A Gas Fire works by combustion, using oxygen from the air to burn fuel (natural gas or LPG) and produce Carbon Dioxide and dangerous waste gases (Carbon Monoxide, Nitrous Oxide), because of this they should never be used in a confined or un-ventilated spaces. they come in 3 types Traditional flued, Balanced Flue and Catalytic.
Traditional Gas Fire
Traditional gas fires are open flamed and draw oxygen from air in the room, the room has to be fitted with an air vent to supply oxygen. The waste gases are usually expelled through a flue built into an existing chimney. In some modern homes, precast flues are built in and these can be used. Your gas registered engineer will advise you of the correct flue requirements for your choice of fire.
These fires can be one of 3 types
- Inset - The most popular are set into an existing hearth and flued up the chimney
- Outset - Standing proud of the hearth covering the opening and flued up the chimney
- Hole in the wall - Usually inserted into an existing chimney-breast and flued up the chimney
More recently inset fires are available as glass fronted units, these have a higher heat output than similar models. and an increased net efficiency of 80%+
For homes without a chimney or properties where the chimney is not suitable. The fire can be fitted with a flue with an electronically driven fan system on the outside of the wall (Powerflue system).
Balanced Flue Systems
Balanced Flue Gas Fires are a self-contained system which does not require a chimney or separate ducting.
Because of the design, balanced flues are the most efficient types of traditional gas fires. They can be extremely powerful so you will need to check that the one you choose is suitable for the size of space you need to heat.
A balanced flue gas fire is a glass fronted, completely sealed appliance that has a double skinned ducting pipe that is channelled through an external wall.
The outer pipe sucks air into the fire and waste gases are ducted out through the inner pipe.
The fire radiates heat through the glass front and combines it with convected heat, which is produced by drawing cool air into the base of the fire passing it through a through a heat exchanger, then emitting the warmed air through an upper vent.
Catalytic Gas Fire
Traditional and balanced flue gas fires need to exhaust the waste gases they give off away from the property through a fixed flue. This means they are fixed to a wall (usually an outside one or chimney breast) and are not movable.
With advances in technology, catalytic gas fires are now available which are 100% efficient, turning most of the gas to heat and do not need to be flued. they can be fitted on any wall where a gas supply can be run and can be moved and refitted very easily.
These are glass-fronted sealed units which use a catalytic converter to obtain complete combustion of the fuel giving 100% efficiency. This compares very favourably with the 50% to 90% efficiency of traditional or balanced flue gas fires.
You can have a flueless gas fire fitted anywhere in the house as long as you can get a gas supply to it and your room is a minmum of 30m3 (1059 ft3 ).
If your room is this size or larger then talk to a gas safe registered engineer before buying one.
Unlike a sealed balanced flue system, flueless fires draw air from inside the room, so they can only be used in well-ventilated rooms.
The guidelines are 'The space to be heated must have a wall vent of at least 100cm² of ventilation sited at least 1 metre away from the fire and an openable window or patio door'.
Burning gas also produces a lot of water vapour, in a traditional gas heater it is flued out along with the harmful waste gases, the flueless gas heater vents the vapour back into the room, so unless there is good air circulation and ventilation, this will cause excessive humidity.
Only buy a flueless gas fire fitted with these two safety devices:
- Oxygen depletion sensor, this will automatically shut it down if they sense a dangerous fall in oxygen supply. It is illegal in the UK to sell a flueless fire without one fitted.
- A flame monitoring system which cuts of the gas supply it the fire goes out
Under no circumstances must you install a flueless gas fire in a bathroom or bedroom!
Burning 1 cubic metre of gas in a flueless gas fire produces one cubic metre of carbon dioxide and 2 cubic metres of water vapour.
Liquid Petroleum Gas (LPG) Fires
Usually called Calor gas fires
If your home does not have a mains gas supply it does not mean you cannot have a gas fire.
As well as dedicated LPG fires many mains gas fires can be converted to run on LPG. If you already have an LPG central heating system you can connect a fire to it or you can install a fixed fire using an LPG Bottled Gas supply.
Using an existing LPG system
If you decide to have an LPG fire fitted onto an existing LPG central heating system the requirements that have to be followed are exactly the same as having a mains gas fire fitted, it will have to be fitted by a qualified LPG installer
Using Bottled LPG
This is not the same as attaching a bottle to a simple fitting as you would for a portable Calor Gas heater.
You will be using larger propane bottles which will be stored outdoors and the gas piped through the wall to the fire.
The bottles will need to be protected from damage with a cage or cabinet.
The recommended installation is a twin bottle system with a changeover valve.
A changeover valve means that as one bottle empties it can be switched to the second and you can order a replacement for the empty one while still using your fire.
Some valves can be set to switch automatically without interrupting your gas supply.
Before using a gas fire with a gas bottle supply always carefully check the manufacturer's instructions, and if in doubt about any aspect of the installation contact a qualified and registered LPG installer. UKLPG is the trade association representing the LPG industry in the UK and has a list of approved installers.
If you already use LPG gas to supply for a cooker in your home and wish to extend this to include one or more fixed gas fires then you may want to consider having a bulk tank installed as this is preferable to bottles.
If you have any questions about a gas instillation or appliance, do not rely on a friend, or someone who 'knows what they are talking about'. The slihghtest mistake with gas can cause fires, explosions, injury or death.
Do not take chances or be tempted to DIY. For any work involving a gas appliance or installation, you must use a gas safe registered engineer.
Take a look at our Twitter feed list of recommended local gas safe engineers. If you can't find one on our list in your area try visiting the Gas Safe Register.
For work on LPG use the UKLPG trade association register to find a qualified installer.
All Gas Safe registered engineers and LPG qualified installers carry ID cards with their registration details, always check them properly before letting them start work.
Warning: Smoke detectors do not detect Carbon Monoxide!
Carbon Monoxide (CO) is a toxic gas produced by burning fossil fuels such as gas and coal.
It is invisible and has no smell or taste, it is very dangerous because your body will absorb it instead of oxygen and starve your vital organs, such as the brain, nervous tissues and the heart of oxygen.
Breathing CO can cause headaches, dizziness, vomiting, and nausea. Exposure to moderate and high levels of CO over long periods of time increases the risk of heart disease.
If it builds up in a room you will feel tired and sleepy, you will then lose consciousness and suffocate and most likely die. People who survive severe CO poisoning may suffer long-term health problems.
We advise fitting an audible Carbon Monoxide alarm in any room where a gas burning appliance is being fitted,
A decent audible alarm costs about £15 from your local DIY store if you are not sure about how to fit or use it, ask the Gas safe engineer who is installing your fire.
If you are interested in the technical side of gas fires and want to know more about how they work here are a couple of books we recommend.
We strongly advise against attempting any DIY work on or installation of gas/LPG appliances
Efficiency is the measurement of how much of the fuel energy your gas fire uses against what is actually gives out in heat energy.
Fuel is what you are paying for if you spend £100 on gas and your fire is 50% efficient, £50 is wasted on smoke, soot and waste gases.
- Flueless gas heaters are the most efficient at a fraction under100%.
- Balanced flue gas heaters are 75% and 90% efficient.
- Sealed Glass fronted gas heaters vented into a chimney or flue, are 70% to 80% efficient.
- Open Living Flame Fires are between 50% and 70% efficient.
- Ceramic backed hot boxes, (fireplace inserts that look like open fires) are between 30% and 50% efficient.
- Gas trays or fire baskets are mainly for decoration and are about 25% Efficient.