas of the country, the water is harder (meaning it has more minerals in it).

If you live in an area with hard water, your tankless water heater may need to be descaled twice a year to avoid damage to your heat exchanger.


U.S. hard water map. Source: https://water.usgs.gov

Check the hard water map above to see if your region has high or low concentrations of hard water. Here in Phoenix, AZ we have very hard water.

To learn more about hard water, read our article, “Why Arizona’s Hard Water Secretly Makes Your Life Harder (And What You Can Do About It).”

#2: Your tankless water heater is set to a high temperature

If your water heater’s temperature is set too high, you’re at risk for scale buildup—especially if you live in an area with hard water.

You see, many chemicals dissolve faster when heat is applied. So the hotter your water heater is, the faster limescale builds around the heating elements.

So, do this: Check your tankless water heater thermostat to see what temperature it’s set to. Does your thermostat show a hot temperature greater than 120° F? Then it’s time to have a professional perform regular maintenance on your tankless water heater and clean mineral buildup from the heat exchanger.

Need to schedule your annual water heater maintenance?

Contact George Brazil Plumbing to schedule a water heater maintenance appointment with one of our professionals.

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