MegaSack DRAW - This year's winner is user - rgwb
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Our Ild 3 stove is great. Brilliant burn, next to no ash and great heat. Makes a big difference to our very old and draughty house.
However, when we open the door to add wood, we get a lot of smoke into the room. Tried opening door a crack, waiting a minute, then opening properly or waiting till flames die down and a couple of other things but nothing really makes any difference.
Now, as its above 5kW rated, its got an external air supply but my theory is that this means that as the door opens, the natural draw is not from the room into the fire area but from the external supply to the fire area meaning the natural flow isn't preventing the smoke from entering the room.
I was thinking of experimenting by blocking the external air supply from the outside as our house is plenty leaky enough to provide enough air, including two other open fireplaces/chimneys. I know this goes against building regs, but as long as the wood burn still goes well then it's getting enough air. If it doesn't burn well then I'll unblock immediately.
Any reason I can't / shouldn't try this out?
including two other open fireplaces/chimneys.
I'm no expert, but years ago friends naively knocked thru in an old cottage, between lounge / dining room, both rooms had fireplaces. Two fireplaces in now, what was effectively one big open room, caused havoc with draw. Like I say, no expert, but maybe your issue if this is what you have done?.
Can't think of any reason not to block it but also, are you sure the flue is installed correctly with regard to number of bends, angles etc so that you're getting the correct temp differential to enable proper draw. I'm no expert but I've recently been getting into Part J ahead of a self install and the permitted bends etc are gone into in detail.
You might find that you make it draughty blocking the ducted air supply as it would then be pulling air across the room to the stove.
It sounds like when you open the door there is a bigger draw from one of the other flues or even an open staircase. I would try blocking the other redundant chimneys first.
Air supply and carbon monoxide aren’t things I think I would mess with.
Your flue should be sucking the fumes upwards strongly enough that opening the door of the stove should make the flames roar and flare up, not turn round and head the wrong way!
Is the flue a big old stone one in a cold chimney breast or is it square section built into a brick gable or is it clay rings in a modern house or is it lined with a flexible SS liner? In order of increasing efficiency, that's what you want so as to a achieve a smooth column of rising hot fumes. If the fumes emerge from the pot sluggishly and don't rise in a column, your combustion temperature is too low or your flue too cold.
As Bear writes above, just opening the door will create low pressure in the room as warm air escapes and blasts up the stairs.
How tall is the flue? Where is the flue? What is the layout of the house and how tall is it? In particular, is part of the house taller than the flue? If you opened a window in the room with the stove before opening the stove, does it still spill smoke?
are you burning a strong fire or are you one of those people that gets the flames up then shuts it in to make the wood last longer ?
Because ..... my folks are these people and they always get smoke back in the house when they open to top up.... yet when i have control of their fire burning it cleanly not only does their glass clean up but they get no smoke inside.
What TR says, also 'next to no ash' ??? How is that possible and are you thinking that is a good thing? Had our stove for 8 years now, always burns hottest with a good 3 or 4 inches of hot ash below the logs.
I tend to empty it as little as I can, and even then I leave a bit of ash.
You should only open the door when its gone through a burn cycle, there would be no smoke. i suggest maybe reading the instructions.
Most stove problems are caused by user error, damp wood, incorrect lighting procedure, putting too large logs on, i could go on but i've retired now and am no longer qualified to give advice.
Our stove is a bit of a struggle too, but we can keep any smoke to a minimum by letting the fire burn well down, so it's a red glow with no visible flame or smoke. Still get some fumes into the house (I can see the odd speck of ash waft out) but not the irritation of smoke. I also turn down the vent (it has a control on the external air intake) just for refuelling in the hope that it will suck more air in from the room (vent is usually pretty well open and I do try to run it hot in general). And opening the door gently with logs ready to put on quickly of course.
I think the basic issue is we have a draughty open-plan house with the stove on the middle of what is effectively 3 open floors and the flue top barely above ceiling level due to the roof line. When the wind is blowing the wrong way it comes down the hillside out the back of the house and it's hard to stop it blowing down the flue and out of the door. Fortunately such days are rare but they are also the coldest. Beast from the east was an entertaining few days for us. I remember the top floor open fire in my grandmother's old house was always a smoky beast too, while downstairs was fine. There's just less vertical draw from the shorter chimney.
I'm also a little suspicious of the airtightness of the flue itself - the sections have a screw lock system and the joints may not be quite airtight, I don't believe sealant was used. However there is no general leak of smoke in use, it's just out the door when I open the stove. It looks like it's drawing fine in normal use.
From the roaring noise our bottom vent makes when you open it with the stove on full chat, I reckon you would be able to hear air rushing into a leaking flue if the leak was bad enough to allow fresh air to bypass the grate.
Having recently suffered an unpleasant episode of tarry condensation dribbling down our flue and stinking the house out, we have realised the importance of giving the stove a good hard burn for the first hour in order to warm the flue properly, creating updraft and hence rapid movement of any moisture out of the flue. All fuel contains a small amount of moisture; it can't be totally dry.
I'm def no expert but it sounds like not enough draw into the flue.
I don't see why you've got an external supply when you've also got two open fires/flues - I'd disconnect that and see what happens.
With both our stoves (1 x 5kw and 1 x 8Kw but neither with external supplies) if you open the door slightly it will draw air through the door and go into rocket mode, but this will calm down when you open the door more.
I'd also question why you're getting any smoke at all - if your wood is dry there really shouldn't be any. Damp wood would also explain an under-heated flue and the associated lower draw.
End of the burning season is a classic time for damp wood as many log suppliers may have run out of the properly seasoned supplies and are selling stuff that was only cut a couple of months ago.
If you're positive the wood is dry then I'd be looking at the flue - once a fire is established there really shouldn't be anything getting into the room when the door is opened.
btw chief, if i understand correctly you have an OAK (outside air kit), feeding air from outside straight to the stove. you DONT need that under regs. what you're stove does need as its over 5kw, is either the oak, OR the room needs suitably sized airbricks/vents to outside. the oak is nice as it means the stove doesn;t cause more drafts and isn't sucking warm air from the room, but room air is fine under regs so long as the room has enough air supply. its in the regs..something like 5cm2 per kW over 5kW and i think it is supposed to be within a certain distance of the stove too, but not sure.
I would have thought that with the door open the stove would get its air from the room more easily than the OAK pipe. if it doesn't it suggests that the room is sealed tighter than the oak pipe opening, or other things like stack affect are causing a back draft down the flue. Need to know more about the house, where the stove is, and the flue to rule that out/in.
Cheers for all the responses folks....
Two fireplaces in now, what was effectively one big open room, caused havoc with draw.
Whilst not exactly the same, might be a similar issue. Stove is in open plan area at back of house with multiple areas open to each other (kitchen/living/upstairs hall/downstairs hall).
are you sure the flue is installed correctly with regard to number of bends, angles etc so that you’re getting the correct temp differential to enable proper draw.
Its a 5 year-old install, straight flue all the way.
It sounds like when you open the door there is a bigger draw from one of the other flues or even an open staircase. I would try blocking the other redundant chimneys first.
Only one is redundant and its blocked already. The other is not used at the same time as the stove although it does have a plate i can close to block the flue. After reading this i did just that and it may have helped (not sure with all the other variables that affect these things like wind direction/speed/air temp etc.
Is the flue a big old stone one in a cold chimney breast or is it square section built into a brick gable or is it clay rings in a modern house or is it lined with a flexible SS liner?
Its a Stovax flue system in a new extension of the house. Solid flue, no bends at all, top of flue in line with top of house.
are you burning a strong fire or are you one of those people that gets the flames up then shuts it in to make the wood last longer ?
Always a strong fire. I let it go through a full cycle i.e. only orange embers left, before opening door.
You should only open the door when its gone through a burn cycle, there would be no smoke. i suggest maybe reading the instructions.
Most stove problems are caused by user error, damp wood, incorrect lighting procedure, putting too large logs on, i could go on but i’ve retired now and am no longer qualified to give advice.
Just as well. I couldn't take being patronised like that! 😉
I don’t see why you’ve got an external supply when you’ve also got two open fires/flues – I’d disconnect that and see what happens.
Agreed - its overkill. As neilnevill says, its 54mm² per kW over 5kW i believe so we only need < 150mm² - i reckon the seal (or lack of) around our front door takes most of that!
We always burn the driest of wood, have a good strong fire (whole thing glows orange/glass and walls are completely clear), it only creates very little ash and what it does produce is usually very fine. We leave the ash in place as should be done with woodburners and only clear it every now and then when it gets too much.
We don't get visible smoke into the room, just a smell of smoke for a short while after opening/closing the door.
My money is on the house layout being too open plan, causing trouble with air flow. I'll see if i can sort by closing doors etc.
Ta much people!
Sounds like your setup is similar to ours with similar issues. Ours is also hugely affected by the wind conditions due to the house being built partly into the hillside.
Once when it had got a bit smoky we unthinkingly opened a window which happened to be on the lee side of the house (and close to the roof level) to get some fresh air. The stove promptly went into reverse, blowing a jet of smoke strongly out of the air vent at the front...(we have a new stove with external air now, so at least that can't happen). I reckon the house could benefit from a bit more draught-proofing though being an old stone design it needs some ventilation. But not as much as it has!
Wow, that must have been a shock!
Is there a damper in the flue?
Me? No, no damper here. External air has a (thermostatically-adjusted) control which works fine when we want to turn it down a bit. Previous stove had a damper which we only used to shut the flue over the summer when the fire wasn't in use - and were careful to re-open in the autumn :-). The performance of the stove in all respects is excellent, while the door is shut. And it's also far better than the old one (with a room vent and solid cast doors) ever was. If it wasn't for the small amount of leakage when we re-fuel it, it would be perfect.
Yes globalti it was indeed a shock - my wife (up in the eaves with the open window) was a bit upset by my forceful language as I politely suggested the window should perhaps be closed at her earliest convenience....
Of course it might just be a design thing - I've read that some stoves frequently leak some smoke into the room when the door is opened.
I'm with captain on wind conditions could be the cause. when you said your stove was in a new extension I was 'Ahh stack effect' but then you said the flue extends to level with the top of the house so no, its not that. Open plan isn't necessarily trouble. My house is an old 1930s originally built with a study, lounge and a separate dining room plus a kitchen and loo downstairs. its now virtually all open plan (except for the loo!) and a stove in each of the fireplaces (lounge had one, dinning room had one). both drawer like trains, even with a massive extractor on in the kitchen and small ones in the loo and bathroom upstairs. However wind can do funny things. If the oak inlet is on the windward side of the house it might be at a positive pressure. could you simply disconnect the oak from the stove? leave it venting the air to the room but let the stove suck room air? see if it still spills smoke. Open a window on a windward side to let the room equalise in pressure with that side of the building, see if it still spills.
As to curing it...can you fit another piece to the flue? an extra metre would help, two would be amazing but might look odd. You don't say how long the flue is overall? I'm assuming a 2 storey house and flue of around 8m ish which should be good for draw but if its a single storey and flue is 4-5 m then draw would be marginal. either way, more flue = more draw. Get the draw good enough and it won't spill. A different style of cap might also help if its to do with wind over the top, but I can't help on what to look at there.