Introduction to Central Heating Boilers

Boiler Efficiency

A reliable, energy efficient central heating boiler is one of the most important appliances that you will have in your home (particularly during cold spells). The most popular types of modern central heating boilers are gas or oil based with a smaller demand for solid-fuel boilers.

Boilers are often mistakenly overlooked by householders in terms of general maintenance – a qualified engineer should service a boiler annually. If your boiler has not been serviced regularly then it is likely that you will experience a problem with your boiler in the not too distant future. There are some that can be fixed by the householder which we have detailed in our section, but in the main it is important to understand that any boiler maintenance that involves the dismantling of parts must be carried out by a qualified CORGI (The Council for Registered Gas Installers) registered engineer, so please do not attempt to fix your boiler yourself – pay an engineer to do the work for you.

Taking out a boiler maintenance plan

There are schemes available where you can pay a monthly fee, which will cover the maintenance and any breakdown of your boiler or full central heating system. The most popular and well regarded of these is the British Gas HomeCare plan . If you have a temperamental boiler in your home, it can be extremely reassuring to know that in the event of any problems or breakdowns with your boiler, you could simply call the HomeCare team and they would send out a qualified engineer to fix the boiler problem at no extra cost (other than your regular monthly fee which can be as low as £9).

Buying a new central heating boiler

It is also worth considering whether your boiler needs replacing in its entirety. All new central heating boilers are manufactured to be extremely highly energy efficient, they can save carbon emissions by up to 25% and also reduce your heating bills by 40% in some instances. British Gas often has sales on new boilers so it is worth checking for cheap boiler offers on the British Gas boiler offers page. Usually, the cheapest deals on boilers can be found in the summer months to stimulate sales for the manufacturers during periods when boilers are not often at the forefront of people’s minds.

Energy efficiency of your old boiler

For your convenience we have produced a list of all known boilers on the market in the UK and broken this down by manufacturer (A – Z), model name and SAP (SAP Seasonal Efficiency) rating. We would suggest that you use this data to search for your current boiler make and model and check the SAP rating to see how energy efficient it is. If the SAP rating is poor, you should certainly consider purchasing a new boiler . Alternatively, you could use the list of boilers to research the models with the best SAP ratings as these would be the boilers that would save you the most money on your heating bills.

The SAP system of boiler ratings was devised by the Department for Environment Rood and Rural Affairs in conjunction with boiler manufacturers to gauge the energy efficiency of boilers. These ratings are then transposed into a more reader friendly A – G scale (A being the most energy efficient – G the least efficient). This A – G scale is known as the SEDBUK (Seasonal Efficiency of Domestic Boilers in the UK) rating and all modern boilers should have one of these ratings.

The breakdown of each of the SEDBUK category bands is as follows –

A – 90% and above
B – 86% – 90%
C – 82% – 86%
D – 78% – 82%
E – 78% – 82%
F – 70% – 74%
G – below 70%
When you are checking our boiler lists, if your current boiler falls in the E – G range, you should certainly consider upgrading to a more efficient model as this will prove to be more environmentally friendly and also help to save you money on your heating bills.

According to data from SEDBUK the savings that can be made by buying an energy efficient boiler are dramatic.

They state the following –

Typical Annual Fuel Costs

Style of boiler SAP rating Flat Bungalow Terraced Semi-detached Detached
Old boiler (heavy weight) 55% £267 £341 £354 £397 £550
Old boiler (light weight) 65% £231 £293 £304 £340 £470
New boiler (non-condensing) 78% £197 £249 £258 £289 £396
New boiler (condensing) 88% £178 £224 £232 £259 £355


The full data can be found here.

Boiler Scrappage Scheme

*please note that the government scrappage scheme has now ended, however several companies including British Gas continue to offer similar schemes*

December 2009 saw the announcement from the UK government that they will introduce a boiler scrappage scheme which will provide a £400 rebate towards replacing energy inefficient boilers rated G or worse with energy efficient boilers. The government has pledged £50 million so far which means approximately 125,000 boilers will be replaced. However, there are 4.5 million households that currently have boilers which would qualify under the government boiler scrappage scheme so if you plan to apply it is incredibly important to do so as quickly as possible because the money for boiler rebates will run out fast.

Government Boiler Scrappage Scheme Summary

In summary, you will likely qualify for the government boiler scrappage scheme if :

1. Your boiler has a G energy rating or worse
2. The boiler is in working order and is the main boiler used to heat the home

Next Steps

If you have found that your old boiler will likely qualify for a boiler scrappage scheme by checking our boiler energy rating database and have found that your boiler is rated at 70% efficiency or G rating or worse, you will need to act very quickly to apply for the scrappage scheme as there are far too many people that would qualify for the scheme compared with the funds that the government have allocated, therefore, you need to apply without delay so that you don’t miss out.