As local gas-safe engineers and plumbers in Watford, Hertofrdshire we are often asked about the different types of boilers on the market today and which boiler is best. I have put together a quick guide to some of the different types of boilers available. Which is best for your home will depend on the individual situation and is best advised on by a professional installer.
Condensing boilers cover most types of modern boiler. The condensing part means that it has the ability to extract heat from otherwise wasted flue gasses. Traditional boilers usually have a single combustion chamber and expel hot waste gases through the flue at the top of the boiler at around 180°C. Condensing boilers however, have a larger or second heat exchanger, and gasses are released at around 55°C. This wastes far less energy and can be up to 90% efficient saving you up to £130 a year according to the Energy Saving Trust. Condensing boilers produce water droplets that have to be drained away. If the drain is exposed to frost then they can freeze and cause the boiler to shut down. However there are a number of different solutions that can solve this problem.
This is the most common boiler set up in the UK at the moment. They work in conjunction with a hot water cylinder and cold water storage tanks. Because there is a tank of stored hot water you are not limited on flow or pressure and if plumbed correctly the flow of hot water is not effected by multiple draw-offs. They are less efficient than a combination boiler and takes up more space. As the hot water supply takes time to heat up there is only a certain amount of hot water before it runs cold.
Combination boilers work by taking cold water straight from the mains and heating it directly. This means you have an unlimited supply of hot water at any time. You won’t need a storage cylinder in the airing cupboard or a cold water tank in the loft, saving a lot of space. Because of the way that they heat your water, combi boilers are usually more efficient than other boiler types. However, unless you have a model with a storage tank they have a limited output. This means that your hot water supply can be affected if someone turns a tap on somewhere else in the house.
Back boilers are fitted in the chimney behind a gas fire. They are not used these days unless a suitable alternative can’t be found. They are typically only 78% efficient which makes them more expensive to run. Back boilers are “open flued” which means that there must be an open vent to allow fresh air in to replace the fumes that go up the flue. This means that if a fault develops with the ventilation, flue or boiler itself, potentially lethal gasses can be released.
Servicing and safety
Boilers should be serviced annually to maintain a safe and efficient appliance. This by law needs to include a gas analysis and must be undertaken by a Gas Safe registered engineer.
It is strongly advised that all homes should have a carbon monoxide alarm to detect any leakage of the potentially lethal gas.