Gas Combi Boilers are great for giving you central heating and hot water throughout your home. They supply an endless amount of hot water as the water is heated directly from the mains supply. There is no need for a water cylinder or water tank and therefore will save you space. Some disadvantages are that the flow of water is only mains pressure. Therefore if you have more than one tap or shower running, there may not be much pressure. You also have no back up hot water solution i.e. an immersion heater, if your boiler packs up.

A new gas combi boiler will set you back approximately £1500 including fitting, which is a significant investment. Todays condensing combi boilers are far more economical than previos systems and are therefore well worth the outlay.

Check out  this thread on moneysavingexpert.com. A few people seem to be quoted far too much for their combi boiler by British Gas.