Home » Information & Service » Fireplaces – FAQ’s

Fireplaces – FAQ’s

What is the right kW fireplace for my house?

This is not a straightforward question, and the answer depends on many factors and variables. To calculate the right kilowatt we apply a common formula used throughout the fireplace industry.

Firstly, we need to know what size area needs to be heated?

The room’s length x depth x height = Cubic meters (m3).

Once we’ve done this, we calculate the kilowatt needed to heat the area, and then we look at which fireplaces are certified to provide that kilowatt in heat.

The cubic volume of the room (m3) divided by 25, plus 2 = the kilowatt rating of the fireplace needed to heat the room volume. This means that for every 25 cubic meters you require approximately 1 kilowatt.

This becomes tricky as this calculation is very subjective to variables such as – the insulation of the room and house, number of windows, and the outside temperature. Generally, most houses in South Africa are not well sealed. The desired room temperature should also be considered.

With hot air rising, the room heats from the top downwards. So, if your ceiling is more than 2.6 meters or you have no ceiling at all, then the calculation above would not necessarily adequately apply, as you would need a higher kilowatt output.

The kW of your fireplace and the heat distribution can always be complemented with a ceiling fan to circulate the hot air downwards, or you could purchase one of our Stovepro heat powered fans. Some fireplace models come with ‘optional extra’ or integrated fans.

All closed combustion fireplaces carry a kilowatt rating. When you are choosing your fireplace, bear in mind that you can always go bigger and burn less, but you can never go smaller and overfire, as this will damage the fireplace by trying to heat an area that it is not designed to heat and ultimately nullify your warranty.

It all comes down to experience, so please feel free to contact us if you are not sure which fireplace best suits your space.

What about kW & efficiency?

The kW rating on your closed combustion fireplace is more like a measure of the ‘ideal’ thermal output that your fireplace can maintain inside during the burning process, whilst maintaining a certain level of efficiency, and without prematurely damaging the fireplace body or internal components.

The manufacturers will choose which data suits the market they are targeting and publish accordingly. For example, a fireplace rated as 10 kW with 75% efficiency, may be able to comfortably kick out 14 kW during the testing process without too much trouble. However, the efficiency at 14 kW may be reduced to 70%, which does not suit the manufacturer’s target market, so they publish the results based on the 10 kW figures.

The efficiency rating is supposed to be the measure of how much of a fuel’s energy is given to your room during the burning process. The ‘scientists’ set a measure for the amount of fuel to be used (weight etc) and how often the re-fuelling will take place. They then test the emitted flue gases in the flue pipe (chimney) for temperature and carbon content. This happens during the burning process and it allows them to calculate how much energy contained in a given fuel has been radiated from the fireplace to the room compared to how much has not been.

The difference gives you a percentage rating for how efficient the fireplace is. E.g. a fireplace with a 75% efficiency rating is effectively transferring 75% of the energy stored in the fuel consumed to heating the room. The other 25% of this potential heat energy heats the flue, and the rest is lost out the chimney. These calculations are useful in principle. The problem is that each manufacturer may use its own test conditions to measure the efficiency, which makes it very subjective! Even within regulated countries like the UK, they can choose which fuel, how much fuel, refuelling times and the oxygen intake they want to use under the test conditions.

This makes it close to impossible to measure exactly ‘like for like’, as you do not know what the test conditions set by the manufacturer are. However, some manufacturers will publish their test conditions and refuelling times which means that you have a much more genuine result and can make a better comparison with others (provided they also publish their test conditions).

Why is it important to follow the directions of 'Lighting my first fire'?

Instructions for your first fire

Don’t use your fireplace for the first 24 hours as the waterproofing needs to dry. Failure to do so will invalidate your guarantee.

Very important: When making your first fire you should leave the door slightly open, with the handle left out of the locked position. The curing paint can cause the fire rope in the door to stick to the fireplace, so avoid pressing the fire rope against the paint in the first few hours. Leave the door unlocked until the first fire dies out naturally & the fireplace has cooled down completely. The fire rope is manufactured out of specialised glass fiber & not asbestos.

NB! – The demonstration fire done by the installer using newspapers does not qualify as an “Initial Ignition”.

Empty the fireplace & ash pan. Remove tools, paperwork, & gloves from inside, & anything from on top of the fireplace. If you are self-installing you should also remove anything stuck to the glass window.
Slide the lower primary & top secondary air controls wide open. With no bottom air vent, open the ash drawer below the door by about 1cm. Most Built-in Fireplaces have air vents situated below the window/door.
Your first fire should be started very small & be gradually built up to increase the temperature slowly over 3-4 hrs. Start the fire with a blitz & kindling, & then add 2 logs of wood when it’s burning well. Once the fire is going you can close the vents halfway to 2/3^rds, & overtime you can refuel by adding 1-2 logs every time.
During the first fire, the paint will start curing. Some odour & even a bit of smoke may come off your fireplace, but this will go away after a few fires.

How do I make fires after the ‘first paint curing fire’?

Instructions for Ignitions after the first fire:

Empty the ash pan & unclog the grate (do this only when it’s cooled down).
Fully open the bottom, Primary air vent, or the ash pan by about 1cm.
Fully open the top, Secondary air vent.
Add chopped wood kindling & Blitz starter blocks. Light the fire, close the door & allow the fire to burn well.
Add 1-2 logs of fuel to maintain fire & close the door. Feed the logs carefully into the fireplace to avoid damaging the glass window, fire brick & to avoid dislodging the baffle plate situated inside the upper part of the combustion chamber. Fuel added after this should be added when the current fuel has reached a basic fire bed.
After starting the fire & achieving a comfortable burn, the air vents need to be partially shut by 1 to 2/3rds & the ash pan needs to be closed.
Please note – a tumble dryer, extraction fan, or open window within the same area of the fireplace can alter the extraction draft in the flue; create bad burning conditions & a backdraft of smoke into the room.

What is a closed combustion fireplace?

In short, closed (or slow) combustion refers to the process of burning solid fuel in a closed metal box or stove and thereby increasing the heat output, and at the same time reducing the fuel consumption by 20-30% when compared to a traditional open fireplace.

Instead of feeding fuel into a freely, oxygenated open fireplace, where it is burnt up very quickly and where much of the heat is lost up the chimney, you can now control how much oxygen your fireplace receives with various air vents on your closed combustion fireplace.

This means that you can regulate the heat much better than with an open fireplace. In addition, by burning the fuel in a stove your fuel achieves a much higher temperature than it would if burned in an open fireplace. The result is a regulated fire with more heat for less fuel, and a monetary saving over time.

Some fireplaces have advanced technology that decreases the number of emissions released, resulting in an environmentally friendly burn. Look at for fireplaces with SIA 2022 Eco-designs, DEFRA certifications, and BLU technology. You’ll find these in the Charnwood and Northern Flame Ranges on our website. Going for closed combustion supports eco-sustainability and is an environmentally-friendly choice.

Why is closed combustion so much better than an open fireplace or hearth?

To sum it up, modern closed combustion fireplaces are efficient and with their sophisticated technology, they ensure that the wood is burned as cleanly and as efficiently as possible.

Unfortunately, this is not so with an open fire fireplace. The first major difference is that all modern closed combustion fireplaces are sealed with a door and this ‘sealed combustion’ increases the temperature in the combustion chamber. With new technology and design, many modern units feature extra insulation in the combustion chamber such as vermiculite bricks or Accumote, which retain and reflect heat into the room.

Flue gases are also expelled through clean combustion technology making them more environmentally friendly. An open fire achieves just a 15% yield especially because it loses a lot of warmth up through the chimney. A modern closed combustion fireplace achieves an average of 60 – 80% yield. The emissions from an open fire are also much higher, as the open fire emits about 15 times more CO2 and about 50 times more fine-particle pollutants than a closed combustion wood-burning fireplace. So, closed combustion is not only safe, but it’s also more environmentally friendly.

Should I purchase a cast iron or a steel fireplace?

The honest and simple answer is that they both have their strengths and weaknesses.

How valuable is your time? Cast iron takes a little longer to heat up but it can retain the heat for a little longer, while steel heats up quickly but also loses heat quickly when the fire has died.

Some entry-level cast iron fireplaces do not offer the same levels of control over the airflow into the firebox as their plate steel counterparts. Due to the molding process of some cast-iron models, some of the individual parts may miss the precision at which they are manufactured.

How do you rate price vs. quality? Steel fireplaces allow for more contemporary designs than cast iron, which is why steel fireplaces have become so popular over the years. Steel fireplaces manufactured of slightly thinner plate steel (≤ 3mm) are less expensive too, but will not last as long as cast iron. Either way, look after your fireplace with regular maintenance and always use dry wood.

These days, with advanced CNC technology, the majority of manufacturers are moving towards steel.

To make a long story short: there is not too much difference between steel and cast iron. If you purchase either from a reputable company, you will more than likely be happy to wave the flag for either, no matter which fireplace you buy.

If you want to cover both options you can always choose a steel fireplace with cast iron internal parts and a cast iron door.

Primary air, Secondary air/Air wash, Clean burn and Tertiary air explained

Primary air

In the mid-19th century, long before the days of global warming discussions, stoves were being widely produced in Europe as cast-iron boxes with many chambers, designed with a firebox in the bottom chamber. Air entered the stove in many cases at the base of the fire bed to ignite and burn the fuel. This was known as Primary air. Primary air is still used today in multifuel fireplaces as a controllable inlet at the base of the stove door. It is the primary or main combustion air inlet into the fireplace chamber under the fuel bed. This air ensures good ignition of fossil and non-fossil fuels and if it is not controlled by the air inlet control it will cause the multifuel stove to burn fiercely. Multifuel fireplaces in the not so recent past had solid cast-iron doors, as pyroceramic glass was not available. As woodburning and multifuel fireplaces advanced, secondary air was developed with panes of pyroceramic glass and better fuel combustion (a requirement to reduce emissions).

Secondary air
Secondary air is an extra addition of air through an air inlet or inlets above the fireplace door. The Secondary air exit vent is close to the angled baffle plate at the top of the fire chamber and angles downwards appearing as a narrow vent above the fireplace door and glass. This vent introduces a stream of warm air just as the unburnt gases rise to pass by the baffle plate, and enter the gas exit chamber. The warm air ignites the gases, resulting in a Secondary burn with more heat and fewer emissions. The Secondary warm air from the vent flows downwards behind the glass to the top of the fire bed, also aiding in Secondary combustion and creating a warm air film over the glass. This hinders the smoke from blackening the glass. As the temperature in the fire chamber rises and the secondary air flowing downwards behind the glass gets hotter, you can see the hot air visibly clean the glass. This action is called air-wash. Woodburning fireplaces work best after initial ignition by only using this upper controllable inlet, as they burn differently than fireplaces that burn fossil fuels. The Secondary air inlet should also be used to control multifuel fireplaces, once the fire is well established, with the opening up of the primary air inlet again when more fossil fuel is added or if the fuel is not combusting well.

Cleanburn or preheated Secondary air
Cleanburn is really preheated Secondary air. The Secondary air, instead of entering the woodburning or multifuel fireplace at an inlet or inlets above the door, is very often brought up via ducts from the lower back of the fireplace. The air is partially fed into the lower part of the fire chamber and the rest of the hot air, is ducted above the fireplace door to a similar exit vent as described above, near the edge of the baffle plate. It again flows down over the door to give a hot air wash and then travels into the fire chamber as hot Secondary air. The next time you have a good look at a fireplace you will see the same channel just inside, above the door on both a Secondary air and a clean burn fireplace. The difference being the clean burn fireplace will normally have its Secondary inlet control at the base of the fireplace. This preheated Secondary air ignites some unburnt gases in the lower and upper parts of the fire chamber, which burn off at higher temperatures than the direct Secondary air can achieve. The glass usually stays super clean with preheated secondary air systems. The result of the clean burn or preheated Secondary air is much better combustion and lower emissions from a woodburning fireplace.

Tertiary air
Tertiary air further compliments the clean burn system as a third air intake, which is often seen working in Norwegian fireplaces and modern/contemporary woodburning fireplaces with large combustion chambers. The air is normally drawn up the back of the fireplace via a series of chambers and it is then injected into the back of the upper combustion chamber through small steel jets. The jets of extremely hot air then ignite the remainder of the gases that only burn off at very high temperatures. As long as dry seasoned wood is being burnt, the emissions from these fireplaces are very low. Many of these contemporary/modern woodburning fireplaces carry the Din + standard for high combustion and low emissions. Look at for fireplaces with SIA 2022 Eco-designs, DEFRA certifications, and BLU technology. You’ll find these in the Charnwood and Northern Flame Ranges on our website. Going for closed combustion supports eco-sustainability and is an environmentally-friendly choice.

Which fuel should I use in my fireplace?

Always use very dry, well-seasoned wood. Use firelighters such as Blitz & chopped kindling wood for starting the fire. Wet wood causes a smoking fireplace; soot-blackened windows; a 50% drop in heat output & the fuel usage to double. Bluegum is often an economically priced South African favourite.

Don’t use liquid fuels, tarred wood, shavings, fine coal, and pallet crates, or use the fireplace like a furnace to burn garbage and waste.

What guarantees are there on the fireplaces?

Charnwood – 10 Year limited guarantee on all their fireplaces.
Northern Flame – 2 Year limited guarantee on their built-in / inserts, and a 5-year limited guarantee on their freestanding models.
Invincible cast iron fireplaces & Earthfire ceramic pots – 10-year limited guarantee.
Spartherm, Kratki, Invincible (plate steel fireplaces), Hydrofire Boiler Fireplaces, Dovre, Godin – 5-year limited guarantee.
Canature, Sentinel – 3-year limited guarantee.
Hydrofire – a 2-year limited guarantee for their steel fireplaces and a 5-year limited guarantee on their cast iron units.
Chad-o-Chef – come with a 2-year limited guarantee.

All loose internal parts like the grate, ash pan, bricks, and baffle plate are guaranteed for 1 year with Hydrofire, Dovre, Godin, and Invincible fireplaces, and 2 years with the Charnwood fireplaces. All the guarantees are limited in the sense that there are no guarantees on the glass, paint, and ceramic rope.

At the discretion of GC Fires, we will either repair or replace defective parts. The labour cost to replace defective parts will be covered by the guarantee for the first year only.

GC Fires is not liable for any consequential loss or incidental loss, damage or injury whatsoever caused. The guarantee will become null & void if the fireplace is not installed in accordance with the installation instructions; is not serviced annually; is subject to misuse or neglect, including the use of non-recommended fuel; or if the unit was damaged due to over firing or water leaks.

To avoid overheating you can purchase a stove thermometer which will help you manage the temperature of your fireplace.

All claims must be made in writing to GC Fires and must be accompanied by photographs and by proof of purchase. Nothing in this guarantee shall affect your statutory rights.

Do you refurbish old units?

Yes, we do, outside of our peak season.

You are welcome to deliver it to our warehouse for a free assessment and quote, or we can collect it for a fee (Cape Town and Helderberg area only).

Please keep in mind that we are not magicians and that some things are just beyond repair. If that is the case, we will advise you on the best replacement for your budget.