Boilers Explained

What is a high efficiency condensing boiler?

A high efficiency condensing boiler works on the principle of recovering as much as possible of the waste heat which is normally wasted from the flue of a conventional (non-condensing) boiler. The best high efficiency condensing boilers convert more than 90% of their fuel into heat, compared to 78% for conventional types.

What types of high efficiency boilers are available?

There are basically three types:

1. Combination
   
2. Heat Only
   
3. System

A combination boiler provides heat & hot water from the same unit. These are the most popular boilers fitted in the UK. The main benefits are:

• Can be fitted where space is at a premium. No need for tanks in the loft-space.
  
• Provides continuous hot water.
  
• Uses fuel for hot water only when there is a demand.
  
• Modulates outputs to suit central heating loads.

A Heat Only boiler provides the heat source for indirect hot water & heating systems. They are generally used on systems where there is a hot water cylinder and tank configuration. Benefits include:

• Used a direct replacement for standard efficiency boilers on open vented systems.
  
• Used in-conjunction with cylinders where there is multiple hot water demand.
  
• Can also be used on sealed systems, with sealed system components external to the boiler.
  

A System boiler is used in the same way as a heat only boiler, but is used only on sealed systems. The boiler incorporates the pump & components required for a sealed system within the boiler. Benefits include:

• All sealed system components within one unit.
  
• Used in-conjunction with cylinders where hot water demand is high, but space at a premium.
  
• Can have a dry loft.