Wood insert modified and improved .... in every respect

[bidouille23]

Bonjour,

as the title indicates I will present you the best result and yes too caught up in the work, I zap to take photos from the start ... arff

in short here is the beast:

Originally it is therefore a brand log insert ????
So I made two half side covers (see that we can not see the back of the stove and for lack of time because the cold appears, etc ... the aesthetics will be reviewed next year or after .. ) and a covering on top all in 1.5 mm sheet.



I will put videos to follow so you will see the attempt at heat recovery, this too is another subject on which to perform some tests but same as for aesthetics, in the state it works so ....)

So I will try to summarize the goal of a thermal renovation in order to obtain the best possible combustion, in my eyes:

. Obtain and keep an operating temperature at least equal to 580 ° C in the cold part of the hearth, since the effective pyrolysis and the self-combustion starts at this temperature, maintaining the high point at this limit seems essential to me.

. Having a sufficient amount of air (in my previous tests I underestimated my air intakes, assessment the operation is far behind that of this stove).

.have an agreement between adequate draft and combustion therefore have enough air for combustion but also for the activation of embers in the lower part of the hearth (which will allow to maintain the desired temperature in the hearth) (the 2nd air being fixed because fully opened once the correct temperature is reached).

. Succeed in ensuring that the fumes and gases remain at least 2 sec in the hearth in contact and mixing with the air supplied in the upper part

Have a good mixture of gases and secondary air

The whole being a system whose characteristics will change according to the hearth temperature but also according to the outside time ...


So two photos of the stove is pretty funny they are taken to follow, one with the flash and the other without , it's funny as would say that the fire died with the flash, photo and I close the parenthesis.

without flash:



with flash:



Now let's go inside:

As you can see the stove has been in service for a week, you can note the surface condition of the walls it is clean nickel, there is only the window which has a very light layer of black when I do not open the primary air fully when the fire ends during the burning of embers, otherwise when I open well the primary air and I close the second air when burning embers I get only a light layer of gray, and this after 6 to 8 hours of combustion each time.


front view



then what is brown on the periphery are insulating plates, 3 cm thick, composed of 5 parts of vermiculite and a part of molten cement (pure refractory cement).

Small remark and questioning, at the beginning the cement is gray the yellow white vermiculite and the mixture of the whole gray yellow, in the other frying pan which I modified it changed color for black but not reddish like there, and that makes me think of the color of a spark plug, pile hair the right ratio for a two stroke when the candle is reddish like that, I think there must be a report what do you think?

Just make a frame of 3 cm (or more but the first 3 cm is the most important) thick (wooden) with a background (on which you can make drawings even;)), in this frame will be molded a large plate, which once dry will be cut with a saw simply to dress the fireplace.

It takes a little bit less than double the actual volume in mixing, then put everything in the mold, and press with a roller until everything comes in, in order to obtain a plate dense enough not to break when handling and use.
as a roller I took a piece of scrap metal tube ...;)

At the bottom, we can see a horizontal stainless steel tube (316 L here because the scrap dealer used it and the diameter was perfect ), in short this is therefore my primary air, each hole is 4 mm in diameter and there are 128 of them, which gives a surface of 16 cm ² (I will explain below the why of the how;)).

On the top have seen the deflector and the secondary air supply tubes.

here have them see better:



So what we have seen is:

a stainless steel box that supports two tubes and a small deflector that we can see on the top of the photo here:



This small deflector on the large deflector is used to "hold" or slow down the evacuation of fumes and therefore gases and heat, heat which is the essential thing in order to achieve good combustion (hence the insulation .. .), Roughly 580 ° c is the goal ...

For my part at the beginning I said ok understood then I said to myself ??? yes 580 ° c but where .
Now I can say it without being mistaken I think (whatever ..;)), just below the deflector it takes 580 ° c, "at the coldest point" in fact;) (below it is the embers so necessarily hotter ... ) .

So here is a deflector, and a secondary air supply:

Two stainless steel tubes (316L again ) pierced by for the one at the bottom of ??? I no longer know how many holes but with a diameter of 3mm, the holes are directed towards the deflector (they heat the air in the deflector box, like a gas train under a box in fact ), at the beginning I thought to push the gases towards the front tube, so that it is then attracted by a sort of venturi effect (by the air leaving the second tube closest therefore to the window) in order to have an optimal mix.
This second tube therefore has larger holes in fewer numbers therefore than the other.
In total there is 8 cm² of total opening.

Oddly enough sometimes with regard to the venturi it does it many times no, I did not seal between the insulating plate at the bottom and the underside of the deflector, there is therefore a draft of the gases by the background .
But in the end it's pretty good in fact, because part of the gas passes through the back the other through the front, and through the rear the gases are forced to pass through a small space of barely 0.5 cm at the most just and 1 cm at the widest, that is to say a compulsory mixture of the secondary air which passes by there with the gases.

Balance as shown in the photos everything remains nickel, and by burning the fir tree please (3/4 fir 1/4 hardwood, and also birch ...).

For those who have an eye, yes I crashed when I implanted the plate on my primary air tube balance sheet I had to cut the insulating plate grrrrr and in the speed I did not watch out before final assembly, check too fast not good

Have also seen on the last photo the background which is original and which has a grid with large holes, following the tests of which I will give you the results just after, I put a cast iron plate from the recycling of a other insert, so I took a piece of one side cut the fins which were originally used for heat exchange but not entirely in order to keep resistance during heating, I then made full full full small holes of 3 mm that I put on the rectangle space that we can see on the photo, I would take a photo if necessary but hey ... I will do a measurement again and I will tell you my conclusions will be better.

Speaking of measures, here is what, for the moment, I have been able to measure:

Measurement of consumption and therefore of power:

19 Kg of wood in 6 H or 3.33 Kg per hour, and only 192 gr of ash (with the large holes in the bottom grid I will re-measure with the new grid with small holes).



using a low-cost digital thermometer with probe type K 400 ° c.

Glass temperature: 230 ° c to 280 ° c in nominal operation, 345 ° c (after that heats up too much and I have no more confidence than that in the 800 ° c of the glass ...) a small photo at 335.9 ° vs



A short video in nominal operation:

http://www.dailymotion.com/video/xvjfe8 ... l_creation


Bell temperature 165 ° c when the glass is at 280 ° c (to give an idea)

http://www.dailymotion.com/video/xvjfjb ... e_creation

T ° smoke outlet at the start of the stone duct: 167 ° c with the probe in the smoke so the yield is quite important .

T ° glass / T ° under deflector,
I made this measurement at the end of the blaze when there was only a heap of embers left.
The glass was at 150 ° c roughly below the deflector at 300 ° c, a coef of two mini so.

On this point I would need, to have a fair measurement, pierced to put a probe, I will therefore rely on the color of the stainless steel which rises to dark red and say that the 580 ° c have when the glass is at 250 ° c, as well as 300 ° c on the glass or the color of the stainless steel still corresponds, in short I think the ratio 580/250 = 2.37, so roughly 2.3 for the difference in heat between the glass and the cold point of the fireplace is quite reasonable (in any case in my case) ...

to illustrate operation in nominal cool mode :

http://www.dailymotion.com/video/xvjflj ... c_creation


As for controls, here are the things:



The rectangle thing at the bottom is the primary air, the "U" handle above is the secondary air (ok I have to review the straightness ok ), in short at the end of the "U" there is a bar which is connected to two valves of the same kind as the one visible here.
The principle I used is: the welded angle "U" with welded hinge has a plate itself welded to the air supply tube.
As a valve, an iron plate that slides between the angle frame and the bottom plate connect to the tube (I stuck a seal in ceramic cord to make a good seal, the system is largely improving but it works, I note nonetheless bad improvement has brought on this side, to follow ...

you will understand that there is therefore a large duct for the primary air and two for the secondary air.
Why two? and well in the stainless steel case which serves as a deflector in the fireplace, I put an internal separation to create two separate air passages in order to have pressure in the two tubes.

As for air calculations, not being really trained in this area, but I work the thing;), I read a lot and I retained two thing:

The first is here

http://www.google.fr/url?url=http://www ... -E6-t371Aw

and this

http://www.google.fr/url?url=https://da ... 22vr7AHljA

in the first one we find the way to calculate the amount of air, in the second I find a method to best size the opening surfaces based on a realization has rather high efficiency and which has already proven itself .

I'm getting tired it is late if someone wants me to specify the calculations I could do it without worries later;).

For all omissions and there are some it is on, and any question do not hesitate;.

for fun, two other videos in half power mode.

http://www.dailymotion.com/video/xvjgpp ... e_creation

http://www.dailymotion.com/video/xvjgqo ... d_creation

thanking you for the time you spent at and hoping to have helped at least a little ...

A yes I almost forgot I happen to have 19 in the rooms with less wood consumed when the old stove was running, and never it did 19 in the rooms at the time, the two stoves had the same capacity .

[the middle]

Hello Bidouille,
I have been using this kind of stove for over ten years.
(Vermiculite interior, with reflector and double combustion)
It took me a long time to use it the best because the temperature inside rises very high.
Now that the house is + - insulated, it is often too hot.
13kw.
The problem is when we put a new log: too much gas comes out of the log, in a short time.
If I increase the air to burn these gases, the temperature rises even more, it is endless.
So, I cut my logs very finely.
Fir? I burned tons of them, without any problem; so I confirm, it works with this kind of stove.
Small tip at home, as the temperatures at the stove exit are very high, I built directly at the exit of the stove, a small refractory brick pad, which continues to heat the house at night, when the stove is off. (it's just great)
Good heating

[bidouille23]

Hello fair,


me it's been a week since I finished making it but I think I have mastered it;), I'm his father anyway

You fall well, in addition to the stove do you have a temperature probe to measure the temperature of the glass in nominal operation?
I am also looking at how many can have a glass before it deforms or shatters and how much temperature difference between two distant point on the same glass becomes critical (before shattering) because on my stove I could measure acart of thirty degrees on the glass at 5 cm difference) ???

Sinon
"The problem is when we put a new log: too much gas comes out of the log, in a short time."

for my part when I put back a log everything is fine if I put it at the right time;

too early (I mean by too early the moment when there are still too many embers): there are too many flames in my stove but the combustion is not bad look at the penultimate video I come to put a piece of fir in it;), the black smoke mounted on the deflector, and when we looked under at this moment at the end of the second air-breathing tube there are flames everywhere, in short apart from a questioning on the fact that there I may have a little a lot of wood, nothing bad.

Too late (more than enough embers therefore more than enough heat to cause auto_combustion: oblige to put pieces of 5 of max diameter, two three pieces and I open the draw fully two three minute, I close as long as the small flames blue red dances between the deflector and the wood I re-open the drawer, the goal being that the first flames of the outgoing gas be so to speak glued to the wood without however being it, and remain in this state when the drawer has closed and reduce the air first (a little as if you had poured alcohol on the logs), then re-fueled so as to have the right layer of embers.

At the right time (a bed of very active embers with still some sparks by so by there): the log is set, a quick blow of primary air and more and back to normal draft and everything goes for the best everything remains in balance ...

In the first stove that I modified I had the same problem as yours, in that the balance is extremely better, that's why I present it here.


In short according to the design finding the right setting to have a balance of the machine is not won in advance ... you have to master the beast , Olé.

for my part if I touch the primary air from 0.2 to 0.3 miles more or less the reaction is rapid, immediately felt the heat emitted which varies and the flames which change.


"If I turn up the air to burn these gases, the temperature goes up even more, it's endless.
Suddenly, I cut my logs very finely. "

The thing is not necessarily to increase the air , if your internal temperature is good, your wood is dry enough not to cool the hearth, then you do not touch anything, the air which will allow the good combustion of your gases will be injected at the top.

In any case what I think I can say and which is confirmed rather radically on this construction, is that:

The primary air is used to heat the fireplace and keep it at temperature for good combustion, but does not give air for the combustion of gases or very little. hence the advantage of having an air supply with small holes which suddenly increases the air pressure and therefore the penetration which gives a first intense combustion whatever the opening of the control valve.

The secondary air permanently opens it completely when when the right temperature is reached, it will mix with the gases and allow their good combustion.
It is there that it is important to have a slow passage of the gases in the top of the hearth under the deflector and therefore at the level of the injectors and an injection by larger holes for better mixing.

if the speed of passage of the gases in the hearth too fast the mixture is bad and the temperature of the hard hearth to keep high, and it is an endless cycle.

not fast enough well, I would say that there is an effective lack of draft so the fire will die more or less quickly.

In fact all that I would say that it also comes and simply from the chimney draft which must be in agreement with the heating system. In my case I knew that I had too much draft when the duct is hot so I took the risk of putting a bell in which the smoke rises in the middle and goes down on the sides to come out just above the upper level of the deflector is app 50 cm between the top of the bell and the smoke outlet, (a bit like your duct ).
A stroke of luck (my instinct did not betray me;)) it's perfect and no start-up problem .


For logs like this not too big not too small, 5 to 8 in diameter.


I have already seen your conduit it is a very good idea and effective, because simple and really functional.
View that the house where I am is only temporary I will not bother too much for the moment but when it will be renovated there it will not be the same story .

Good sorry for the sandwich;), as usual. what had it been a while since i had come back .

[Alain G]

Hi Bidouille and Alain!


If that can inspire you for the design and future modifications, I invite you to read this subject on a wonderful stove that I had and unfortunately discontinued probably in relation to its high manufacturing price!

https://www.econologie.com/forums/avis-poele ... t9950.html

[bidouille23]

Re, Slut Alain,

I read the post, and I would say that the principle is the same for all stoves with injection of secondary air to reheat worthy of the name.

everything then goes into the dimensioning and positioning of certain parts which make all the difference.

Take the deflector for example, change its angle and you modify the movement of the fumes etc etc ...

For my part I have rather in the perspective of trying to create a kind of vortex in the stove in order to have an optimal mixture between air and gas;).

I had the effect in my insert during the outbreak, I think of the fact that there were embers on one side and much less on the other, between the breath of the tube near the glass and the difference pressure in the firebox the flames are set to spin in the direction of the depth, therefore perpendicular to the draft, one half exiting from the back the other from the front.

As for the heated air;), my primary air tube becomes clear cherry red so the air that comes in even at the bottom is hot;), and that of it must be around 500 ° C so hot too .

And for the cleaning of the window ben a blow of paper without nothing above just the paper and it is clean. Anyway I think that the photos speak for themselves on the clean combustion side.

[Alain G]

Hi Bidouille!

On the FX-3000 a plate located under the chimney outlet with edges inclined downward at 45 ° at the front and rear and almost 5 cm long retains the flame and ensures good burning of the hot gases which could pass without burning.

Too bad the company no longer makes it!

[bidouille23]

Personally when I see what is sold in France ... the furry man lol, I prefer my stove two hundred times which cost me 200 euros of material (but quite a lot of work time), but who at final is equivalent in combustion to a chard which I would have paid much much much more expensive (personally I think that I should have put 2000 euros at least to have a combustion of this type under 14 Kw calculate that I use at 3.3 kg of wood * hour or 3.3 * 4 Kw / Kg = 13.2 Kw * h

$200 and the house gets warmer in a full week of use the house went from 12 ° c in the morning to 15 ° c this morning , unheard of until now ...

[bidouille23]

bonsoir,

http://www.dailymotion.com/video/xvk8rl ... aible_tech

I loaded a little more wood to have more embers suddenly I further reduced the primary air supply and always a temperature of 250 at the level of the window, results in a perfectly clean window, and all without air passing in front of the glass as for the "clean glass" system.
I wanted to try without the system because everything is ready there are only the holes to do for the clean glass system on my insert;), but no need in fact

[Alain G]

Good morning Bidouille!

Your flame is faster than on slow combustion and must consume wood fairly quickly, right?


Are you able to keep embers after 8 hours and 4 logs?


This is what I got!


For the window it is clear that it stays clean!

[bidouille23]

Hello, from the beginning of the afternoon,

Having not yet had the chance to see a real flame from a good slow-burning stove I could not say if indeed my flame is faster or slower, so I trust you on this point.

I think I can slow it down again, this I think on the condition that I increase the amount of embers a little more in order to keep the right combustion temperature.

I will try this during the next outbreak, this evening already I will redo a weighing of the wood consumed by the hour with this new setting;), I think I am below the 3,3 KG measured during my first setting road, but which gave me a slightly blackish gray window much faster, and a little more ash.

Ash side this morning, good apart from the fact that there is a nice piece of charcoal from the biggest log (so a window that has slightly blackened during the extinction phase), the ash around is almost absent . there I am even happier.

So for this evening the program, empty and clean the stove of its ashes, weigh the wood consumed, and tomorrow measure the weight of the ashes see charcoal remaining in the hearth.

FYI, with this new setting the temperature of the house has climbed again, without fire in the house it is 17 ° c this afternoon, unheard of in this old house with holes ...