Anode Rod, WH shut-down & Combustion Air: Water Heater Maintenance Part 3

Water heater maintenance Part 3 explains sacrificial Anode Rod maintenance, vacation and extended shut-down of the water heater, water heater’s combustion air.


You have reached Part 3 of Tank Gas Water Heater Maintenance

Water Heater Maintenance
Part 1
Water Heater Maintenance
Part 2
Water Heater Maintenance
Part 3

Use the navigation above to revisit Parts 1 & 2 of this important gas water heater maintenance procedure.
Part 3 covers the following:

  • Sacrificial Anode Rod maintenance
  • Vacation and extended shut-down of the water heater
  • Water heater’s combustion air – extremely important!

Tank gas water heater maintenance – the Sacrificial Anode Rod

The anode rod purpose is to prolong the life of the water heater’s glass lined tank. While protecting the tank from corrosion the rod deteriorates. It’s performance and the life span depend on the water conditions in your area, which will influence the time intervals for the anode rod’s evaluation, and replacement if such is required.

If you have a good quality water supply and you’re not using any water softening systems, water heater maintenance will not be that extensive and you can expect the sacrificial anode rod to last approximately 3-5 years. However, the softener system or an acidic water source will cut that time in half or even more thus increasing water heater maintenance

Therefore, my suggestion is to have a professional performing at least the first time evaluation of the water heater’s sacrificial anode rod. The plumber will be able to show you what tool would be the best to remove it (1 1/16″ socket wrench in most cases), how to determine the remaining life span of the rod, and hopefully come up with a time frame for the next check-up.

Water heater maintenance - most typical / exposed sacrificial anode rod hex head locationWater heater maintenance - replace deteriorated anode rodWater heater maintenance 3 – Tank water heater sacrificial anode rod access.
In most residential tank type water heaters it is fairly simple to locate the anode hex head screw on top of the appliance’s enclosure.

However, in some water heater tanks this access might be obscured and without information about a particular appliance design and extra tools you may not be able to find it – get a plumber.

Water heater maintenance 3 – Perform the anode rod maintenance inspection by following these steps:

  1. Turn off the water heater’s gas supply (lower the thermostat to minimum, set the regulator to OFF and / or turn OFF the shutoff valve) / turn off the electrical power supply if such exists
  2. Turn off the cold water supply at the water heater cold line and at the the main water shutoff
  3. Release the water pressure by opening any of the water faucets located below the top part of the water heater’s tank level. If you have any faucets on the floors above the water heater level, open those faucets as well and wait until there’s no water coming out of the lowest faucet (leave it open for the rod inspection)
  4. If there’s no faucets below the water heater’s top plate level (for example: a water heater located in the crawlspace or a basement with no extra sink) you’ll have to used the WH’s drain valve to release the pressure and drain water from the system
  5. Use a 1 1/16″ socket wrench to unscrew the rod (you may also need a breaker bar, especially on older water heaters)
  6. Carefully (to prevent it from breaking apart if severely deteriorated) pull the anode rod from the water heater’s tank and depending on its condition: clean it or replace it with a new one. I’ll try to get some pictures for you so you know what to expect.
  7. Reverse the procedures above

Completely removing the anode rod from the water heater’s tank (except for inspection and/or replacement) will void the warranty and shorten the life span of the glass lined tank.

Tank gas water heater maintenance Part 3 – Vacation and Extended Shut-Down of the water heater

Whenever your water heater is to remain unused for an extended period of time, you can save money and energy by simply turning off the gas, power supply (in some models), and water feed to the appliance.  This will also prevent a build-up of dangerous hydrogen gas.

Hydrogen gas can be produced in a hot water heater that has not been used for some period of time, usually more than 2 weeks.


To safely disperse such gas and minimize risk of injury, open the kitchen hot water faucet for several minutes prior to operating any of the electrical appliances that might be connected to the hot water system. Refrain from smoking or using an open flame near the faucet.

A typical hydrogen confirmation presence is a sound of air escaping through the open faucet as the water begins to flow.

Water heater maintenance 3 – Planning to leave your house completely unattended during the winter / concerned about freezing?

  • Consider draining the tank water heater and piping if they might be subjected to freezing temperatures. If it’s a long shut-down period, have a professional check your water heater’s operation. If you decide doing it on your own, make sure the water heater is re- filled completely prior to starting its heating cycle.

Water heater maintenance 3 – plumbing system draining pros:

  • If you turn off the water to your property and properly drain / air blow the entire system, you don’t have to worry about freezing, cracking  pipes, and flooding.

Water heater maintenance 3 – plumbing system draining cons:

  • Anode rod helps to protect water heater’s tank from corroding but only while filled with water. Even its interior walls are glass-like ceramic coated, its rust-resistance will be compromised when empty.

Final gas water heater maintenance requirement – combustion air (applies to all fuel burning appliances)

Gas water heaters require oxygen from air to burn its fuel (gas or oil), which is called a combustion process. Consequently, this air required for water heater’s combustion is called “combustion air”.

An insufficient amount of combustion air supply results in an incomplete combustion process. As a bi-product of such incomplete combustion, Carbon Monoxide is released to the WH surrounding area, and this could be deadly for you.
Unfortunately many of us don’t understand it or simply forget about it. Therefore, I highly recommend following this link and educate yourself about combustion air – combustion air minimum requirement

Some basics of the water heater maintenance concerning combustion air:

  • The water heater takes its combustion air through the openings around its base (sides and / or underneath the bottom plate). DO NOT block or obstruct any of those combustion air inlets. Keep anything at least 1” away from them.
  • DO NOT store ANY combustible materials (wood, paper, fabrics, etc.) or flammable liquids (paint, paint thinners, aerosol spray, gasoline, etc.) near the water heater.
  • Make sure that the water heater location has plenty of fresh air circulation – combustion air
  • Maintain functional Carbon Monoxide detector(s) and smoke alarms in your home – check Home Safety category for details.

That concludes Part 3 of the tank gas water heater maintenance, let me know if you have any questions. If this is where you have started from, make sure that you go over Parts 1 & 2 of water heater maintenance.

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