With this current cold Winter, just as in the previous two years, quite naturally we have a prolonged period of time where we want to keep the Lovenholm stove burning nice and hot, putting a constant heat into the house. That means regular stoking up with smokeless fuel or wood several times every day. So how do we ensure consistent heat output during continuous use…. It’s all about airflow.
It’s cold outside
Whether burning smokeless fuel or wood… this means we are going to produce a fair bit of ash. The more fuel we burn the more ash we will produce, meaning more times we will need to empty the ash pan under the riddling grate. Of course the ash pan does not catch all the ash that falls through the grate, and sometimes the pan itself gets overfull, especially at the sides and back of the chamber.
Now accessing this peripheral ash is not all that easy whilst the fire is burning still, but it needs to be removed to some extent to prevent restricting airflow under the grate. If this is allowed to build up unchecked, then it will not only restrict air from the sides, but also ash blocks the holes at the back of the chamber and eventually drops into the void at the back blocking the airflow from the bottom or base plate air inlet that flows under the grate and feeds the fire from the bottom.
Something in the air
We have already discussed that airflow to the bottom of the fire is especially important when burning smokeless fuels such as coke or Excel, etc for two reasons. Smokeless fuel, just like coal, burns best from the bottom up, so the riddling grate needs to be in the forward open position on the Lovenholm stove for example, allowing pre-heated air to be drawn up through the fire itself and burn in a self cleaning way. Self cleaning coal ?? Well, since the majority of ash will be created nearest to the source of fresh air reaching the burning coals, the lower coals will burn completely before the upper layers, and turn to ash, which will fall away through the grate more readily, thus keeping the air passages open, and so on.
As these lower coals continue to burn away the ash falls into the catch pan out of the way, and eventually the fire collapses in on itself, leaving room on top for a layer of fresh fuel. Burning top down with coal creates ash at the top of the fire, and that then has nowhere to go, so starting to block up the air passages and preventing complete combustion. This makes for a much cooler burn, and a colder fire means not so much heat output and lots more ash as a result.
Up in smoke
Secondly, the reason for cool air flowing under the grate is also to keep the grate itself in good condition. If the grate were to get too hot, then there’s a good chance that the elements could distort as they get close to melting point. Many a fire grate in an open fireplace has burnt out to an unusable condition when there has been a good fire, and a strong wind outside. Blast furnace conditions in effect, and potentially expensive to remedy.
Having discussed the benefits of good clear airflow, let’s turn our attentions to what happens if we were to carry on regardless. As mentioned airflow would become restricted and in essence choke the fire, preventing a good clean burn. This in turn reduces the fires heat output, and so all fuel will burn inefficiently until the stove is strip down cleaned again . Less heat into the room and more money just up the chimney as we then add more fuel to try and compensate for the poor heat output. Throwing good money after bad.
If we want to keep those home fires burning almost continuously during the depths of Winter, we need to be prepared to keep those airways clear. This means more frequent ash pan emptying, maybe twice a day if we do it right, and also remembering to do a strip clean to maintain air flow throughout the body of the stove. Airflow is also key when wanting to get the best heat from burning wood.
Summary: Keep it clean