July 31st, 2023 by Shauna Hammond

Water heaters are an incredibly important part of your home or workplace and with so many different types available on the market, for those of us who are not experts in the subject, it can be confusing understanding the difference between the range of models and types available and choosing the right one to suit your needs. In this blog, we will look to outline the difference in the most popular kinds of water heaters in order to give you a better understanding so you can select the right unit to suit your needs.

Instant Vs Non-instant

Most of us are likely familiar with traditional water heaters which consist of a large tank of hot water that is heated up as needed, these tanks will often hold a certain amount of hot water which will then need to heat up again after use. These water heaters have been most common in the UK for years and are still found in older homes. However, with the advancement in technology, we have seen a recent surge in the popularity of instant or tankless water heaters.

Unlike more traditional water heaters, instant hot water heaters do not have a storage tank and therefore do not store or hold hot water. Instead, these units use a combination of electricity and a heating element to heat up water (instantly) and will continue to provide hot water for as long as your run the faucet.

This means that instantaneously heating your home's plumbing will use less energy than maintaining a constant flow through your pipes by keeping them warm all the time (which is what happens when you use a traditional heater). However, instant hot water heaters do also have their set back such as if someone turns on their shower while another person is taking one in another room, there won't be enough hot water for both showers. This is why the installation of multiple water heaters may be required. The temperature is also dictated by the amount of water pressure too, so it is important to check your water pressure to see what sort of temperature you can achieve, after all, you do not want to make the switch to an instant hot water heater to find that you can only enjoy lukewarm water. If you have low pressure or do not have the space to accommodate multiple units then a tank is likely to be more suitable for your needs.

Instant hot water heaters are often a popular choice, for smaller homes such as flats or bungalows. They are also a great option for businesses such as hair salons, cafes, and restaurants where a constant supply of hot water is required.

Perfect 45 Instant Undersink Instant Water Heater, 4.5KW

Price: £125.94

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Vented

While browsing for your new hot water system you will likely come across vented and unvented units, but what exactly are they? Well, Vented water heaters use a combustion chamber where a burner ignites fuel (such as natural gas or propane) that will then heat up the water. This combustion process then produces by-products and gases that need to be safely directed out of the combustion chamber which is done by the presence of a flue or a vent pipe – this vent usually runs from the water heater towards the ceiling to direct the by-products out of the home via the vent or some older models may use a chimney this ensures that these gases do not accumulate in the home and become a health risk.

Vented water heaters are considered safe and have been used for many years, however, they do require proper installation to ensure it is correctly ventilated these units also require regular maintenance in order to continue operating safely. This is to ensure that the vent does not become damaged or that the system does not become blocked with debris which can result in a potentially hazardous build-up of gas.

Unvented

This brings us to the next water heater on our list which is unvented heaters, unlike their vented counterparts these units are more energy efficient and they also have a longer life span too. These unvented units usually have a small tank capacity or no tank at all – such as instant hot water heaters.

Unvented water heaters can use either electric heating elements or gas burners to heat the water either on demand or in a storage tank.  Gas-powered unvented water heaters use what is known as a heat exchanger which transfers the heat generated by burning gas to the water passing through the unit or electric models use electric resistance coils to heat the water directly.

Newlec 15 Litre Under Sink Unvented Water Heater

Price: £263.99

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Under-Sink

An under-sink water heater is a small tank that can be installed underneath your kitchen sink. It's connected to the plumbing system, and it heats up the water by using electricity or gas. The heat source is usually in an electric resistance coil (which is similar to what you find in hair dryers), but some models use natural gas or propane as well. The benefits of having an under-sink heater are that they are easy to install since they just need to be connected to your existing pipes. Since they are installed under sinks they also do not take up too much room and they are also out of sight which makes them more appealing for use in homes.  They also require minimal maintenance; however, these units do have a shorter life span than some other models.

Over-the-Sink

Over-the-sink water heaters are a great option for small kitchens, but they do come with some drawbacks. They're easy to install, but they require a dedicated circuit and are more expensive than other types of tankless units. They also have higher efficiency ratings than vented models--which means that you'll save money on your energy bill even after you factor in the cost of the unit itself. These types of water heaters are usually more suitable for hand wash sinks, or for use in hair salons to be installed above basins.

Newlec Manual Hand Wash Unit 3KW, NLMHW3KW

Price: £133.79

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Choosing the Right Water Heater for Your Needs

So now that we hopefully have a better understanding of the different kinds of water heaters, you are hopefully better able to select the right kind of unit for your needs. However, if you are still not sure here are a few things to consider:

What is your heater going to be used for – for example, is it solely going to be used as a hand wash basin or do you want it to heat water for multiple outlets?

Is it important to be able to have multiple supplies at once – will multiple outlets be using hot water at one time?  

How much space do you have to spare this is especially important if you are considering a storage tank – as the more storage you require the larger the tank will be.

Finally, carefully consider the price of both the initial purchase and installation but also consider the running cost and maintenance costs and ensure that this is achievable and within your price range.

As you can see, there are many different types of water heaters available for sale today. The most important thing is to choose one that works best for your needs and lifestyle. Take time to consider all the options, and discuss in detail with the professional who will be installing your unit as they will also be able to provide assistance in terms of technical queries.