Wood burning boiler Deville 35kW, lack of power?

[denis08]

Hello everyone
I need your help, I have a wood heating system.
natural draft 35kw boiler with 1000 l buffer tank
this go up by a pro but big concern
the ball loses 40 degrees in 8 hours after several changes nothing changes
I do not know what to do
if you can help me
please

[dirk pitt]

we want to try to help you but we will have to explain in detail how your installation is done: a schema would be simpler than a great speech. from there, we can say a little more.

[Christophe]

+ 1 with dirk

I assume that the buffer is lost when the boiler is turned off?

40 ° C losses on 8h with 1000L this does not make a large stored energy nor a large heating power.

Thermal balance:

Energy contained in 1000L of water with delta of 40 ° C = 4185 * 1000 * 40 = 167 MJ = 46 kWh = 4.6L of oil equivalent (6 L with a boiler efficiency of 80%)

Over 8 hours, this makes an average "loss" power of: 167 / (8 * 3.6) = 5.8 kW, which is "normal" or even low power to heat a house ... and there it all depends on the type of house, level of 'insulation...

For me this loss seems normal to me: it is a question of heating power required ...

For the calculation of the buffer tank see: https://www.econologie.com/forums/bois-energ ... t4267.html

[Did67]

I join Christophe! This is not surprising at first sight. Of course, to say the least, we would need some guidance on the house (surfaces, insulation) and the climate.

1 000 l, it's not huge for a buffer ... if your house is of average surface (120 to 150 m²), especially if it is of mediocre insulation (not BBC for a penny) ...

Who can heat a house with 5 l of fuel by the weather (weather) that run?

[denis08]

Good evening
to answer you
home 160 m2 full foot lost height insulates 2 200 times
insulated walls 10 + 100 block of 15
slabs films plastic more polystrene of 60 mm under slab windows pvc 4 / 10 / 4
I am in the ardennes
I will post the heating scheme
mreci to you

[Did67]

Yes. Weather Ardennes + 160 sqm foot [which is not the most economical form for heating: a maximum of contact surfaces with the outer for this living area) + good insulation. What you observed, without great calculations, seems normal.

What were you waiting for ??? Did not you do a ladle calculation ???

For greater autonomy in cold weather (so a buffer that empties less quickly and therefore less boiler ignition constraints), it would probably have had to store 2 000 2 500 liters ...

[Christophe]

it might have been necessary to store 2 000 2 500 liters ...

And consume even more wood to heat the balloon ...

Put a ball of 1000L on the circuit can be possible ... not to lower the consumption but to increase the comfort ...

[Did67]

Yes. Of course.

Buffering only "serves" to store calories to reduce the number of recharges (therefore ignition of the boiler and therefore "chores").

When we "calculate" an installation, we proceed by "reverse calculation":

a) assess the maximum need of the house, on 24 h, in very cold weather (according to surfaces, insulation, occupant requirements)

b) option on 1 or 2 filling per 24 h [1 refill doubles the buffer, but limits the "chore"; it is therefore a strategic choice for the occupant - more comfort for more or more on-call for less; the available space can be a crucial criterion]

c) according to the emitters (radiators - types, power - or floors), we have the delta t, and from there, we calculate the volume of the buffer

d) and finally, knowing the volume of water and the delta t, we calculate the volume of the wood to be burned at one time, which determines the volume of the hearth of the boiler

[Note that the power of the boiler is ... anecdotal, but often put forward by installers!]

In the end, whether in 1 or 2 or 5 outbreaks per day, the conso of wood will be the same: it is the compensation for calories lost in the house during this day!

The only thing: if we go into "smoldering" mode, it is a disaster in terms of performance (and pollution), and the consumption ultimately increases.

You need flare-ups, at a good temperature, if possible with a controlled draft [do not flambé too much too strong because the exchangers would not be able to extract the calories from the fumes ... It takes both a fire at high temperature, guaranteeing a good combustion, so a good performance, but not too much, otherwise too many calories go in too hot fumes ... In any case, by decoupling consumption of calories by the house and production of calories by the boiler, the buffer allows to optimize the combustion without influencing the heating]

[denis08]

bonsoir a tous
to answer you I had to fall on a charlot (heating engineer)
wood consumption issue this is not the problem
returned at night to 18h30 it is 16 degrees in the house for over a year it starts to be long
my solution
boiler 45 kw two buffer tank 1000 l
and insulation by the outside by a more insulating wood clasp
otherwise I do not see anything else I do not have fuel or gas
please

[Did67]

Yes, Charlie!

I think it has not been calculated!

If wood is not a problem, and if you have room, indeed, double your buffer. It is easy to do. And we find generic for not very expensive ...

Keep the boiler, you recharge as soon as the 1ère flambé has made a little room ... Or you do two successive outbreaks in the evening, just to stuff the 2 buffers block, and a quick morning, just to put the calories consumed at night ... Forget the power. What matters is the amount of dry wood that you burn without making your life impossible ...

If you put clapboard, take advantage of it to put a real external insulation underneath. The clapboard, in itself, is little. Especially for their conservation, we circulate the air below (it depends on the clapboard).

It is to be seen as a "sealing skin", not as an insulation

[for info, my house is covered with Red Cedar clapboard, with air circulation below]