Loss and power pellet boiler

[bnohit]

Hello everybody

I'm new to this forum, and I will need your advice to best size my heating power.

I want to build a new house, and am interested in installing central heating (PC + DHW + radiators), with an Okofen Pellematic pellet boiler.

I think I found my heating engineer, who advised me a PE15 (5-15KW). The latter established a thermal balance of my house, which indicates losses of about 17KW. I specify that this project is a house of 187m2 habitable, with total s / s + ground floor + attic.

I read the many posts (extremely interesting), on the settings and powers of pellet boilers (which should be avoided to oversize as much as possible!) And I just wanted to know, if for you, I find myself in that case.
Is there a particular formula to apply in relation to the losses, to know the ideal power of the pellet boiler?

Thank you in advance for your answers !

PS: Ah, while I'm at it , my heating engineer offers me this boiler with an adjoining silo (so manual filling). I have not found any info on how to fill a Pellematic manually?!? Can the top cover open?

[dirk pitt]

if your calculated losses give a maximum power of 17kw, putting a PS15 boiler is a good choice.
indeed, the maximum power is calculated for the lowest known reference temperature (which occurs only very rarely)
at worst, if that day is a bit tight, we can endure 18 ° instead of 20 ° or put a supplement.
often, rapid heat balances do not take into account external inputs such as computers, stove, oven, etc., etc.
to do well, it would be necessary to know the values ​​which it took to make its calculation and to make a small check.

manual filling is not really planned but if the silo is attached, there is a worm which pulls in the silo.
see the okofen site where there are small drawings of the different config.

[bnohit]

Great, thanks for your response dirk pitt

For the lowest reference temperature, I believe it took -7 ° C in its balance sheet. For the addition, we have planned thereafter, to install a wood stove which would come, punctually, to create a small warm atmosphere on winter days; and this info, we communicated to him, so I think he took it into account.

But to come back to the rule to apply, if I understand correctly, the losses of the house must be approximately equal to the power of the boiler, is that right? I do not realize but 17KW in losses for a new house (at the latest current standards) it does not look a little "sieve" house anyway?

For the adjoining silo, he did not tell me about a "hard" silo He told me that the PE15 contained (by default) a small integrated tank of 50Kg (he told us about 100Kg on the Pellematic maxi versions). Suddenly, we agreed with him that this system will force us to restock every 2 days approximately ... But given our budget, we are ready for this sacrifice at first, while waiting for a silo worthy of what last name.
Does this reserve of 50Kg mean anything to you? I imagine it speaks maybe of the buffer zone or are the pellets stored in the boiler? But if so, is there easy access to this reserve?

[tomgey]

Hello,
This reserve corresponds to the intermediate hopper of the PES, that is to say of the Okofen intended to be fed by a suction system: The granules are taken from a silo of several tonnes (6 at my house) to be "injected" into a Closed air circuit which circulates between the hopper and the silo to fill this famous hopper.
Small drawing on the Okofen site:
http://www.okofen.fr/fr/3/18/28/32.html
As you can see, the silo is not necessarily in the same room as the boiler. Distance can be up to 20m
The hopper is the part of the boiler with a conical cap. It is possible to open it to fill manually if necessary, but it is not intended for at the base.
I am surprised that your heating engineer does not offer you a silo because on the one hand you are going to have the chore of daily or even twice daily filling in very cold weather which is a shame for a boiler which is also fully automatic, it loses a bit of sound interest! On the other hand you will pay much more for your pellets because you will have to buy them in bags: the price per tonne goes from 210-230 € on average to 280-300 €.
For this type of boiler, it is imperative to consider a silo of 4 or 5 tonnes. Being satisfied with the intermediate hopper is like saying that you are going to connect your gas boiler to a butane bottle or feed an oil boiler with a jerry can!
If you are building, you have every interest in planning the silo right away. Two possibilities: the "turnkey" silo, see Okofen site or others, practical but more expensive (I'm not criticizing, I have one!). Otherwise you can reduce the cost to a few hundred dollars by doing it yourself. According to those who have done it, very accessible to the average handyman. Advantages: low cost and better adapted to the shape of the room.
Regarding heat loss, it actually does a lot for a new house. A house like yours well designed and well constructed should not need more than 8 to 12kW of power. So either wrong calculation of the losses, or review the insulation of your future home a little!
cordially

[dirk pitt]

actually the 50kgn tank is ONLY on the suction version.
you could not install afterwards an angled screw for adjoining hard silo but only the suction system which is more expensive.
forget about manual filling.
seen that you build, easy to predict the layout of the silo room next to the boiler.
look at the page OKOFEN
forget the automatic ashtray option, it is useless.

[tomgey]

forget the automatic ashtray option, it is useless.

You are harsh! I have it, it allows to avoid kneeling for the chore of ashes and to avoid the dust, even if I agree that it is not a big chore. It's a bit like going to the end of the automatic concept of the boiler.
We will say not essential but comfortable! A bit like the automatic lighting of headlights and windshield wipers in a car ...
To put in relation with the price of the option, it is true not given.
cordially

[dirk pitt]

..
To put in relation with the price of the option, it is true not given.
cordially

that's what I had in my memory.
all this for 2 or 3 manual empties per heating season, for me, it's not worth it.

[bnohit]

Yes, the heating engineer had counted the silo at the start, but it was we who preferred (to earn 2000 Euro on the invoice) to withdraw this option, in order to stay within our budget for our heating station.
Obviously, this solution would only be temporary. I understand very well the "absurdity" of the thing, by choosing a fully automatic high-end boiler, without taking advantage of the supply system. The comparison of tomgey with an oil-fired boiler supplied by a jerricane is completely similar indeed
Anyway, suddenly we still ask ourselves the question for the silo to do at the same time ... not easy all that.

In any case, thank you, because you have already answered my first question for this famous tank, suddenly integrated in the Pellematic delivered with the suction kit. Only, admitting that a boiler operates without its conical top hatch, how do we get there? Does the hood above the boiler open, or should we operate with a bare boiler, without its casing?

For losses, I do not understand so much either? However, we have fairly good materials, and insulation not too weak in principle (320mm of wool in the roof, 100mm in the walls, 20cm brick house, aluminum windows + argon + FE etc ...) In short, something pretty standard certainly for a house today, but not too much really below what makes it
I may take the time to do it myself, just to see if I fall more or less on these values.

For the ash pan option, I admit that I also asked myself the question (I put it, does not?) ... Do you have an idea of ​​the price? Is it the tank located on the front of the Pellematic, with the metal handle on the top?

[tomgey]

Have you been doing a simulation on the Okofen site? It can give a good approximation.

Regarding the hopper, the conical cap is removed and gives access to the top of the tank, the cover of which is easy to dismantle. I already did it to pour a few bags of pellets into it while waiting for a delivery of pellets that I ordered a little late.

Again, if the reason for putting the silo on hold is financial, think of self-construction (around 600-700 €), even if you are not a handyman.
cordially

[Christophe]

Again, if the reason for putting the silo on hold is financial, think of self-construction (around 600-700 €), even if you are not a handyman.
cordially

To help you, here is a little photo report of self-construction of a pellet / wood pellet silo.

The beginning of the file begins here: https://www.econologie.com/pourquoi-choi ... -3606.html

You can even imagine doing like us: tinkering with a silo based on old pallets (euro more resistant than the fakes): https://www.econologie.com/forums/bricoler-u ... t7945.html





We didn't build it for pellets (we have briquettes see photo) but we have pellets inside (delivered in a bag). In the case of delivery by blower truck, a dust cover must be provided (recommended that it be removable).

The waterproofing is done by flexible reconstituted wooden plates of 3 mm which are fixed on the inside of the pallets.

What is good with pallets are the constant dimensions: 120 * 80 cm.

Since then I have enlarged it so that it has a storage volume of 3 big bags of briquettes (1 more than in the photo) = sufficient for a heating season.

Price of this silo: a few dozen screws, 9 recovery pallets (2 more than on the photo config), otherwise it's 10 to 15 € per pallet, a few hours (1 dozen), a few m² of plates 3mm (within 20 €) ... short within 100-120 € if we had paid for the pallets ....within 30 € if not for about 3.5m3 ... who says better?

In my case I do not have the hopper in the bottom, but it would not increase the price so much! It would suffice to put the floor a little tilted.

Do not hesitate to make a new subject to have other ideas of self-construction of a pellet silo! There are several members of forums who have already done so!