How Does A Water Heater Work?

Hot water is most often given less credit for its essentiality in the house. You only notice this when your water heater malfunctions or refuses to work entirely, thereby causing delay or difficulties in utilizing some basic things like hot showering, using the dishwasher, or doing the laundry. 

To avoid this, you need some basic knowledge of how a water heater works to ensure proper maintenance of said heater in your home. Also, see here for the Best Electric Swimming Pool Water Heaters For In-Ground and Above-Ground Pools. Another important aspect in your home that you must always check is the ‘cleanliness’ of your drinking water. If you want the most innovative way of keeping your house’s water supply free from toxic chemicals, might as well install a Springwell salt water softener

How Does A Water Heater Work?

Most homeowners don’t know how to properly maintain their water heater as the said heaters are known for their utmost functionality and durability. But these are machines and when not fully accorded their dues, will start misbehaving. 

Water heater systems can be majorly categorized into two (though there are different types of each) which are tank-type and tank-less water heaters. Check out water heater maintenance for more information.

Tank-Type Water Heater 

Tank-type water heaters look like big metal cylinders equipped with a heating mechanism at the bottom or inside depending on their source of energy. 

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Components of Tank-Type Water Heater


This is the drum or metal cylinder that houses water and where all the processes of heating the water come to play. The inner compartment of the tank is a heavy metal-containing water protective liner while the exterior of the tank is protected with insulating material. Over that, there is a decorative outer shell and possibly an additional insulating blanket. 

A typical tank can hold 40 – 80 gallons of water depending on the household requirements.  You can also check out water heater problems for more great options.

Dip Tube 

Here cold or cool water enters the heater by passing through the dip tube at the top of the water heater. While the water travels to the bottom of the heater where it is been heated. 

Shut-Off Valve 

The shut-off valve stops the inflow of water into the heater. It is a separate component from the heater and is always located at the top of the unit. 

Heat-Out Pipe 

The heat-out pipe allows hot water out of the heaters whenever said is been called for. Suspended at the top of the heater, the heat-out pipe distributes hot water throughout the house. Hot water always stays at the top of the heater. 


This is the combination of a thermometer and temperature control device. It is used to regulate the temperature of the water in the heater. 

Heating Mechanism 

For electric heaters, the heating element is always inside the heaters to heat the water. While gas water heaters make use of burner and chimney system attached to the bottom of the heater. The gas burner light sending hot toxic air out through the chimney while the metal of the chimney is been heated which consequently heat the water in the tank. 

Drain Valve 

The purpose of the drain valve is to make it easy to empty the content of the tank, remove the element or sediments. It is located at the bottom of the heater. 

Pressure Relief Valve 

This helps to keep the pressure in the heater within safe limits. This ensures the water heater doesn’t explode. The pressure relief valve will open to release water if the pressure of the water is too high or the temperature is too much. 

Sacrificial Anode Rod 

The rod is made of magnesium of aluminum with a steel core. This rod rust faster than the metal making up the heater tank thereby preventing the heater tank from rusting. 

Tank-Less Water Heater 

As the name implies, this water heater doesn’t have the storage capacity to keep hot water and as such provides water on demand or instantaneously often fitted where it is needed. 

It can either be a point-of-use model or whole-house systems, but both make use of the same strategy in heating water with slight differences. 

Its sources of energy can be propane and natural gas for whole-house heaters while electricity is often used for point-of-use heaters. 

Depending on the required flow rate and temperature, you can choose between the two. 

How it works

When the hot water tap is switched on and water is drawn into the unit, a flow sensor activates an electric heating element or gas burner which will warm the internal heat exchanger. 

Coldwater passing through the heat exchanger get warm to a preset temperature from the thermostat. 

It has similar components to the tank-type heater such as a valve for emptying the tank, an anode rod against the heater rusting, a heat-out valve for hot water distribution, cold water in the pipe, burner, or electric element.