Hot Water Heater Parts

Review of the main parts on gas and electric water heater

This page is about hot water heater parts, where we are explaining the main components on electric and gas heating appliances. With the better understanding of component parts like gas valve, thermocouple, pilot light, venting system; it is much easier to pinpoint the problem and troubleshooting is simpler. With the help of these instructions there will be no need to call the expensive plumber or HVAC technician to repair or replace parts.

Hot water heater parts article will cover mainly storage gas and electric tank heaters as the most common source of the residential water heating. Use this article for tankless water heater parts.

Further, through the following articles we will review different manufacturers like Rheem, GE, Whirlpool, Bradford White, AO Smith, to show you the difference, what the common replacement parts and heating process technology are.

The main Gas and Electric Water Heater Parts

thermostatSome water heater components are almost mandatory in the heater design and construction, whilst other are for efficient heating operation and better safety. Such a difference will provide longer warranty and higher prices.

Majority of storage tank heaters are made of carbon steel, Rheem Marathon electric heater is constructed of the plastic tank that automatically eliminates the need of using the anode rode for corrosion protection.

Gas valve

gas valveRobertshaw and White-Rodgers are two of the most used manufacturers for gas control valves. Gas valve is the heart of the water heater as it supplies natural or propane gas to the burner and pilot light, and is also a safety device.

Both manufacturers have similar elements like gas control knob, reset button, high water temperature limit safety and temperature dial.

Heating elements

Electric heating elements are the source of heat within electrical appliances, usually consisted of the upper and lower elements. These electric water heater parts can be also found in solar heating systems.

Anode rod

hot water heater anode rodAnode rod protects the steel metal tank from corrosion, together with tank's glass or ceramic lining. Usually called sacrificial anodes, it sacrifices itself in order to extend tank's life.

How it affects your water heater performance and what are the common problems with water heater anode read further.


Venting system serves to vent products of combustion out through the flue baffle and vent pipes, and in some models to draw the fresh air in, needed for gas combustion. Based on your preference, your home design and construction, location of the heater and other requirements you can find different types of venting systems:

  • Two-pipe closed combustion system eliminates problems caused by insufficient indoor ventilation, while it draws fresh air from outside the home.

  • Two-pipe or one-pipe atmospheric vent system with drafthood.

  • Concentric vent system is consisted of two pipes; larger pipe is used to draw the air in, inside pipe is designed to direct the gases out. It can be used with or without electric powered blower.

emergency plumber


Electric blower is using 110/120 volt electrical system, usually rating 3 amps or less and is equipped with 6-foot cord.

Dip tube

Dip tube is the cold water inlet extension, and some manufacturers like Bradford White are using a perforated tube to reduce the lime and sediment buildup and maximize hot water output. It is usually made of PEX polymer.

Gas burner assembly

The most important among hot water heater parts on gas fired appliances is the gas burner assembly, consisting of several components such as:

  • Main burner, manufacturers Rheem, AO Smith, Bradford White, are promoting Eco-friendly burners that reduce NOx emissions by one third when compares to the standard burners.

  • Burner orifice

  • Manifold tube

  • Pilot burner / pilot light with pilot tube and orifice. On water heaters with pilot light, pilot burner remains ON once it is manually lit. It is used to ignite the gas. Some manufacturers are using hot surface or electrodes instead of pilot flame.

  • Igniter like piezo electric is used to lit the gas.

  • Thermocouple is the safety part used to send the signal from pilot light to the gas control valve, by the small electrical current, to inform is the flame present or not.

  • ECO or Energy Cut Off is the metal tube (temperature probe) which is mounted onto the back of the gas valve and immersed inside the water tank and acts as the temperature high limit.

  • TCO or Thermal Cut Off Switch is a resettable thermal switch, constructed to shut off the gas supply if the temperature of products of combustion is too high.

  • Mechanical type thermostats are used on standard residential water heaters. Thermostats are usually factory set on 120 F to prevent scalding water, and they operate with certain tolerance. If it is set on 120 F, they might turn the burner off at hot water temperature between 110 and 130 F.


Fire-proof flame arrestor, built in the water heater base, is part of FVIR or Flammable Vapor Ignition Resistant technology that deals with the accidental or unintended ignition of flammable vapors.

TPR valve

TPR valve or temperature and pressure relief valve is used to protect the system from the excessive hot water pressure. It is usually combined with discharge pipe to an adequate drain.

Air pressure switch

Air pressure switch is used on all gas water heaters that are using electric powered blower for venting products of combustion. It is used for all power vent and power direct vent heaters to verify that operational conditions are met.


Different foam thickness around the tank will provide more or less savings in energy and heat waste, efficiency and performance improvement. This is why some manufacturers are designing hot water heaters with 2" inch high quality insulation, while with low efficient heaters you have to use an insulation blanket.


Installing the electric water heater timer is one of the great ways to save you money on your electric bills and water heating costs. The water heater timer is designed with one goal only; to turn the water heating off during periods when hot water is not used.

Majority of the above water heater parts are the main components on gas units, while electric appliances are much simpler.

What you should know when ordering gas or electric water heater parts:

  • Have complete part number and description.

  • Have water heater model, series and serial number.

Note: If any part of the water heater has been under water, you should call a qualified service technician. If water heater has been subjected to the flood conditions or any of its component parts including gas controls, main burner, pilot light submerged in water, you should replace the entire water heater.

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