Most people wanting to improve a domestic boiler system have five options – improve the system you have or consider the four types of boiler available.
These boilers just heat water. A separate hot water storage cylinder and pump are often fitted in an airing cupboard, and there may be an expansion vessel to automatically top up the central heating and accommodate water expansion.
A system boiler incorporates the pump and expansion vessel, however you still need a separate storage cylinder. Central heating and hot water both draw from this even though the boiler is not a “combination”.
This one piece solution was heavily promoted by a previous government because on the face of it they should be energy efficient. However they are only suitable for smaller homes (two adults) and don’t always save on bills either. Recent studies indicate that modern, well-insulated boiler and tank systems are just as fuel efficient overall because combis waste energy and water in the way they cycle on and off.
The cost of replacing a single boiler of any type is roughly the same, but installing a combi from scratch is cheapest as no additional tanks are needed.
Storage Combination Boilers
These are combi boilers with an additional hot water storage tank. They are capable of supporting slightly bigger households and even more than one bathroom, but they are expensive to install.
Commercial and residential buildings (blocks of flats for example) often use technologies such as heat pumps instead of boilers. Some councils offer incentives or have planning requirements about this.
Also be aware that combination boilers cannot be combined with solar hot water panels. You can still tie ordinary solar panels into your electrical supply.
A modern insulated cylinder might make a bigger improvement in your energy efficiency at a lower cost. Replacing an open-venting expansion vessel with a closed system is another possibility, and smart thermostats and timers can also make a difference. An experienced company like http://www.rjplumbingandheating.co.uk/boilerServicing.htm will advise you on the costs and benefits (they also provide boiler service in Guildford).
Long Term Investment
Remember that boilers also vary in quality. A cheap boiler that lasts only five years will cost more in the long run than one that’s good for 20 years or more.