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How to Maintain a Tankless Water Heater

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Tankless water heaters usually provide an endless hot water supply, but not if maintenance is ignored. Keep your tankless water heater in excellent working order and safeguard your investment! Use the guidelines below to clean out your tankless water heater and limescale.

The procedure of descaling a water heater is also referred to as flushing. This crucial stage in tankless water heater upkeep should be done every six months to two years, depending on the condition of your tap water. Just as limescale builds up on showerheads and sinks aerators, so does it build upon your tankless water heater. It’s important to remove it, so you don’t damage the unit. Start by gathering the necessary supplies.

Supplies to Flush a Tankless Water Heater

  • Sump pump
  • Also called a submersible utility pump. The 1/6 hp capacity is ideal for decalcifying a tankless water heater. Be careful if you use a pump with more than 1/4 hp.
  • Three gallons of white distilled vinegar
  • One five-gallon bucket.
  • Two sections of hose (2 – 4 feet) with the necessary fittings.
  • They are similar to water hoses in washing machines. These should have been included with your unit. 

How to Flush a Tankless Water Heater

  • Prepare the project.

Disconnect the gas line or turn off the circuit breaker if it is an electrical appliance.

Remove the access panel or cover, usually held in place with a few small screws or tabs.

Connect the hose to the water heater inlet where the cold water enters the system. There should be a separate hose for this, or you may have to remove the existing cold water supply hose. At the other end of this hose, connect a small sump pump. Immerse the pump in a 5-gallon bucket filled with three gallons of white distilled vinegar.

  • Fill with vinegar

You create a closed system, so the vinegar that goes into the water heater goes back out into the bucket before recirculating. If you are not using a separate connection to flush an existing hose, be sure to open the valve before proceeding.

  • Once the hoses are properly connected, run the cesspool pump for one hour.

The vinegar will go through the system, removing limescale and mineral deposits from the pipes. Replace the water with new water after one hour to remove all the vinegar from the system.

  • After that, turn off the pump, remove the flushing hoses and close the valves.

This process usually begins with turning on the water and then turning on the gas or electricity. Turn off the water to the area and connect the water hoses to the tankless water heater. 

How to Clean the Water Filter in Your Tankless Water Heater

A filter is typically included with tankless water heaters to prevent larger particles from entering the heating element. These strainers are generally used throughout the life of a tankless water heater and may be washed in running water or soaked in white vinegar until they’re clean. If you can’t find it, refer to the manufacturer’s instructions.

Professional Tankless Water Heater Maintenance

Tankless water heaters can last for decades with proper care. Regular maintenance is important to keep them running smoothly. If you are too busy to flush your tankless water heater or are a little confused about it, Plumber Etobicoke Pro can help.


If you reside in a hard-water region, we recommend installing a water softener to increase the life of all your plumbing components. We can assist you with that! Call us or schedule an appointment online for a water heater service.