The Basics About Water Heaters: Types, Parts and How They Work 

Water heaters are among the most essential appliances in your home or business. It allows you to get warm water for a refreshing shower, or wash up, or it can be a critical resource or health and safety element within your business.

A water heater requires regular maintenance to ensure its peak performance and this is only possible when you understand its operation. 

But how many homeowners know the type or understand the functionality of their water heater? Here are all the vital electrical water heater fundamentals you should know. 

Total Boiler Services are experts in all types of water heaters, boilers and plumbing. If you need help or advice please contact us today on 02922 407934 and one of our advisors can answer any questions you may have.

What are water heaters? 

A water heater is an electric appliance that heats water in a property and circulates it to different water fixtures for showering, washing, laundry and much more. A water heater uses electricity or gas as fuel to heat cold water. Whilst electric-supplied heaters use an electrical element to warm the water, gas heaters apply combustion to do the same thing. A water heater is essential for energy efficiency and comfort in a property as they heat water on demand. 

What are the different parts of a water heater?

There are three main sections on a water heater that work to heat cold water, these include:

The Tank 

The water heater tank is the reservoir that holds the water, usually made from heavy metal like steel. The interior of the tank features a protective lining to prevent corrosion, and the exterior is covered with an insulating material such as polyurethane foam to reduce heat loss. 


The thermostat acts as a regulator in the water heating system and controls the water’s temperature. It is located close to the burner and controls the temperature to which the water is heated. 

The Heating Element 

The heating element is used in an electric water heater, whilst a burner is applied to gas water heaters. The heating element is usually located at the bottom of the tank and functions to warm cold water. 

What are the types of water heaters? 

There are five common water heater types that perform the same function but in different ways. Understanding these differences will help you select the suitable unit for use at home: 

Storage Water Heater 

Storage or tank water heaters are the most common and come with a large tank in which the cold water is heated and kept at the required temperature.

These either use electricity or gas as a power source. Typically, an electric water heater is cheaper, whereas gas water heaters or gas burners provide faster heating. A tank water heater must be cleaned and flushed regularly to remain in good working condition. 

Tankless Water Heater

These water heaters don’t have a tank to store cold water. Instead, they heat the water on demand as it flows through them, allowing you to enjoy an unlimited hot water supply via a drain valve. Tankless water heaters tend to be more power efficient since they only heat the water when it’s needed and not continually heating the water in a tank. 

The only downside of a tankless water heater is that it has a higher initial investment cost than a storage water heater. They may also struggle to supply water to several fixtures simultaneously, which can be inconvenient. 

Heat Pump Water Heaters 

These water heaters don’t use the traditional heating element to warm the water. Instead, they transfer heat in the air outside a building to the water in the reservoir. This more efficient unit results in lower energy bills as little energy is required to operate the system. 

A heat pump water heater can only operate outside under a specific minimum temperature, making them suitable for use only in warmer climates. They may not function in extremely cold locations. 

Solar Water Heaters 

Solar water heaters are fitted with solar panels that absorb solar energy to heat the water. The most significant benefit of these types of water heaters is that they operate freely, and you don’t have to control them. They will heat your water when the sun is out. On the other hand, they can only be effective in areas that are warmer with more constant sunshine. When there is a lot of cloud cover or the weather is rainy, the heater won’t work effectively. 

Condensing Water Heaters 

This type of water heater can only work in residences with a natural gas heating element. This is because they use exhaust gases from the central heating system as an energy source to power the heating element instead of using the gas directly, as in standard water heaters. This is also an energy-efficient option that can save you money in the long run.

Water Heaters

What are the typical water heater issues? 

A water heater may start experiencing different issues due to its age or when it is neglected and isn’t serviced and maintained as it should be. The main issues include: 

Temperature Issues 

When there is no hot water from your shower, or the water temperature keeps fluctuating, there might be a problem with the heating element or thermostat. These might need repairs or replacements. 


A leaking water heater signifies a range of problems, including a faulty pressure relief valve, incorrect water pressure, a spoilt gasket, a stuck valve, or loose bolts on the heating element. In any case, you should call a plumber to check it out. 

Discoloured Water 

When the water coming is dirty or murky, chances are the metallic elements inside the heater are rusting, and this will contaminate the water and change its colour. 

Noisy Water Heaters 

A standard water heater produces a little noise when operating, but this can sometimes get louder than usual, signifying something is wrong. Usually, it’s because of a build-up in mineral segments at the base of the tank that vibrates to produce the concerning noise.

What to do when a water heater develops issues 

The best thing to do when your water heater is not working as it should be is to call a professional heating engineer. They know how to accurately check and diagnose the problem before carrying out the required repairs.

 In Summary 

Understanding how your water heater works goes a long way to keeping it functional in the long run. While there are many types of water heaters, they all apply the same concept in their workings, which you need to know to maintain and care for your water heater appropriately.

If you are unsure of the water heater you have or need, Total Boiler Services Heating Engineers will come out and assess your system and property and advise you of the best system for you, or which water heater you have. Our expert and qualified engineers offer advice based on their ongoing training and industry knowledge and will only recommend a change to you if it is needed and it is beneficial to you in the long run.

Contact us on 02922 407934 or email us today to book your no-obligation assessment, repair, service or new installation for your home or business.