Fully Pumped Sealed System
Boilers
Central heating systems currently being installed in the UK are increasingly of the sealed primary circuit type. This means the water heated by the boiler, which circulates around the radiators is held in a closed circuit under pressure. Such an arrangement has a number of advantages over 'open-, vented' or 'conventional' heating systems. Sealed systems are low maintenance, but are not maintenance free. Combination boilers invariably have sealed circuits.
Some of the advantages of sealed systems are:
- They are simpler to install since there is no header tank in the roof space, and consequently none of the associated problems (i.e. overflowing or freezing).
- They are easy to fill since air is expelled under pressure when bleeding the radiators.
- As the system is sealed, the problem of air being drawn into the system through open vents is eliminated, therefore the likelihood of airlocks, corrosion and sludge build up is significantly reduced.
- Increased pressure raises the boiling point of the water within the boiler, promoting quieter operation.
- There is a fixed volume of water within the system (i.e. the system will not replenish any losses automatically), so in the unfortunate event of a leak the escaping water is limited.
- They save space in locations such as flats, where there are usually no convenient locations for the header tank.
- The system can be flushed out under pressure using the mains water supply.