Units that are not combination boilers are commonly referred to as ‘regular’, ‘conventional’ or ‘heat only’ boilers. They can be wall-
Regular boilers installed after 1st June 2005 must be of the condensing type with limited exceptions.
Combination or combi boilers provide both space & hot water heating directly. The most common is the instantaneous combi boiler, which heats water on demand & does not maintain a large internal store of already heated water.
These boilers are capable of providing a continuous flow of hot water, but at a lower rate than typical hot water storage systems. As such, they may be less suitable for dwellings where there may be simultaneous demands for hot water, i.e., multiple bathroom / shower room dwellings.
Combi boilers save space because:
• they are fed directly from the water main, with no need for a hot water storage cylinder or cold water feed cistern.
• they are usually intended for use in a sealed system which does not require a feed-
Before selecting a combi boiler the following points need to be considered.
• to guard against inadequate hot water performance, checks will need to be carried out to ensure that the dwelling has both satisfactory water pressure & and adequately-
• there may also be the need to increase the size of the gas supply pipe as combi boilers require a greater gas input.
Combination boilers installed after 1st June 2005 must be of the condensing type with limited exceptions.
Combined primary storage units (CPSU’s) are a special category of storage combi boiler. They include a very large store of water (70 litres) designed to buffer both the hot water & space heating requirements. CPSU’s allow radiators to warm up very quickly & are capable of providing hot tap water at a high flow rate