Anyone who has owned a log stove will be aware of the problems of the stove glass sooting up.  Some stoves seem worse than others, but it is something that all stoves do over a period of time.

There appears to be two main causes:

  • Poor fuel: This usually means logs/wood that is still damp.  The drier the wood the better.  Logs should really be air dried for up to a year.  This will get their water content down to 20-25%.  If you want to be extra sure, you can use kiln dried logs.  These are frequently down to about 10-15%;
  • Not enough air: This leads to poor combustion and smoke.  This will eventually blacken the glass.

The solution seems to be:

  • Use the correct wood fuel;
  • Ensure that the fire has enough air.  There are usually two vents – one allowing air in from the bottom and one allowing air from the top.  Logs burn best with air from on top.  Start the fire with all the vents open.  Once the fire has started going, shut the bottom air off.  For example with our Firebelly stove, we leave the top vent open 3/4 of a turn.  This never changes.  We open up the bottom vent fully when starting the fire, we let the fire burn through (this warms the chimney/flue and establishes a good draft), then we add more wood and half close the bottom vent.  Once the fire is fully established, we close the bottom vent completely.  The top vent is always left in the same position;
  • Make sure the fire is burning hot enough.  We have a Stovax flue thermometer that shows the optimum temperature for the flue.  This ensures that the exhaust products from the fire reach the right temperature to be burnt off.  They cost about £10 and are a good investment.

All of the above works really well with our Firebelly FB1.  We seem to be able to burn just about anything on it (we never put treated or painted wood on the fire) and it never soots up.  The Spartherm unit (Arte 3RL) is a different story.  Despite only putting kiln dried wood onto the fire, it always seems to soot up.  The Spartherm glass goes black all over. While some sooting up is inevitable, this seems to happen within 1-2 hours.  There is only one control on the front.  This controls the air flow from underneath.  There seems to be little control of the flow from above.  There is also no opportunity to view the temperature, so it is difficult to tell whether it is hot enough.

We wrote to the manufacturer.  Their response was to send us the manual that we already had (the same one that was supplied with the unit).

We have found the easiest way to clean it is using Stovax clear glass cleaner, but it soots up so quickly, we really avoid using it too much.  It is shame since it is a nice looking unit.  But we have better things to do that clean the glass everyday.  The Firebelly unit is a completely different story.  We have used it continually and have only had to resort to cleaning it once a month.  And that is often just to take the odd black soot mark off the glass.  It takes all of 5 minutes.

Stovax glass cleaner. This works a treat. It is caustic so be careful when you use it. It says to apply it liberally and leave it for 5 minutes before removing with a damp cloth. I use it sparingly and clean off within a minute or so. It is expensive, but you don't need to use much of it.

Stovax glass cleaner. This works a treat. It is caustic so be careful when you use it. It says to apply it liberally and leave it for 5 minutes before removing with a damp cloth. I use it sparingly and clean off within a minute or so. It is expensive, but you don’t need to use much of it.

A rather dusty Firebelly FB1 showing the top vent and the bottom vent control (the "U" shape poking out from the door underneath the glass pane. You can also see the Stovax flue thermometer in place too.

A rather dusty Firebelly FB1 showing the top vent and the bottom vent control (the “U” shape poking out from the door underneath the glass pane). You can also see the Stovax flue thermometer in place too.

We always leave this slightly open. It provices air to the top of the fire - exactly what logs need. We fully close it and then open 3/4 of a turn. We only adjust the bottom vent.

We always leave this slightly open. It provices air to the top of the fire – exactly what logs need. We fully close it and then open 3/4 of a turn. We only adjust the bottom vent.

While the glass does soot up very quickly (within a matter of 1-2 doors), the soot does clean off easily with Stovax glass cleaner.

While the glass does soot up very quickly (within a matter of 1-2 hours), the soot does clean off easily with Stovax glass cleaner.