The Ultimate Guide to Keep a Fire Burning in your Fireplace or Stove
This article will focus on the important things to consider which if followed will 'keep the home fire burning'
After following the advice given in our article "How to Set a Fire in an Open Fireplace or Stove" you should now have a roaring log or coal fire in your fireplace. Now all you need to do is keep the fire alight and performing at its most efficient in terms of the heat produced balanced with the amount of fuel used. So how do you keep the fire going in your fireplace or wood burner or multi fuel stove? Follow the advice below for that perfect fire.
The 2 Essential Components to Maximise Heat Output
In essence there are two essential components that need to be controlled to get the most out of your fuel and gain maximum heat output from your fire, fire insert or stove. These are the fuel itself and the draft, in other words controlling the air intake to the fire, stove or fire insert. With a little experience you will soon master the real skills and knowledge needed to get the best returns from your fire. Note we use the words skills and knowledge, as maintaining a well performing fire is as much a science as it is a skill. Understanding the science behind a fire will help you develop the skills required, as you, and I kid you not, kindle a deep relationship with your fire, stove or fire insert.
Using the Correct Fuel
As already discussed in greater detail in our previous blogs it is essential you find a well trusted coal or log merchant. They will supply and ensure you are using the correct solid fuel for your open fire or appliance. If you choose to use wood as fuel a good quality supplier will make sure it is well seasoned or dry, this is of course unless you intend to source your own wood and season it yourself. Ideally your logs should have a moisture content of less than 20%. If you are burning kiln dried timber off cuts with a moisture content of less than 10% try to mix this with air dried, seasoned logs to raise the moisture content of the load, this will maximise the efficiency of the fuel and therefore the heat output.
There is remarkably little difference in the calorific value by weight between tree species once the logs are well seasoned however there is a difference by volume. In other words one cubic metre or firebox/grate of hardwood will have a much higher calorific value or potential heat output than the same volume of softwood. Keep this in mind and burn softwoods in the autumn and spring and on milder days when not so much heat is required and save hard woods for the depth of winter.For further information relating to firewood logs and their calorific value take a look at this article on 'using wood as a fuel source'.
Quick Summary Guide
Find a trusted coal or log merchant or if sourcing own wood season well.
Only burn wood with moisture content 20% or less.
Burn soft woods in milder weather.
How to get the Most Heat from Your Fire and Fuel
To get the most heat out of your fuel whilst lowering the risk of a chimney fire through creosote build up in your chimney you will need to burn bright, hot fires, the added benefit of this is that it will also reduce air pollution. When burning wood as a fuel, there should always be flames until the fire reaches it third and final phase of combustion, the embers or charcoal stage.
When refuelling a wood fire pull the embers or charcoals from the back of the fire to the front nearest the air supply whether it is the hearth front or front of the fire box of a wood burning or multi-fuel stove or fire insert. This also provides the ideal opportunity to remove ash if need be.
Do remember a fire, particularly a log fire, performs better on a half inch bed of ash but don’t let this build up over two inches. If the fire has died right back it may be necessary to add more kindling to rejuvenate it before placing four or five logs on the fire. If there are plenty of hot embers and you time it right which you will with experience the logs should catch immediately. Leave the air intakes open for between five and twenty minutes depending on the size and moisture content of the wood or until the hearth or firebox is full of bright dancing flames and the outside of the logs are beginning to charcoal. Once the wood is beginning to char you can regulate the air intake to help control the heat output and the length of burn you want. It may be necessary to reduce the air intake to your stove or insert in stages depending on the wood and the appliance, again this will be learnt with experience. If you are using an open fire it may be necessary to poke the fire to introduce more air or add additional kindling to reinvigorate the fire.
Never let logs smoulder with no flame this not only wastes fuel as the energy giving heat is contained within the smoke as volatile gases which if left un-burnt will potentially damage your chimney, appliance and add to the problem of air pollution.
How to Load Logs for Maximum Efficiency
You can also control the heat output and gain the most from your fuel by the way you load the fire. A small loosely stacked load can burn hot and quickly take the chill of the space you want to heat without overheating the room. A loosely stacked criss-crossed load of smaller. logs will provide plenty of space for air to enter the fire and promote a faster combustion of the fuel. In milder weather burn smaller loads and logs more loosely packed than in colder weather. A more densely packed firebox or hearth will provide a longer lasting higher heat output fire ideal for colder weather. Another tip is in warmer weather orientate the fuel from east-west in other words from one side of the fire grate to the other and in colder weather lay your logs north-south i.e. front to back. When loading the logs east-west the wood breaks down more slowly as the combustion air reaches the fuel at the sides of the logs giving you a longer lower temperature burn ideal for milder weather. This will save you fuel and help prevent the home from becoming overheated. By loading the logs north-south the heat and flame can penetrate the fuel more easily giving you a higher more consistent heat output. A north-south configuration also enables more logs to be loaded giving a longer burn in spite of a higher heat output.
Quick Summary Guide
Burn hot, bright fires
Rake the ashes forward before re-fuelling
Fire each load hot before restricting air intake
Change the way you lay the logs and how you pack them depending on the heat output required.
Never leave fires to smoulder
Understanding the Complete Cycle of a Fire to Suit Your Daily Needs
Don’t fall into the trap of adding one or two logs an hour to a fire in an attempt to maintain a consistent heat output. Wood fires burn best in cycles. The cycle starts when you refuel the fire pulling the hot embers forward placing the new fuel behind them and watch the logs ignite. The cycle ends when the fuel is reduced to a hot bed of charcoal embers. You can not expect a log fire to give you a perfectly consistent heat output. The heat output will vary depending at what stage of the burning cycle the fire is at. The most heat is given off at the pyrolysis stage where the cellulose within the wood breaks down releasing volatile organic gases that ignite releasing the heat contained within the fuel as heat. A complete cycle should provide between three and eight hours of burning time and heat. The burning time as already explained is dependent on the fuel- hard or soft woods, how much fuel is loaded, how the fuel is laid, and the heat output required. Try and plan the burning cycle around your lifestyle.
If somebody is at home throughout the day then it is more apt to use a short burning cycle. It is possible to extend the time of the burn cycle by packing large logs close together with little space for air to penetrate to the heart of the fuel. To maximise the burn time once a large load of fuel is in place, in the hearth, or firebox, open the air intakes or draft plate for 15-30 minutes or until the outer logs have a layer of charcoal on them then close the air intakes or draft plate in stages until the required burn rate is obtained. The outer layer of charcoaled logs will insulate the rest of the wood and helps arrest the release of the woods combustible gases prolonging the burn time. There should at all times be visible flickering flames and wood should never be left to flamelessly smoulder unless in the final stage of carbon burn. To leave a fire smouldering is not only polluting the atmosphere but a gross waste of fuel and therefore money or your hard labour if you cut and process your own logs.
Once the fire has been lit and is performing well returning the desired heat output sit back, relax, and enjoy. It is only necessary to refuel a fire at the end of its burn cycle when you will notice a temperature drop in the room, house or space you are heating.
Fires do not return a perfectly consistent heat output
Burn wood in cycles
You can to some extent control the length of the burn cycle by the fuel used and how you load the fuel.
Sit back and enjoy
Only refuel when the fire reaches the end of its burn cycle and you notice a drop in room temperature.
Visual Checks to See if Your Fire is Performing Well
The introduction of glass viewing doors to modern stoves and fire inserts has made the use of flue or stove top thermometers generally redundant, although, some manufacturers still recommend their use. It is obviously a different story with the older non-glass door type stoves where you are in effect burning the fire blind with little indication of how the fire is performing within the concealed firebox.
There are plenty of visual signs which will help to determine how your stove or fire insert is performing. When wood is burning flames should always be visible until the fire reaches the final stage of carbon burn. If you have fire bricks within your stove or fire insert’s firebox they should be tan or biscuit in colour and not stained black with tar and soot. The viewing glass door on an air wash stove or insert should be clear or maybe a little hazy in the case of a non- air wash appliance, but again never black. Any exposed metal within the firebox of the stove or fire insert should be light or dark brown in colour and never black and shiny. Another visual indication of how your fire is performing can be gleaned by a brief interlude outside to view the chimney. You should expect a little white smoke to be present immediately after re-fuelling otherwise a properly burning fire should produce little or no visible smoke plume. A blue or grey smoke plume indicates the fire is smouldering with inadequate air flow to maintain combustion or you are using green or wet wood both will result in poor heat output.
Quick Summary Guide
Flames should always be visible; fires should not be left to smoulder.
Fire bricks, if present should be biscuit in colour
Glass door should be clear
Check the smoke from chimney, a little white smoke after re-fuelling is okay.
A properly burning fire should produce little or no smoke and never blue or grey smoke.
How Efficient is a Fire
It does need to be said no matter how aesthetically appealing an open fire they are by definition grossly inefficient and unfortunately, polluting to the atmosphere and potentially hazardous. An open fire returns at best an efficiency rating or 10-20%, if not a negative efficiency rating with any complimentary heating appliance having to pick up any short fall or deficit. Many argue open fires are as near as useless as a heat source being far more suited to the stone age alternative to television and in our opinion admirable past time of fire watching. For further in-depth information regarding open fires see the accompanying article The Myth, the Science and the Solution to Open log Fires.
Pollution Levels of Open Fires and Stove Fires
Open fires in comparison to stoves and fire inserts are quite polluting emitting between 30 and 60 grams of particulates an hour depending on whether hard or soft woods are used as fuel older log burning stoves such as pot belly stoves, the older cast iron box stoves, and welded steel airtight stoves return a fuel efficiency rating in the region of 40 to 50% with a particulate emission rate of 15-20 grams for hard woods and up to 60 grams per hour when softwoods are burnt. The newer burn clean technology stoves or fire inserts whether they are of the catalytic converter or non catalytic converter type using the new clean burn technologies return a fuel efficiency rating of 60 to 80% + with a particulate emission rate of 2-5 grams per hour.
Quick Summary Guide
Open fires are grossly inefficient and polluting more suited to fire-watching than as heat source.
Upgrade to a new advanced combustion stove or fire insert and use 1/3 less fuel
Non-catalytic converter clean burn technology Using the Correct Fuel
Reasons Why No Two Fires Burn in the Same Way
This brief guide on how to achieve a hearty, efficient and safe fire should set you on the right pathway to gain the most out of your fire, stove or fire insert. Furthermore the advice offered illustrates a number of ways to control the heat output of your fire other than solely restricting the air flow reducing the fire to an atmosphere polluting, inefficient, fuel wasting fire returning very little heat output. Remember to obtain the best results from your fire in terms of heat output, fuel efficiency, and levels of pollution control your fire through the types of fuel you burn, fuel load size, fuel configuration and fuel orientation. No two fireplaces, stoves or fire insert will act the same and even if identical appliances are installed in similar properties and situations they will behave differently due to differences between chimneys, atmospheric pressures etc. We always advise where an open fire or any other heating appliance, bio-mass, or fossil fuelled, is installed also install the appropriate smoke and carbon monoxide alarms and do check them regularly. You never know they might just save your life!
You will soon learn the distinct characteristics of your particular fireplace, stove or fireplace insert and greatly enjoy the unique heat, style and ambience your choice of fire and fireplace surround lends to your home. The advice given within this article is by no means the definitive answer to maintaining a good welcoming fire at the heart of your home and we look forward to your contributions and experiences we can all lean from and build upon the advice given through our blogging facility.
Read more about Fireplace Maintenance
Read more about Solid Fuel
With Thanks to Contributors
Nic Snell - Certainly Wood
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