Pellet stove as sole heating in MOB

Heating, insulation, ventilation, VMC, cooling ... short thermal comfort. Insulation, wood energy, heat pumps but also electricity, gas or oil, VMC ... Help in choosing and implementation, problem solving, optimization, tips and tricks ...
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Did67
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by Did67 » 13/01/13, 18:23

Sorry: MOB = timber frame house

[which have a certain number of advantages - storage of CO², "natural" insulation, absence of thermal bridges, "charm" ... but also, from a thermal point of view, the absence of inertia which can be the cause of "overheating" in summer because they are extremely reactive to small amounts of calories - which is an advantage for heating, but a problem for heatwaves!]
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bidouille23
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by bidouille23 » 13/01/13, 19:46

did I partly agree with you :) , on the inertia of a MOB, you can correct the problem as you said by adding mass, in partitions, slab, staircase etc etc ...

Over dimensioning with 10 kw can be but I repeat it is only an estimate :) .

Regarding the over-dimensioning, actually I skipped the fact that it is a calculation for the coldest moments, or it is already over-dimensioning with 7 Kw in theory ...

By cons what I also said is that with a hydro system, you make a kind of buffer that allows you to minimize the start stops, right?

As for the heater, the best I think is to take the heat after the fireplace, or better still around the fireplace, as in a link given by looping on the stove-solar panel coupling ...
The manufacturer has put a car radiator and a shell around its insert, and blows the heated air through the car radiator, which is connected to a low temperature heating circuit in the floor of the bedrooms upstairs ... And a priori it works very well.

And recover ...

For a mass stove even Kacheloffen, there is either the copper which heats it but the one should especially not put it in the hearth or close so as not to change the combustion it would be a shame.

A yes for summer comfort, depending on the insulation used and the use or no sun protection for glass surfaces, that changes everything.
Glass wool is almost ineffective in summer due to its low density, unlike cotton wool or wood wool it is as effective in summer as in winter ...
A well calculated pergola or cap, hides you from the blazing sun in summer and puts you in full sun in winter ...

So a MOB if it is well made and well thought out has no more defect than another construction or even less;) ....
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by Did67 » 13/01/13, 22:14

bidouille23 wrote:
By cons what I also said is that with a hydro system, you make a kind of buffer that allows you to minimize the start stops, right?



So a MOB if it is well made and well thought out has no more defect than another construction or even less;) ....


1) I was thinking of commercial "hydro" pellet stoves: in this case, the water bag is too small to avoid the yoyo!

It must be seen that if the need for the maiosn is estimated say at 6 KW for very cold spluas, 6 kW cover an internal temp - external temp difference of 30 °.

As we will more often be with + 5 ° outside, the difference will be only 15 °, or a heating requirement of 3 kW ... With a 6 KW stove? that will be fine ...

If we "hit" wide, like 10 kW "to be sure", we will have a stove which will already have to do the "yoyo", despite the buffer which will only lengthen the cycle a little!

At 15 kW, this becomes catastrophic!

Hence my "alert" !.

2) An MOB has many qualities; Except for this small inconvenience, which must be managed. Otherwise, deconifture.

You gave some selections:

- a concrete / wall / staircase part etc in the center
- caps / pergola of course
- shutters on the south and west sides (motorized and programmable if possible - they even close at basement, avoiding overheating!)
- wood wool or cellulose wadding have an interesting effect, it is the thermal phase shift (for the same level of insulation): the heat wave of the afternoon will "come in" as for a LDV having the same R, but it will do it late ... so probably at a time when it will start to cool outside again so we can "get rid" by opening !!! This is very important ... This is called "thermal phase shift".


So yes, they can be "very good". You just have to pay close attention to this "sensitive point", this congenital fragility! But I see that the obsession is insulation compared to heating. Very few thoughts, especially among self-builders, for the heat wave ... And there, there are some damn bad surprises (especially if they confuse insulation, thermal inertia, phase shift and happily mix all that!)
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by moulino51 » 13/01/13, 22:27

Did67 wrote:Sorry: MOB = timber frame house

[which have a certain number of advantages - storage of CO², "natural" insulation, absence of thermal bridges, "charm" ... but also, from a thermal point of view, the absence of inertia which can be the cause of "overheating" in summer because they are extremely reactive to small amounts of calories - which is a benefit for heating, but a problem for heatwaves!]


Thank you Did67 for the definition, I still have gaps.
It would therefore be interesting in this type of house to create, for example, a central wall which would store calories or freshness a bit like the "Trombe" wall, this is ultimately also what the mass of the BT heating floor does by playing on inertia.

GS
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bidouille23
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by bidouille23 » 14/01/13, 12:16

Slut,

did67, thank you for this nice explanation of the phase shift.
Which is directly related to the density :) ... so talking about density is talking about phase shift, but actually you have to know it to understand it, so the explanation was vital to give, as much for me;) ..


I understood your reasoning well and I said it the 10 kw seems to me completely exaggerated, and to know as well as possible which power to choose it is necessary to make a real calculation, taking into account if possible real temperatures, and the real composition of walls and floor with insulation and air control, type of vmc etcetc and make a complete assessment and suddenly a real estimate.

So even 7 kw as you say did67 is an approximation and in no case a value to buy it on a whim ...

That says a stove say 7 kwh, in the end it means nothing :) ...

Compared to a conventional combustion of logs, burning pellet is simpler, due to the fact that the quantities of air are supplied mechanically, and that the quantities are "pre-regulated", so for a pellet stove it does not. It is not a question of talking about a power, but rather a range of power.
A pellet stove of 7 kW can therefore be a stove of 7 kWh maximum or 7 kWh at nominal speed or 7 kWh at minimum speed.
In all logic with a good dimensioning of hearth, on a stove of 4.5 / 7 Kwh, that it is at 4.5 kw until 7 kw the combustion will be good.
A stove does not have a furnace (boiler) which is dimensioned differently, thus imposing a different operation.

Either it must be refined the calculation I repeat again, but imagined to turn to a maximum power of 7kwh seems to completely match our remarks :) .
Either are not all far from reality I think ...
and in any case all agree that 10 or 15 kwh are too important unless you want to be dry human sausages, or foul and pollute a maximum ... In all cases this is not not good :) .
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by Did67 » 14/01/13, 16:06

bidouille23 wrote:
Compared to a conventional combustion of logs, burning pellet is simpler, due to the fact that the quantities of air are supplied mechanically, and that the quantities are "pre-regulated", so for a pellet stove it does not. It is not a question of talking about a power, but rather a range of power.
A pellet stove of 7 kW can therefore be a stove of 7 kWh maximum or 7 kWh at nominal speed or 7 kWh at minimum speed.
In all logic with a good dimensioning of hearth, on a stove of 4.5 / 7 Kwh, that it is at 4.5 kw until 7 kw the combustion will be good.


I confirm and specify:

- for log stoves, the powers are very very indicative; it's a bit folk!
- for pellets, the fuel is standardized and combustion controlled, so the powers are fairly precise!
- normally, the power indicated is the nominal power, which, apart from an abnormal setting, is also the maximum power
- depending on the software, the modulation (flexible power management) can be up to 25 or 30% of this power (to be checked on each notice);
- therefore a 7 kW pellet stove should flexibly supply between 2,5 kW (minimum power) and 7 kW (maximum power), as required ...
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