Dry firewood in the greenhouse in winter.

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Rabbit
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Dry firewood in the greenhouse in winter.




by Rabbit » 08/10/12, 18:07

Having evacuated my grilled tomatoes by freezing last night, I
would like to dry my firewood in the greenhouse.
So this morning I covered the floor with plastic sheets all over
the surface to block soil moisture.
Then with a thermometer / Hygrometer I took at regular intervals
the two measurements and have them through the calculator. http://www.cactus2000.de/fr/unit/pophum.shtml

What surprises me is that the amount of water in the air remains constant:
between 5 and 6 gr per m³.
Is this normal? I expected the water to condense (what it does)
on the plastic of the greenhouse and evacuated by the periphery of the greenhouse.
The amount of water in the air should therefore have decreased. Why does she do it
not.
To complete the data, I have cord + -2 m³ of wood (spruce) almost green, well ventilated.
8)
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by chatelot16 » 08/10/12, 19:07

the amount of water in the air is low: the slightest small draft in a greenhouse that is not waterproof like a submarine provides air that contains the same humidity as the outside

with a large pile of damp wood in the greenhouse it will be different the water from the pile of wood will raise the humidity in the greenhouse not sufficiently ventilated: it is therefore necessary to open the greenhouse to the maximum, only use it as a shelter

it will be better than a shelter with an opaque roof: the sun can heat a little
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Re: Dry firewood in the greenhouse in winter.




by dedeleco » 08/10/12, 19:24

Rabbit wrote:Having evacuated my grilled tomatoes by freezing last night, I
would like to dry my firewood in the greenhouse.
So this morning I covered the floor with plastic sheets all over
the surface to block soil moisture.
Then with a thermometer / Hygrometer I took at regular intervals
the two measurements and have them through the calculator. http://www.cactus2000.de/fr/unit/pophum.shtml

What surprises me is that the amount of water in the air remains constant:
between 5 and 6 gr per m³.
Is this normal? I expected the water to condense (what it does)
on the plastic of the greenhouse and evacuated by the periphery of the greenhouse.
The amount of water in the air should therefore have decreased. Why does she do it
not.
To complete the data, I have cord + -2 m³ of wood (spruce) almost green, well ventilated.
8)


The answer by cactus is simple:
there is a place in the greenhouse, where the tomatoes have frozen, which stays very cold, earth from the ground around the periphery, with the night's T approximately, 1 to 5 ° C, which condenses all the air, which elsewhere stays at this% of water, even if much hotter, against the walls in the daylight.

The greenhouse is probably not airtight, and the outside air brings its humidity.
If there is wood to dry it provides moisture by drying if it is warmer under the sun.
The warmer earth in the center gives off moisture easily, and plastics on the ground are not waterproof enough to block, in general.

To have a complete gas tightness, great care is required, with watertight welds.

To dry the wood, it must be well heated in the sun, with a good draft, to condense the evaporated water on the very cold points.
It is necessary to avoid, at night having the wood too cold by infrared radiation towards the sky, on which the humidity comes to condense, which destroys the drying of the day with beautiful sun !!
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by Rabbit » 08/10/12, 20:29

If I understand correctly, will it be necessary to open during the day?

I believe I will offer a wood moisture tester.
This will allow me to better follow the drying of the wood.
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by chatelot16 » 08/10/12, 20:44

open when the outside air contains the least amount of water! and it is when it is coldest that the outside air contains the least water: therefore open at night so that the humidity leaves the hot wood to condense or it is cold

and close the day to accumulate the heat of the sun

Finally I am not sure that it is useful to close the day: do not break your head and leave it open day and night
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by Ahmed » 08/10/12, 21:09

From a general point of view, drying is a function of temperature and ventilation.

In the case of a greenhouse, a real dryer, the optimum obviously corresponds to the hot season, however it is possible to alternate vegetable production and wood drying in the off season.
The principle to be respected is simple: in the greenhouse it is the temperature factor which is the most active, it must nevertheless be combined with aeration.
I explain: in autumn-winter, alternate, roughly humid / cool and cold / sunny periods.
Each time the sun is present, the temperature rises and water from the wood is released into the air of the greenhouse; it is easy to provide an outlet in the upper part through which the moist air will escape by convection; in the lower part, it will, of course, correspond to an inlet of cooler and drier air, so as to complete the circuit.
The dimensions of the orifices are a compromise to be found between the rise in temperature and the evacuation of moisture: it is therefore necessary that said orifices are quite reduced.

Wood moisture testers are expensive and unreliable for firewood; rather choose a few logs that you will weigh at various intervals: this will give you a good idea of ​​the drying process.
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by dedeleco » 08/10/12, 21:32

Above all, the wood is hotter than the humid air which often reaches 100% humidity in winter, from outside or from the greenhouse floor, so that this air thus heated is then found at much less than 100% moisture on the wood and dry it quickly.
The test can be done with a cloth or towel to dry, without expensive device, quickly dries in the sun at 40 ° C in summer and a little wind (one to two hours if not too thick less than 0,3 cm and a little wrung out !!).
So, without a device, in less than an hour, quickly, we know if the conditions dry the fine fabric or wet it, as happens at night, even in summer !!

At cold night, protect the wood from condensation on the wood or the tarpaulin against, often below the tarpaulin that rewets the wood !!

The choice of outside air depends on whether this air is humid (hot rain, then to be avoided) or dry, then open during the day with good ventilation.
The orifices are to be adjusted according to this.

The ideal is to keep the wood warmer, at least a little more than the coldest points of the greenhouse, this at night (very difficult) and during the day, with sufficient air circulation, but weak enough to not do not cool the wood too much.
The circulation can be from the outside, or internal, but with the air coming from the cold zone, after condensation, to heat and pass over the wood, then become dry air, to dry and come back to cool the water evaporated.
With the outside open we do the same to dry.

So having a thermal heat stock, kept overnight for the night is useful to keep the wood a little warmer (water tank or block of earth, heated during the day more than at night, like a Canadian well).

With a Canadian well of the type www.dlsc.ca on a greenhouse, even a much smaller one, we can prevent the greenhouse from freezing easily, by bringing in the heat of the deep earth, increased by the summer heat that has been stored there.
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by Ahmed » 08/10/12, 21:49

When the conditions are favorable, the wood will dry and otherwise nothing will move: it is not necessary in practice to worry about closing and opening the vents.
The humidity brought in by the soil only comes into play at the start, with the remains of the previous watering ...
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by dedeleco » 08/10/12, 21:58

otherwise nothing will move


if it takes up water in equilibrium with the ambient humidity and the temperature !!!

So be wary of this inaccurate idea, which prevents having very dry wood, as just, when it was dried in summer at 40 ° C, if kept in normal conditions, identical to pellets which with time take the ambient humidity !!!
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by Ahmed » 08/10/12, 22:06

Of course, the wood being hygroscopic tends to balance with the variations of the ambient environment, this is why there cannot exist anhydrous wood spontaneously.
However, from a practical point of view and in the present case, this is negligible.
In fact, the rise in temperature being also the engine of the air circulation of the greenhouse with the outside, the variations of intra-plastoc humidity in the periods without sun will be weak (once the residual water of the ground evaporated).
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