How to Repair a Tankless Water Heater and Replacements

You might be struggling with your heater, your prized and most dependable home equipment is suddenly not heating up water like it used to. Or the gas burner produces more noise than flame. These are common problems that could be solved and your heater will return to its original state without costing you a dime.

We will show you how to take care of the easiest and common repairs yourself, but as a precaution you must read the manufacturer’s manual thoroughly in order to avoid any unfortunate incidents.


There are two variants of heaters based on the fuel supply but both do not have any storage unit for water. Instead the water keeps running through the main source and gets heated. The two types of tankless heaters are:

  1. Gas
  2. Electric

Common problems and solutions

For both types, hard water stops the flow of water if hard water is being used. All of them rely on narrow plumbing inside them that make it possible to heat up the water while it is flowing from the main source. If the water is hard, it would contain salts and minerals that will clog up the pipeline resulting in poor operation of the system. This is why it is almost always recommended to use soft water.

The other basic solutions are to always make sure you have a running water supply. The gas or power supply must also be adequate, consistent and enough for the heater to function. At times when the flow of water is too slow or none at all, your plumbing might be choked.

If the water is not available from the main source, clear out your pipeline and see to it it’s not being clogged. The external atmosphere and temperature also play a part, and in cases when the plumbing is outside and the weather is too cold the water might freeze or cool during its journey through the pipeline.

Repairing Gas Heaters

One of the most common problems with gas heater is the source of heating itself, the burner. At times the burner may become clogged and as a result the burner either does not heat up properly or does not heat up at all. The outlets of water inside the system can get clogged due to hard water and to get rid of it, the internal plumbing has to be flushed.

This must be done every few months and is part of the maintenance. Flushing the pipes isn’t that hard a job so you can do it yourself. Alternatively you can hire a professional plumber. If you are elf-repairing you would need:

  • A large bucket
  • 2 gallons of white vinegar
  • 2 hoses
  • A submersible pump

Once you have these supplies just follow the steps:

  • Shut down all the water valves (there are usually 3) for all the pipelines ( incoming and outgoing)
  • Shut down the gas supply to your system
  • Fill the bucket up with white vinegar and place the submersible pumps suction pickup in the bucket. Attach one hose from the bucket to the pressure-relief valve, and attach the other hose from the submersible pump and inlet of the heater.
  • Turn on the pump and vinegar will clean the internal plumbing by flowing through the system and dissolving salt deposit on the system walls orifices.
  • Near the water inlet, there is an inbuilt filter. Screw it off and clean its screen filter before placing it back.
  • After pumping the vinegar though the system, run the pump again and let cold fresh water flow through the system. This will clean your internal plumbing again and afterwards you can use your heater to heat up the water and this time it will work.

Repairing Electric Heaters

With gas heaters, the problem could be the burner. With electric heaters, the problem might lie with the heating element that may have run its utility. You need to change and replace the heating element to regain function and the process is simple enough.

First read the manufacturers manual and find out where the heating element is located. Once you know, you can follow these simple and easy steps:

  • Switch off the main power supply to the heater
  • Shut off the water from its source
  • Open the hot water tap and drain out all hot water
  • Drain out the water by removing the plate at the bottom of the heater the heating chamber. After the water has drained, place the plate back.
  • By using extreme caution disconnect the wires that are attached to the main heating unit
  • Push a thick cloth in the main unit to make sure no water runs through
  • Use an adjustable wrench and detach the heating element from the main unit by unscrewing the nuts holding it in place
  • Replace the heating element with a similar one. Make sure the capacity of the element is the same and the O-ring is set it position adequately
  • Test if the new heating element is working by turning back the power and water on

Regular maintenance of water heaters and checking to make sure they run properly are not causes for concern, neither is delay in water being heated as certain conditions can account for the delay. If you notice a spinning fan after switching off the power, do not be alarmed as the fan only vents out the exhaust gases through ventilators.