Insulated flues

[Chris Pink]

There is an article in the latest NABO News by Glyn Hughes of The Solid Fuel Technology Institute (www.soliftec.com) that shows that an insulated flue on a boat burner will use half the fuel and produce the same heat output. This is because an uninsulated flue produces a bad draught and a lot of fuel goes into keeping the flue hot.

 

So.....

 

for discussion....

 

I know you can buy stainless insulated flues, but only in 5" and 6" diameter and not in cranked sections. My flue pipe is 4" diameter and cranked to go out the roof.

 

Can anyone come up with ideas for retro-fitting insulation so it meets the following criteria;

 

1. Fireproof

2. can be retro-fitted to the ubiquitous 4" steel pipe

3. (most important of all) is aesthetically pleasing (or at least acceptable)

 

I realise that non NABO members may not have read this article yet so I'll try and find reference on the solitec site but in the meantime I found this interesting document

 

http://www.soliftec.com/Boat%20Stoves%201-page.pdf

[dor]

"Well he would say that wouldn't he".

 

Whilst I am sure they are very knowledeable about solid fuel stoves, I'm struggling to go with this.

 

My stove has a standard 4" steel pipe for a flue, with a chimney extgending about a foot or so above the roof.

 

I can control the stove from a barely perceptible glow up to a roaring blast furnace. Not that t ever gets anywhere near that.

 

I can't see that an insulated flue would give me any more control over the fire, or see how it would improve combustion. The combustion rate is determined by the amount of oxygen fed in and the degree of draught and that seems fine to me.

I agree that some of the heat produced will heat the flue, but that then gets radiated into the room. As I've said before, I suspect that as much as 50% of the heat produced by the fuel radiates from the flue. With an insulated flue, a lot of heat must be lost going up the flue. My chimney never gets hot and the paint on the collar doesn't suffer much, so I reckon that most of the heat produced by the fuel stays in the boat. How do you get much more efficient than that?

[Proper Job]

Got to agree with dor on this.

 

A fair bit of heat that gets radiated in to the cabin comes from the flue. Obviously this will cool the flue gas and have an effect on the natural 'draw' that the flue/chimney gives. I don't see how it will reduce the fuel consumption by half.

 

In a ideal world, the main thing you should be aiming for is to make sure that the flue gas does not get below the dew point temperature. The condensation mixes with the sulphur dioxide and forms acid that can corrode the flue/chimney (usually very evident at the top of your chimney)

[Chris Pink]

Well these two posts are the received wisdom but these findings are challenging that view. I can't find this article on the website so as it stands it's a NABO exclusive(!)

 

 

But it's a convincing argument and I don't understand "well they would say that" why would they?

 

http://nabo.org.uk/files/nabo-news/nn-2011/6.pdf

[smileypete]

I'd agree that an insulated chimney is more forgiving, but that doesn't guarantee it's always more efficient.

 

I can't actually acess the article, does he have figures to back up what he says?

 

cheers,

Pete.

[Chalky]

There's a thread I started last week about insulated flues and BS8511. I found a company that makes insulation that can be used to retrofit existing steel pipes. Lot cheaper than a new flue.

I'm not associated with them in any way.

[WotEver]

http://nabo.org.uk/files/nabo-news/nn-2011/6.pdf

Available to NABO members only.

 

Tony

 

There is an article in the latest NABO News by Glyn Hughes of The Solid Fuel Technology Institute (www.soliftec.com) that shows that an insulated flue on a boat burner will use half the fuel and produce the same heat output.

Heat output measured how? How much the boat heats up, or how hot the stove alone gets? If the latter, then you've lost the heating effect from the flue, as both Dor and PJ have already pointed out.

 

Tony

 

When we had our BSC a couple of months back, the stove was tested with a smoke bomb. With no heat whatsoever (the stove wasn't lit) the smoke was drawn straight up the flue very efficiently.

[rjasmith]

I am also unsure about the effectiveness of insulated flues on boats and would love to see some real test results.

 

It's a pity non members can't read the NABO article.

 

I wonder if the Soliftec man's words have been taken out of context and were more referring to a household flue situation where the length of flue and where it runs (ie outside or in an uninsulated roof space) make it far more important to use an insulated flue.

 

I am still convinced that the requirement in BS 8511 for insulated flues has been simply transferred over from Building Regs Part J without a great deal/any comparative tests done to establish the benefit in a boat.

 

Richard

[carlt]

 

It's a pity non members can't read the NABO article.

 

Why should an organisation, that claims to represent all boat owners, show any altruism towards boat owners who are not members?

[Chris Pink]

 

It's a pity non members can't read the NABO article.

 

 

I agree, that at this time of year, it is a shame you'll have to wait until November to read this article (penned by a researcher at Solitec - read the OP!).

 

I am unable, through a conflict of interest, to post the article here but the original research is not a secret and was performed on a simulation of a narrow boat with a narrow boat stove.

 

Maybe you could ask Soliftec ( link in the OP)?

Edited September 28, 2011 by Chris Pink

[carlt]

I would dispute that an insulated flue, inside the boat, is more efficient, though.

 

Surely forcing more heat to escape to the outside, rather than allowing it to heat the boat, through an uninsulated flue, requires more fuel to be burnt, to maintain the cabin temperature?

[WotEver]

Maybe you could ask Soliftec ( link in the OP)?

Have you looked at their site? No contact information whatsoever is offered. No telephone, no email, no address.

 

Tony

[Ally]

The rights or wrongs of the 'insulated chimney' aside, the actual insulated flues available at the moment from the likes of Morso will fit a 4" I believe, once you have allowed for the thickness of the 2 s/s parts and the insulation. We have just fitted our first...a Chilli penguin stove...Morso flue. The flue kit can be purchased as either a straight OR angled flue...there are also restrictions on the angles you can use acceptably in the standard...and don't forget it's not just the flue but the chimneys as well.

Puffer parts are getting them together also, should be about out now I think...straight, but I believe they will make angled ones to a template also.

Chilli penguin kindly made us a stove collar to fit the new flue specifically bless them. Be warned, the Morso kits are highly expensive, and the angled ones mean you can only put them in one of 2 positions really...they come in 2 parts to allow some flexibility.

[David Mack]

I would dispute that an insulated flue, inside the boat, is more efficient, though.

 

Surely forcing more heat to escape to the outside, rather than allowing it to heat the boat, through an uninsulated flue, requires more fuel to be burnt, to maintain the cabin temperature?

 

But the standards aren't about efficiency - they're about safety.

[carlt]

But the standards aren't about efficiency - they're about safety.

I assume you haven't read the OP then.

[Chris Pink]

Have you looked at their site? No contact information whatsoever is offered. No telephone, no email, no address.

 

Tony

 

Didn't take me long to find Glyn Hughes email info@soliftec.com. where were you looking?

 

The rights or wrongs of the 'insulated chimney' aside, the actual insulated flues available at the moment from the likes of Morso will fit a 4" I believe, once you have allowed for the thickness of the 2 s/s parts and the insulation. We have just fitted our first...a Chilli penguin stove...Morso flue. The flue kit can be purchased as either a straight OR angled flue...there are also restrictions on the angles you can use acceptably in the standard...and don't forget it's not just the flue but the chimneys as well.

 

Do you have a link for the Morso kit?

[WotEver]

Didn't take me long to find Glyn Hughes email info@soliftec.com. where were you looking?

I started with:

Home Page | Building Rules | Fireplace Doctor | Fuel Costs | Installation | Join | News |

 

... and when it wasn't under any of those, I tried Home Page, Advertise, Air Supply, BS1251 Fireplaces, BS3248 Sparkguards, BS3376 Convector Fires, BS4834 Open Fires, BS8423 Fireguards, Building Rules, Carbon Monoxide, CE Marking, Dictionary, Efficiency, Electricity - CHP, EN12815 Cookers, EN13229 Inset Stoves, EN13240 Stoves, EN14785 Pellet Stoves, EN15250 Masonry stoves, EN1856 Metal Chimneys, EN1860 Barbecues, Fascinating Facts, Fireplace Doctor, Fuel Costs, Fuel Properties, Heat Need, Heroes, Installation, Join, Legislation, Manufacturers, News, Open Fires, RSS Newsfeed, Smoke, Solid Fuels, Standards, Statistics, Supporters, Test Laboratories, Thatched Roofs, The Carbon Cycle, The Chimney Effect, The Library, The Register, Wood Fuel, About.

 

Where did you find it?

 

Tony

 

Why not simply have a "Contact Us" link like everyone else?

[Chris Pink]

I tried Home Page, Advertise, Air Supply, BS1251 Fireplaces, BS3248 Sparkguards, BS3376 Convector Fires, BS4834 Open Fires, BS8423 Fireguards, Building Rules, Carbon Monoxide, CE Marking, Dictionary, Efficiency, Electricity - CHP, EN12815 Cookers, EN13229 Inset Stoves, EN13240 Stoves, EN14785 Pellet Stoves, EN15250 Masonry stoves, EN1856 Metal Chimneys, EN1860 Barbecues, Fascinating Facts, Fireplace Doctor, Fuel Costs, Fuel Properties, Heat Need, Heroes, Installation, Join, Legislation, Manufacturers, News, Open Fires, RSS Newsfeed, Smoke, Solid Fuels, Standards, Statistics, Supporters, Test Laboratories, Thatched Roofs, The Carbon Cycle, The Chimney Effect, The Library, The Register, Wood Fuel, About.

 

Where did you find it?

 

 

yes, that's right, it's on one of those.

[Iain Sutherland]

The rights or wrongs of the 'insulated chimney' aside, the actual insulated flues available at the moment from the likes of Morso will fit a 4" I believe, once you have allowed for the thickness of the 2 s/s parts and the insulation. We have just fitted our first...a Chilli penguin stove...Morso flue. The flue kit can be purchased as either a straight OR angled flue...there are also restrictions on the angles you can use acceptably in the standard...and don't forget it's not just the flue but the chimneys as well.

Puffer parts are getting them together also, should be about out now I think...straight, but I believe they will make angled ones to a template also.

Chilli penguin kindly made us a stove collar to fit the new flue specifically bless them. Be warned, the Morso kits are highly expensive, and the angled ones mean you can only put them in one of 2 positions really...they come in 2 parts to allow some flexibility.

[/quote

We have thes in stock and can provide angled ones to a template or drawing ours are a simple clean design and reasonably priced we can also insulate some chimneys

Iain

[Chris Pink]

Glyn from Solitec has been kind enough to give me a copy of his article for more general reading.

 

It's downloadable here (480KB pdf)

[blackrose]

I've talked to flue suppliers about this and I was told that over the short lengths of boat flues, an insulated flue will make no discernable difference. Where insulation does make a difference is where you have a long flue going up the outside wall of a building for example.

 

Given the fact that you wouldn't need (or want) an insulated flue inside the boat and would only have a couple of feet of chimney insulated on the outside, I have to agree with what I was told.

 

I once tested the theory on a cold dry night by wrapping my 2ft chimney with rockwool and duck tape. It made absolutely no difference to the draw of the stove, heat produced or fuel consumption.

Edited October 10, 2011 by blackrose

[rjasmith]

Glyn from Solitec has been kind enough to give me a copy of his article for more general reading.

 

It's downloadable here (480KB pdf)

 

Yes - I got one from him as well following your earlier suggestion to ask Soliftec direct.

 

It's a very interesting article and I hope NABO won't mind non members like me getting to read it!

 

I'm now a little more convinced about the benefit of flue insulation which from Glyn's tests would seem to lead to a reduction in fuel consumption as a result of being able to control the stove down to a lower burn rate without it going out.

 

With an uninsulated flue he suggests that boat stoves have to be run at a higher burn rate simply to keep alight and therefore the fuel is used up faster and probably the boat temp is higher than really necessary.

 

When I finally get our stove properly installed (rather than just as a test rig on an unfinished fit out!) I shall have a go at some tests of my own using the flue pipe insulation that Chalky found and described in this thread.

 

As Glyn's tests were done in the Soliftec lab rather than on an actual boat, he asks for boat owners to pass on their own results to him at Soliftec.

 

Richard

[blackrose]

 

With an uninsulated flue he suggests that boat stoves have to be run at a higher burn rate simply to keep alight and therefore the fuel is used up faster and probably the boat temp is higher than really necessary.

 

 

Perhaps that was his experience, but it wasn't mine. Each stove and each installation is different.

 

For example, Glyn says "An uninsulated boat chimney will only get to about 90°C" - my uninsulated flue can easily get to about 250°C (hotter if I'm not careful), and I can close my stove right down without it going out.

 

Glyn also says "Where I could really do with some help is by real people out there letting me know what happens."

 

Where are his contact details? I might let him know that I tried insulating my flue and nothing happened!

Edited October 10, 2011 by blackrose

[Ally]

Morso link as requested,Mid Chand's do the flue kits:

http://www.midlandchandlers.co.uk/Products/Heating/SolidFuel/FlueKits.aspx

 

 

Cannot be bought direct from Morso unless you are a main Morso supplier. I assume other Morso suppliers can get them and probably cheaper!

 

The flue length is indeed an issue, but the new standard does state a 2m flue height in total when moored, thus the new insulated chimneys are taller.

[rjasmith]

Perhaps that was his experience, but it wasn't mine. Each stove and each installation is different.

 

For example, Glyn says "An uninsulated boat chimney will only get to about 90°C" - my uninsulated flue can easily get to about 250°C (hotter if I'm not careful), and I can close my stove right down without it going out.

 

Glyn also says "Where I could really do with some help is by real people out there letting me know what happens."

 

Where are his contact details? I might let him know that I tried insulating my flue and nothing happened!

 

Agreed - I measured about 250deg C (how do you do degree symbols?) at the bottom of mine, tailing off to about 100deg C at the top just below the collar. I shall certainly do more testing one day just to see if I can repeat Glyn's tests with insulation all the way up my standard steel flue pipe. I got those temps with the stove (Hamlet Hardy 4) going reasonably well and I haven't really tried to make it slumber properly yet.

 

Glyn's contact details are on the Soliftec website but rather difficult to find.

 

I used info@soliftec.com initially but we subsequently corresponded using our private emails

 

I could PM you his private one if you need it.

 

Richard