woodburning safety (avoiding the fireplace)

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woodburning safety (avoiding the fireplace)




by Christophe » 18/10/10, 10:46

What are and how to reduce (cancel?) The risk of chimney fire?

We can quickly summarize:

a) always burn a quality fuel, that is to say dry and untreated. Do not trust wood deliverers. Re-dry it yourself ... We were fooled once. You can check with a moisture meter to measure the humidity of your wood. The humidity should be between 10 and 15%.

b) never smother the fire (mini draw) before having embers

c) use a quality device: prefer performance to design !! Banish the stoves too design and too inefficient! Please note that the Green Flame label is insufficient to guarantee real good performance: https://www.econologie.com/forums/label-flam ... t9210.html

d) according to the use sweep regularly: we can say all the X steres ... X will be defined in this subject.

For more details, in particular on the need to tub or not an existing chimney, read this subject:
https://www.econologie.com/forums/que-penser ... 10032.html
Last edited by Christophe the 16 / 11 / 10, 14: 56, 1 edited once.
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by Christophe » 18/10/10, 11:14

Some extracts from the above subject: https://www.econologie.com/forums/que-penser ... 10032.html

dodo wrote:attached a photo of the duct:
Image
I couldn't see if it was cement or terracotta.


Christophe wrote:There is an interesting passage to know the qualities of firewood on http://www.stuv.com/fr/Support.cfm

Image
Image

And here is what is said on the installation doc:

Recommendations
- For the actual connection, we recommend a stainless steel conduit, if possible rigid.
- Standard outlet diameter: 180 mm
- Some chimney configurations may require a different diameter than that provided as standard. Please consult Stûv.
- In all cases, ensure a seal between the body of the device and the smoke outlet.
- It is advisable to insulate the flue, to promote draft and avoid condensation.


dedeleco wrote:With Christophe we have the same reactions and we agree on common sense!
Good efficiency of stove equals smoke very low temperature (110 ° C and if condensation much less than 100 ° C !!), etc .....
Beware of pseudo-professionals who have the commercial cheek to assert anything and show their incompetence and their complete misunderstanding of basic phenomena

We even agree for ask professionals to provide the written text of the latest DTUs that they never have and that nevertheless they must respect (2000 to 3000 € to pay to have what they must respect !!!). Even with a legal expert I couldn't get it !!!
He all say yes like us !!!!

Otherwise compared to my fireplace, the dodo fireplace is much more surrounded by wood which makes it more difficult to insulate it better with copper plates slipped between the wood and the chimney !!!
Only safe solution! and planned at DTU as far as I remember ???
but by removing the boards that were used to block the cement in the construction, should we be able to ??? In addition we would see a part of the bricks of the bushels appear.
On the picture there is a little red in the upper right corner of the fireplace which shows the double wall brick bushel from the 1970s to the 1980s. By looking carefully on the spot, we must be able to confirm !!
You can make a hell of a fire in the chimney and measure the temperature of the beam and the chimney by sliding a thermocuple between wood and cement or brick (small welding of copper wire with millivotmeter).
The beam under the tiles is well ventilated in the cold and therefore well cooled with more difficult to burn wood (much more than polyurethane or polystyrene) !!
I made the involuntary experiment with the very strong lightning which pierced the roof and the tiles, not set fire to the ridge beams but set fire to a rubber much more flammable !!!

On the other hand the insurances, which cover the installers, oblige them to respect the rules of the art of which DTU, ie the rules imposed by the judgments of justice on report of the legal experts.
For 15 to 20 years, given some very old unsuitable cracked chimneys not tested by professionals, the fashion is for the systematic casing of everything with aluminum tubes, accentuated by the industrial lobby which takes the opportunity to sell many more of these casings, which pays more than keeping the chimneys in good condition or repairing cracks with cement.
In addition to repair, requires reflection, skill, understanding, endangered qualities that waste time !!
The casing which brings in money (and pollution in Hungary) requires no reflection, worse we do not even get tired of sweeping the old chimney properly and perfectly (hard work) (ask if it is requested and required by DTU ???? Very important) and we see on the internet a collection of people furious at having had a chimney fire after casing !!!!!
I bet the DTU does not require it to check the quality of the old chimney which, if full of soot and tars, much more heated after casing (for you section 3,5 times lower therefore 3,5 times hotter ) and well insulated between the bushel and the casing catches fire whereas it would not have burned without casing (reason which invites you to take 18cm in casing) !!
Tap on google; casing fire chimney, with variants and read everything thoroughly hundreds of pages, not 12 or 48 but an armada of info, like the DTU hidden somewhere !!
http://forums.futura-sciences.com/habit ... minee.html
http://www.bricozone.be/fr/galeres-et-h ... 14923.html
http://www.bricozone.fr/cheminee-tubage ... -1427.html

Above all, even with casing you will have to sweep 2 times a year mechanically and not only with a deceptive chimney sweeping log useful before sweeping only !!

Whenever I sweep my tubing, I ask myself the question and I am afraid that the brush to be swept will use and pierce the casing in aluminum foil without me realizing it !!!!
In my opinion, bushel chimney fireplaces will last much longer than aluminum, which wears out mechanically and degrades by long-term oxidation.
The lobbies often distort the rules and DTU to their advantage to sell much more !!
Herbicides, GMOs and insecticides (and asbestos) are a clear example of Lobbys figuring out how to sell a lot of poisons with clever manipulations, leading to the illusion that what is more dangerous for insects and microbes is not everything dangerous for us however little !!
An incredible and criminal lie with truncated studies over 3 months and never embryos !!!

Search on google if someone had a fire on the beam against the brick bushel with a waterproof chimney ???
If you don't find one, you notice an absurdity


Christophe wrote:Ah "not bad" the consequence of the chimney fire on the 2nd link ... it's scary:

Image

Corn to get there is that there was another serious error than an absence of casing (which I repeat does not eliminate the risk): a chimney can very well burn "alone" ... as long as it holds mechanically and therefore that the fire remains confined in the fireplace, there is almost no risk of serious consequences for the rest of the house ...

It is also noted what we have just said:

It is reduced, but not deleted. Here is the house of the neighbors across the street, one evening in January 2008. The chimney had been lined, but not to the top. The house, a Jumatt, was razed to the ground, there was nothing left.


When you are told not to burn everything and anything, it's not for nothing: use quality wood on quality appliances and in good condition ....


Christophe wrote:No, you don't have to and no, if you don't tube, you won't necessarily set fire to your house ... rolalala it takes a while to understand ...

And if that can reassure you: we have a recent stove that we use exclusively for heating (we have no other means of heating except solar heating), it is modern and there is no tubing in our fireplace ...

What it takes is whether it is cased or not, sweep regularly. We only need to do it every 2 winters (because we only consume 5 cubic meters per winter which isn't much for a winter). If you burn poor quality wood then you will foul it much faster, I have experienced it ... some chimneys only need to be swept every 5 years ... it depends ...

I am sure that most people in the forum that heat with wood do not have a cased chimney ... casing has only been around for a short time ...

What is the relationship between casing and logs at bedtime? I think you mix a lot of stuff there ... :|


dedeleco wrote:In my insert with its chimney swept well myself I put lots of dry logs that burn in 2 to 3 hours max at full power (house at the start at 6 ° C in winter at the start of the weekend) and I sleep one to 2 sleep cycles (1:30 to 3 hours) to put wood back , otherwise the next day I will curdle with a house that is not hot enough !!
The following days with hot ashes like the house, the fire is much weaker and turns longer at reduced speed, 4 to 6 hours.

But I check the sweeping and test of the soot deposit by tapping the exchange plates and I sweep if they are full of falling soot because the chimney becomes too loaded with soot (a few mm, while the fire occurs at cm of thick, sheer madness not to sweep before).
Thus, I did not have the beginning of fire, because still almost nothing of soot in the casing.

A good stove with good efficiency, burns wood much better and therefore less soot which will also be deposited mainly in the exchanger.
A good stove must have a second combustion and a long smoke circuit in the exchanger, otherwise its efficiency is low, with the fumes too hot in the chimney.
A good performance, these are fumes at 110 ° C to 130 ° c in the chimney therefore not very hot and impossible to start a fire at less than 150 ° C, very slow to start at 200 ° C !!

So if the stove has a real good performance, the fumes will never be hotter than 150 ° C at the bottom of the chimney and therefore much less at the top of the chimney through the bushels against the ridge beam !!

I suspect a lot of French stoves to display good performance with measurement conditions not corresponding to those usual, given the surface of the exchangers small (otherwise too much sweeping of the exchangers clogged with soot) which let out too hot fumes !!
To know,
it is necessary to measure the temperature of the fumes which leave after exchanger with a thermometer in the stove at customers with this stove !!
On the outlet pipe, outside, the hand should burn only very slowly 30s because 600 ° C is less than the second !!

This is only valid with a chimney swept never having more than a few mm of soot !! So you have to check regularly if the soot accumulates every month, especially if the wood is damp and if it is a softwood.



Christophe wrote:
dedeleco wrote:Above all, even with casing you will have to sweep 2 times a year mechanically and not only with a deceptive chimney sweeping log useful before sweeping only !!


I had overlooked this remark: it is quite true, the chimney sweeps do nothing but make the soot fall into the bottom of the chimney, that is to say towards the heater generally, therefore potential increase in the fire of chimney if creosotes are not removed mechanically.

We used 2 times (1 for the saey 1 for the deom) and in both cases we had to mechanically unclog the nozzle arriving at the chimney a few days later.

I don't know when the previous pickup was made.

I won't use it anymore.

Well I think it's time to make a topic on the safety of firewood ...
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by Christophe » 18/10/10, 11:52

And finally, here is a very complete page on the safety of wood heating:

http://www.bois-sec-chauffage-firewood. ... curite.htm

excerpts:

The fundamental principles governing the combustion of wood

When burning, firewood undergoes three transformations:

Evaporation of water - Up to half the weight of a freshly cut log consists of water. After sufficient drying, the water content is reduced to approximately 20%. As the wood heats up in the combustion chamber, the water evaporates while consuming thermal energy. The wetter the wood, the more thermal energy it takes to evaporate the water. This is why wet firewood hisses, sizzles and burns with difficulty, while well-dried wood catches fire and burns easily.

Smoke - When the temperature of the wood rises above the boiling point of the water, it begins to smoke. Smoke is the concrete sign of the decomposition of solid wood which vaporizes into a cloud of combustible gas and tar droplets. The smoke itself will burn at a sufficiently high temperature and the presence of oxygen. When the smoke burns, it produces the bright flames that characterize the burning of wood. However, smoke that does not burn in the combustion chamber leaves the appliance to end up in the connection pipe and the chimney, where it condenses and forms creosote deposits or escapes into the atmosphere under form of pollution. Unburned smoke represents a loss of efficiency since it contains a large part of the total energy supplied by the wood. Advanced combustion systems are designed to burn smoke before it leaves the stove; this is one of the reasons why they are more efficient than old installations.

Carbonization - As the fire progresses and most of the gases and tar have evaporated from the wood, only charcoal remains. Coal is made up almost entirely of carbon; it produces a red glow when burning and a little flame or smoke when it has sufficient oxygen. Coal is a good fuel that burns easily. However, burning coal often produces carbon monoxide, a harmful indoor air pollutant.

Image

In practice, the three phases of wood combustion occur simultaneously. In fact, the wood gases can ignite while the ends of the log are red due to the combustion of charcoal and the water still present inside the wood continues to evaporate. The key to burning wood effectively is to quickly evaporate the water and allow the smoke to burn before leaving the firebox.

In the new models of advanced combustion appliances, the flames are divided into two often visible zones: that of the primary flame which rises from the wood and that of the transparent secondary flame which swirls above the wood. When the fire is burning hot, close the combustion air supply ports and you will see the primary flames become less vivid and smaller. For efficient combustion, always make sure you have secondary flames. In these improved models, not only is the combustion better and less polluting, but the flame has a better appearance, which represents a significant advantage.


Other practical advice

Fuel disposal - Small pieces of crisscrossed firewood arranged in a clear arrangement burn quickly, because the combustion air can reach all the pieces at the same time. Larger pieces stacked tightly burn slowly because there is little space between the pieces where air can infiltrate. Try adding more than one piece of wood to a fire at a time. At least three pieces of wood are needed to form a good layer of embers in which the heat used to fuel the fire is transmitted and retained.

Heating cycles - Do not expect the fire to produce perfectly constant heat, as the wood burns cyclically. The heating cycle extends from the period between the ignition of a new charge of wood from the embers and the moment when this wood is reduced to the state of embers. Each cycle provides between three and eight hours of heating, depending on the amount of wood used, the amount of heat required and the size of the combustion chamber. Match these cycles to your household habits. Be careful not to leave the stove unattended when you leave the house.

Flash fire - Flash fire involves burning a small amount of wood quickly. Use this technique in the spring or fall when you want to get the cold out of the house. By adopting this technique, you will avoid smoldering fires, which is common during these two seasons. To start a flash fire, bring the embers to the air intake and place several pieces of wood on and behind the embers. Intercross the pieces or stack them in a loose fashion. Then open the air intake port to produce a bright, warm fire. You can slightly reduce the air intake as soon as the fire gets bigger, but never to the point of extinguishing the flames.

Extended fire - To burn a fire for a long time to heat the house overnight or when you are away from home, bring the embers to the air intake and pack the large pieces of wood well the combustion chamber. Thus, as heat and flames cannot penetrate the load, the pieces of wood will burn up later in the cycle. Fully open the air intake port for 5 to 20 minutes, depending on the size of the load and the moisture content of the wood. When the pieces of wood on the surface are covered with a thick layer of embers, gradually reduce the air supply to the desired level.

Ash removal - Some advanced combustion stoves have ashtrays available as standard or optional equipment. Some have a simple grate where the ashes fall into the ashtray. Others have a cover on the bottom surface of the combustion chamber which can be lifted and which allows the ashes to fall into the ashtray. After dropping the ashes, be sure to close and seal this opening. If your stove does not have an ashtray, you can remove the ashes through the loading door using a shovel that you purchased from a retailer.

Ash sometimes contains hot coals which can stay hot for days. If you don't take proper steps to get rid of it, it can present a fire hazard. Place the ash in a metal container reserved for this purpose and store it on a non-combustible floor, preferably outside the house. It is possible to obtain, in the stores where stoves and fireplaces are sold, ash receptacles with double bottom, the hermetic lid of which is designed for the preservation of the ashes until they cool.

Using a thermometer - A thermometer can help you use your wood stove more efficiently, especially if you can't see the fire through a glass door. There are two kinds of thermometers. The first includes a probe that is inserted into a small orifice located in the connection pipe so that it comes into contact with the gases circulating in the flue. The second is the magnetic thermometer which adheres to the outside of the connection pipe or above the stove.

Install the probe thermometer in the connecting pipe approximately 50 cm (20 in.) Above the outlet of the device, but never on the device itself. This thermometer indicates the temperature of the combustion gases.

As for the magnetic thermometer, it actually measures the temperature of the flue. The temperature it records will therefore be lower than that measured using a probe thermometer.

Some manufacturers recommend using a thermometer that fits over the stove itself, rather than a flue thermometer. It works the same way, except that it displays different temperature ranges since it measures the surface temperature of the stove.

When you heat the stove to remove moisture from the fuel, the thermometer tells you when to reduce the air intake. Each heater behaves differently and the thermometers vary so that exact reference temperatures cannot be given. However, to avoid damaging the internal parts of the stove, please note that the temperature of the duct should never be allowed to rise above 460 ° C (860 ° F) for more than a few minutes. Familiarize yourself with the maneuvers that vary the measured flue gas temperature. With the help of experience, you will be able to determine if you have reduced the air intake too much or if the timing is right for recharging.

Advanced wood stoves do not need thermometers like old stoves. It is enough to visually check the state of the fire. If the fire burns well, the glass door stays clean. On the other hand, if a veil forms on the glass or if brown spots appear quickly, it is because the fire burns at too low a rate, or that the firewood is too humid. If the heat output of the fire is high and the firewood is of good quality, the glass should not get dirty. The flame is also a good indicator: the more complex the flame, the better the combustion in the stove.


Efficient wood burning in an advanced stove

Once you have mastered efficient wood heating techniques, here is what you should observe:

* When wood burns, it produces flames until only charcoal remains. If there are no flames, something is wrong.
* If the combustion chamber is lined with refractory bricks, these must be ocher in color, never black.
* The steel or cast iron pieces of the combustion chamber must be of a color ranging from light brown to dark brown, but never black and shiny.
* If your wood is dry and well split, the air intake openings fairly open and the pieces of wood correctly arranged in the stove, you will get instant ignition of a new load of wood; some pieces will even catch fire before you close the door. If the unit has a glass door but no air sweep, the glass may be somewhat cloudy, but should never be black.
* The gases escaping from the top of the chimney must be clear or, in winter, white due to the vapor. A plume of blue or gray smoke indicates a smoldering fire and poor combustion.


I think we went around there : Cheesy:
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by Ahmed » 19/10/10, 21:56

Christophe, you write:
The humidity should be between 10 and 15%.

That seems optimistic to me: wood being a hygroscopic material, it cannot be drier than the ambient air (except of course temporarily, in the case of artificial dehydration).

For practical and economic reasons, commercial wood cannot reach optimum drying levels *, it is therefore preferable (as you recommend), if possible, to provide personal storage of your wood so as to have a year in advance.

* except in the case of small producers who market only the excess of their past personal consumption.
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by aerialcastor » 19/10/10, 22:28

Ahmed wrote: wood is a hygroscopic material, it can not be drier than the ambient air (except of course temporarily, in the case of artificial dehydration).


Ah yes and fortunately because with a relative humidity of the air which can easily go from 20 to 70% we would have some sacred withdrawals.


Wood hygroscopy is a function of air hygroscopy and air temperature.

A small summary table:
http://www.arbao.fr/Docs/ARBAOEquilibreHygroscopiquedubois.pdf

mirror: https://www.econologie.info/share/partag ... ukzJQQ.pdf
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by Ahmed » 19/10/10, 22:35

I correct my sentence, too visibly imprecise: the wood cannot be drier than the minimum of ambient air.
Obviously, and fortunately, as you rightly point out, wood has good hygroscopic inertia.
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by aerialcastor » 19/10/10, 23:25

If the wood can be drier than the surrounding air, it is always so.


For example in air at 65% RH and 30 ° C will balance at 12% humidity.

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by dedeleco » 20/10/10, 01:44

Useful this curve that we find where on the internet ???
But it is variable depending on the wood (coniferous ??) and an important factor is the speed of drying of the wood which takes 2 years and more in logs at ordinary T !!
In addition, for example, if the wood is heated in ordinary air taken at 60% humidity at the start at 20 ° C to 60 ° C, the relative degree of humidity then decreases much more than half and the wood will be dry with 5% humidity, if it has time to dry in this air heated to 60 ° C !!
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by aerialcastor » 20/10/10, 08:58

Curve found here

Thanks to the hygroscopic wood balance research.

Et leaves a site on natural wood drying.
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by Christophe » 20/10/10, 10:03

Ahmed wrote:That seems optimistic to me: wood being a hygroscopic material, it cannot be drier than the ambient air (except of course temporarily, in the case of artificial dehydration).


Yes when I say must be it is ideally therefore it is optimistic. A wood is considered dry at 20% ... but nothing prevents it from going down above (the less the better).

Standardized pellets (artificially dried) are at% RH <8% or 10% (industrial quality). So for the wood in logs, very dry, we can be under 20%. But you're right, I should rather have said between 15 and 20% but what do you mean, I'm a little idealistic :)

The definitions of wood and air humidity have nothing to do with it, so we cannot compare them directly:
a) For air, it is in% of saturation for a desired T °. It varies greatly from the T °.
b) For a material it is in% by mass. I do not believe that it varies compared to the T ° except when the water begins to evaporate from the material obviously.


This is why we have much lower rates in materials.
Besides, it is quite impossible to exceed a certain humidity threshold in the materials since at 100% we would have more than water !!

We have a subject on the Molier diagram: https://www.econologie.com/forums/humidite-c ... t5928.html
and moisture in insulating materials (case a little apart because they contain a lot of air): https://www.econologie.com/forums/humidite-d ... t9956.html
Last edited by Christophe the 20 / 10 / 10, 13: 12, 1 edited once.
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