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Chimney smoke sinking after it leaves flue and re-enters cabin


jetzi

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2 year old stove has a new problem that has just started earlier this week. The smoke from my Morso squirrel stove leaves the chimney and then immediately sinks and enters the cabin through air vents. I'm feeling quite sick from the smoke!

 

It might just be the direction of the wind, which was blowing smoke from the chimney at the bow end straight along the length of the boat. I've moved the boat around a corner and it seems to have helped a bit but unfortunately smoke is still getting in. 

 

The smoke leaves the 18" twin skin chimney and instead of rising vertically it just moves horizontally. 

 

I have tried firing the stove hotter but that just made more smoke. 

 

I'll buy the tallest chimney I can find this weekend to use while moored. But I'm not sure if that will even help if the smoke is just too cool to rise? 

 

I swept the flue fairly recently but I'll do so again today, not sure if that will help. The stove has been serviced about 3 months ago with new baffle, firebricks and ropes all around. 

What if I lagged the flue to try to keep the smoke hotter? 

 

Is it just bad luck with the way the wind blows and I should just move the boat? 

 

Any advice or ideas appreciated!

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That's an interesting one. You could try opening a window, might make the air a bit higher pressure inside than out, there must be some pressure difference that makes it come back in but it will probably just go away when the wind blows. It is flat calm here today.

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How close are the roof vents to the chimney? Turn the boat round 180 degrees, so the closest vent is up wind!

Double skin chimneys, like you've got, keep the gas hotter and help it rise.

What are you burning in the stove? Brand of smokeless fuel, or house coal, or wood, or old tyres? ?

Some days, the smoke does just sink.

3 minutes ago, jetzi said:

What if I lagged the flue to try to keep the smoke hotter? 

This is the theory behind double skin insulated flue pipes. They are expensive though and most people still use single skin pipes with no problem.

 

Jen

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The Squirrel should consume its own smoke to a great extent, more top air vent so there are flames in the fire. Burn decent DRY smokeless fuel or DRY wood.  Wait till Spring.  It has been so cold and damp of late that nobody's smoke is rising.

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2 minutes ago, Bee said:

That's an interesting one. You could try opening a window, might make the air a bit higher pressure inside than out, there must be some pressure difference that makes it come back in but it will probably just go away when the wind blows. It is flat calm here today.

Yes, if I open the bow doors the wind comes in and solves the smoke problem (I guess equalises the pressure?), but it creates a new problem in that I freeze my t*ts off! If I open a window, smoke comes in there too :(

 

3 minutes ago, Jen-in-Wellies said:

What are you burning in the stove? Brand of smokeless fuel, or house coal, or wood, or old tyres? ?

Some days, the smoke does just sink.

Good point! I am a devoted Excel fanboy, but I bought several bags of "Wulfruna Wulfimix" smokeless fuel from Wheaton Aston (orange bags), it does seem to produce more smoke than the Excel and it smells a little worse but it isn't bad, I was pretty happy with it the last few weeks. I will also try a fire with Excel later and see if that makes a difference.

 

2 minutes ago, Tracy D'arth said:

The Squirrel should consume its own smoke to a great extent, more top air vent so there are flames in the fire.

It usually does, once the fire is hot I almost never see smoke. This is kind of a new problem! I leave the top air vent permanently closed and only open the bottom as little as I can. I can try opening the top vent and see if it makes a difference.

 

3 minutes ago, Tracy D'arth said:

Burn decent DRY smokeless fuel

My fuel is stored outside so always a little bit wet. Never really been a problem though! Is the intention just to produce less smoke or will the smoke rise better?

 

4 minutes ago, Tracy D'arth said:

Wait till Spring.  It has been so cold and damp of late that nobody's smoke is rising.

But winter is just getting started! This is my biggest worry - this will be the first winter on the boat the whole time without respite so I'm worried that this is just how it is sometimes :(

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It does happen as others have said, especially on foggy or damp days. Wind direction dependant also but very still air is bad. If you have a roof vent close that doesn't help. You deffo need to open top vent on stove a little. 

Edited by mrsmelly
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4 minutes ago, jetzi said:

 

 

It usually does, once the fire is hot I almost never see smoke. This is kind of a new problem! I leave the top air vent permanently closed and only open the bottom as little as I can. I can try opening the top vent and see if it makes a difference.

 

My fuel is stored outside so always a little bit wet. Never really been a problem though! Is the intention just to produce less smoke or will the smoke rise better?

 

What did you think the top air vent was made for?

 

Never burn wet fuel, it smokes and it blocks your chimney.

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1 minute ago, Tracy D'arth said:

What did you think the top air vent was made for?

 

Never burn wet fuel, it smokes and it blocks your chimney.

To be fair, the instructions usually given say to use the top vent to burn wood and the bottom to burn smokeless fuel. It is more complicated than that and I typically use equal amounts of both on my Squirrel.

Jen

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4 minutes ago, Jen-in-Wellies said:

To be fair, the instructions usually given say to use the top vent to burn wood and the bottom to burn smokeless fuel. It is more complicated than that and I typically use equal amounts of both on my Squirrel.

Jen

Keeping the top vent open a little also helps keep my glass clear.

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No, its not the stove that is the problem, its the other means of air exiting and entering your boat.  If the vents are such that the wind before your chimney finds it easier to enter the boat than leave it then your boat will be slightly pressurised and the vents behind the chimney will be exit not entry vents and will not take in smoke.  You need more entry-favouring vents on the upwind end/side of your boat.  The difference required is quite slight and does not require you to freeze.  The orientation of your boat to the wind is obviously a factor.  I recommend experimenting with opening & closing all possible combinations of your vents, windows etc. to see what works, even the apparently unlikely ones.  All IMHO.

edit: written based on single skin chimney experience.

Edited by system 4-50
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Thanks, lots of votes for opening the top vent. I will try that! 

9 minutes ago, Tracy D'arth said:

What did you think the top air vent was made for?

As @Jen-in-Wellies said, for burning wood. That is what the instructions say. 

 

Just now, Arthur Marshall said:

It a normal thing, unfortunately, due to the boat flues not being long enough.

6 minutes ago, nb Innisfree said:

30" double skinned chimney sorted it

Thanks for these comments! I will get a long chimney, it can't hurt right?

 

4 minutes ago, system 4-50 said:

 If the vents are such that the wind before your chimney finds it easier to enter the boat than leave it then your boat will be slightly pressurised and the vents behind the chimney will be exit not entry vents and will not take in smoke.  You need more entry-favouring vents on the upwind end/side of your boat.  The difference required is quite slight and does not require you to freeze.  

Thanks, this makes sense to me, I will try some different combinations!

 

Lots of good advice here, thank you all - will try all of it

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What I cant believe is that a 2 year old stove required new fire bricks and baffle plate!! And people say squirrels are a good stove, our boatman is 10 years old now and had no repairs other than being painted almond last year, Janyne didnt like it black

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This is a new issue so something must have changed. I would treat it like any other fault finding task. Start at the beginning and work through all possible causes. I would put my money on either dodgy fuel (cheap and nasty or wet) or chimney/flue needing sweeping.

I have a Squirrel with a single skinned flue ,an 18" double skinned chimney and colie hat. 

 

 

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17 minutes ago, Slim said:

This is a new issue so something must have changed. I would treat it like any other fault finding task. Start at the beginning and work through all possible causes. I would put my money on either dodgy fuel (cheap and nasty or wet) or chimney/flue needing sweeping.

I have a Squirrel with a single skinned flue ,an 18" double skinned chimney and colie hat. 

 

 

Not a new issue, we had the problem in 2007, wouldn't have known but for the CO detector registering a low count (LED only) never registered if we were off the boat, I assume it was body movement causing air movement? 

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4 hours ago, nb Innisfree said:

It didn't stop smoke curling down but it meant it was high enough to miss the vent. 

I won't assume the longer chimney is a silver bullet but it should also help draw. And if nothing else the smoke should be further from the cabin so it should be an improvement.

 

4 hours ago, Ex Brummie said:

What sort of location are you moored in? If in cuttings or woods or even high hedges, than the wind is less likely to clear your flue.

It actually happened first on an embankment, I thought maybe since I was more exposed to the wind that was the problem. So moved into a more flat wooded area but hasn't solved totally.

 

2 hours ago, David Mack said:

Never used one myself but some people swear by cowls on the chimney top to cure smoke problems. Some use the rotating sort that have a small vane to turn the outlet so it is always facing downwind. Others suggest an H cowl.

I'm not sure how this would help? The smoke does already drift downwind, the problem is that the smoke immediately sinks down to cabin level. Or is it something to do with decreasing pressure at the "muzzle" of the chimney?

 

2 hours ago, Slim said:

This is a new issue so something must have changed. I would treat it like any other fault finding task. Start at the beginning and work through all possible causes. I would put my money on either dodgy fuel (cheap and nasty or wet) or chimney/flue needing sweeping.

I have a Squirrel with a single skinned flue ,an 18" double skinned chimney and colie hat. 

You're right, I've never had this issue before. I thought it might just be weather?

 

I will sweep and I will see if Excel fuel works better. Thanks.

 

I have the exact same set up less the hat (I used to have a hat but that ended up at the bottom of the Staffs and Worcs courtesy of an incident with a tree).

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have you got low level vents and are they blocked?  the air and smoke going up the flue has to come from the cabin and will reduce the air pressure in the cabin thus drawing in more air via the vents. If the only vents that will let air air in are near the chimney....   The low level air vents should provide sufficient air, but at the price of cooler feet, solved by big slippers or a footstool.

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3 hours ago, nb Innisfree said:

Not a new issue, we had the problem in 2007, wouldn't have known but for the CO detector registering a low count (LED only) never registered if we were off the boat, I assume it was body movement causing air movement? 

When I said 'new issue' I meant for the OP

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