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Combination (Combi) boilers have become the best selling boiler type for gas central heating in the UK. They are small; fitting into cupboards, and very economical to run. And because they heat water directly from the mains, you don’t have to wait for water to heat up – and your stream of hot water will be endless.
They are more economical than other types too. Because combi boilers don’t use an external hot water tank, there is no cylinder to heat first, and no need to reheat the same water again if you’ve let it run cold.
However, for this same reason – the lack of a hot water storage tank – your nice hot shower will be interrupted if anyone else starts running the hot water in your home at the same time.
Is this the right boiler for me?
If you live in a small house or flat, without multiple bathrooms, or are short for space then a combination boiler will be an excellent choice for you.
If you currently have a cold-water tank in the loft but want to convert your loft space into an additional room, swapping your old boiler for a combination boiler will eliminate the need for the tank, and free up more space.
A combination boiler is the only way to have instant, on-demand hot water in your home without the inconvenience of having to wait for the water tank to be heated and you’ll also get drinkable water from every tap.
2. Sealed system boilers (unvented)
A system boiler (also known as a closed or sealed system boiler) works on the principle of stored hot water. This means that you will need an airing cupboard or other space for the hot water storage tank.
Although a tank is needed in the airing cupboard, a system boiler still needs less space than a traditional open vent or heating only boiler, which utilises a second tank in the loft. Also, many of the individual components of the heating and hot water system are built in, which means that installation is quicker, neater, easier and more efficient.
With a system boiler you can run hot water from a range of outlets simultaneously, without someone else’s shower running cold on them. You will also get good water pressure.
A system boiler is a great choice for a larger home or family with hot water needs that can’t be met by a combi boiler, but who want to keep loft space free. You will need a tank in the airing cupboard though.
However, you’ll have to wait for water to be heated when you want it, and it could run out if it’s used too quickly.
Many people with older systems such as open vent boilers choose an unvented sealed system for their central heating and hot water. Although it is more expensive than simply replacing your boiler with the old system, you will be able to free up more space in your home.
3. Open vent and open vent sealed system boilers
An open vent boiler is the existing system in most people’s homes. This type of system uses two water tanks, both located in the loft, and a hot water storage cylinder in the airing cupboard so it is very space hungry. One tank draws water from the mains supply and feeds the storage cylinder which, when heated by the boiler, can release hot water to taps all over the house.
The second tank is the feed and expansion tank which contains the correct level of water for your heating system, allowing for water expansion when you turn the heat on.
Showers, taps and running baths can be drawn in any room at the same time, but be aware that if the cylinder should run cold it will take a little time to reheat.
Many people switch from a traditional open vent boiler to an open vent sealed system boiler. This is a relatively cheap switch to make and will cut the need for one of the tanks in your loft.
Because it’s the existing system in many people’s homes, an open vented boiler is inexpensive to replace and making the switch to an open vent sealed system is also relatively cheap. However, both these systems use up loft space.
Like system boilers, open vent systems allow you to run hot water from a range of outlets simultaneously, without the water running cold elsewhere in your house. The water pressure is low though, and you’ll only have drinkable water from one outlet, because it uses a storage system.
The hot water might also run out, and you’ll have to wait for it to reheat.
An annual boiler safety check and boiler service, carried out by a professional service engineer ensures that your boiler is functioning properly. Regular servicing of your boiler is important as it ensures that the boiler is working to the specifications designed by the boiler manufacturer. This will help prolong the life of the boiler as well as reduce the risk of faults and expensive repairs down the line.
-Soot production from the combustion process coats the heat exchanger surfaces.
-The critical air-to-fuel combustion ratio changes due to gradual component wear.
A boiler service will remove any sooting and, by adjustment, will re-establish the optimum combustion conditions. But while optimising operating efficiency is paramount in these days of rising fuel costs, there are other important benefits in having your boiler serviced:
By checking the safety controls, early failures can be detected and rectified in good time.
A variety of operational systems and components will be checked including:
– Gas leaks
– Boiler start-up performance
– Noises that give an early warning signal of pending component failures.
Just like cars, boilers can operate for many years without servicing but generally with fuel consumption penalties, undermined reliability and even safety implications.
radiators. They work by sensing the air temperature in the room and adjusting the heat accordingly, saving money and cutting CO2 emissions.
Most of us have a central heating system controlled by an electronic thermostat, but by fitting thermostatic valves to each individual radiator too you can vary the temperature according to the room – so you don’t need to be heating the whole house just to get the living room warm.
In Britain, keeping our homes warm accounts for around 20% of the CO2 that we can directly control. Having inappropriate heating controls, or using them incorrectly, means your central heating system works unnecessary overtime and could be adding 17% on top of your energy bill each year.
“Changing from a G rated boiler to an A rated boiler could save the householder up to £235 per year.
The following HHIC checklist of typical examples can help householders identify whether they have a band G boiler:
-For Floor Standing Boilers: Pre 2002 with permanent pilot ignition
-Wall mounted boilers: Pre 2002 with cast iron heat exchanger and permanent pilot ignition
-Combi boilers: Pre 1998
-Back Boilers: Pre 2002
-Flue: We also believe that a boiler installed with an open flue is likely to be a band G boiler
-In addition, OFGEM (Office of the Gas and Electricity Markets) has a list of all manufacturers’ band G boilers on their website.
A side effect is that this water, known as condensate, which is slightly acidic, has to be piped away to a drain or soak away.