Fire Installation

Before you purchase your new gas fire, you will need to know a few details - the type of chimney or flue you have. The energy output of the fire in relation to the size of the room and any requirement for additional ventilation.


Which type of chimney or flue you have usually dictates your choice of fire.


It is not always necessary to install a gas fire into a traditional chimney with a conventional flue. There are many gas fires available that can offer you the option of a balanced flue system which will exit discreetly from your property via a twin-wall pipe.


To help you understand which gas fires are suitable for your home, we have compiled a short informative list to help identify your property's chimney or flue and to give you an idea of the size of fire you need. Please note that this only serves as a guide, if you are unsure Contact Us for further information and advice.

Once you have identified your chimney or flue type, and the size you require check out the fires available at our most commonly used suppliers.


Heat & Plumb

Plumb Center

B&Q TradePoint



Note It may be necessary to have your chimney swept if converting from solid fuel to natural gas.

If you have any uncertainties, we are more than happy to assist you before we install.

For every 1kW of heat output, your fire will heat approximately ;
25m3 - Good insulated area.
15m3 - Average insulated area.
10m3 - Poor insulated area.

If your room measurements were
Height: 2.8m, Width: 4m, Length: 7m
Total room volume: 2.8m x 4m x 7m = 78.4m3
The house has an average insulated rating. (double glazing and basic insulation).
Average Insulation = 1kW will heat 15m3
Heat needed for the room is: 78.4m3 ÷ 15m3 = 5.2kW


Chimney types
Class 1 terminal
Class 1 terminal

Brick Chimney - Class 1 The chimney stack rises above the roofline and is topped by a chimney pot or gas terminal. This type of chimney relies on the natural circulation of heated air to send the products of combustion up and out your chimney.

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Class 1&2 terminal
Class 1&2 terminal

Pre-cast Flue - Class 1&2 You will see a metal flue cowl on your roof. Some are totally metal whilst others may terminate through a short rectangular pot. This style flue create the same circulation of heated air as a brick chimney.

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precast terminal
precast terminal

Pre-cast Flues - Class 2 Most modern homes have been built with such flues. You can easily identify them by either a metal flue cowl or a raised ridge terminal on your roof. The natural circulation of heated air expels the products of combustion.

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balanced flue terminal
balanced flue terminal

Balanced Flue Balanced flues work in conjunction with glass fronted gas fires. The appliance is completely sealed from the room in which it is installed. It is vented and flued directly via a twin wall pipe direct to the property exterior. Dependent on the fire, the twin-walled pipe may exit horizontally through an external wall or vertically through the roof.

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