Product Guide - Fires
Welcome to the Gasflair Product Guide. In this guide we will describe the various types of fires available and their basic installation requirements. Please remember that installing gas appliances is not a DIY job. All gas appliances must be installed by a qualified CORGI registered engineer.
The information given here is a guide only. To confirm suitability of any gas fire to work correctly with your flue or chimney you should employ a CORGI registered engineer to conduct a site survey and report. We recommend that you have your flue checked prior to ordering, as the return of an unsuitable product that is not faulty will incur a handling and carriage charge. See our terms and conditions for further details.
Types of Flues
Class 1 Flue
This is usually a brick chimney of a minimum internal diameter of 7 inches. This type of flue will usually accommodate any type of open flued gas fire. Be wary of chimneys that have previously has a gas back boiler and fire installed as they may have a 5 inch diameter flexible flue liner installed inside them (in effect making them a Class 2 flue).
Class 2 Flues
These flues are usually Class 1 flues (chimney) lined with a flexible flue liner of 5 inches diameter or 'twin wall' rigid metal flue pipes. A metal tube or terminal emerging from the roof can indicate the presence of a Class 2 flue.
House builders began to install this type of flue in new houses in the 1970's in order to save the space that a chimney breast would occupy in the room. They are constructed from pre-cast concrete blocks that are built into the structure of the house. Due to the narrower depth and smaller cross-sectional area of the flue not all fires can be installed in this type of flue. Some pre-cast flues, usually in newer houses have a small 'chimney breast' that protrudes into the room 4 or 5 inches; others have no protrusion at all.
Balanced Flues and Fanned Flues
Balanced Flues go horizontally through the outside wall of the house. A balanced flue exits from the back of the gas fire and obtains its air for burning from the outside. It in turn expels the products of combustion (gas fumes) to the outside through the same flue. The balanced flue is manufactured as part of the gas fire and cannot be installed separately.
Fanned flues look similar in appearance to balanced flues but take their air for burning from the room in which they are installed. They use an electrically powered fan to expel the products of combustion horizontally to the outside. Some fanned flue fires are can be fitted on internal walls with flue pipes that run several metres to an outside wall and even around corners.
Most gas fires are designed for use with Natural Gas (NG). Some are manufactured as or can be converted to use Liquefied Petroleum Gas (LPG or LP Gas) or bottled gas. Depending on the fire manufacturer LPG models are supplied specifically for use with LPG or LPG kits can be purchased separately to convert the natural gas burner to use LPG.
Types of Fires
Inset Gas Fires
This type of fire is recessed into the fireplace opening just like a traditional coal fire. Models are available to fit Class 1, Class 2 and Pre-cast flues. The depths of the fires vary considerably, the deepest only suitable to fit into a traditional brick built chimney. However, many models are suitable for installation into pre-cast flues. Most inset fires are open fronted although some incorporate a glass front panel to increase heat output and efficiency. Balanced flued versions of some models are available.
Outset Gas Fires
This type of fire sits proud of the flue. It usually has living flames and a glass front to increase efficiency and will fit in Class 1, Class 2 and Pre-cast flues. Some fires can be wall mounted and therefore do not require a hearth or fireplace. Balanced flue versions of some models are available.
Radiant Gas Fires
The traditional gas fire with white radiants (ceramic pots). These are economical to run and very controllable. Most models can be hearth or wall mounted and they are suitable for Class 1, Class 2 and Pre-cast flues.
Balanced Flue Gas Fires
Can be installed in homes that do not have a flue of chimney. They are installed onto an outside wall and take their air for combustion and expel their products of combustion through a horizontal flue consisting of two concentric metal tubes. These fires always have a glass front and are sometimes called 'room sealed'. This type of fire is very efficient in operation and has lower running costs.
Outset and inset models are available. Inset models can be recessed into the inner leaf of a cavity wall, or special fireplaces can be constructed (a 'rebated' surround) to accommodate the inset depth of the fire.
Fan Flue Gas Fires
Similar to balanced flue fires in that they are installed on an outside wall. They are usually open fronted giving them a more realistic look. They are not room sealed and use air from the room for combustion and expel the products of combustion (fumes) to the outside using an integrated electrical fan. Some noise can be heard from the fan although this is minimal and most owners find a slight humming noise acceptable. Some versions of these fires use a longer tube to expel the products of combustion enabling them to be fitted on internal walls.
Flueless Gas Fires and Stoves
Flueless or 'catalytic' fires operate without a flue or outside wall. A catalytic converter inside the fire 'scrubs' the flue gasses (fumes) and removes all undesirable elements. All that emerges from the fire is carbon dioxide and water vapour. This type of fire is classed as 100% heat efficient as no heat escapes through the flue. A thermostat on the fire adjusts the heat output and flame picture. Permanent ventilation must be installed in the room where the fire is sited (such as an air brick or floor vent of 100cm sq). An openable window or louvre is also required in the room the appliance is to be installed into. The minimum sized room suitable for the use of a flueless fire is around 30-40 cubic metres depending on the model. 40 cubic metres is around the size of a 14ft by 14ft room or 30 cubic metres a 12ft by 12ft room.
Hole in the Wall fires
Some inset gas fires are designed to fit into a 'Hole in the Wall' situation rather than into a fireplace. Gasflair recommends that a hearth be installed at floor level to maintain safety especially where children, the old or infirm have access to the fire.
Gas Stoves are constructed from cast iron or heavy gauge steel. All models have a glass windowed door, some models have double doors. They are available in conventional flue and balanced flue versions. The heat output is usually quite high, as is the heat efficiency. Flue pipes are not usually included with the stove and must be purchased separately.
Electric Fires and Stoves
The real benefit of Electric fires is that they require no specialist installation. Inset electric fires usually require some sort of recess to accommodate the back of the fire. This can be a fireplace opening or a specially designed fire place (see the Electric Firesuites product guide for details). Some models come with the option of a removable spacer frame that allows the fire to be used freestanding without the need to create a recess. Most fires have a 2kW fan heater hidden under the canopy of the fire, some even have thermostatic control. The flame effect on the fires are very convincing and supply a comforting flickering flame effect independently of the heating element.
Electric stoves have similar features to electric inset fires and are all freestanding. Their cast iron look is achieved by using a special paint coating.
This document is copyright Gasflair 2003 and cannot be reproduced in part or whole without the express permission of the author.