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working on gas boiler


It is illegal to undertake any work on gas appliances, unless registered as qualified under the Gas Safe scheme

CO2 Mechanical Engineering is registered - number 226713.

High efficiency boilers

What are they?

There are three different types of domestic heating and hot water boiler, combination boilers (known as ‘combi's’), system boilers and open vented boilers. Since April 2005 your new boiler must, by law, be a high efficiency boiler or condensing boiler. This is a boiler that recovers heat that would otherwise be wasted and uses it to improve the boiler’s heating efficiency.

gas boiler schematicHow do they work

High efficiency or condensing boilers (they are the same thing) have a heat exchanger that uses heat in the flue gasses to pre-heat the water. (They are called condensing boilers because most of the heat recovered comes from condensing water vapour in the flue gasses.) The condensed water is drained away and much less energy is required to raise the temperature of the preheated circulating water to the desired level.

How energy efficient are they?

New boilers operate with an annual average efficiency of over 90%. Typically, older types of conventional boilers only achieve efficiencies of 56%. That means your condensing boiler will use 35% less energy to deliver heating and hot water to your home.Meaning that a condensing boiler can save as much as 35p in every £1 you spend on energy. This can amount to a saving of over £240 on your annual home heating bill.

There are three types of boiler

The most popular boiler in the UK

A sealed system boiler requiring a cylinder

Heat only boiler that requires cylinder and tank