Building a fire to keep us warm is perhaps the activity that reconnects us with nature and our primitive instincts.
Whether a wood stove, an open fire, an outdoor campfire, or even a simple firepit, collecting wood and building a fire for warmth is as romantic as it is practical.
In this environmentally and cost-conscious world we live in, efficiency is an important topic and, in this context, means thinking about getting maximum heat output from minimal wood fuel input.
Throughout this piece, we’re going to be exploring what some refer to as ‘upside-down fires’, and more specifically, how to build a top down fire in a wood stove.
What is a top down fire?
Before we continue, it’s worth setting out here exactly what we mean by a top down fire.
If you grew up with a wood stove or open fire, you’ll have likely been taught to build the fire using traditional methods, most notably using firelighters (or newspaper) and kindling, with the kindling arranged in either a tepee pattern or like a jenga stack with gaps. Once the fire had taken hold of the kindling and some heat was being generated, it was at that point that the actual wooden fuel was added and the fire would build from there.
With top down fire building, the wooden fuel is added first with the kindling and firelighters placed on top of it, hence the reason some people refer to it as an upside-down fire.
Benefits of a top down fire – why is it better?
What’s wrong with the traditional methods, why the need to do things differently?
Well, as mentioned above, efficiency is important as is the amount of toxins we release into the atmosphere as our fire burns – if we can burn cleanly, we’re ensuring that the environmental impact of using a wood stove is kept to a minimum.
With conventional ‘bottom up’ methods of building a fire in a wood stove or open fire, a considerable amount of smoke (ie gasses) is generated which goes straight up the chimney into the atmosphere. With the top down method, these gasses are still generated but because the hottest part of the fire is on top, the flames will ignite any gasses rising from the main fuel load on the bottom of the fire which in turn will mean a vast reduction in smoke (which contains pollutants) at the same time as generating additional heat from the same fuel load.
This is why the method is kinder on both your wallet and the environment.
Top down fire lighting method
So, how exactly do you build a top down fire? Well, everyone will have their own specific way of doing things and I’ll detail mine below but all will follow the key principle that the larger logs are on the bottom layer, on top of that is the smaller logs, then on top of those is the kindling.
Here’s how I personally build mine.
- Select the correct wood
For this, I choose two larger split logs and two smaller ones. The important thing here is that the height of each pair is the same so that as you stack the smaller splits on top of the larger splits, then the kindling on top of the smaller splits, it’s all fairly level and unlikely to fall over.
I normally burn silver beech so never really have very large splits which I’d probably only use to burn individually once the fire is established. You’ll get an idea of the relative size difference between each pair in the photographs that follow.
- Ensure a good bed of ash
This is specific to wood burning stoves with a solid base as opposed to multi-fuel stoves which have a grate. A bed of ash from previous fires acts as an insulator and can make for a more efficient fire. How much you need should be dictated by your stove manufacturer’s instructions and you should never exceed the recommended maximum. For my own stove, the bed of ash I’d say is around an inch thick.
- Build your fire
Once you have everything ready, it’s time to start placing the fuel and kindling in your stove. The configuration you choose will largely depend on the shape of your own stove, mine is quite wide but shallow so I place the larger base logs in a diagonal configuration running from the bottom-left corner of the ash bed to the top-right of it.
Once the large splits are down, it’s then a case of sitting the smaller splits on top in the opposite direction to ensure plenty of airflow. I simply place these running left to right.
The left image below shows how the base splits will sit in the stove. The image on the right shows how the smaller splits then sit on top of them.
The next step is to add your kindling and a couple of firelighters on top of the smaller splits. I put three larger pieces on the bottom of the kindling stack with a natural firelighter in between each one, followed by another three slightly smaller pieces on top running in the opposite direction and then a final layer on top of that which are smaller again and running in the same direction as the first kindling layer. I sometimes add a fourth layer if some I have some very thin kindling to hand. It should end up looking like a bit of a criss-cross pattern with plenty of space for airflow and the higher up the stove the full stack goes, the smaller each item will be.
I then add an additional natural firelighter towards the front of the stove in the gap between the two largest splits just to assist in them igniting once the temperature of the stove increases.
The whole stack should be tall enough that it will quickly heat the stove pipe to assist the draw from the chimney whilst keeping the flames contained in the firebox only – don’t stack it so high that you’re sending roaring flames directly up the chimney which presents a chimney fire risk.
- Light the fire
This is the moment! I use long safety matches to get underneath the firelighters and if time allows, I try to light the front and back of each one.
Once lit, close the door but not completely – leave it open by a very small amount to give the flames more air than what the air controls would with the door closed completely whilst keeping any smoke contained in the firebox (you don’t want this coming out into your room). Give it 10 – 15 seconds with the door like this then close the door completely. This is another advantage of the top down method, a very small amount of time with the door not completely closed is needed whereas conventional fire building methods generally require more than this to get the fire started.
And that’s it, the fire is lit and you just need to monitor it, respond appropriately to what you’re seeing, and refuel when needed. Guidance for all of these things is detailed in the next section.
How do you feed an upside down fire?
Another key benefit of an upside down fire is that once lit, it takes very little management.
When you light the first load, it’s likely that you’ll have 30 – 45 minutes where you don’t need to touch it apart from maybe adjusting the amount of air being fed in. If built properly, the fire will establish itself and then die down to a bed of glowing embers which is your prompt to add some more fuel (ie another log or two).
I like to ensure I run my wood stove as efficiently as possible so I use a stove pipe thermometer which I monitor during each burn cycle. Using a combination of this and visual prompts allows me to reload at a time when I have the least chance of any smoke entering the room when I open the stove door (which shouldn’t happen if there are just glowing embers left) whilst ensuring that the stove is still hot enough so that it doesn’t take too long for the new fuel load to ignite.
The thermometer I use is one of the magnetic types which sits roughly 18” above the top of the stove on the outside of the stove pipe. This is how I use it:
- When my fire is established and the thermometer is reading around 500 degrees Fahrenheit, I turn the air intake down to 50% (I start the fire with it fully open and because my stove is a dedicated wood burning stove, I only have one air intake control – not a primary and secondary which multi-fuel stoves have)
- The temperature then is likely to flatten out before starting to drop
- When the temperature drops to around 325 degrees Fahrenheit (and the flames are really starting to die down), I open the air control back to full in preparation for a fuel reload
- When the thermometer reads 300 degrees Fahrenheit, as long as the flames are largely gone and all I see is glowing embers, I open the door slowly (pause a couple of seconds when you first open it to let the air pressure normalize and avoid drawing smoke out of the stove) and reload it to a suitable level (on my stove this normally consists of a large split log or two smaller ones)
- Because the stove is still at a reasonable temperature, the newly added wood should ignite reasonably quickly (within 30 seconds). The temperature will begin to rise and then fall again similar to what I described above for the first burn and you should use the air control as needed, starting at step 3 above when you get to the appropriate part of the burn cycle
Summary – does an upside down fire work?
There’s no doubt that if built and managed correctly, the upside down or top down fire method absolutely works. When used correctly it should mean that you spend less on wood fuel at the same time as minimizing pollutants and the environmental impact of using a wood stove.
Such is the effectiveness of it that in 2010 there was a nationwide campaign in Norway promoting the benefits of the top down fire and as a result, you’re likely to see a lot of Scandinavians using the method today.