Here are five things you should know before you get started on updating your central heating.

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1. Take the size of your home into account

The size of your home, especially the number of bathrooms or shower rooms you have, and how much heating and hot water your household uses, will largely determine your choice of boiler.

There are three main types of boiler: regular, system and combi.

Regular boilers need a cylinder (to store hot water) and tanks.

System boilers also need a hot-water cylinder, which allows them to feed several outlets, such as taps and showers, at the same time, but they don't need tanks.

2. Combis are great if you only have one bathroom

Combis are a popular choice, as you only have to find room for the boiler itself - there are no tanks or cylinder, although some combis have a built-in tank, which gives the higher flow rate needed in a bigger property.

Combis heat water on demand, so you only pay for what you use, and they deliver it at mains pressure. Combis are most suitable for homes with one bathroom/shower room, although they can work in homes with two, providing they're powerful enough.

If you have more bathrooms than that, a combi probably isn't suitable.

3. Find out if you’ll have to change the whole system

If you're renovating a property that hasn't been updated in decades, it may be necessary to change the whole central heating system.

A new boiler, cylinder, radiators and adjustable radiator valves should make a big difference to how good - and efficient - the system is, but don't overlook the pipework.

If the central heating system is gravity fed and you're switching to a pressurised system, the pipework will be under pressure for the first time and may leak as a result.

Old copper pipework may not be done to today's standards and may even be leaking without you knowing, so leaving it in place can be a false economy.

Most plumbers now use plastic pipework where it can't be seen, such as under floorboards, because it's quicker and easier to fit than copper.

They should use copper where it can be seen, such as radiator pipes, and close to the boiler, where it's too hot for plastic.

4. Get rid of old hot-water cylinders

If your boiler has a hot-water cylinder, you may want to get rid of it by fitting a combi, or relocate the cylinder, as new cylinders are often a different shape and size to old ones.  

This could free up space in your bathroom for a shower cubicle where the airing cupboard/cylinder was, for example.

Old boilers also tend to be large, but many new ones aren't and some are so small that they fit in a kitchen wall unit, saving space and giving the kitchen a neater look because the boiler's hidden.

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5. Think about future home improvements

Think about any big home improvements, such as an extension or loft conversion, you may make in future and how this will impact on the boiler.

Will the existing boiler be able to comfortably supply more radiators and bathrooms, or will you need a new one?

If there's a tank for the boiler in the loft and you're planning to convert the loft, the tank will probably have to be changed to one that fits in the eaves' storage, so a boiler without tanks may be better.