How To Clean Tankless Water Heater?

Do you know how to clean a tankless water heater? Well, if you don’t, the good news is that it doesn’t have to be troubling anymore.

Usually, as water keeps flowing through your tankless water heater, minerals and other residue do clog up in the system. This results in inefficiency and ineffective operation. Specifically, heat exchange systems and unit filters are potential targets of clogging.

As a homeowner, it is advisable to embrace regular cleaning practices to avert possible high energy bills. Ensure you have clean and healthy water for all your supply needs.  Besides, you will enjoy enough space courtesy of the nature of the tankless water heater installations like wall mounting.

Thanks to this in-depth research, you don’t have to always rely on a technician to do basic cleaning of your tankless water heater. All you need is to spare some time for the exercise around the year to stay on top of the maintenance.

What you Need to know Before Cleaning the Tankless System

Flushing is one of the ways of cleaning your unit. When buying your tankless water heater, check whether it comes with a flushing kit. It includes a pump, bucket, and a number of hoses for the convenience of the flushing.

You can clean your tankless water heater using vinegar or any other recommended cleaner.   This is because they are effective in cleaning the stubborn calcium and magnesium ions that form a hard build up on heating parts over time.

Remember, the cleaning needs to remove the coating or build up that sometimes might result in water heaters, boilers, and other parts burning longer than is normal. Additionally, this might put a lot of strain on the unit operation, shortening its lifespan.

See also – How to Flush a Tankless Water Heater?

How to Clean a Tankless Water heater

Before you do the cleaning, you will need;

  • Gloves
  • About 5 gallons of food-grade vinegar
  • A 5-gallon bucket
  • 2 quality stainless steel washing machine hoses
  • Submersible pump
  • Screwdriver

Ensure these materials are ready with you during the whole process to avoid wasting time reaching out for them.

Steps to Cleaning your Tankless Unit

Step 1: Do a prep

  • Whether you own an electric or gas tankless water heater, have a better understanding of your type of tankless system.
  • This is where your user manual from the manufacturer becomes handy. Thereafter, you will need to identify where the shutoff valves that supply gas, hot water, and cold water to the system are positioned.
  • Make sure you shut off these valves, including the power supply. To be sure, just unplug the unit from the wall socket completely. This is to avoid experiencing a short circuit as you stay safe.

Step 2: Start off Unscrewing the Valves

  • Make sure your bucket is just below the tankless water heater. Have one of the hoses ready and direct one of its ends to face the inside of the bucket and another near the valve to unscrew to redirect the water into the bucket.
  • In case any water in the valves spills out, you don’t want it all over the floor. Take your screwdriver and unscrew the valve that supplies cold water to the unit.
  • Once the unscrewing is done for the cold water supply valve, do the same with the hot water supply valve. In case of any hot water in the valve, you need to take precautions not to burn yourself.
  • Of course, this depends on how your water is before turning the system off before the cleaning process and the time of unscrewing the valve.

Step 3: Get your Vinegar and Pump Ready

  • If you collected any amount of water from step 2, it is time you empty your 5-gallon buckets.
  • Fill the 5-gallon bucket with food grade vinegar before you connect one of the hoses to the pump at the bottom of the bucket.
  • Check that the connection going to the hot water valve is stable before redirecting the other end to the bucket with the submersible pump. The hose needs to be loosely positioned on top of the inlet to the bucket.
  • Plug in the pump into the power outlet to help circulate the vinegar through the valve, supplying the cold water out through the valve supplying the hot water to the bucket. An hour on this process should be enough to efficiently help clean the unit.
  • You will have to remove the faceplate (this depends on your design) of the tankless system using your screwdriver in order to expose the interior parts. As the vinegar is circulating, ensure that the air absorption filter, usually located inside the unit, is well cleaned. Consider drying the filter before reinstallation using a dry towel.
  • After this, replace the tankless water heater faceplate. Once the hour recommended for cleaning is done, turn off the pump.

Step 4: Winding up the Process

  • Close the inlet port and detach the hose from the pump. Let the cold water supply run through the tankless water heater to flush out any vinegar that might be remaining in the unit.
  • Close the outlet port and detach the second hose and empty the contents of vinegar that might be in your bucket.
  • Turn off the water and gas supply line to the rest of your house or building. Turn on also the power button. Let the water rush into the system and then open the hot water valve to destination supply extensions. Your tankless water heater should be cleaning successfully at this point.

Related content – Importance of Tankless Water Heater Maintenance


Now you have all the details on how to clean a tankless water heater. Most units have displays that will indicate when the operation is normal. Therefore, it is important to consider going for a quality model with advanced features. Modern units have self-diagnostic systems and sensors to detect any problem.

This will provide you the convenience of understanding when the tankless water heater needs special attention through its display system. I suggest you check that the warranty of your unit is convenient to in-built related repair problems. I hope your appliance would not let you down when you need it most just because you can’t be able to go around the cleaning.