How modern Gas Fires should help reduce your energy bills

By March 3, 2017Blog

We are a nation of fireplace lovers, having been the centre piece of homes up and down the country for what was once a necessity, fireplaces are still a popular feature for home owners and developers though central heating systems have now taken over the job of keeping us warm. So how can this aged old family favourite actually help us in our battle to reduce our energy costs?
Firing up the average boiler can burn anything from 28kw – 32kw of fuel per hour as it aims to warm between 8-12 radiators within the home. With rising energy costs our aim is reduce our overall spend whilst maintaining the comforts we have become accustomed to. So, reducing the total time the main central heating is on full power would be an obvious place to start. This can be achieved by warming individual rooms with gas fired appliances when there is no need to warm the entire home. Ensuring the gas fired appliance is one that is very efficient and has low running cost should help in making a saving on your fuel costs this winter. We aim to run you through the different gas fire options you have available in today’s market and how to avoid buying an unsuitable gas appliance.

Sitting in the comfort of your home in front of a burning fire on a cold winter or autumn evening is still one of life’s little pleasures. Senses aroused, the pleasure can quickly be dampened by the pending fuel bill due to rising energy costs and the use of inefficient decorative gas fired appliances which are not fit for purpose (in this case to provide adequate heating). You can be forgiven for asking “well, why have a gas fire which doesn’t give heat? what if we don’t want to warm our entire house and instead just the main living room in which we are spending the evening?”.

Firstly it is important to distinguish between Gas Fires which are highly efficient and designed for supplementary heating, and the less efficient Decorative Gas Fires. Here we will discuss how the basics of how a Gas Fire works and how technology is helping to improve heat output and overall efficiency.

gas fireplace Birmingham

Contrary to what some may believe, a high efficiency Gas Fire should be designed to warm an average sized living room if the main heating isn’t needed to warm the entire house. There are some factors to consider when looking to achieve this; if we are looking to reduce our overall fuel spend we must firstly look at the input and output ratio of our gas appliances, in simple terms this is the amount of fuel burned (input) and the resulting heat power (output) which is pushed into the room and is calculated in Kilowatt Hours. Output is important as we look toward a reliable and convenient source of heating and we would say anything below 4kw of output wouldn’t be sufficient to be considered as a direct source of alternative heating.

Similarly the input of gas is also very important as this will determine how efficient your appliance is, the efficiency is generally calculated as a difference between the input of fuel and the output of heat. Most Decorative Gas Fires will quote a heat output of 3.5kw, this is around 50% of the input (6.9kw) and as such the appliance is around 50% efficient. This means 50% of the heat will disappear up the chimney. Increasing the input of gas fuel to give more heat output doesn’t necessarily work; for safety most gas fires will try to keep the input of gas below 7kw, an input above 7kw requires the installation of an airvent to bring in fresh oxygen to replace the additional oxygen being drawn out of the room (the fire requires oxygen to burn). The additional cold air drawn in to the room from an airvent coupled with the additional gas/fuel being used makes this a counterproductive solution to the problem.

So what are the solutions?

This isn’t necessarily a new problem, before Gas Fired Central Heating was commonplace we demanded a convenient a sufficient source of heating and in the mid 80’s we saw a shift from the old draughty open chimney fires to a more box shaped unit which hung on the wall.

80's fireplace

This type of fire came in many guises but generally had a set of tiles to the front which once warmed up radiated heat as well as offering a convector to help exchange cold air for warm air, the basic concept of a convector is as follows…

A convector box draws cool air from the room into the bottom of the appliance/convection chamber, the cool air is then warmed as it passes over the hot surfaces of the chamber and the hot air is then pushed back into the room via the top convection slot.

As these fires were most popular at a time when efficient Central Heating systems were not commonplace it would be fair to say this is the standard by which most fires are measured today, certainly in terms of heat output.

Tiled gas fires generally have a heat output of 4kw with an efficiency rating of around 70%. As the unit did not sit within a draughty chimney opening most of the heat was pushed back in to the room instead of up the chimney. Although these fires are still available for sale today, they do not offer much in terms of choice and the bulky style means they either do not fit in to or keep up with the modern fireplace trends.

As time moved on we saw a massive shift toward central heating systems, demand for bulky high output fires waned and instead we were happy to compromise on heat and efficiency in return for style with inset gas fires all the craze. This was of course until energy prices began to rise and we realised that running the main central heating system as the sole source of heating was an expensive and sometimes impractical option.

At this stage it is important to note that although we are finding a significant shift in both demand and supply of powerful and efficient Gas Fires, Decorative Gas Fires still have their place in today’s market. Some clients are limited due to their existing fireplace. Some are limited due to budget and others are simply unaware alternatives exist, most if not all gas fires offered within entry level packages at the big Warehouses such as B&Q will be rated as “decorative” only.

Research and development in aesthetically appealing, ergonomic and efficient gas fires has resulted in a whole new generation of gas fires available to the UK consumer today. Taking the fundamentals from the older wall hung gas fires we now have some powerful alternatives to choose from.

First we must understand heat distribution, in the most gas fires distribute heat via radiation. The gas fire works by radiating heat generated from the burning ceramic fuel bed. The concept here is to warm objects rather than the atmosphere, hence the closer you are the appliance the warmer you feel. A convector as described above is added to the appliance to help with warming the atmosphere:

Decorative Radiant Fires

Decorative Radiant Fires are also normally exposed to the draught chimney they sit within the chinney opening causing most of the heat generated to be lost up the flue:

Cross section of chimney opening.

You can from this image below how a wall hung unit can reduce heat loss up the chimney compared to the decorative inset fire above. Here the harmful fumes and some heat is extracted via a small letter box flue on the face of the chimney.

As technology has developed the fundamentals of using convectors and reducing exposure to chimney openings are being used in more modern looking fires. Below we have compiled a list of all the different types of Gas Fires available in the UK today, ranging from the least efficient/least heat output, to the most efficient and warmest.
Open Fronted Radiant Fires:

Very similar in appearance to more efficient and powerful versions, the fact that this is an open fronted fire means the oxygen required for combustion is drawn from the room, further reducing the warm air in the room impacting the overall efficiency and ability to warm an average sized room. As these inset fires are sitting within and exposed to an open draughty chimney much of the heat will rise and disappear up the flue. The fact it doesn’t include a convector means it has no other means of quickly and efficiently warming your room. Most fires of this type can be bought on budget:

Heat Type Radiant only
Maximum Heat Output 3.0kW
Maximum Heat Input 6.9kW
Ventilation Required? Not normally required
Net Efficiency 44%

Open Fronted Radiant with Convector:

Similar in appearance to the Decorative gas fires listed above, they can usually be distinguished by the front hood under which the exchanged warm air is pushed back in to the rooms atmosphere. Although a little more expensive to purchase than a Decorative Gas Fire, the benefits offered by a convector certainly pay off. Although the unit is inset within the chimney the convection chamber encases the fire in a double skin and ensures most of the heat is distributed back in to the room with only a small amount of heat lost up the chimney via a small flap at the top/rear of the appliance.

Heat Type Radiant and Convector
Maximum Heat Output 4.0kW
Maximum Heat Input 6.9kW
Ventilation Required? Not normally required
Net Efficiency 60%

Tiled Radiant with convector fires:

Traditional (some would say old fashioned) gas fires which are still available on the market today, the ceramic tiles are warmed to give radiant heat with an inbuilt convector to help heat the atmosphere too. Still by far one of the most impressive in terms of heat output and efficiency on the market today, the unit sits in front of the normally draughty chimney with a small letter box opening used in the rear to extract the harmful fumes meaning most of the heat produced is pushed in to the room. Prices for these units are generally based on style and brand however some models can cost as much as modern alternatives.

Heat Type Radiant and Convector
Maximum Heat Output 5.2kW
Maximum Heat Input 6.9kW
Ventilation Required Not normally required
Net Efficiency 84%

Glass Fronted Convector Fires:

As you can see these type of fires come in many shapes and styles. The only compromise (if you can call it that) being the glass front, you can now have the most traditional to the most modern options with this type of gas fire and the choices now seem endless. Demand for this type of fire has meant manufacturers have made available almost all fires within their portfolios as a high efficiency glass fronted version.

A glass front is used to both help seal the unit for safety and reduce heat loss from the warm air usually drawn in for combustion. The hot glass radiates heat along with the regular ceramic fuel bed giving additional warmth as well as the useful convector working its magic. Efficiency is further pushed up by reducing the actual input of gas. Here the input is minimised so as to reduce the amount of raw energy used, this fuel is then converted to heat in the most efficient manner and in most cases giving you up to 90% of the heat back in to the room. Heat loss up the chimney is reduced by the style and shape of the fire chamber as with the convector fires described above.
Lower fuel input plus higher heat output equals more efficiency and lower running costs, and as most of these fires offer more than 4kw of heat output you will find they are sufficient for heating an average sized room independently.

Heat Type Radiant and Convector
Maximum Heat Output 5.1kW
Maximum Heat Input 4.5kW
Ventilation Required Not normally required
Net Efficiency 89%

So now you have our breakdown of how a high efficiency glass fronted gas fire which doesn’t compromise on style can be used as an independent source of heat to warm an average sized living room – without having to turn on the main central heating system to warm the entire house.
Here at Superior Fireplaces you can expect professional and genuine advice from our team of Fireplace specialists. Why not contact us today on 01213824047 or visit our showroom where we have many working models of all the different types of gas fires discussed here.