The government’s drive to reduce the UK’s carbon footprint has prompted millions of householders across Britain to upgrade their central heating systems.
System boilers are best suited to large households with two bathrooms and sufficient storage space to accommodate a hot water tank or cylinder.
Modern boilers are much more energy efficient than old boilers and can save hundreds of pounds on your heating bill. According to estimates published by The Energy Savings Trust, detached homes can save as much as £305 a year.
| Old Boiler Rating | Semi-Detached House | Detached House | Detached Bungalow |
| G <70% | £200 | £305 | £155 |
| F <70-74% | £140 | £210 | £105 |
| E <74-78% | £120 | £180 | £90 |
| D <78-82% | £105 | £165 | £85 |
System boilers are ideal for larger homes and properties that use large quantities of water. Before investing in a new system boiler, it is important to consider certain factors.
Pressurised system boilers are also known as ‘sealed system boilers’ and are ideal for supplying water to multiple users at the same time without losing any pressure.
Other than being more cost-effective to run than conventional boilers, they also take up less space. System boilers have heating components built into the unit and do not require a cold water storage tank.
How Does A System Boiler Work?
System boilers take water directly from the mains and heat it in a single storage cylinder. This water is then distributed to radiators, taps and showers. As a result, you get hot water on demand almost instantaneously.
The only drawback is that hot water cylinders can only hold a certain amount of hot water at any one time. This can result in the loss of hot water when running a bath or taking a shower if a lot of water has been used over a short space of time.
How Much Do System Boilers Cost?
There are numerous pressurised system boilers available on the UK market. The price will depend on the manufacturer, model and size in kW. System boilers can cost anywhere between £500 and £3,500.
The cost of fitting a system boiler in your home will also vary from one installation company to the next. It is advisable to look for at least three quotes in order to find the best deal.
Pros and Cons of a System Boiler
Advantages
- Saves space in loft or garage
- Instant access to hot water
- Acquires water directly from mains
- Hot water available to several users at the same time
- Easy to install and operate
- Compatible with solar-panel heating systems
Disadvantages
- Storage space has to be large enough to accommodate a hot water cylinder
- Risk of running out of hot water
- Can’t be installed into an old heating system
System Boiler v Condensing Boiler
System boilers and condensing boilers, or combi-boilers are similar in that they both supply water from the mains. However, there are significant differences between the two that you should be aware of.
Condensing boilers are best suited to small homes. The units are much smaller than system boilers so don’t take up as much space. A combi-boiler is small enough to fit into a kitchen cupboard or under the stairs.
System boilers require a tank or cylinder in which to hold and heat water. This still means you can get hot water on demand but the units take up more space.
The advantage is that multiple users can source hot water at the same time from a system boiler. With a combi-boiler, a shower will lose power and heat if you run water from a tap.
Combi boilers also give priority to hot water, so you may find you radiators lose heat whilst the shower or bath is running. System boilers can maintain both the radiators and water without losing pressure.
System boilers do not prioritise where heat is distributed. However, they can run out of hot water if you use more than is stored in the tank.
System Boiler v Regular Boiler
System boilers and regular boilers are better suited to larger households, and whilst both have pros and cons, there are subtle differences you should be aware of.
The main difference is that system boilers only have one tank which is used to heat the hot water. Regular boilers, also known as heat-only boilers, need a second tank to store cold water.
Although regular boilers require more storage space, they have an advantage over system boilers in that they never run out of hot water. Heat-only boilers consistently source water from a cold water tank so that the hot water is always full.
On the other hand, system boilers save space and you don’t have the risk of cisterns fitted in the loft or garage freezing over when temperatures hit below zero.
Regular boilers are better suited to houses that have traditional heating systems installed, although they do take longer to fit than system boilers. Subsequently, the cost of installation and repair is typically higher than system boilers.
Best System Boilers
There are many makes and models of pressurised system boilers. Below we have picked out a selection of the best system boilers available in the UK that are recommended by professional boiler engineers and customers ratings.
| Manufacturer | Ranges | Outputs | Warranty | Price |
| Ideal | Logic and Vogue | 15-40kW | 5-10 years | £926-£1135 |
| Worcester-Bosch | Greenstar | 18-34kW | 5-years | £759-1847 |
| Viessmann | Vitodens | 4.7-35kW | 2-5 years | £1013-£1444 |
| Baxi | EcoBlue, Megaflo | 12-32kW | 7-years | £639-£1130 |
| Glow Worm | Flexicom, Ultracom | 12-38kW | 5, 6,or 7-years | £615-1788 |
Interested in buying a System Boiler?
Now you’ve decided that a pressurised system boiler is the best heating solution for your home, why not use our free service to help you find the best quote. We recommend obtaining at least three quotes from reputable installers so why not take advantage of our no-obligation service today.