Wood boiler for greenhouse

[antoine35]

hello everyone, I'm new to the forum.... excuse me in advance for any errors.


I have to assemble a wood boiler for a friend horticulturalist who wants to heat via the ground a greenhouse. I do not have all the data surface, boiler power etc .....

I would have liked to have your first advice. I think that a buffer tank will be ideal (if so how to calculate its volume?) having another network on the ground that can absorb a possible surplus of calories should we still have a thermal valve or simply send in this network will be enough in terms of security?

and of course if you have other advice or link on this kind of installation I thank you in advance.

A+

[Christophe]

Uh I will surely say a stupidity but pkoi go through a boiler and not a wood stove much simpler to implement in the case of a greenhouse?

For the calculation of the buffer tank you can read this where there is a detailed method: https://www.econologie.com/forums/bois-energ ... t4267.html

The thermal valve is, it seems to me, obligatory with the wood boilers question of insurance (to verify) ... even if it will never be used ...

[the middle]

The thermal valve is, it seems to me, obligatory with the wood boilers question of insurance (to verify) ... even if it will never be used ...

Hello,
A friend has just installed a wood boiler; his valve has already spat several times for various reasons.(one of them is a badly adapted or badly mounted anti return device).
So very useful!

[Did67]

1) I think we are talking about a professional horticulturist? So "medium power" boiler ???

2) The first thing: I would rather think of chips than logs, for reasons of automation ... weekends, etc ... No room for error ...

3) Yes, a tampon seems essential to me; to determine its volume, you have to do the calculation "backwards": what power is needed; hence the boiler model, hence its focus, hence the amount of energy released by an outbreak, hence the volume of the buffer ...

4) You have the chance to operate at low temperature, therefore regulation to be tweaked, because according to the cultivated plants, a lowering at night will be favorable ...

5) Honestly, given the stake represented by the cost of energy in horticultural production, I would not "tinker". It takes a serious study by a specialized company ...

Finally, if the objective is not to go bankrupt if possible and to make a living from the activity - see my point 1

6) The valve: yes, sure. But in the case, it is not even worth digging ... If we are within a valve!

[dedeleco]

The ultimate economic and ecological solution to recover the heat of summer in winter (on inexpensive simple thermal solar panels and the one used to cool greenhouses in summer) stored in the ground in depth (more than 2m) for the winter.
For large greenhouses, after the initial investment, the economy can be very significant, since we find a good part of the heat of the summer.
Even to store on several days is interesting, because the earth only costs the holes, no expensive tank and 50cm for a week of days without sun on tens of tons of earth
It is much easier for a greenhouse than to heat a house, because greenhouses are content with 10 ° C instead of 20 ° C.
Simply raise the temperature of the earth in the greenhouse or next to a few degrees (from 12 ° C to 14 ° C on an annual average with nothing much more like 20 ° C) which is found in winter from several meters depth over months is easy without too many means and very effective for a greenhouse, much easier than for a house that requires at least 25 to 30 ° C before exchanger.
See how heating works:
http://www.dlsc.ca/borehole.htm
Holes more than 2m deep are enough for example 6m.
and the various discussions on econology like
https://www.econologie.com/forums/post185929.html#185929
https://www.econologie.com/forums/post183703.html#183703
https://www.econologie.com/forums/post183841.html#183841

The possibility of greatly reducing the heating is totally missed and neglected due to a lack of understanding of the diffusion of heat because diffusion means depth of penetration in depth like the square root of time, so 144 = 12x12 days (almost 5 months and 3 meters of penetration ) penetrate only 12 times the distance of a day (3m / 12) and therefore lthe heat stored on large volumes of dimensions clearly more than 3m is found, distributed and decreased in proportion, on a volume increased by 3m maximum in the periphery at the end of winter!!!
The earth only costs the price of small holes (if soft topsoil alluvial much easier) at 2m max distance from each other for tubes responsible for heating the earth in summer and recovering this heat in winter.
The summer heat exchangers responsible for cooling the greenhouse in summer from the colder earth are used to heat it in winter, in reverse.
And the heating bill is greatly reduced, much better than with a simple Canadian well, (which often is not heated in summer to a sufficient depth).

[antoine35]

the problem of bankruptcy or other economic concern is not at stake in his case.
by that I mean that it has been operating without heating for years and that it has found a wood boiler at a very good price so it wants to take advantage of it to improve its production.
it is true that we are not a valve away, it was to have your opinion on the obligation or the superflux.

otherwise the calculation of the buffer seems a little complex ....... maybe it applies especially in very precise and well calculated situations so in my case, can I not determine a little ladle since my colleague may tinker it himself following an approximation and the tank he will be able to find.

A+

[Christophe]

(one of them is a badly adapted or badly mounted anti return device).

In this case necessarily ...

So very useful!

Yes very useful in case of problem ... but in "normal" use (99.9% of the time) it does not have to "spit" ...

But yes you have to mount one, otherwise there are material risks, even human ...

[dedeleco]

otherwise the calculation of the buffer seems a little complex ....... maybe it applies especially in very precise and well calculated situations so in my case, can I not determine a little ladle since my colleague may tinker it himself following an approximation and the tank he will be able to find.

Simple calculation from Christophe is for an extra dry volume of wood that fills his boiler 50 liters for water between 30 to 40 ° C and max 80 to 90 ° C in the buffer which must be 2,2m3) for a house !!

If you only put 5 liters of wood (a good log) you need 10 times less 200 liters !!!
The buffer is not essential in a house (except domestic hot water), which with its very hot radiators at 90 ° C and its concrete makes buffer !!

On the contrary, a greenhouse cannot tolerate water at 90 ° C and therefore the buffer is much more essential so that the water circulating in the soil does not burn the roots.
The boiler works well with water at least 40 ° C and therefore a buffer is crucial with valve ensuring the mixing of hot water with cold water which must be well ensured to limit the temperature of the circulating water in the soil around 20 ° C.

The buffers are fixed by the necessary power (surface of the greenhouse, its insulation, the desired temperature compared to that outside) and the rate of refill of the wooden boiler which fixes the quantity of wood necessary for each refill (a log or a big number).
A minimum of practical information is necessary to fix the orders of magnitude.

Concretely, the valve is essential to avoid the explosion of the vaporized water in the boiler if overheated (breakdown of the circulator, etc. and fatal danger, see past stories of steam locomotives which exploded with dead people !!!)

Finally if the greenhouses already work well without heating, a simple solar thermal heating with buffer could be enough to increase the temperature of the little bit necessary with the advantage of not taking care of the wood to be recharged?

[antoine35]

I specify that the plants are above ground therefore less sensitive to possible high water temperatures.

I will try to have more information so as not to discuss too much in a vacuum.

thank you for your comments anyway ....

A+

[dedeleco]

the plants are above ground

These are often large areas, hundreds or thousands of m2 ????
What region ?
What season, desired temperatures.
Area,
Solar would make big savings in heating especially by storing summer heat for winter, easier especially since the associated surfaces and volumes are large !!!
1000m3 of earth (25 holes at 10m depth spaced 2m on 100m2 are effective for storage from summer to winter.
The somewhat isolated greenhouses are good solar collectors and maybe it is enough to keep the solar heat for a few days for the days with clouds ???
So very easy underground at shallow depth.