Fire It Up: Mastering the Art of Lighting Your Sauna Stove

Fire built using the top down method

In the ever expanding sauna community one of the questions which keeps coming up concerns what is the best way to fire up the stove and get your sauna nice and hot. It might seem simple, just pile some wood in the firebox and get her going, however not all fires are made equally and there are strategies we can use to ensure maximum heat efficiency and lowest emissions. 

If you are not already familiar with the Top Down Method, then this post is for you. 

Building a fire using TDM, involves placing two or three medium size logs in the firebox, towards the back, on top of the grate, taking care to make sure there is still room for airflow through the grate. Chop some medium logs into smaller pieces, perhaps splitting each log into four quarters, and then lay these across the logs already in the firebox, in a criss-cross of ‘jenga’ formation. Next layer on some kindling, which will be even smaller than the chopped logs, again using the jenga structure; and then finally add one or two firelighters on the very top of the pile, with one or two more pieces of kindling balance on top. Ignite the firelighters, closing the stove door, and opening the ash-drawer a couple of inches to increase air flow. 

As the fire is getting going, you can use this time to chop down some more logs so you have a small supply to keep adding to the fire as it’s burning down. It will take some time for the fire to build and as it does so the logs underneath will gradually begin to burn, and during this time you can add two or three chopped logs at a time to keep feeding the fire. Eventually you will see that the biggest logs on the bottom will also catch and start to burn. As this process progresses you will notice that a nice bed of thermal mass will begin to build in the firebox. This will look like glowing orange and white fiery-hot embers, with tall long flames flickering upwards. Once this stage has been reached you can now add medium logs, one or two at a time, to this hot bed and they will catch and burn effectively. Continue this process over the next 60-90 mins to reach a temperature inside your sauna between 80-90 degrees, and at this point, if not before, close the ash-drawer. 

You need to continually feed the fire every 20 minutes or so throughout this heating up time to maintain the tall, long flames which send heat up the stove, heating the stones inside your sauna stove inside the sauna. Once you have reached adequate temperature, you can then place one medium-large log every 20-30 mins to keep the fire burning throughout the day. If you place a log that is ‘too large’ there is a risk that this will not catch and burn effectively and may just smoulder around the edges creating insufficient heat. It is always better to chop a very large log at least in half to ensure a more efficient burn. The reason being, when you chop a log in half you are increasing the surface area which then begins to burn producing more flames. 

The top-down fire method produces the least emissions because it controls how gases are released and burned. By lighting the fire at the top, the volatile gases from the cold wood below are drawn up through an already hot area where they combust cleanly instead of escaping as smoke. This creates a steadier burn, higher combustion temperatures, and far fewer particulates and unburned hydrocarbons. In simple terms… the fire eats its own smoke before it can leave the stove or sauna heater, which is why it’s both cleaner and more efficient, pretty cool.

Following this procedure, should maintain a good heat and toasty sauna throughout the day, or however long your sauna is in session. If the fire dies down, or the heat of the sauna decreases due to frequent opening of the door as bathers enter or exit, or bathers putting large amounts of cold water on the stones, then simply open the ash-drawer slightly to increase airflow which may give the fire the boost it needs, and if necessary go back to adding smaller chopped logs to get the fire going again. Close the ash-drawer when it has built back up and resume feeding the fire with medium logs. 

If the sauna is getting too hot, ensure the ash-drawer is closed, and place just one large log on every half hour to keep it ticking over. There may be times where the sauna is fired up but no bathers are inside - perhaps if you have an empty booking slot, and this can lead to it becoming hotter and hotter inside the sauna, as the interior bakes. There are a couple of quick solutions to this, the simplest being open the sauna door and allow a brief period of ventilation which will allow hot air to escape and cooler air to rush in. This may be enough. If you find the sauna benches and back-rests are burning hot with radiant heat, another easy fix is to splash the wood with cold water which again will remove some of this heat allowing new bathers entering the sauna to sit more comfortably. You may also wish to splash a ladle of water on the rocks too, but not too much, as you don't want to cool down the sauna rocks. 

It is worth noting, when bathers enter the sauna, they are yet to acclimatise to the heat and may find it uncomfortably hot if the benches are red-hot and the steam - the löyly - is really hot too. This is a great reason to encourage bathers to wear a sauna hat, which covers the head and hair and gives some protection to the delicate skin on the face. For sauna newbies, having the head uncovered can prevent them from really enjoying the delicious enveloping heat of the löyly, as they are too distracted by the fierce heat around the head and face, which can lead them to tense up slightly. If you are intrigued to learn more about the benefits of sauna hats - check out the post on ‘what is a sauna hat and why do we need them?’.

One final note on the heat experience inside the sauna concerns having adequate ventilation, which will drastically effect the sauna experience - poor ventilation can make it feel difficult to breath and a thick atmosphere, whereas a good ventilation system will ensure adequate air-flow, resulting in the whole body being wrapped in heat, from to top to toe - and agai if you are interested do check out the dedicated post on that too - ‘Vents, air flow, and thermal gradients’.

If you enjoyed this post, want to share your top tips, or anything else, then do leave a comment below, we love to hear from you.