Overnight Burning - Need to know if I'm on the right path

[richardwale]

I think those holes create the secondary burn. I’ve had the glass replaced for free by Burley which was great but the fly ash still sticks to the glass and obscures the view. Brilliant stove apart from that. 

[Stubby]

2 hours ago, richardwale said:

I think those holes create the secondary burn. I’ve had the glass replaced for free by Burley which was great but the fly ash still sticks to the glass and obscures the view. Brilliant stove apart from that. 

OK was not too sure . I don't get ash sticking to the glass though .

[Rob_the_Sparky]

I get a little ash on the glass on my CLearView, which has air vents similar to those described.  Bit of damp paper and ash though and it wipes off very easily and builds up again fairly slowly.

[sandspider]

I get ash on the glass of my Burley too. Even with a good hot burn. The occasional wipe and it's fine, but it would be nice if it stayed clear. My other stove (Heta Inspire) has a much better airwash system, or at least, the glass stays totally clean.

[openspaceman]

2 hours ago, richardwale said:

I think those holes create the secondary burn. I’ve had the glass replaced for free by Burley which was great but the fly ash still sticks to the glass and obscures the view. Brilliant stove apart from that. 

I think the pre heated air jets that comes from those holes is additional secondary air just to ensure a complete secondary burn.

 

With a modern wood, not multifuel, stove it seems that all the air is "over" air, the main air, including the air wash down the glass, acts as both primary and secondary air.

 

My multifule stove has a provision for primary air under the grate but it is not used when burning wood as 70% of a wood fire is volatiles burning, whereas a coal fire is 90% fixed carbon burning.

 

A traditional up draught coal burning fire requires the primary air under the hot coal, to gasify the solid carbon to a mix of carbon monoxide and carbon dioxide, the CO then burns out in a secondary flame.

33 minutes ago, Stubby said:

OK was not too sure . I don't get ash sticking to the glass though .

 

1 minute ago, Rob_the_Sparky said:

I get a little ash on the glass on my CLearView, which has air vents similar to those described.  Bit of damp paper and ash though and it wipes off very easily and builds up again fairly slowly.

Oddly I do have a slight hazing of the glass if I burn vigorously for a long time, it wipes off next morning with a damp tissue. I take it this is fly ash wafted of the surface of logs with pyrolysis offgas. It shows that not all particulates from a stove are black carbon but also this fly ash, which I take to be things like calcium, potassium and carbonates and oxides of these metals with oxides of phosphorus, I can see if left on the glass with a very hot burn they could form a eutectic mixture with the silicon dioxide or boron silicates of the glass and melt into the glass.

 

My previous stove did not have any glass and until now I had not appreciated how much radiant heat was given off through the glass.

[woodrascal]

I'm finding this 'hazing' of the glass a problem in my Vision 500.

 

I have modified the stove to burn cleaner by replacing the steel baffle with vermiculite board and adding an adjustable pre-heated tertiary air supply. It burns so much cleaner but the fly ash is melting into the glass due to the very high firebox temperatures.

 

 

[Stubby]

16 minutes ago, woodrascal said:

I'm finding this 'hazing' of the glass a problem in my Vision 500.

 

I have modified the stove to burn cleaner by replacing the steel baffle with vermiculite board and adding an adjustable pre-heated tertiary air supply. It burns so much cleaner but the fly ash is melting into the glass due to the very high firebox temperatures.

 

 

Ah . I did not appreciate what " fly ash " is . Yes I do have a slight hazing on the glass . Looks worse when the stove is not alight . When burning it is not so intrusive . It is also double glazed .   

[openspaceman]

1 hour ago, woodrascal said:

I'm finding this 'hazing' of the glass a problem in my Vision 500.

 

I have modified the stove to burn cleaner by replacing the steel baffle with vermiculite board and adding an adjustable pre-heated tertiary air supply. It burns so much cleaner but the fly ash is melting into the glass due to the very high firebox temperatures.

 

 

I cannot help with that  but I tried to explain how the vapours of the alkali metal species given off in a hot fire actually lower the glass fusion temperature when they condense on the glass surface.

 

I used to know a naval engineer who operated a "ship's" boiler to burn straw for power generation. Straw has a higher mineral content than wood and he could see the vapours condensing on the superheater tube and dripping off as molten slag.

 

Most of the ash will be from bark.

[richardwale]

I wipe the glass clear each morning with a damp paper towel and it's always a clean wipe, but the fly ash is always there and does obscure the view when burning. Just something Burley need to sort really as the flame pattern is great to watch but could be even better with clear  glass. After all one of the  primary reasons for a large viewing area is to watch the fire.

[Paul in the woods]

This has been a useful thread. Recently I've converted our multifuel stove to wood only (basically removing the grate). It seems to burn the wood much better but I've now got the problem of the fly ash settling on the glass. When the grate was in and I only burned wood there didn't seem to be much of a problem with ash on the glass. I close the bottom vents once the fire is going and tend to leave the top, air-wash, vent open most of the time.