System Boiler Heating Systems

System boilers come in two types, a vented low pressure and an un-vented high pressure system. Both require a Hot Water cylinder. Vented system boilers require a storage tank but most of the other components are held in the unit itself which means that installation is quicker and cheaper. Also, the hot primary water is pumped through the system to the radiators and hot water cylinder resulting in a faster response and more economical running costs.

Un-vented system boilers incorporate the equipment necessary to form a sealed system including a pressure relief valve and a pressure gauge, removing the need for a feed and expansion tank.

What are the advantages of a System Boiler Heating System?

• Good in areas with poor water pressure
• Suitable for houses with 2 or more bathrooms
• Stores water in tank should there be a shortage
• Heating circuit for the radiators is sealed avoiding contamination
• Hot water can be pressurised if used in conjunction with an un-vented hot water cylinder
• High Efficiency Condensing versions are available
• The pressure gauge for the central heating will detect leaks

Disadvantages of a System Boiler Heating System

• Need 1 tanks in the loft and a hot water cylinder
• System can be more expensive for new installations or where an un-vented cylinder in added
• As the central heating is under pressure there may be a chance of older systems leaking
• Hot water can be an open circuit vulnerable to contamination (not the case with and un-vented cylinder)

Selecting a System Boiler

Once you have decided a System boiler design is best for you, you then can decide on a boiler.

We recommend a condensing boiler from one of the following 2 boiler manufacturers:

• 
• 

We recommend these manufacturers for their:

• Quality
• Reliability
• Comfort
• Customer care
• Value

Two other manufacturers that rank highly and may have appeal for those on a budget are:

• 
• 

System boilers

Make	Model	Power	Warranty	Controls	Size (mm) HxWxD
Worcester-Bosch	Greenstar 30Cdi Sys	30kW	2 years	Central Heating, Display	760x440x360
Worcester-Bosch	Greenstar 12i Sys	12kW	2 years	Central Heating	710x400x330
Worcester-Bosch	Greenstar 24i Sys	24kW	2 years	Central Heating	710x400x330
Vaillant	Ecotec Plus 612	12kW	2 years	Central Heating, Display	720x440x335
Vaillant	Ecotec Plus 615	15kW	2 years	Central Heating, Display	720x440x335
Vaillant	Ecotec Plus 618	18kW	2 years	Central Heating, Display	720x440x335
Vaillant	Ecotec Plus 624	24kW	2 years	Central Heating, Display	720x440x335
Vaillant	Ecotec Plus 630	30kW	2 years	Central Heating, Display	720x440x335
Vaillant	Ecotec Plus 637	37kW	2 years	Central Heating, Display	720x440x335
Alpha	CD12S	12kW	3 years	Central Heating, LEDs	720x440x340
Alpha	CD20S	20KW	3 years	Central Heating, LEDs	720x440x340
Alpha	CD28S	28KW	3 years	Central Heating, LEDs	720x440x340
Baxi	Megaflo 24HE Sys	24KW	2 years	Central Heating, LEDs	780x450x345
Baxi	Megaflo 28HE Sys	28KW	2 years	Central Heating, LEDs	780x450x345