Guide To Fireplace Efficiency

Our Guide to Fireplace Efficiency

"By installing a Blade HE Gas Fire in my home I reduced my overall gas bills by 46% saving £170 between Jan 2013 & April 2013" Read how installing a modern, CVO, high efficiency gas fire can help reduce your overall heating bills.

Install a Flueless Gas Fire instead of an Electric fire and you will save 70% in running costs.

To compare the true running costs of different gas fire types you compare them "like for like" using the "input kw rating". The table below summarises the different types of fireplace and compares appliances with the same heat input. The heat input is your running cost. The efficiency of the appliance decides how much of that heat ends up in the room.

Example ApplianceEfficiency RatingHeat InputHeat that comes into RoomRunning Cost per HourAnnual Cost
Flueless Gas Fire
HE Chimney Fire
Balanced Flue Gas Fire
Electric Fire
Wood Burning Stove
Bio-Ethanol Fire
  • Gas @ 4.5p per Kw/Hr
  • Electric @ 13.8p per Kw/Hr
  • Bio-Ethanol @ 275p per Litre
  • Wood Supply @ 41.7p per Kw/Hr [Based on buying 60kg of logs at £239 and using 0.6kg/hour]
  • Annual Cost is based on 3 hours per night for 120 days (4 months).

Conclusion. The most cost effective way to add extra heat is to use gas. If you need 4kW or less heat you should choose a flueless gas fire if you need more than 4kW of heat then you should choose a balanced flue gas fire. The amount of heat you require depends on the size of the room and how well insulated your house is. If you are unsure then please call us and we can advise. To give you an idea of what 4kW is like just imagine a room with two extra radiators.


Are you looking for energy efficiency to save money on your heating bills or to get more heat into your room?

Energy Efficiency is not just about the efficiency rating of the fire. There are other factors that need to be taken into account. The most energy efficient product you can buy today will use gas and will either be a flueless gas fire that does not need any chimney or a HE Chimney fire which uses an existing chimney and upgrades it to high efficiency or a balanced flue gas fire which need a special flue system. All other forms of heating may provide heat but will cost you more for that heat. Its a fact - gas is the cheapest fuel per Kw of heat.

Heres an example of saving money while having the same heat in the room.

If you have a 6kw open flame inset fire this will cost you 27p/hour to run and provide 1.5kw of heat into your room. If you replace this with a CVO high efficiency inset fire like the Glamour it will only cost you 9p/hour to run and still give you 1.5kw into the room. That's a saving of 67% on running costs. This because the glamour has a 2kw burner and is glass fronted with 77% efficiency.

Here is an example of saving money and also getting more heat into your room.

If you have a 6kw open flame inset fire this will cost you 27p/hour to run and provide 1.5kw of heat into your room. If you replace this with a CVO high efficiency wall mounted fire like the blade it will only cost you 21p/hour to run but will give you 3.9kw of heat into the room. That's an additional 150% of heat with 22% less cost. This is because the blade has a 4.6kw burner and is glass fronted with 84% efficiency.

Now you can understand why choosing the right fire for the right reasons is critical!

Here is a quick guide to gas fire types and efficiency:

These are 100% energy efficient, running costs are generally low - 5p to 10p per hour. Most models are either wall hung or are as part of a traditional suite with surround hearth etc. The gas burner is designed to have very low emissions and this combined with the ODS safety device and the air vent in the room means the fires are very safe and reliable. The flueless gas fires manufactured by CVO are unique as they do not have glass on the front or filters - as they are not needed. Read more about flueless gas fires 

These have an efficiency of around 85% and can use any existing chimney, pre cast flue or a flue liner. These gas fires are typically glass fronted, especially the higher efficiency models. No air vent is required in the room as long as the power rating is below 7kw. There are many styles available from HE inset fires that can be used as an immediate swap for an old inefficient inset fire or modern wall mounted contemporary designs. Running costs are typically around 10p/hour. Read more about high efficiency gas fires.

These have an efficiency of around 50% and use an existing chimney, pre cast flue or a flue liner. These gas fires are open flamed and no air vent is required in the room as long as the power rating is below 7kw. The beauty of open flamed gas fires is that they are visually pleasing and are able to be custom made to customer specification. With open flame fires options are unlimited. Our range includes many design styles of open flame gas fireplaces from small 2kw designs to large 20kw ribbon fires. Running costs can be between 4p/hour to 30p/hour depending on size. Read more about chimney fires.

These have an efficiency of around 85% and use a special flue liner which has two pipes. The first brings air in from outside the other takes away the emissions. Generally these fires are expensive to install due to the construction of the burner. All balanced flue gas fires are glass fronted. No air vent is required in the room, but a flue pipe is required to be put through the wall. The running cost depends on the Kw rating of the fire chosen and care needs to be taken not to choose a high power appliance as the efficiency will mean too much heat is generated. Balanced Flue Gas Fires have a higher purchase price and can have a high cost of installation [building work and the flue pipes]. Read more about balanced flue gas fires.

These have an efficiency of 90% and use small flue pipes of 32mm, 54mm or 80mm diameter. This makes the fires easy to install in any location in a room as the pipes can be installed in the walls or under the floor. The flue pipes can run for up to 40 meters in length. The flue outlet is a small plate the size of a saucer and can be positioned on a wall or roof. These are glass fronted, room sealed appliances with high efficiency and low running costs. Read more about power flue gas fires.

These should be only considered if heat is required periodically. These fires operate on liquid bio ethanol fuel which is filled into a burner tray from a bottle. The fuel is then lit with a match. The heat generated is maintained in the room and the amount of heat depends on the strength of the burner. They have running costs of over 20x more than a gas fire for the same heat output which is why they should be used periodically. If heat is required all the time a gas fire should be chosen. Read more about our bio-ethanol fireplaces.

All of the gas fires sold by Spirit Fires Limited are tested to the latest CE regulations and include safety devices, gas fires are strictly controlled and monitored to ensure they are 100% safe.

These will cost 3x more than a gas fire for the same heat in the room. The main benefits are ease of installation and use, some models are portable meaning they can be transported to different areas depending on where heat is required. Electric fires are sold under our Spirit brand. These are shown on a dirrent website - Easyfire

WOOD BURNER [25% to 80%]
If this is an open flame wood burner the efficiency is very low and glass fronted wood burner like a stove has higher efficiency and will provide heat. The downside to these fires is the cost of buying and then storing the logs. Unless you have access to fr4ee wood which may exist in some rural areas the running costs can be 10x that of a gas fire hence why lots of customers are now converting back to gas. Where as a stove may appear glamorous the use ability and safety aspects should be considered. For instance the CO given off by a flueless gas fire is only about 2% that of a wood burning stove hence why, by law, you must have a CO monitor in your room. This is not a requirement of a flueless gas fire as the gas fire has a safety device the stove does not. We do not sell wood burners.


If in doubt about fireplace efficiency please call us to discuss your requirements 01325-301020. All our contemporary gas fires are designed to operate on Natural Gas or LPG and carry full CE approval.




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