Hot Water Cylinder Buying Guide
A hot water cylinder stores hot water and supplies it throughout your home, whether that’s to showers, baths, or taps. If you’re looking to upgrade your current hot water cylinder, perhaps to increase water capacity or because the existing tank is a little worn, then you’ll need to know which type of cylinder you need, and this depends on your heating system.
In this guide, we’ll cover the two different types of hot water cylinder available along with their unique features and how they work.
Different Types of Hot Water Cylinders
Hot water cylinders come in two different types; unvented and vented. Both heat water in the same way, which is via a coil housed within the cylinder. However, the key difference is how they are fed water. An unvented cylinder takes water directly from the mains supply, whereas a vented cylinder is fed water from a cold water tank.
Unvented Hot Water Cylinder
An unvented hot water cylinder is fed directly from cold water mains meaning there’s no requirement for a water tank in the loft. A key benefit of not needing a water tank means there’s less risk of reduced water supply, as tanks can freeze over in colder months.
They also don’t require a cistern tank so they can be installed pretty much anywhere in the home. As they take water directly from the mains supply this allows for increased water pressure, which helps to improve water flow to things like baths and showers and negates the need for installing a pressure pump. A popular option, unvented cylinders are considerably quieter when compared to vented cylinders, keeping noise and disruption to a minimum.
That said, they tend to be more complicated to install due to the additional safety measures needing to be carried out. Storing and heating water directly from the mains water supply means they operate under high pressure resulting in increased maintenance and servicing costs.
Advantages
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No requirement for a cold water tank
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Can be installed in most places
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Better water pressure
Things to Consider
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Complicated to install
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Higher servicing and maintenance costs
Vented Hot Water Cylinder
A vented hot water cylinder takes on a more traditional function where a vent pipe connects from the cylinder to a water storage tank that’s usually located in the loft. So, instead of being fed water directly from the mains supply, it takes it from the water tank.
As a vented cylinder relies on gravity this does mean that it needs to be located beneath the water tank. Compared to unvented cylinders, water pressure can sometimes be lower which impacts water flow to your taps and showers, especially those in lower or ground floors. Typically, the higher the water tank the greater the water pressure. That said, water pressure can be improved by installing a pressure pump.
While they require more space due to their need for a cold water tank, their simple design does mean they’re easy to install and maintain with easy access to the tank, if required. Keep in mind that if your loft gets particularly cold in winter months, the tank could freeze over hindering water supply.
Advantages
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Lower purchase price
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Easy to maintain and install
Things to Consider
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Water supply can be affected if tank freezes over
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They require more space
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Lower water pressure
Key Hot Water Cylinder Features
Hot Water Cylinder Material
The majority of hot water cylinders are available in either copper or stainless steel. Stainless steel is much more resistant to corrosion making the cylinder more durable. However, copper has a higher thermal conductivity meaning that water stays hotter for longer. For this reason, copper cylinders usually carry a higher price tag although they’re less expensive to run due to the increased heat conductivity.
Hot Water Tank Capacity
Tank capacity refers to how much water can be stored within the cylinder. Before purchasing a new one, it’s important to consider how much hot water you need to supply your home and this will be based on the size of the household. As well as baths, showers, and sinks don’t forget about other common household appliances such as dishwashers and washing machines.
Direct VS Indirect
An indirect hot water cylinder is fed hot water from a boiler. This hot water passes through a coil within the cylinder and the heat transfers to the water housed inside getting it up to temperature. Conversely, a direct hot water cylinder has no coil but instead an immersion heater which heats the water. Some indirect cylinders also feature immersion heaters but these are typically used as a back-up.
Energy Efficiency
An unvented water cylinder is usually more efficient when compared to vented as it draws water directly from the mains supply. Another consideration is the size of the cylinder, larger tanks require more energy to heat up the water and tend to encounter heat loss due to the volume of water. A good way to improve the energy efficiency is by installing a hot water cylinder jacket which can help to retain the heat.
