Important factors to look for in fires and heaters

Fireplace Supermarket discusses the important factors to look for in the various types of fires and heaters available today.

High-efficiency gas fires come in three forms: conventional flue, which uses a chimney; balanced flue, which has a pipe through the outside wall like a modern combi boiler; and catalytic flueless, which uses a catalyst to absorb harmful fumes from the exhaust gases.

Standard non-efficient fires, on the other hand, work by having a slight slope to the back of the fire, which causes a small build-up of heat just above the burner.

While some of this heats up the room, the vast majority is pulled up the flue.

The pressure builds up from the expanded or heated air, causing it to rise in the flue, due to the pressure differential from the outside to inside the warm room.

This creates suction up the flue and continues to draw more gas and a lot of heat from the room.

Most of these fires are a maximum of up to 40 per cent efficient; the reason that certain models provide an output of up to 4.5kW is that they inject more gas in to burn.

Most will stick to 6.9kW input as a vent in the room is required above this figure.

However, for a high-output open-fronted fire, the user will need to place it in a 100cm3 air vent as a precautionary measure.

This means that when the fire is off, he or she will have an opening in the wall on one side and a long open chimney to provide a pleasant draft.

Decorative gas fires are a small substrain of standard gas fires; however, these items provide such a small output that manufacturers do not pay Gastech to measure the efficiency.

These fires usually have the heat output of a light bulb and an efficiency of around one to two per cent.

The main use for them is in gas baskets and cast-iron trays.

These items do not have the space available to create a higher efficiency.

They have large fixed openings that usually require class-one flues; they then use a small gas burner, thus wasting a lot of money.

Power-flue or fan-flue gas fires are, essentially, the same as the conventional flue standard fires but with one major difference.

Instead of an opening in the top of the fire to allow the fumes to vent through up to the chimney or flue, these fires have high-pressure extractors positioned on the exterior of the building.

This means that, rather than the passive draw of heat movement up the flue, the user has a powerful fan sucking out the fumes as well as the majority of the heat.

Most power-flue fires are around 10 per cent efficient, which is a large expense for a decorative flame.

These fires have a higher input than standard fires; the efficiency is so low that they require the extra input to provide a similar output to the room.

As a result of this, several UK manufacturers have now stopped producing these models.

It is also advised that the government will be forcing manufacturers to cease producing the items for reasons of efficiency.

The last thing to consider is that all power-flue systems require an electricity source, which means that the user is utilising both gas and electricity to power a fan - this figure is never included in efficiency ratings.

Should the user have no electricity for a power shortage, the fire will not turn on.

There is one product on the market that is it 60 per cent efficient and has a draft-barricade appliance on the exterior, contained within the fan flue.

The Apex Clarkdale draft-barricade power-flue gas fire actually shuts the opening through the wall when the fire turns off, reducing drafts and increasing the efficiency of a home.

High-efficient conventional flue gas fires for chimneys have a glass front as well as a convector box.

This is a channel that goes from the front base of the fire to the front top of the fire, wrapping the engine of the fire.

This channel will allow cold air to enter underneath the fire and heat up as it rises around the burner.

This then leaves the fire as convected warm air through the convector grill.

The user also has the glass front, which holds the heat within the fire box for longer, allowing it to escape into the room through the convector channel.

From a glass-fronted high-efficiency gas fire, it is possible to get efficiencies of up to 89 per cent, cutting wastage right down to only 11 per cent, rather than the 70 per cent seen on open-fronted fires.

High-efficient balanced flue gas fires work in a similar way to conventional flue high-efficient gas fires as they have a glass front allowing a slower movement of air and a convector box allowing convected heat to warm up through the convector channel and heat the room, along with radiant heat from the heated ceramics.

However, they do not require a chimney.

Balanced flue gas fires vent any fumes by exiting through a wall to the outside.

There are several different ways of doing this: via two pipes, one at the top venting exhaust and the lower one providing fresh air into the burner to supply oxygen to the flames; or through a twin-walled system, which uses one pipe inside of another, the internal pipe being used to exhaust hot fumes, which, in turn, warm up the fresh air coming in through the exterior pipe, allowing a higher efficiency as the air is preheated ready to burn.

The latter flueing system of the twin-wall pipe work also allows flexibility when it comes to installation, as the user can allow several bends and extensions should he or she be limited with the suitability in the home.

Several large glass windowed products are also available, along with two-sided glass-fronted fires, which can be used as room dividers, along with many other designs to choose from.

The efficiency of balanced flue gas fires is usually limited to up to around 86 per cent as the exhausting system allows a vacuum-like airflow through the item due to the fire having an open flue to the outside.

As they are sealed units, they will not require a vent in the room.

High-efficiency catalytic flueless gas fires work by having a sealed flame behind glass, which forces the fumes to rise up through the fire and into a catalytic converter.

The catalytic converter is a honeycomb membrane that is impregnated with a catalyst chemical; this noble metal speeds up reactions and enables the modification of molecules into others with less energy.

Any harmful chemicals are turned into CO2, which is harmless in the proportions of a room.

It can also be so effective that it will aid in cleaning out allergens in the air from a room as well as providing heat.

All flueless fires are designed as a supplement to a primary heating source, as burning natural gas produces a wet flame.

Catalysts have been tested and have a lifespan extending beyond 16,957 hours.

This is equivalent to about 27 years of average use (four hours a day, five months of the year).

The efficiency of catalytic flueless gas fires is set at a fixed 100 per cent.

A downfall of catalytic flueless gas fires is that they require an air vent in the room, although most homes do have one of these.

There are several methods to provide heat from an electric source (convector heaters, fan heaters and oil-filled radiators).

Convector heaters and fires provide heat into the room up to a maximum of 2.4kW (2,400W).

They work by having a heating element, which is a piece of metal wire that heats up due to electrical current.

This, in turn, heats up a proportion of air within the product.

As this air heats up and expands, it rises through the product and creates a draw (suction) in through the grills at the base, allowing cold air to be pulled up through the heating element and into the cavity of the fire to be heated.

This then starts a cycle, which will eventually provide a circle of air around the room until the fire cuts off as the air temperature within the room has hit the limit on the thermostat.

These items are 100 per cent efficient, much like the Tesy CN01 240 wall-mounted panel convector heater.

As well as convector radiators, there are various hang-on-the-wall electric fires available that are also convector fires; these work in the same way but have a more aesthetic design.

Oil-filled convection heaters and radiators work much like the convector radiators and heaters but, instead of an open cavity in which air can flow through the heating element, they are sealed spaces filled with oil.

This is heated by the element and then the warmth is convected through the metal casing to the surrounding air.

The grilled exterior allows the maximum volume of air to come into contact with the metal and heat up, rising through the grills and creating a draw.

Oil-filled radiators supply a small amount of radiant heat.

Most people presume that it is possible to get more heat from an oil-filled radiator than a simple convected one, which is incorrect; it is possible to get the same outputs from either, dependant upon the size of the heating element within the model.

There are a couple of issues that are commonly mistaken.

For instance, the oil within the heater has a high specific heat capacity, meaning that it is able to absorb a lot of heat before it starts to give heat back out into the room.

As a result, there is a small delay after it is turned on before any heat can be felt; this delay is relative to the volume of oil, the size of the heating element and the pressure of the oils within.

Although this delay on such a small volume is never more than a few minutes, this can be a problem if the heater has been purchased for speed of heat.

Fan-assisted heaters work by having a fan or blower that forces cold air over a heating element.

This, in turn, blows warm air out of the appliance into the room.

Benefits of this system include a higher heat output from a fan heater because it does not need to wait until the heated air rises by convection out of the fire, but instead forces the air through.

The additional benefit from certain models - much like the Apex Mirage Deluxe - is that the fans point downwards towards the floor, making it possible to place a television or shelving units above the item without too much hassle.

Light-emitting diodes (LEDs) are strong and durable and have an extraordinary lifespan.

White LEDs quickly matched and overtook the efficiency of standard incandescent lighting systems.

While standard bulbs work at around 16 per cent efficiency, measured by its light output per unit power input, LEDs work at around 90 per cent.

Typical lifetimes are 25,000 to 100,000 hours - this is either 11 years of non-stop operation or 22 years of operation at 50 per cent.

The long operational life of an LED lamp is a contrast to the standard lifespan of an incandescent bulb, which is around 5,000 hours.

This means less changes and more value for money.

Electric fires and heaters are all 100 per cent heat efficient, while the lighting will depend upon the bulbs being used.

If the user goes for a standard bulb, it will be around 60 per cent, while LED fires such as the Drugasar Metro 120e will be around 90 per cent.

Overall, LED electric fires are around 95 per cent efficient, while standard electric fires are, on average, 80 per cent efficient.

A single kilowatt-hour of electricity in an LED version will generate 1.34lb (610g) of CO2 emissions.

Assuming the average light bulb is on for 10 hours a day, a single 40W incandescent bulb will generate 196lb (89kg) of CO2 every year.

The 13W LED equivalent will only be responsible for 63lb (29kg) of CO2 over the same time span.

Gas and electric heating in homes is always presumed to be less efficient than the central combi-boiler heating systems, but this is incorrect - dependant on individual home lifestyles.

The most efficient way of heating a home is to use combi central heating to produce a background heating source to provide a minimal temperature in the home (usually around 16C).

Reducing room temperature by 1C could cut heating bills by up to 10 per cent and typically saves around GBP55 per year.

For those with a programmer, heating and hot water should be set to come on only when required, rather than all the time.

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