Tankless Water Heater Maintenance

What you should know about regular and required tankless water heater maintenance and how it affects the heater's performance, property and your safety.

If you are the owner of the gas-powered water heater with the on-demand heating, either condensing or non-condensing, use this article to find out is the tankless maintenance demanding, expensive and beneficial, and about the steps you should take for the proper care. Recommendation from the manufacturers is to check and clean the complete water heating system once a year. Only properly maintained water heater will provide years of the reliable and trouble-free operation.



Before you perform the maintenance

Tankless water heater maintenance should not be performed unless you do the following:
  • Unplug the electric cord which powers the water heater. You can also turn the unit OFF on the circuit breaker and electric panel.

  • Use the manual gas valve to turn the gas supply to the heater OFF.

  • Turn the water supply OFF, again on the main valve. Most of the time shut off valve (or isolation valves) are installed so you can isolate the unit for service or flushing, for example.

  • Make sure the unit and inside water are not scalding hot before performing maintenance.

What needs to be checked and cleaned

Test a pressure relief valve

Pressure relief valve must be installed to release any water and lower the pressure, if the pressure inside the system has increased above the allowed. To maintain a proper operation, check the PRV once a year and test it by lifting and releasing the lever few times. The lever should easily go back into the closed position (should seat properly). After you open the valve use the bucket to collect the discharged water but be careful as the water might be scalding hot.

Elements to be checked and cleaned

Use the compressed air and dry cloth to remove the dust, debris and dirt from the combustion chamber, heat exchanger, vents, fan and its motor. When cleaning the vent system make sure there are no obstructions and pipe defects. All vent connections should be tight and gaskets in a good condition.

Check also the water filter and remove the mineral deposits if needed. Flow sensor should preserve its capability to spin freely. If it doesn't spin properly you can use the lemon juice to clean it, or if it doesn't help, replace it.

Locate the ignition rod and use the sandpaper (fine one) to clean the tip of the rod to a bright finish. Be careful when cleaning the flame sensors to maintain the factory position.

You can use a shop vacuum for vacuuming.


emergency plumber

Sediment and limescale build-up

Most of the tankless water heaters are equipped with the diagnostic tools which will notify you when the flushing is needed to remove the deposits. The hard water is the reason for this problem, especially inside the heat exchanger and the copper coils. Rinnai models, for example, will show codes such as LC1 or LC2. Use the descaling procedure or flushing to remove the sediment and limescale build-up.

Checking the flame color and pattern

All gas water heaters are equipped with one or two gas burners. As part of the regular tankless water heater maintenance, visually inspect and check the burner flame for anything unusual. The flame must burn clear with a blue flame and stable; not yellow, red or burning with the smoke. Irregular combustion and flame pattern is what can cause smoke, soot build-up and blockage of the heat exchanger. Also check for cracks on the heat exchanger and flue gas spillage.

Maintenance during the winter time

During the winter time, especially when it is snowing or during icy cold weather, make sure that the snow or ice does not cover the vent passages.

If planning to leave during the cold weather, so the water heater will be idle for some time, do not use anti-freeze, but make sure to drain the water from the heater.

After you are done with the tankless water heater maintenance, always check for possible gas and water leaks. Remove all the tools and material used in cleaning the unit, and make sure that there are no combustible materials (such as gasoline) close to the unit.

If something goes bad during or after the maintenance; there are damaged components, abnormal sounds during the operation, defects in the appearance, do not try to fix and repair the unit. Turn the gas, electricity and water supply OFF and call the licensed technician.


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