System Boilers supply the heat used in the central heating system in your building, and they are also used to produce the hot water used throughout the building. They are often called sealed boiler systems. As part of the heating system, hot water is heated and pumped around the sealed heating system to the radiators and storage tanks.

System boilers are rated by quality and the highest rating which is used to denote reliability, is the SEDBUK 'A' Rating. Costs of the boilers can vary, and they will depend a lot the quality and also on the options that are included.

System boilers can be more efficient as they are compact units that feature built-in operating components. These units are relatively easy to install, and take up very little space in your home or place of business. No water feeds or reservoirs are needed, and they cost less to operate and can also lower your heating costs. The water is fed directly from the main water supply, which can contribute to maintaining higher pressures; however, a hot water storage tank is needed. These boilers are often seen as a hybrid between popular combi-boilers because stored hot water is needed, as in the conventional boiler systems.

The boiler will often include an expansion container, which eliminates the requirements for water supply feeds, and no installation of tanks is needed in the loft area. These additional features allow homeowners to make more efficient use of space.

There are several Advantages to the use boilers of these types.
€ Because water is held in storage, higher pressures can be maintained.
€ No cold water tank is needed; space is saved as the water is delivered directly from the main water supply.
€ The installation is compact and neat, as all the major components needed for the operation are actually built in the boiler assembly.
€ They are suitable for larger homes, where hot water can be supplied to multiple outlets at the same time.
€ They are much simpler to install and easier to operate.

There may be also be a few disadvantages when compare to other types of boilers

Although they may be easy to install, depending on your environment or placement, installation can be expensive, and repairing them can also be expensive. You will also need some space for a hot water cylinder.
Boilers of these types may be more suitable for larger residences, as hot water can be supplied to several outlets simultaneously. Water flows are usually consistent, as no extensive piping is needed. Because they are lower maintenance, the boilers may also have a longer lifespan than other boiler types.

Dealers may offer different types of warranties on these boiler units, as they can offer the satisfaction of knowing that your boiler will operate with a minimum of interruption, and can be quickly repaired or replaced if necessary. The choice of warranty will depend on your expected usage, and other factors that may include how long you plan to stay in the residence.

System boilers can offer the advantages of convenience, while they also save space. Because system boilers do not need separate cold water sources, they can be used in larger homes, where hot water is sent to multiple outlets.