If you are replacing an older model of boiler, the chances are that you will have a regular boiler. A typical conventional boiler system incorporates a boiler and extended controls, a feed and expansion cistern, and a copper hot water cylinder (usually in the airing cupboard) which is often fed by a cold water storage cistern located in the loft.
This will enjoy all the energy efficiency characteristics of all the other condensing boiler systems but might take more space in your home.
Loft space requirements
The header or feeder tank will be in the loft space and takes water from your cold water system and stores it in a small expansion tank. This is used to continually feed water to your central heating system when any is lost. You may find that this takes space in your loft which you need for other purposes or complicates any plans you may have for converting the loft space into a living area.
Airing Cupboard space
The hot water created by the system is stored in a hot water cylinder often located in an upstairs airing cupboard. This is then used to provide domestic hot water through your hot water taps. Again, whilst this is no issue to many families, you may find that you would welcome the additional storage space if you were able to dispense with the hot water cylinder.
Advantages
The advantages of regular boilers are that the hot water flow rate will tend to be higher than that with combi boilers as the hot water is stored within the hot water cylinder ready for use rather than being heated on demand.
A combi boiler needs a minimum water pressure from the mains and this may not be available in all areas.
Disadvantages of regular boilers
In addition to the storage issue running costs can be higher for regular boilers than for combi boiler systems as there are heat losses throughout the day from the cylinder or boiler pipework.
