Combination / Combi Central Heating
Combination boilers has the name suggests combine most of the components of a conventional system i.e. boiler, cylinder, pump, control valves and thermostats into one unit (combi boiler). with the combi boiler there is no stored water in loft or airing cupboard, therefore saving space & no risk of freezing pipes, instantaneous hot water twenty four hours a day, seven days a week. There is high pressure showers without the need for mechanical power showers. This is also the most economical type of boiler, only pay for exactly the hot water you use. Combi boilers can be sited almost anywhere in the house because of the enormous flueing options i.e. loft, airing cupboard, garage etc Although very energy efficient, the problem with running more than one tap at a time is exasperated if more than three people live in the home or if there is more than one bathroom.

Conventional Heating/ Hot Water Systems
This type of system is most common in the United Kingdom today, it comprises of a cold water storage tank (normally in the loft area), hot water storage cylinder and a separate boiler (traditionally installed within the kitchen). With conventional systems you can have hot water to several taps at the same time, greater volume of water, which means a bath will fill quickly. Conventional systems allow you to have heating and hot water at the same time.
It is generally suitable for average to larger homes where hot water will be needed at more than one tap at a time such as families of three or more with perhaps more than one bathroom/shower room.
When fitted with fast recovery/high efficiency hot water cylinders this type of system will be almost as efficient as a combination boiler but will serve several taps at a time.

Unvented / Pressurised Central Heating
This type of system accommodates almost all needs as it gives hot water to several taps at any one time at high pressure. It eliminates the need for cold water storage tanks in the loft area. It is a very good option if you are considering converting your loft space into living space. It also gives a very high pressure shower without the need for a mechanical pump. This is not only a saving on the cost of a shower pump but, also eliminates the noise element involved with mechanical pumps