Puffin draw + a trick with magnets

[youthoftoday]

I got a Villager Puffin (mostly on the advice of forum members) and, whilst I was at it, one of those insulated flues you hear so much about. I got the Mørso flue kit (which is very expensive at Midland, item FK-002 but much cheaper if you buy the stove from them too) because I thought it would be well built (it is) and because it's telescopic for easy installation.

 

I'm having some issues with my stove. I don't know whether it's over or under drawing. I mostly suspect that my wood's not up to scratch, having sat in flood water for a long time! We're also burning smokeless solid fuel.

 

The internal diameter of the flue is a tiny bit larger than the diameter of the collar (I think 4½ inches vs 4¾ I got an adapter), but I can't see that it makes much difference. The Squirrel manual says that the flue must be 4 metres. Mine isn't anything like that. It's a standard narrowboat set-up (although it's a widebeam so the ceiling is even a bit higher) and other people on the forum seem to be getting good results.

 

But I think that the stove, designed for a longer flue, is under-drawing meaning that the (small) vents are meant to have more 'suck' to get more air through.

 

One thing we discovered with is that if you take off the front knob you get 50% more vent, so 50% more airflow! You can get magnets off ebay (normal fridge magnets not the incredibly strong + expensive neodymium), stick them to the front, then move them around with a stick to control airflow. They look quite neat I think.

 

 

 

This seems to help a huge amount. Especially with the smokeless. It's not the perfect answer because it means the wood doesn't burn how it should, with the air-wash from above.

 

So, I recommend you try it if you want to get more air from the bottom vent.

 

Anyone got any ideas about the draw?

[forsberg]

What do you do to get air into the cabin so that the stove has something to draw from?

[craftycarper]

I got a Villager Puffin (mostly on the advice of forum members) and, whilst I was at it, one of those insulated flues you hear so much about. I got the Mørso flue kit (which is very expensive at Midland, item FK-002 but much cheaper if you buy the stove from them too) because I thought it would be well built (it is) and because it's telescopic for easy installation.

 

I'm having some issues with my stove. I don't know whether it's over or under drawing. I mostly suspect that my wood's not up to scratch, having sat in flood water for a long time! We're also burning smokeless solid fuel.

 

The internal diameter of the flue is a tiny bit larger than the diameter of the collar (I think 4½ inches vs 4¾ I got an adapter), but I can't see that it makes much difference. The Squirrel manual says that the flue must be 4 metres. Mine isn't anything like that. It's a standard narrowboat set-up (although it's a widebeam so the ceiling is even a bit higher) and other people on the forum seem to be getting good results.

 

But I think that the stove, designed for a longer flue, is under-drawing meaning that the (small) vents are meant to have more 'suck' to get more air through.

 

One thing we discovered with is that if you take off the front knob you get 50% more vent, so 50% more airflow! You can get magnets off ebay (normal fridge magnets not the incredibly strong + expensive neodymium), stick them to the front, then move them around with a stick to control airflow. They look quite neat I think.

 

 

 

This seems to help a huge amount. Especially with the smokeless. It's not the perfect answer because it means the wood doesn't burn how it should, with the air-wash from above.

 

So, I recommend you try it if you want to get more air from the bottom vent.

 

Anyone got any ideas about the draw?

 

. Put a smokey joe cowel on top your chimney,it looks like a bird and revolves so it's back is always against the wind, I put one on mine about two years ago and the draw is much improved plus I don't get those little gusts that blow down the chimney and fill the cab with smoke on stormy days

[nicknorman]

With an insulated flue you should get a better draw than a non-insulated one. Looking at the amount of vent opening in you photo, that is massive and if that is needed, there must be something wrong, probably a fuel issue. Trying to burn damp wood is a waste of everything.

 

Apart from anything else, with that much vent there will be a lot of hot air going up the chimney - heat that is wasted. On our squirrel with its rotary disc vent controls, I find between 1/2 and 1 turn open is right. 1/2 overnight and 1 to get a good heat up, so that is an aperture of perhaps 1mm max over perhaps 4" circumference of the vent control, x 2

[SamKingfisher]

Aye Nick, but don't forget the baltic issue "both vents fully open, and ash tray door adjar" with a firebox full of small section super dry wood. Warms a freezing boat in about 15 mins!

[nicknorman]

Aye Nick, but don't forget the baltic issue "both vents fully open, and ash tray door adjar" with a firebox full of small section super dry wood. Warms a freezing boat in about 15 mins!

I'm not sure it does though. With all those vents open, a lot of heat goes up the chimney. You might as well have an open fire (25% efficient) vs a good stove (85% efficient). I certainly find that after lighting the fire and with plenty of draught to get it going, there is not that much heating effect other than close range radiant. But as soon as I shut the air flow down, it suddenly gets a lot hotter. Sure, you need to open the vents when you first light it to get it going but it is burning a lot of wood/coal for not that much heat output.

[smileypete]

Is there a baffle in the stove below the flue?

 

Seems to me baffles may be more suited for domestic installs with long flues that draw really well (or too well?)

 

ETA: This might help:

 

http://www.canalworld.net/forums/index.php?showtopic=62536

 

cheers, Pete.

~smpt~

Edited February 10, 2015 by smileypete

[SamKingfisher]

I'm not sure it does though. With all those vents open, a lot of heat goes up the chimney. You might as well have an open fire (25% efficient) vs a good stove (85% efficient). I certainly find that after lighting the fire and with plenty of draught to get it going, there is not that much heating effect other than close range radiant. But as soon as I shut the air flow down, it suddenly gets a lot hotter. Sure, you need to open the vents when you first light it to get it going but it is burning a lot of wood/coal for not that much heat output.

It's inefficient I grant you, but it smashes it. Helps to have the back boiler on it too. A red hot flue kicks out some heat. I mean surely it's obvious that a hotter stove means a hotter boat?

[nicknorman]

It's inefficient I grant you, but it smashes it. Helps to have the back boiler on it too. A red hot flue kicks out some heat. I mean surely it's obvious that a hotter stove means a hotter boat?

Yeabut the air going up the chimney takes all the heat out of the boat. Years ago I lived in a rented granite farm cottage in rural Aberdeenshire. Bloody freezing! It had electric panel heaters plus an open coal fire in the living room. Having got the living room vaguely warm by leccy, when you lit the fire the temperature noticeably dropped until the fire really got going, because it was pulling all that electrically-heated warm air up the chimney and away, and that was replaced by freezing outside air.

[SamKingfisher]

Yes, but there's a massive difference between any stove and an open fire. In the case of my squirrel, all the air going up the chimney has first to pass through the fire, acting like a little blast furnace. In an open fire (they are dreadful concept really) a shed load can and does go up the chimney regardless of the fire. So we're not talking anything like the same volume of air. Watching it coming out the chimney is a good clue.

 

Anywa

 

Y

 

It works!

[Alan Saunders]

Youthoftoday, I agree with Nick; with that amount of air my Squirrel would be 'running away', far too hot and, possibly, dangerous. With about 1.3m of single skin flue to the deck-head and and a 60cm (?) chimney above it will slumber on solid fuel (warm to the touch) with both air vents closed, there are no other air leaks.

 

I admit that I am impatient when lighting the fire and I jam the ash-pan door open a cm but this is a dangerous practice, that's why the ash door is sprung closed, and requires continuous monitoring.

 

Having been brought up with open coal fires, having a 'Parkray' solid fuel stove in my first house and a large 'Bosky' central heating/cooker multifuel stove and a Jotul woodburner in a small cottage I am certain that there is something wrong with your installation.

 

It may be that your Puffin will not perform well or light easily with 'wet' wood but even rain-soaked well-seasoned wood should work well enough once you get it going. Similarly, wet coal may be difficult to light, even from plastic bags.

 

Without a doubt, an insulated flue is the most efficient, especially with the short flues on canal boats. To provide an adequate draught the flue must be warm, thus difficulties in lighting the fire and why the top-lighting method works for some. A stove with an insulated flue wastes less heat warming the flue and less heat escapes up the chimney, i.e. a more efficient stove.

 

Solid fuel stoves are particularly good at providing radiant heat and superheating the deckhead, no need for more radiant heat from the flue, which is why you will see many boats with doors wide open, the occupants complaining of being too hot and simultaneously claiming that their bedroom is too cold (<15C?).

 

I can only hope that the OP gets a few clues from my ramblings.

 

Alan

[youthoftoday]

Thanks for your replies!

- plenty of ventilation in the cabin, but a good thought

- there's the standard baffle in the stove, but no vent-reducer (can't remember what it's called)

- the flue is insulated so if it gets hot inside, most of the heat stays inside

- it's all new so no chance of build-up

Based on your replies I suspect that most of my problem is that I have rubbish wood at the moment (two years of floods, possibly a bit mouldy, it never really burned that well), and that's not something I can fix immediately! As I said, smokeless burns well (even wet), but that's a different story to wood.

I'll give a cowl a go, they look interesting. Also considering sticking an extra bit on the flue to see if that helps.

Cheers

[SamKingfisher]

Every time you burn wet wood, an angel cries. Just put it aside for next winter and get it under cover, ideally raised above the ground on a pallet with the three sides away from the prevailing wind uncovered.

[youthoftoday]

To be clear, the wood is damp rather than green. I've had it three years (and it was supposedly seasoned to begin with) but just when I need it the last 2 years, it's flooded. I'll make something raised when I get around to it.

[tree monkey]

Every time you burn wet wood, an angel cries. Just put it aside for next winter and get it under cover, ideally raised above the ground on a pallet with the three sides away from the prevailing wind uncovered.

☺☺ I love that, I admit to watching people burning, or at least trying, to burn unseasoned oak and having a little cry

[Starcoaster]

Is the baffle plate removable? I ask because I have an old model Villager and it is welded in, because stupid.

Tar then lands on the baffle plate, and if you do not keep on top of your contortionist skills to get it off the plate regularly, it soon builds up into clag and blocks the flue.

Edited February 11, 2015 by Starcoaster

[youthoftoday]

New puffin baffle is completely free. It sits on the firebrick sides and back and retains them. Everything comes out.

[David Mack]

- the flue is insulated so if it gets hot inside, most of the heat stays inside

 

But because the flue gases stay hotter there is a bigger differential density between the flue gases and the air outside, meaning a better draft, which in turn means you should be able to close the air vent down. Since you are needing to increase the air, the problem is obviously something else- blockage or damp nearly incombustible fuel.

[blackrose]

What do you do to get air into the cabin so that the stove has something to draw from?

Boats have non-closeable vents so why would that be an issue?

[blackrose]

I think that closing the vents down definitely holds the heat in the stove rather than letting it escape up the chimney.

[blackrose]

Youthoftoday, how big is your stove in kw? I have a 9kW stove on my widebeam and have some issues with insufficient draw. My theory is that there's a correlation between stove size and flue length, so the bigger the stove the longer the flue has to be to get a decent draw. My morso panther specifies a minimum of 4m combined flue + chimney, while I think the morso squirrel is 3.5m. Of course, squirrel owners aren't going to get that flue length either on a narrowboat, but I just think you're more likely to get a good draw on a boat with a smaller stove.

Edited February 12, 2015 by blackrose

[blackrose]

I've also tried some different cowls and I think it's a myth that any of them increase the draw - unless they have electrically powered fans! On a windy day any flue will draw well, it's the still days when they don't and then a cowl isn't going to help.

Edited February 12, 2015 by blackrose

[youthoftoday]

Hi Blackrose,

 

I'm on a widebeam too and the Puffin is rated at about 4 kW.

 

The length of the flue certainly is important! The instructions say 4 metres, which is impossible on a boat (without some extra engineering!), but I thought that since others recommended them that 4 metres wasn't actually necessary.

[nicknorman]

Are you sure the flue is correctly sealed to the stove etc? An air leak in the flue somewhere will allow air to be pulled in from the room, rather than through the stove, thus reducing the "draw".

[blackrose]

Hi Blackrose,

 

I'm on a widebeam too and the Puffin is rated at about 4 kW.

 

 

Well, there goes my theory then!