How do I know if my tankless water heater needs to be flushed?

Author: Ramona Braun  |  Last update: Wednesday, April 2, 2025

Common signs it's time to flush or drain your water heater include:
  1. Low water pressure.
  2. Water takes a long time to heat up.
  3. Water isn't the correct temperature or fluctuates.
  4. Noises coming from the tank, such as rumbling or popping.
  5. Sludge or discolored water.
  6. Frequent Repairs.

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.

How often should a tankless water heater be flushed?

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.

Can I flush my own tankless water heater?

A tank heater is very easy to flush, you just need a garden hose, drain it fill and check anode rod. A tankless is also easy to flush, you will also need a pump and a bucket.

What happens if you don't clean a 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.

How To Flush A Tankless Water Heater The Easy Way | DIY Plumbing

How much does it cost to flush a tankless hot 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.

Can I flush my water heater myself?

You can flush your water heater yourself if it's done on a regular basis. This guide will take you through the steps to drain and flush a gas or electric water heater. Learning how to clean a water heater is an essential part of maintaining your plumbing system.

How much does a plumber charge to flush a water heater?

The national average cost to flush a water heater is $160, but prices can vary in increments based on the tank size. A 30-gallon tank will cost between $90 and $120 on average, while a 70-gallon tank could cost anywhere between $180 and $250.

What is the maintenance required for a tankless water heater?

Don't Skip These 3 Important Maintenance Tasks for Tankless Water Heaters
  • Clean or replace water line filter. Many tankless water heater models have a water line filter that protects against hard water, scale, and sediment. ...
  • Clean the air filter. ...
  • Descaling and flushing the system.

What is a flush kit for a tankless water heater?

Tankless water heater flush kit helps keep tankless heat exchangers free of scale build up. The flush kit connects easily to the tankless service valves. Once connected you can run a solution of water and vinegar to clean the heat exchanger of any scale deposits.

How do I know if my water heater needs to be flushed?

Keep an eye out for debris suddenly showing up in your water. If you notice sediment or any brown sludge coming out of your faucet, that's probably an indication that it's time for a water heater flush. If you see any of these signs, it's a good indication that your water heater needs maintenance.

Should I flush my 10 year old water heater?

Performing annual maintenance on a tank-style water heater by flushing it will extend its lifespan. This can help you keep your water heater running in tip-top shape for years to come — and prevent an expensive disaster that involves a late-night or weekend call to a local plumber.

How long should you flush a tankless water heater with vinegar?

After inspecting the heating elements for damage, place them in the copper chambers and rinse the chamber with vinegar for 90 minutes to two hours. After flushing, drain the vinegar and replace the heating elements and wires.

How do you unclog a tankless water heater?

You can use 5 gallons of regular old vinegar white vinegar or you can go to a supply store and buy some of the tankless heat exchanger flushing fluid at some of the supply houses they have a kit It comes with everything you need the pump the hoses directions or you can just get you got to get it like a fountain pump ...

Why am I not getting hot water from my tankless water heater?

Tankless water heaters rely on ignition to heat water on demand. If the ignition fails, you'll be left with cold water. This could be due to a variety of reasons such as a faulty igniter, gas supply issues, or a dirty burner. In such cases, it's best to consult a professional technician to diagnose and fix the problem.

When should I drain my tankless water heater?

Whenever your tankless water heater will not be used for an extended period, drain the water heater. Any standing water in the unit will expand if it freezes, which could cause damage.

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

As water flows through your tankless water heater, it will leave behind small amounts of minerals and sediment. Over time, this can create buildup within the unit that may negatively impact the heat exchanger and restrict water flow.

Can I service my own tankless water heater?

Can I Do My Own Tankless Water Heater Maintenance? Navien tankless water heater maintenance is relatively simple. You certainly don't need to be a professional plumber, but it doesn't hurt if you are comfortable tackling the occasional DIY project. Whether or not you're ready is entirely up to you.

How much does it cost to service a tankless water heater?

Common Tankless Water Heater Maintenance Expenses

Labor costs can range from $50 to $150 per hour, while replacement parts can cost between $20 to $500, depending on the part's complexity and brand.

Why do plumbers charge so much to replace water heater?

This is because the process of installing a new water heater can be quite complex and often requires the use of special tools and equipment. Additionally, the cost of labor for this type of project can be quite high.

How often should you flush a tankless water heater?

Whether you're a recent convert, or you've owned your tankless water heater for several years, you likely have questions about how often you should clean the unit. Most manufacturers recommend annual flushing of your water heater.

How often should I replace my anode rod?

Anode rods require routine inspection and replacement, approximately every three to five years. Without proper maintenance, the anode rod loses its ability to divert damaging particulates from your tank and can accelerate rust and corrosion from chemical reactions, excessive heat, and imbalanced pH levels.

How do you know when to flush your water heater?

The more sediment and mineralization between the heating element and the water, the less efficient and effective your water heater will be. If you live in an area with hard water, you really need to be draining and flushing out this mineral buildup every 4-6 months.

How to tell if your hot water heater is full of sediment?

Common signs that sediment buildup is significant include bubbling and gurgling sounds and diminished hot water when bathing, cooking, or cleaning. You may also notice water discoloration, a leaking pressure relief valve, or cracks in the tank or its connections.

Is it worth flushing water heater?

It is recommended that you flush your water heater at least once per year. Doing so will help to prevent the potential problems that sediment can bring over time. Typically, it takes one to two hours to flush a water heater. The size of your tank will impact the amount of time it takes to drain.

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