The efficiency of a valid wood stove at full power

[chatelot16]

I find that reducing the size of the hearth is not very useful: it is especially necessary to reduce the size of the fire ... so split the wood finer, and cut it shorter ... alas it does work, but to do savings you have to pay the price

you also have to choose the wood according to the season: burn the big logs when it is very cold and you need a big fire ... burn the small branches cut into small pieces when you need a little fire

the problem is that the small wood must be reloaded often otherwise it goes out, I do not like steel fireplaces which cool the embers too much: it goes out completely: I prefer that the bottom of the firebox is entirely in brick: when all the wood has finished burning there remains red embers for quite a long time: as soon as we put the wood back in, it lights up again by itself

[Obamot]

Yes indeed, the output surely depends on all the parameters mentioned so far (oxygenation of the fireplace according to its size, good dimensioning of the chimney relative to the stove and also the efficiency of the flue gas outlet valve to avoid backflow in high winds. . and of course the temperature of the focus required for the stick to work on the hair), with all these parameters, adjusting the draft with the solution - it is true clever - of an electric motor / fan seems to me tangent (and even more for béotien) I would therefore see a solutio that works "without", I explain myself by raising a few questions: because if we have a power failure with a double flow CMV it's okay, we can wait. There we can no longer heat at all without smoking, which becomes untenable. Let's even admit a chimney fire, the engine burns, what is going on?

In addition and in my humble opinion, the engine poses two other problems. It greatly complicates sweeping and the coil-exchanger, motor or not, will it not tend to accumulate soot in certain places (?), Since it will tend to increase due to the fact that it heats less , if so, which would increase the fire risk by as much. Finally, if the engine evacuates the smoke well, and the heat recovery is done correctly, it will be necessary to add a Canadian well to it, because the evacuated air must be replaced and come from somewhere ... (those who have the air conditioning know what I'm talking about) Otherwise what is recovered is lost by the very cold air which arrives, the pulsed air which leaves before irremediably be replaced (air which in any case, even put at approx. 12 ° C with a Canadian well, should still be brought to temperature ten degrees higher ...)

Whereas when you heat at high enough speed, you have "enough under your feet" to warm up the air coming in from the outside.

With all these drawbacks, and with this element which complicates the system, it becomes complicated to implement, which is not easy without it.

I say that, I say nothing, I may be wrong, but it is already not easy to adjust "without", then "with" it must of course be adjusted by a good heating engineer, I would be incapable to implement it on your own, a configuration changes so much from one house to another (what about fire insurance questions if you do it yourself? And how to solve all these technical problems? Thanks for the answers.)

[Flytox]

In the instructions for the pellet stove I just bought, they advertise the following yields:



There is a permanent ventilation for the evacuation of smoke.

[hic]

In the instructions for the pellet stove I just bought, they advertise the following yields:



There is a permanent ventilation for the evacuation of smoke.

Hi Flytox
The proof that oxygenation is essential for performance

Forced draft solves the problem of poor combustion of natural draft at low speed.

Perhaps it would be necessary to add the "post combustion system" with natural draft
to the system that promotes low-speed combustion?

[Christophe]

Here is an old subject on the normalization of the powers of wood stoves: https://www.econologie.com/forums/rendement- ... t9209.html

It contains interesting information.

For example: a stove of 15kw of normalized power can go up to more than 30kw in peak ...

[chatelot16]

when we look for how performance is measured we come up against 2 problem

1) non-public standards, you would have to pay to have them: this principle is absurd! manufacturers say that their device meets this or that standard, but the customer cannot know what it contains

2) measurement made only once under conditions that the user does not even know how to reproduce: therefore a result which has as much value as the measurement of pollution by Wolkswagen!

the only useful measure is what the user can do himself ... relatively easy with a water boiler: we could install a heat meter on the water circuit and note the amount of wood we burn each days, and calculate with the number of kWh produced each day ... it will not give the yield but simply the consumption in Kg of wood / khw ... a useful figure like the consumption of a car in l / 100km

with a stove it is more complicated because impossible to measure the heat produced with both radiation and convection

we could pack the stove of an insulated box with air blower to cancel the radiation and put all the heat in the air flow, and make a heat meter

we can do a reverse measurement: do not measure the heat given off for the heating but the heat lost by the chimney: it is easier because the flow is lower than the convection air around the stove, and especially because the furnace pipe already exists ... no need to build a gas plant like to make an air flow around the stove

how to measure the smoke flow: a venturi: 2 cones in sheet metal welded together, and a pressure sensor

[hic]

The evaluation of the efficiency of a fireplace is done by smell

when a wood-fired boiler room malfunctions,
she makes tar
it stinks in the boiler room and outside


It stinks of tar !!!!
There is no standard for this!

[Obamot]

Yes, if ... we could normalize it with the feathers: as long as they do not adhere to the tar, it is because it is not hot enough!
Whereas if it stinks, it means that it is too hot: but there you have more skin

[chatelot16]

at the time when each factory had its steam engine, there was the orsat device to measure the composition of the smoke and monitor the operation of the boilers

we measured a volume of smoke by removing water in a glass recipeinet and we measured the reduction in volume with chemical reagents which absorbed CO, oxygen and CO2 separately

now there are electronic devices that do the same thing to measure gas or oil boilers, but I never see it for wood, I am afraid that wood tar is too dangerous to foul the electronic sensors

the sorsat method resists very well to dirty smoked

if there is CO it is because it lacks oxygen: CO is a combustible gas, therefore a loss of energy, and when there is CO there is necessarily other unburnt ... needless to measure the yield must rather increase the air flow to do less worse

when there is no more CO there is oxygen: the oxygen rate makes it possible to claculate the air flow that there is too much, and there is no need to measure the flow smoke to calculate the yield ... a simple temperature measurement is enough ... the oxygen rate allows to calculate the flow and calculate the yield

the problem with the log stove is that it is too variable ... that's why this kind of measure is mainly used for gas or oil heating which works very regularly

[chatelot16]

Yes, if ... we could normalize it with the feathers: as long as they do not adhere to the tar, it is because it is not hot enough!
Whereas if it stinks, it means that it is too hot: but there you have more skin

tar and feathers should be used for constructors who display superior performance to reality ... it's not just WW