ENERGY EFFICIENT BOILERS

LESSER KNOWN FACTS ABOUT BOILERS

Boilers account for around 55 % of what you spend in a year on energy bills, so an efficient boiler makes a big difference.

A high-efficiency condensing boiler with full sets of heating controls, we would save enough energy to heat nearly 1.9 million homes for a whole year, and save around 6.7 million tonnes of CO2. 

Based on a saving of 25% gas usage, the Energy Saving Trust estimates the average saving per household on energy bills after installing a new boiler to be INR 23817.3.

WHY ARE NEW BOILERS MORE EFFICIENT?

Since October 2010 only boilers that are 88% or more efficient can be installed in homes, and most of the boilers you can buy now are between 88% and 98.7% efficient.

A condensing boiler has a bigger heat exchanger, so it recovers more heat, sends cooler gases up the flue and is more efficient.

Sometimes the flue gases get so cool that the water vapour in the gas condenses out. When this happens, even more energy is recovered from the condensing vapour, and the efficiency gets higher still.

HOW IS BOILER EFFICIENCY CALCULATED?Sedbuk, which stands for Seasonal Efficiency of Domestic Boilers in the UK, is a system used to classify and compare boilers on how efficient they are at converting fuel into heat. 

Sedbuk efficiencies: how boilers compareTraditionally, Sedbuk ratings were shown on labels as a letter A-G, but these letter labels have been withdrawn to avoid confusion with the European energy labels, which use similar ratings but are based on different principles. 

There are currently two different types of Sedbuk ratings you may see on labels, reflecting the old and new types of Sedbuk ratings.

Sedbuk 2005 - this older system of Sedbuk ratings rates boiler efficiency from A to G rating, with A-rated boilers being more than 90% efficient.

Sedbuk 2009 - this newer system of ratings shows boiler efficiency as a percentage, rather than A-G.

All new boilers should be rated using Sedbuk 2009, but you may still see older models which were tested under the old Sedbuk 2005 system.

You can check how the different types of ratings compare using the chart you'll find under our list of frequently asked questions about boilers.Under the new Sedbuk 2009 system, a Sedbuk 2005 90% efficient A-rated gas, oil or LGP boiler works out as 88% efficient. The 2% difference between Sedbuk 2005 and 2009 is mainly down to differences in efficiencies between using a boiler for space heating in the winter months and only using it for water heating in the summer. Manufacturers often prominently display the Sedbuk 2005 in their product literature because it gives them a higher efficiency figure.

WILL AN EFFICIENT NEW BOILER SAVE YOU MONEY?Based on a saving of 25% gas usage, the Energy Saving Trust estimates the average saving per household on energy bills after installing a new boiler to be £310. This does not take into account how much installing a new boiler will cost.The table below illustrates just how much a modern condensing boiler could cut your gas bills by, depending on the size of your house (a boiler that's 15 years old or more is classed as 'old' in these calculations. A lightweight boiler can be attached to a wall; a heavyweight boiler is floor standing.)

Annual fuel costs with different boiler types (source: Sedbuk)Boiler type Efficiency Flat Bungalow Terraced Semi-detached DetachedOld gas heavy weight 55% £779 £1020 £1062 £1204 £1705Old gas light weight 65% £659 £863 £898 £1019 £1442New non-condensing 78% £549 £719 £749 £849 £1202New condensing 89% £481 £630 £656 £744 £1053

These figures are based on a gas unit price of 4.36p per kWh (April 2013)

INSTALLING A NEW BOILER

If it is time to change your boiler, then the first thing is to decide what type of boiler you need.

The right fuel

If you have mains gas, then a gas boiler is usually the cheapest heating system for you.

If you don’t have a gas supply to your home, it might be worth looking into getting a gas connection. If there is no gas pipe near your home then this may not be an option, but if it's available just round the corner then it might be worth paying for a new connection. The company that owns and operates the gas network in your area may be able to help with the cost of getting a new connection, and it may even be fully funded.

To discuss a new gas connection, and to find out if you can obtain help towards all or part of the cost, contact the company that owns the gas network in your area.

The right boiler

Most old gas and oil boilers are regular boilers - they have a separate hot water cylinder to store hot water, rather than providing it directly from the boiler. When you replace your boiler you have a choice of buying a new regular boiler, and keeping your hot water cylinder, or buying a combi boiler that doesn't need a cylinder.

A regular boiler is more efficient than a combi at producing hot water in the first place, but then some heat is lost from the hot water cylinder, so a combi may be more efficient overall. The best option for you will depend on a number of factors:

How much hot water do you use? A large family using lots of hot water could be better off with a regular boiler – a smaller household using less may be better off with a combi.

Are you short of space? A combi boiler doesn’t need a hot water cylinder, and so needs less space.

Are you thinking of installing solar water heating? Many combis are not compatible with solar water heating or cannot use it so effectively.