Chimney fire causes?

[Daniël Bos]

My estranged wife just had a chimney fire. Not much damage done and the kids were with me so no drama. (a house full of firemen made her happy too, they went and checked the house, replaced the smoke alarms in the bedroom [emoji1])

 

She burns in a brand new esse range cooker with backboiler.

Single skin flue to the ceiling with a 45 degree whoopty where it goes through to clear a rafter, then twin walled. All 6“.

 

Wood is all dry (23% was the highest measurement) mainly hawthorn, blackthorn and ash. All split to less than 4", most of it near 3", 8-10" long.

 

Chimney was swept 4 weeks ago.

 

Since it was installed it has been too smokey (when adding wood, the house would fill with smoke) for my liking, never got it to really roar, it was checked over several times by both the installer and esse people and they could find no fault, blamed wet wood and brought some kd beech which was worse (and measured higher mc than my wood)

 

What could have caused it?

 

The only reasons i have left:

the chimney not being high enough? Its a square pyramid shaped house, chimney comes through the middle of one side and is just higher than the peak of the house.

 

Or/and

 

The water being pumped though before its hot enough. The pump and heat exchange system is remote controlled by telemetry from afar. So this should be easy to remedy. But id have thought the installers would have looked there first? (i wasn't involved in the install, we're busy divorcing)

Also, could that cause so much cooling of the firebox to become a major issue?

 

The fire brigade checked everything and ensured her it was safe to burn again. She's reluctant as it was supposedly safe before and v nearly cost her her house!

[Peasgood]

My guess is the very top of the flue gets cold and condensates solidify on that cold bit causing a restriction and almost a blockage. This leads to more soots and tars building up all the way down the flue which eventually catch fire.

You can push a brush through the restriction but a brush won't clear it, you have to get up there and scrape.

 

This seem particularly prevalent where the metal goes up to the very top. I think it just never warms up, especially at this time of year.

[Daniël Bos]

My guess is the very top of the flue gets cold and condensates solidify on that cold bit causing a restriction and almost a blockage. This leads to more soots and tars building up all the way down the flue which eventually catch fire.
You can push a brush through the restriction but a brush won't clear it, you have to get up there and scrape.
 
This seem particularly prevalent where the metal goes up to the very top. I think it just never warms up, especially at this time of year.

That may have happened, but i don't believe it is the root cause as its never really been burning well imo.
If that was the cause it would have slowly got worse.

[Woodworks]

An insulated flue would most definitely help. I have read of something called a Ladomat or similar which controls the water running through the back boiler to easy over cooling of the firebox.

[Daniël Bos]

An insulated flue would most definitely help. I have read of something called a Ladomat or similar which controls the water running through the back boiler to easy over cooling of the firebox.

It is insulated. Twin wall selkirk from the ceiling above the cooker to the cowl. The only single bit is from the cooker to the ceiling.

 

 

It doesn't have a ladomat i think, but a rather more complicated control system

 

 

[Daniël Bos]

I suppose my main question is: can a badly controlled back boiler reduce the firebox temperature so much as to have caused this?

 

 

[peatff]

59 minutes ago, Daniël Bos said:

Since it was installed it has been too smokey (when adding wood, the house would fill with smoke) for my liking, never got it to really roar,

That just sounds like not enough ventilation in the room where the range is. Does it improve if you open a window ?

[Daniël Bos]

That just sounds like not enough ventilation in the room where the range is. Does it improve if you open a window ?

Nope, an extra vent was put in an outside wall, windows/door open makes no difference

[Woodworks]

42 minutes ago, Daniël Bos said:

It is insulated. Twin wall selkirk from the ceiling above the cooker to the cowl. The only single bit is from the cooker to the ceiling. Sorry missed the second part

 

 

It doesn't have a ladomat i think, but a rather more complicated control system

Yes from what I have read more complicated and  expensive but well rated by users

 

 

[Rough Hewn]

Prevailing wind direction?
Does it work better on a still or windy day?
Have you tried burning kindling for an hour to heat the whole chimney, Increasing airflow?