Cleaning Hot Water Heater Tips
(updated 2018)

Cleaning hot water heater is as important as regular maintenance you are suggested to do by the manufacturer. A clean water heater and the environment where it operates is the first thing you should consider when troubleshooting hot water heater. The DIY cleaning guide will help you find the answers how to clean the gas water heater elements such as flame arrestor, gas burner, venting system, thermocouple, and flame rod, how to use vinegar for this and more.

Regular maintenance with cleaning is especially important with the industry regulations and implementation of the flammable vapor ignition resistance, FVIR, as the dirty environment can significantly affect and reduce water heater performance. Some water heater parts have to be cleaned, from simple dust cleaning to removing sediments from a water heater tank or elements.

So how do you clean the inside of a hot water heater?

Required tools like the vacuum cleaner, air compressor, wire brush, flashlight, wrench, grit paper, cloth, soapy water, are easy to find as they are part of the tools you are probably using on a daily or weekly basis.

Keep in mind that professional technicians should do most of the repairs and maintenance. Before calling for help, here are some measures you can take yourself:

  • Keep the water heater clean, especially if you notice the drips from leaky water pipes.
  • Keep the space around the water heater clean from dirt, household cleaners, paint, and flammable materials.
  • Before you perform any maintenance, visual inspection of the external and internal components should be performed regularly.

Cleaning hot water heater is vital, especially if there are spilled or leaked flammable liquids around. It is vital to have all the resources of flame, both main burner and pilot, extinguished.

Cleaning gas water heaters

One of the most important steps when cleaning a gas-powered hot water heater is to clean the combustion chamber and burner elements. The main burner, pilot burner, and flame arrestor have to be cleaned at the periodic intervals, not more than six months.

The air intake screen cleaning is also critical because the air, at the bottom of the water tank heater, is drawn in for gas combustion. Keep this area free of dirt and dust, and free from flammables, so that the proper gas combustion won't be affected.

To clean the combustion chamber, burner assembly and flame arrestor, remove the burner assembly first. This is how...

Cleaning the flame arrestor

The flame arrestor, as part of the FVIR technology, keeps the flame inside the combustion chamber. It is imperative to keep the flame arrestor maintained, and space under the tank cleaned, so that the air can be drawn for combustion.

If there is a problem with the insufficient combustion air, one of the solutions is to clean the flame arrestor. This is how:

  • Remove the access door.
  • Disconnect the main burner, pilot tube, and thermocouple.
  • Remove the burner assembly.
  • Inspect and clean the flame arrestor using a stiff brush. Use the compressed air or vacuum cleaner with blowing capabilities to clear the dust or debris from the flame arrestor. Once you are done with blowing down and through the arrestor ports, use the vacuum below the flame arrestor to collect the dirt.
  • Reinstall burner assembly.
  • Reconnect feedline, pilot, and thermocouple.
  • Bring the access door back.
  • Resume operation.

If your water heater is equipped with the additional screen against the lint, dust and oil, called LDO screen, located at the base of the heater, it has to be cleaned or washed regularly. This area is important as all of the combustion air enters the heater in there. Air intake screen cleaning will improve the performance and save you a costly service call.

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If planning to connect a gas vent to a chimney, ensure that the chimney passageway is free of obstruction and clear, especially if the chimney was previously used with other appliances.

In a case of the "direct venting," the water heater uses the air from outside directly using the sealed intake air pipe. To ensure clean combustion and safe environment, the air must not be contaminated with the chemicals and chemical vapor, due to its highly corrosive nature. This is why direct vent models are recommended for beauty shops, laundries and where the chemicals are used.

How to clean a water heater main burner

The main burner is subjected to carbon deposits, also known as sooting. If the burner is dirty or clogged, one of the solutions is to use soap and hot water to clean it. Simply follow the steps below:

  • Turn the control knob on the gas valve to the OFF position.
  • Remove the inner door assembly.
  • Disconnect the main burner feed line, pilot assembly, and thermocouple.
  • Remove the burner assembly from the combustion chamber.
  • Inspect the burner surface, burner ports and remove the dirt and debris.
  • Remove the main burner orifice, inspect and clean it.
  • Next, wipe clean the pilot assembly (or electrode) from dirt as it might prevent the ignition spark. If there is rust accumulated on the surface, use sandpaper to remove it.

Before installing the gas unit and connecting a vent to the chimney, make sure that chimney passageway is clear and free of obstructions, especially if it was previously used for solid fuel appliances or fireplaces.

Cleaning the thermocouple/flame rod

To learn about water heater thermocouple, what is it used for and how to install/remove it... use this article.

Cleaning the thermocouple regularly will ensure a proper element work. Due to the corrosion, soot, dirt and grime buildup, the thermocouple cannot recognize the flame from the pilot and provide correct measurements (weak flame sensor current), resulting in a pilot outage, flame failure, and no water heating.

The solution for this problem is sanding the end of the thermocouple, a part which is in contact with the flame, by using the ultra fine steel wool or sandpaper and wiping it off with the cloth to remove the particles.

In a case of the tankless water heaters that are equipped with the flame rod or electrodes, use the same idea for cleaning.

Remember, turn the power off before performing any work.

Cleaning a water heater using a vinegar

Cleaning an inside of a water heater with the vinegar is an easy job and recommended way to remove the sediments and limescale deposits from the tank.

The problem with the deposits is that they reduce the efficiency and make the unit run harder than it should do. If the regular flushing cannot remove the buildup and deposits, use vinegar, as it helps to break down and loosen the deposits into small pieces making it easier to flush them out.

You might need a few gallons of vinegar for this job. Basic flushing requires only the drain valve and garden hose, while here you also need access on the tank and where to pour the vinegar.

The perfect spot for that is an opening where the anode rod is installed.

Other than that, the rest of the procedure is the same.

Here are the basics:

  • First, remove a few gallons from the water heater tank using the garden hose.
  • Close the drain valve and all taps.
  • Remove the anode rod located at the top of the unit, and pour the vinegar using the funnel.
  • Put the anode rod back (if it got deteriorated, replace it).
  • Open the cold water supply to fill up the tank and stir up the water/vinegar solution.
  • Let it stay for a few hours then flush it out from the tank. Be aware that some large pieces might clog the drain valve.

Why cleaning hot water heater

There are many problems associated with the dirty and clogged heater elements. The following issues will be easily prevented if cleaning hot water heater regularly.

  • Main burner or pilot will not ignite.
  • Burner flame is yellow.
  • Pilot flame too small.

Reasons: Pilot line, burner line or orifice is dirty and clogged.

  • Smoking and carbon formation.
  • Combustion odors.
  • Sooting.
  • Slow hot water recovery.
  • Burner flame floats and lifts off ports.

Reason: Air supply or flue pipes are obstructed, clogged burner.

Cleaning an electric water heater

If using the electric water heaters, sediment buildup at the tank bottom may create the annoying noise, and if left there, without cleaning, will cause the permanent tank failure.

As the sediments can build-up on the heating elements, for cleaning sediments from a water heater elements follow the instructions to drain, flush and clean it, or if necessary to replace it.

› Cleaning tips

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