How to use airwash on a wood-burning stove

Airwash

Most modern woodburners incorporate an airwash system. This is when the secondary tair supply – the air vent at the top of the stove – is used to direct a thin layer of air over the inside of the stove glass to prevent soot and dirt from settling.

How to operate airwash

When lighting your stove, both the primary and secondary (airwash) vent should be open. That’s because you want to allow as much oxygen as possible into the stove to help the fuel to start burning. Get more information on how to light your stove.

Once the stove is lit, you will no longer want the vents to be wide open because that will allow too much oxygen in and cause the stove too operate at too high a temperature, potentially causing damage to the internal parts of your woodburner.

Burning wood while using airwash

If you are burning wood, you can close the primary (bottom) vent completely once the stove is lit properly. Wood needs an air supply from above to burn effectively, so the secondary air vent does this.

You should also close the secondary vent from its open position during the lighting position BUT don’t close it completely.

Leaving the secondary vent slightly open will allow the airwash system to function correctly, while also allowing sufficient oxygen to the fuel to keep the fire lit. The warm air that is allowed into the firebox also causes unspent flammable gases to be burned before they escape up the flue pipe.

Burning coals while using airwash

If you are burning smokeless or manufactured coals in a multi-fuel stove, you will need to leave the primary (bottom) vent open slightly in order to burn the fuel effectively. Coals burn best with an air supply from below, so it’s important not to fully close the vent.

Avoiding dirty stove glass

Whether burning wood or coal, if the secondary air vent is closed then the stove glass is likely to cover with soot. You just need to experiment to find the optimum level of air supply to ensure the airwash continues to function while still burning your fuel as efficiently as possible.

Remember, airwash helps to keep your glass clean but some build-up of soot is inevitable.

Finish the cleaning process with a spray of specialist stove glass cleaner.

29 thoughts on “How to use airwash on a wood-burning stove

  1. I have a trubond stove. But I have no operating instructions with it. It is cast iron construction with an ash pan. Can I fit it into my house and what fuel can I burn ? The stove came from a house in France , which I am renovating. The stove was manufactured in China. It has a Ce mark and number on the back . The number is EN 13240.

    • Hi Maz,

      That’s not a stove that we stock, so we can’t offer any specific advice on that particular model. Perhaps try checking with the manufacturer or your retailer to find out if there are any known issues or the best way of conducted a minimal dismantling process to access the seized part.

      Thanks,

      Gr8Fires

    • Hi Maz, I to have a Clark wentworth fire and the air wash slider B is also jammed.
      Did you find a solution Maz into unjamming this slider/button airwash control.
      If so Maz would you please share this information with myself.
      Regards Neil.

    • Hi Danny

      It would suggest that either there’s a strong downdraught (your property is exposed to a lot of wind) or there’s a poor draw up the chimney (could be due to a lack of ventilation in the room).

      Thanks,

      Gr8Fires

  2. Hi guys I’ve got an Evergreen ST-800A, this was in the house when we bought it. I have 4 air flows two and the bottom and two at the top. Would you suggest leaving the top open when burning wood?

    • Hi Scott

      That’s right. Not fully open because you don’t want too much oxygen getting in, so just experiment to see how far you can close them without causing the fire to smoulder and burn inefficiently.

      Thanks,

      Gr8fires

  3. Hi! I’m in a rented house with a stove that has two vents. But they’re not top/ bottom, but left/ right! Does that make sense to you? How would that fit I to what you’re saying about top/ bottom?
    I have both wide open when starting out, and have now tried to close them both about half to prevent the fire from getting too hot/ strong. It causes especially the left side to have soot built up.
    No manuals, and the owner was using it as an open fireplace, so he is not much help on how to use it properly, I’m afraid.
    Any advice is greatly appreciated!

    • Hi Johanne

      The idea remains the same, so you’ll just have to experiment to try to close the vents as best you can without causing an inefficient burn.

      Is there a brand name? Perhaps you could track down a manual online.

      Thanks,

      Gr8Fires

      • I find if I open the airwash vent while burning peat the fire roars at an uncomfortable level. By closing the vent it calms down. The window is then totally black. What am I doing wrong?

  4. i have a mazona small orlando stove and when the stove is shut down it still burns as if the vents are open cant build it up and shut it down it just burns away can anyone help

    • Hi,

      Have you checked the seals? Perform a visual check to make sure the rope isn’t squashed, broken or frayed. If it is it will need to be replaced.

      You can also trap a piece of paper in the door and try to remove it. If it pulls out, the seal needs to be replaced.

      It would also be worth checking to make sure there is not soot or tar built up in the vents and preventing them from closing properly.

      Thanks,

      Gr8Fires

  5. Hi, I’ve got a Firefox with a top airwash lever, but it’s totally seized, so not only does the fire not burn as hot as it should but also the glass front gets heavily sooted on every use. Can you suggest what might release the mechanism?

    • Hi Simon

      We can only suggest inspecting the lever and the mechanism for any sooty deposits that might be impeding its movement. If you can’t find anything, you could try extending the lever to give you a bit more ‘oomph’ to get it moving again.

      Thanks,

      Gr8Fires

  6. Hi can you tell me what position air vents need to be at for airwash to work correctly? Always have 2 marks either side ! I clean the glass daily and by evening the sides are black / brown and centre is clear ?

  7. I have a Dovre wood burner model Astro 3CB 8KW.
    The controlling combustion air is:
    1. Primary air slide is open when pulled out controls airflow under the grille & closed when pushed in.
    2. Secondary air slide controls air flow for the glass & vents at the back wall when pulled out.

    Lighting is not a problem but the problem I have the curved door glass & two side glasses get covered in soot after a few hours despite me having secondary air slide pulled out in open position which should give air flow over the door glass.

    Why is this secondary air flow not keeping the glass clear because after a days burning getting the black soot marks off inside of door & side glass is a big problem.

    Can to please advise why this is the case.

    Thank you,
    Peter

    • Hi Peter

      It’s hard to know for certain. It could be:

      – The type, amount or moisture level of the fuel.
      – The operation of the vents (maybe the secondary vent needs to be open wider or maybe the primary needs to be open slightly).
      – Weak draw up the chimney

      Thanks,

      Gr8Fires

  8. I wonder if anyone can assist me. I have purchased a house with a Cosyfire multifuel stove fitted. It is model number AM – 43 and fitted with a back boiler.
    No instructions have been left and I have been unable to find any for this model. However the ones I have read mention a primary air control and a secondary air wash control.
    The secondary airwash control is at the top of the main door. However there is no other control visible other than the ashpan door at the bottom.
    Do I use the ashpan door to control the primary air ??
    Can anyone give me any advice please.

  9. I have a ACR Rowandale and can’t understand why with every fire the glass goes black could it be the airwash system doesn’t work ?

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