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Boiler System Choices

exposed brick room with radiator 640

Choosing a new boiler

Choosing a new boiler when you don’t already have one, or choosing a replacement boiler for an existing central heating system can be confusing, but don’t be daunted!

The size and type of construction of your home are more important factors and you’ll need the help of a professional to help calculate the amount of heat the boilers must produce to keep you cosy in even the most extreme weather. You also need to consider your family size, and your lifestyle.

With a little help from Blue Flame, you can form a view on which type of boiler/system is best suited to your needs.

Whichever system is decided upon, in the majority of homes the boiler will need to be a new high efficiency, condensing -type of boiler.

Why must I have a condensing appliance and what are the benefits?

From 1 April 2005, changes were made to the Building Regulations. Part L says that “with very few exceptions, all new domestic boilers installed must be high efficiency condensing boilers, rated Band A or B using the SEDBUK rating scale”.

SEDBUK stands for Seasonal Efficiency of Domestic Boilers in the UK . Central heating boilers now come with an energy rating, like washing machines for instance, with Band A the most efficient at 90% plus.

The older cast iron central heating boilers were no more efficient than around 78%, and considerably less than that in some cases, so installing a high efficiency condensing boiler will not only reduce the central heating boiler’s energy consumption, and therefore its emissions, but it will also reduce your energy bill too!

In simple terms, for every £1 spent on your heating bills, over 90p is used to heat your home and hot water – a much better return than before. Very useful, particularly with the increases we’ve seen in energy bills in the recent past.

How does it work then?

Condensing boilers use less gas by advances in boiler technology. Whereas the standard-efficiency boilers used to expel their products of combustion (flue gases) straight out into the atmosphere, the high efficiency condensing boilers re-use the heat from those flue gases already generated by passing them through a secondary heat exchanger, to heat the system water.

The flue gases are now discharged on their second cycle and at a much lower temperature, so that they now start to turn to water vapour, so a “plume” of steam can be seen from the flue terminal, and drops of water are run into a drain, or purpose-provided soak-away.

Which type of condensing boiler is right for me?

There are 3 categories of boiler and two types of system – conventional and system boilers using a stored hot water cylinder, and a combination boiler which delivers instantaneous hot water – so you need to consider how you use the hot water now and possibly in the future (perhaps as the family grows, or grows up and leaves home).

conventional boiler is connected to an open-vented central heating system with a header tank (normally) in the loft space, which operates in conjunction with a hot water storage cylinder and external controls, and can deliver plenty of hot water to several taps simultaneously.

Conventional Boiler System Layout 400

A family with a very high hot water demand i.e. multiple hot water usage at once, is almost certain to be better served by a traditional, conventional boiler and system.

Please remember that if you are considering a conventional boiler, an important requirement is the need for a cold water storage tank (normally loft space will be required) plus room to locate the hot water cylinder (and to possibly build an airing cupboard?).

system boiler is similar to the conventional boiler, except that the central heating system is sealed and pressurised (no header tank), and the system boiler would normally have the pump and system controls integrated into it.

The System Boiler Layout 400

If you live in a flat and space is at a premium, then you will almost certainly need to consider a combination boiler. A combination boiler eliminates the need for a hot water storage cylinder, or a cold water storage tank and header tank.

The Combi System Layout 400

Hot water is instead heated instantaneously when a tap is turned on (so you don’t have to keep stored water topped-up or wait for the hot water cylinder to heat up). You’ll never run out of hot water, plus you’ll be able to have a shower at mains pressure too. It can, however, take 2-3 times longer to deliver a bath full of hot water, whilst simultaneous use of more than one tap can result in the flow of water being diminished somewhat to the other outlets.

A couple’s hot water needs are likely to be modest, using relatively small amounts – in which case a combination boiler is possibly the most suitable option. Alternatively you could install an un-vented hot water cylinder.

It must be remembered that both combination boilers and un-vented hot water cylinders are dependant upon the mains water pressure being provided by the local water authority.

System Updates

Do you need the space where your airing cupboard is, or if you’re carrying out a loft conversion does the builder needs the cold water tank out of the way? Then contact Blue Flame Gas Services to provide you with a FREE estimate to convert your conventional system to a combination system, plus to give you energy efficiency tips and advice to reduce your running costs.