How do I protect my tankless water heater from hard water?

Author: Jay O'Reilly  |  Last update: Sunday, April 27, 2025

Install a water softener to protect your tankless water heater. By installing a water softener in your home, you can remove hardness minerals and avoid scale buildup inside of your tankless water heater. This will ensure that your tankless system maintains consistent efficiency levels throughout the year.

How do you maintain a tankless water heater with hard water?

Flush to remove hard water deposits

Your tankless water heater should be flushed at least annually. This is to remove mineral deposits, such as calcium. If you've had hard water problems in your home, you might consider flushing out your heater more than once per year to counter mineral deposits.

Will hard water ruin a tankless water heater?

Any tankless gas water heaters installed when they have hard water the unit will fail because of scale build up inside the unit and when this happens the unit will use more BTU and run longer then nessary to still make the hot water you need.

How do I prevent calcium buildup in my tankless water heater?

One way to prevent limescale in a tankless water heater is with a water softener. A water softener removes that hard minerals - calcium and magnesium, from the water so that no limescale can form.

Can you add a water softener to a tankless water heater?

A water softener is essential for the efficient operation of your tankless water heater. By removing the hardness minerals before they can clump together and form scale, a water softener ensures that your heater runs smoothly and maintains its efficiency.

$30 and 30 Minutes - Tankless Water Heater Freeze Prevention

How often should I flush my tankless water heater if I have a water softener?

If you have hard water, it is important to descale and flush your unit at least once a year. If you have a water softening system, we recommend performing a flush of the system every 3-5 years.

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!

How to protect a tankless water heater from hard water?

Here's how you can help mitigate the issue:
  1. Install a Water Softener: This is one of the most effective ways to prevent sediment buildup. ...
  2. Regular Descaling: If a water softener isn't an option, regular descaling can help.

Can you run vinegar through a tankless water heater?

Use 4 gallons (15.1 liters) of undiluted white vinegar to clean your tankless water heater. Never use chemical solutions of any kind. Since your home's drinking and bathing water mostly likely flows through your tankless water heater, using chemical cleaning solutions could be extremely harmful to your health.

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.

How do I protect my water heater from hard water?

How to Prevent Hard Water from Damaging Your Water Heater
  1. Install a Water Softener: One of the most effective ways to combat hard water is by installing a water softener. ...
  2. Regular Maintenance: ...
  3. Use a Water Filter: ...
  4. Temperature Regulation: ...
  5. Consider Anode Rod Replacement: ...
  6. Monitor Water Quality:

What is one disadvantage of a whole house tankless water heater?

More expensive installation and maintenance.

Tankless systems require special venting, rerouted gas lines, possibly multiple units for a larger household, and sometimes maintenance like installing a softener.

What water filter is best for hard water?

When it comes to addressing hard water comprehensively, especially for drinking, cooking, washing clothes, showering and maintaining appliances and household pipe systems, reverse osmosis (RO) is seriously effective. Here's why undersink RO systems are the best solution.

Will hard water damage a tankless water heater?

Scale buildup can reduce the efficiency — and even shorten the lifespan — of many items in a home. Tankless water heaters are particularly sensitive to hard water, but so are dishwashers, ice-makers and washing machines.

How often should I descale a tankless water heater?

Most manufacturers recommend descaling your system once per year.

How do you fix sediment buildup in a tankless water heater?

Once you've recognized that your water heater has a sediment problem, there are some different things you can do to set things right again.
  1. Flush the unit. ...
  2. Perform a vinegar soak. ...
  3. Keep it at the right temperature. ...
  4. Install a water softener. ...
  5. Call a professional plumber.

Is vinegar or descaler better for tankless water heaters?

A tankless water heater descaler specifically designed for this purpose is recommended for optimal results. Alternatively, you can use vinegar as a natural and affordable descaling solution. Prepare the solution according to the manufacturer's instructions.

Do tankless water heaters need to 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 does my tankless water heater turn blue when I flush with vinegar?

The vinegar will be a bit blue. This is from tiny amounts of corrosion of the copper of the tubes in heater. The copper imparts the blue color. Nothing to worry about.

Should I cover my tankless water heater?

Installing a tankless water heater cover for winter is another option; it will protect the unit from the coldest temperatures, not to mention snow and ice. Run a Faucet on Low: Water is more likely to freeze when not in motion. To reduce the risk of freezing, run a faucet at a low level during extreme cold.

Do I need to flush my tankless water heater if I have a water softener?

You still need to flush a tankless water heater if you have a water softener, but you don't have to do it as often.

How do you fix hard water in a water heater?

Flushing your tank will remove some of the calcium from your water heater. To get rid of the rest, you should treat the calcium with a descaling solution. You can find many descaling solutions at your local hardware store. However, an often cheaper and equally effective option is to use vinegar or lye.

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 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.

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.

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