Hot water cylinders are continually increasing in popularity and can now be found in most homes across the UK. They are commonly used to ensure that a copious amount of stored hot water is available on demand for a multitude of domestic uses. Unvented cylinders are connected directly to the mains water system so there is no cold water tank, which means they offer high water flow rates to provide higher water pressure for showers and baths.
An unvented cylinder is heated by either immersion heaters (a direct model) or by a heat source located outside the vessel such as a boiler or wet solar system (an indirect model).
Unlike vented cylinders, there isn’t a vent pipe or tank to cope with excess water as it heats and expands. To remedy this unvented cylinders have inbuilt safety features like an expansion unit at the top or an air bubble that is inserted at installation.
The installation of an unvented cylinder is considerably less hassle as it can be placed anywhere in your home and, with no water tank needed, doesn’t take up as much physical space.
Hot water cylinder capacity varies between 75 and 400 litres for domestic supply. The below figures are used by industry professionals as a guideline to the size cylinder you would require:
Bedrooms | Showers/Bathrooms | Indirect (litres) | Direct (litres) |
1 | 1 | 75/120 | 120/150 |
2 | 1 | 150 | 180 |
3 | 2 | 180 | 201 |
4 | 2 | 210/250 | 250/300 |
Larger Properties | 300+ | 300+ |
Here are a few brands and models of unvented hot water cylinders we recommend.
Cylinder Model/ Brand | Sizes Available (volume in litres) | ErP Rating (Energy Efficiency) | Heating Method | Warranty |
Megaflo Eco by Heatrae Sadia | 70 / 125 / 145 / 170 / 210 / 250 / 300 | B | Indirect or Direct | Lifetime |
Greenstore by Worcester Bosch | 90 / 120 / 150 / 180 / 210 / 250 / 300 | B | Indirect Only | 25 years |
Vitocell 200-V by Viessmann | 90 / 120 / 150 / 180 / 210 / 250 / 300 | C | Indirect but includes a backup immersion heater | 25 years against corrosion |
StainlessLite by Gledhill | 90 / 120 / 150 / 180 / 150 / 300 / 400 | C | Indirect or Direct | 25 years |
Tempest by Telford | 90 / 125 / 150 / 170 / 200 / 250 / 300 | C | Indirect or Direct | 25 years |
Getting started with boilerPRO is as simple as 1,2 3!
Book your repair, installation or survey using on onsite forms, live chat or calling our team on 0800 810 1112
Our professional team of engineers will be at your property to survey and in most cases, get started with the work.
Whether its a new install or just a fix – we’ll leave your property with high performing heat and hot water.
If you would like some further advice on unvented cylinders and whether or not you would benefit from one, then please give us a call.