Wood burning stoves

[spooky]

We have a woodburning stove which we installed 2 years ago, it's been amazing and cut oil cost dramatically. However early last week I lit it and smoke billowed out from every orifice, the room was engulfed with white smoke. After washing the floor, sofa, soft furnishings the smell eventually subsided after a couple of days. I was convinced it was damp wood so lit it again last night with only paper and kindling and the same thing happened?

[Hobbiniho]

if it hasnt been used in quite some time there is a chance that a bird has made a nest in it/ its got blocked, when was the last time you had the chimney swept? 

[spooky]

I'm embarrassed to say that it hasn't ever been swept!

[paulb]

as above we have a sweep up here.

[AlexandraS]

Our sweep told us that as a wood burner it should "burn clean" and only need sweeping every two winters. We called ours out laste year due to the same problem - he said it's a "lack of use" thing and to stick a hairdryer up it before you light it the first time of the year... worked!

[spooky]

When we installed it we were told it should "burn clean" but I think that some of the wood we have been burning has been too green and it might have caused tar in the flue. It can't be lack of use as we use it frequently.

[Ghostrider]

As Hobbiniho says, it sounds like something is blocked somewhere, bird, bird's nest being the first choice of blame, or if its a particularly high draught chimney, possibly something sucked in from below during strong wind. Wood should burn clean and sweeping rarely needed, I used to burn wood in the Rayburn as much of the time as possible so as to avoid having to sweep, as not only does it produce minimal soot itself over time it "digests" soot created by other fuels. Unless you have a very sharp bend or sudden narrowing of your chimney somewhere (which isn't a good idea for multiple reasons) wood, regardless of "green" or type shouldn't really be capable of producing enough soot to cause any sort of problem for years, even if it all came away and fell down at once due to dampness or condensation during a period of non-use.

 

Outside chance if it isn't a blockage, but were the wind direction/strength similar these two times you lit it and got smoked out? Virtually every house chimney varies in performance depending on the combination of direction and strength of the wind, if both times had similar wind conditions you may just have been unlucky enough that they were those that cause your chimney to perform least well, which is exacerbated when lighting up. Once at operating temperature smoke going out the chimney is assisted by the natural process of hot gas rising and there's a lot less smoke produced anyway, so you may well have had the fire in use in similar conditions in the past without problems as it was already hot. At light up you are relying on the natural flow of air from the room to carry it out, and in many heavily draught-proofed modern houses, there's not a lot of that, add in the additional smoke produced by low temperature combustion, and the combination causes a back up.

Edited November 16, 2014 by Ghostrider

[Scorrie]

+1 on wot Ghostrider said.

 

If it is not a blockage, start off with lighting a small fire with easily combustible materiels to warm the chimney through - then gradually build the fire up.

Avoid banging more stuff on whilst the stove is cold, get some heat into the flue and this will help it draw. A cold flue can make it difficult to get a fire going, sometimes. Also, ensure there's some air movement in the room whilst you're getting it going.

 

Do you have a bird guard/mushroom vent on the chimney?

[spooky]

We have mesh around the top as had a couple of birds come down the chimney. Going to sweep it today

[Rob Howard]

Hi

You say you installed the stove a few years ago  - what type of flue do you have, is it a flexible 5" or 8" stainless liner, double walled insulated flue pipe through the wall or stove pipe through a closing plate into the original masonary / stone flue?

 

You have been burning wood and were told it is clean burning, that is the stove itself is clean burning, the tars and resins produced when burning wood still go up the flue and vary greatly depending on the moisture content and type of wood. A soft wood generally contains more resins than a hard wood and can tar up a flue relatively quickly especially if unseasoned and allowed to smoulder slowly.

 

You need to get the flue swept as a minimum, you may just have a nest up there from the summer or you may find you have a tarred up flue or collapsed liner or loose masonary in the flue. I'm sure you are aware of the risks of a flue fire and the temperatures that can be reached resulting in severe structural damage or loss of the house.

You may also be aware that installation of a stove is notifiable to building control unless installed by a HETAS registered installer who can self certify. If you installed the stove yourself without notification this could be used against you in any insurance claim.

 

I'm offering this advice as a fellow stove user who has installed flues, cowels  and stoves in the past, also swept chimneys and removed tarred up and corroded flue liners. i am not a registered HETAS installer but have completed installations complying to building regs .

 

More info is freely available on the web - i suggest you get this looked into for your own safety, it will not fix itself.