Hot Water Cylinders Guide
If you’re not a heating engineer Hot Water Cylinders are not the easiest thing to get to grips with. There are a few different types available and understanding what you should be looking for can sometimes be a little bit confusing - hopefully our hot water cylinder guide will help to make things a little bit clearer!
In basic terms, the hot water cylinder you need for your property will depend on 2 things:
- How you intend to heat the water
- How you want the hot water to be distributed out across your property.
We provide further details about the different types of cylinder below but for more detailed advice about what you need for your home we advise that you talk to a qualified Gas Safe heating engineer.
Note: We strongly recommend that customers looking to purchase a hot water cylinder double check with their installer first to ensure it is the correct item needed for the installation. The return of hot water cylinders may involve a restocking fee - for further information please contact us or view our terms and conditions.
The water in a direct cylinder is heated ‘directly’ by the cylinder itself. Other appliances, such as boilers or solar panels are not used to generate the hot water within the cylinder. Instead an immersion heater within the cylinder itself is used to heat the water.
Some cylinders have more than 1 immersion heater installed within them to allow a more powerful performance, producing more hot water quickly.
Direct cylinders come as either vented or unvented models (this impacts on how the water is distributed across the property to the hot water outlets such as showers & taps) and they tend to be used when a traditional central heating system is not available.
Indirect Cylinders rely on external appliances to apply the necessary heat to the cylinder – this in turn generates the hot water that is stored, or also used as a backup if the main heat source fails. The water is “indirectly” heated by other appliances, this is typically a boiler but may also include a solar panel installation.
A heat exchanger within the cylinder transfers heat from the external appliance (i.e. boiler) to the water in the cylinder. Some indirect cylinders may contain immersion heaters that enable the cylinder to add additional heat to the hot water that is stored. For this reason indirect cylinders tend to be able to generate hot water more quickly than its direct counterpart and are either vented or unvented (this determines how the water is distributed across the property to the hot water outlets such as showers & taps).
If you need a cylinder that uses the mains water pressure to distribute the hot water around your property for use at your hot water outlets (i.e. taps, showers) then you will need to invest in an unvented hot water cylinder.
Unvented cylinders are commonly used as part of a system boiler installation as this enables you to take advantage of the high pressure water supply. If you have limited space in your loft then you will also be pleased to hear that unvented cylinders take up less space than vented cylinders as no feeder tank is required.
Vented hot water cylinders rely on a feeder tank to provide it with mains fed cold water. This water is then heated and is distributed to the hot water outlets (i.e. taps, showers) as part of a gravity led system.
Vented cylinders tend to be used alongside regular boiler installations, whereas unvented cylinders are commonly used with system boiler installations