Question: problem of oversized granulated boiler?

[dirk pitt]

still a little extra indo: in the technical doc of the pellestar 20kw, it is well indicated: average temperature of the fumes in full load: 120 ° C !!!!!

[Philippe Schutt]

yes, and to all that we must add a quality pellets random.
if you increase the surface of the exchanger, you win in heat exchange, because the gas temperature at the entrance remains the same and they will be colder at the exit. at least initially, because if it causes a bistrage, sticky and not soluble in water, the exchange will be less and less good to return to the initial level or worse.

For these reasons I prefer to stay with devices emitting fumes to 120 °, not even requiring casing of the chimney. A wood stove emits more than 400 °, displays about 80% yield and it does not worry anyone ...

[dirk pitt]

did67 made a comment that just tilt looking at your photos. maybe your problem of bistre comes simply from a non-compliant connection of the chimney. from the photos, it seems that it goes vertically directly from the extractor. if the entire chimney is vertically above the extractor, THIS IS NOT IN ACCORDANCE with the HERZ prescription. indeed, there will necessarily be condensation that will go down in the extractor.
the herz installer recommends a connection to 45 ° with the chimney or at worst 10 ° and that in no case condensation may return to the extractor. they even advocate that the connecting tube (between boiler and chimney) is insulated with minimum insulation thickness 30mm to be sure it does not condense in this area.
I'm enclosing a diagram from another constructor to illustrate. (this one only recommends 3% of slope)
we can see the cone of recovery of condensates

[Did67]

All this is a subtle compromise between these parameters (not to mention the side effects such as bistrage and others that make it that there are certain limits that prevent the best performance). The manufacturer has theoretically calculated and measured all that for to have the best compromise.

Ditto at home. There are 4 tubings that are condemned.

However, my installer told me that he would turn an Okofen into another customer.

I suppose that by closing the pipes (after having removed the springs) and especially by initializing the software (injecting the factory parameters of a 15 kW), we can transform a 20 kW into 15 kW or 10 ... seems that with regard to the "hardware" (burner, air blower, fireplace ...) everything else is the same. I did not explore the question with the installer, hoping not to be concerned!

[blogophil]

White cabbage

The technician made me change settings, but nothing that tempered the heat of the boiler. He just changed the way the boiler was used. I was using a mode where the T ° of the boiler was fixed (70 °). Now this setpoint changes according to the T ° of the external probe and the heating curve parameterized.

As a result, the boiler only starts when the boiler water temperature drops below 45 ° and turns until it reaches 75 °. But it still does not run more than 12 min (4min approximately in combustion start + 4min up in T ° at 50% + 4min in regulation at 30%).

But nothing at the level of the extractor and its operation which is "normal".

I started to question him about the power of the boiler and the impact of the extractor modification, I tried to tell him that it does not regulate as before, I try to advance qque figures and there he tells me nothing has changed. I tell him about the 170 ° T ° fumes and the poor performance that means + the doubling at the bottom word of the number of start, there it starts a little to retreat. The discussion ends up I note it in the file and I talk about it to my technical manager and then we will see that at the next interview.

I asked him about the extractor, he confirms me that it is the one that is now provided with this boiler in France only because one has bad pellet full of dust (I want to believe it seen the m. ... that I was sold two years ago).

So I'll have to go to the next step, write a fax to put it all in writing.

On what point do you advise me to insist on this fax? I will submit the draft for you to give me your opinion. the goal is to do something that forces them to move and especially to show that I'm not going to settle for one I note it ...

@dirk pitt

Here is the photo of the chimney duct. I think it's standard, right?

[dirk pitt]

Yeah, at the time for me, we did not see the horizontal piece on the other photos but it's OK like that with a bonus draw regulator.
me in your place, I will insist on the smoke temperature that does not comply with the doc because on the operating times, although we all agree that it's not normal, it's a little subjective and anyway, there is no standard value in boiler specifications.
it should also be seen if there are boiler specifications on the flue gas flow and the fire temperature.
it's only with numbers and documents that you'll be able to hear reason (maybe)
it is necessary to plead the substantial modification of the product sold.

[Philippe Schutt]

there is that the mini power is by far no longer the one that has been sold to you. That you would not have bought the boiler with the current characteristics, because it no longer meets your needs.
I suggest that you join a consumer association, or a legal aid that will save you money if things get worse.

[jean63]

What a superb installation! of course, insulation on the pipes would be less beautiful but more logical ...

For French pellets, I do not believe it! Christophe has told us that pellets meet a standard and that it is not crap.

Would not the operating life of your boiler be related to the quantity of these pellets?

I asked him about the extractor, he confirms me that it is the one who is now supplied with this boiler in France only because we have bad pellet full of dust (I want to believe it considering the m .... that was sold to me two years ago).

[Philippe Schutt]

Alas, I confirm that there is a lot of poor quality manufacturing here. It is very important to take pellets that meet a standard and print them on the bags, or to buy small quantities first for testing.
some devices are very sensitive to what is put in it, I happened to see a feed screw blocked by pellet dust.
In addition, it is often necessary to change the settings when changing the manufacturer, even remaining in the norm. so think if the granule does not respect any!

[dirk pitt]

I think I remember that our unfortunate friends are from the Lyons region. I use since 2 years at natural energy and I have no worries.
another little trick to not have too much sawdust going to the boiler:
1 - the damping mat hung in the storage room: essential to prevent the granules from exploding when filling by the blower truck.
2- do not make sloped tremie floor in the storage room. as I said in my article published by Christophe, it is useless, it's complicated to do because it must be beefy and as a bonus, all fine sawdust is found in the worm.
whereas if you have a simple flat floor, the finer sawdust interferes between the granules when the whole volume of pellets moves and it goes down on the floor but not all in the screw.