Loss and power pellet boiler

[dirk pitt]

in my opinion, the suction model boiler with its 50KG tank is as expensive as the boiler without the tank but with the bent worm. so I don't really see where the economy is.
for the silo itself, once again, since it is for a new construction, the price of the hard silo must be painless in the price of the general masonry since it is two small 10cm rubble walls in addition to the mason.
then, nothing could be easier than making the wooden floor yourself in the silo.
inquire in detail about the boiler prices in both cases. and what is EXACTLY in both.

[bnohit]

Ouhaou, there's some DIY around! Bravo Christophe !
Indeed, for the silo to do either, I think I can get out of it all in all, and at a lower cost ... cool. The advantage of the suction provided in my boiler compared to the screw, is that I will not find myself blocked if one day I decide to change my silo of place (while remaining less than 20m from the boiler of course ).

Otherwise, to conclude, no one answered my initial question precisely:
To properly size the power of a pellet boiler, the losses of the house (calculated at a fairly low outside temperature), should they be approximately equal to the power of the boiler?

FYI, I made the estimate on the okofen site, which gives me a value between 12KW and 13KW of power required ... unless otherwise stated, it seems to me to stick fairly well with my PE15. Small additional power reserve of course, but as a buffer tank (100L) is provided in the installation, this should smooth "a little", the many starting cycles, linked to the slight surplus of power.

[tomgey]

STOOOOOOP !!! A buffer tank ?? From 100L ????
Two things :
- I take up a recurring remark from several active members of this forum : an automated pellet boiler of the Pelletronic category from Okofen (but this also applies to other brands) well sized does not need a buffer tank because it modulates its power itself according to needs. This applies to a house in which all the rooms are occupied all year round (or more or less). We can consider a LV if for example half of the heated surface is occupied only occasionally in order to absorb the excess power during periods of non-occupation of a boiler that has been sized to heat everything and not to have too short cycles.
- a BT of 100L seems ridiculously small to me. You are not going to store a lot of calories. To put in connection with the internal balloon of the boiler which makes 66L ...

Give us details on your future home: location (region, altitude ...), orientation of the glass surfaces (bay windows to the South?), Other external contributions such as a stove?, Construction materials, materials and thickness of the insulation, type of heating circuit (under the floor, walls, radiators, some of the 3?) ... etc
With that we can refine things. But I have the feeling that a 12kW could probably be suitable ...

[bnohit]

It is true, I have indeed read a bit of everything (especially on this forum) on buffer tanks with pellet boilers capable of modulating relatively well. Some find it comfortable (for the settings), others useless ... not easy to see very clearly.

For construction details:

Region: Ile de France
Altitude: 130m
Exposure: South / North (50% of openings in the south, and 50% in the north)
Ceiling height: 2,60m (floor and ground floor)
Hab surface: 187m2
Construction form: rather in length (ratio L x W = 2/3 x 1/3)
Joint ownership: Detached house, no party wall
Levels: Full basement + Ground floor + converted attic
Masonry: 20cm hollow bricks
Insulation: mineral wool (320mm in the attic, 100mm on the walls)
Joinery: Aluminum with thermal break, double glazing with low emission argon gas
Heating: underfloor throughout the ground floor (anhydrite screed), low temp radiators. upstairs
DHW: 300L storage tank connected to the boiler
Comp. Heating : A wood stove is provided in the living room on the ground floor
Others: Large opening on entry, and staircase communicating with the basement arriving directly in the entry (at the bottom of the staircase, a door giving into a laundry room is planned, heated to minimum (17 ° C approx.), To create a buffer zone with the garage)

That's it, that's about it ... so it's serious doctor? lol

[Christophe]

Uh maybe he meant 1000 L? 100L is a mixing bottle ... not a buffer tank.

But good with pellets a buffer is not compulsory unlike logs ...

I don't know if Dirk Pitt or Did67 have any!

[tomgey]

1) For the BT Maybe a 0 less, actually!
I'm sure Didn't have one. For Dirk I don't know. I don't have one.
The BT is essential for more rustic boilers (I am not saying lower quality) that are not modulating. Schematically: the temperature of the LV drops below the minimum temp, the boiler starts up and heats up thoroughly until the BT reaches its maximum temp then switches off. It will only restart when the BT reaches its minimum temperature again, sometimes several hours later, which avoids repeated starts.
Putting a BT behind an Okofen is a bit of a double financial penalty: you pay the BT in addition and in addition you do not use one of the main interests of this type of boiler which is power modulation and which is responsible for part of the higher price of these boilers.
If you absolutely want a BT, a completely legitimate choice, it may be better to orient yourself towards a log boiler. It seems to me that there are also some good non-modulating pellet boilers, therefore cheaper. In the end, however, it comes down to more or less the same since you are adding the BT ... I hope you followed me!

2) I am far from being an insulation specialist, but 100mm on the walls seems to me little compared to what I have already read on this forum. Perhaps people more competent than me in the matter can answer you.

3) Regarding the power, Did heats in Alsace a well designed house of 250m², around 20 years old with a PE15 which he would like to restrain to 12. Roy heats 500m² in Switzerland with a Fröling of 22kW (house apparently super well insulated that I would like to see one day!). As for me, I heat an old brick house of 300m² in the North with an average height under ceilings of 3,3m (1000m3 of volume) and very average insulation with a PES32 which I will undoubtedly bridle to 25kW.

With that I tell myself that if your house is built respecting all that is done well these days in terms of insulation you could probably heat yourself comfortably with an 8kW, 12kW max.
cordially

[dirk pitt]

I don't have a BT.
the BT can be a palliative to a chuadiere oversizing but it is a pity. it is better to correctly size the boiler.

for the calculation, the losses are in W / m3 ° C
So that means that depending on the indoor / outdoor Delta T that you accept, the maximum power in W can vary quite a bit.
for identical losses, if you accept 20 ° in / out difference instead of 25 °, it can make the difference.
However, as we generally take the lowest possible ext temperature for 20 ° int, the power is generally a bit oversized. I therefore advise not to choose a boiler even more power than the maximum power calculated by the balance sheet especially if you have a backup heater for very cold days.

[roy1361]

Roy heats 500m² in Switzerland with a Fröling of 22kW (apparently super well insulated house that I would like to see one day!) ...

Hello,

It's just for the house, but for the boiler it's only 20 kW.

And when it comes to seeing the house, my door is open to all the curious. Just come with a good mood and voila ...

As for the buffer tank for normal use, I plus what is said above. If engineers in design offices design machines that modulate their power, it is still a shame to install a LV because a heating engineer is not perfected with this system ...

Good sunny Sunday.

[Christophe]

So here is 100L, would it not rather be the famous mixing circuit balancing bottle?

Anyway the DHW tank is a kind of buffer in any case!

[tomgey]

Question of boeotian: what is the interest of a mixing bottle compared to a 3-way valve? Or vice versa, I have nothing against it!
Regards