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Heating Greenhouse's


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#1 Elektroski Justovski

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Posted 16 August 2011 - 11:09 PM

Heating Greenhouse's



In heated greenhouses, we can keep breeding all year round. However, if we decide to heating, we need to calculate the strength of our heating system, taking into account heat loss and temperature as is to be maintained within the maximum drop in temperature during the winter. Depending on the design and materials used, these losses will vary. You should carefully calculate the wall surfaces of the material and then summed up taking into account the permeability coefficients. For example, a temperature of -20 degrees outside, and in the middle of the 15 difference is 35 degrees.

Example
To calculate the heat demand of greenhouses will serve an example: the surface of 20m2, brick plinth of bricks with a height of 0.6 m and a thickness of 25cm, an area of ??10.8 m2, while the rest of the structure is built of glass on a wooden frame, the total area of walls and roof glass is 48m2. Transfer coefficient ordinary glass is 5.2 and 2.0 for the wall of bricks with a thickness of 25cm. In conclusion, the permeability of base - 10.8 x 2 = 21.60, permeability of the walls and roof - 48 x 5.2 = 249.60 to a total sum of the transfer multiplied by the temperature differences: 271.20 x 35 gives us the power of 9492 W, which is needed to maintain the difference over the lowest temperatures.

For more accurate calculations should also take into account the door, skeletal structures, such as timber transfer coefficient is 2.2 for a thickness of 250mm. Heat loss also occurs through the substrate, one can assume that the lowest temperature in the greenhouse soil is 7 degrees and the transfer coefficient for the soil is 1.7 degree which gives us a sample project in addition to 20 x 1.7 x 7 = 238 W. The total the small rounded need heating power 10 KW. An additional factor in the ventilation heat loss is to be included, depending on the type of heating. Heating may be inching from an existing heating system in your home or use a separate installation, which will be allocated only to the greenhouse. Using a boiler in which combustion occurs should also take into account the combustion. In the case of an electric boiler is not needed.

Type of Heating

Water Heating. Hot water passes through the heating pipes or radiators, thus heating the air gives off heat. The energy brought into the greenhouse must be constantly replenished. Water is heated by the boiler for solid fuel, oil or electricity. Heating is easy to use and can be completely automated by connecting the temperature sensors.

Heating air. This method consists of introducing a greenhouse heated air tight. The advantage of this solution is good air circulation, heating rate and the fact that they do not need additional heating elements inside the greenhouse. Disadvantages of a quick losing temperatures while blowing does not work, and air drying. Hot air heating is inefficient because they are used in small greenhouses.

Heating shock. Heating by electric convector heaters or oil is expensive to operate but does not entail additional investment and, for the heaters in the summer may be coming from the greenhouse. Using heating cables is difficult to heat the entire greenhouse, rather they are used to heat the soil in the beds of small and greenhouses.

Gas heating. Gas heating appliances are not suitable for the greenhouse. They may apply only in plastic tents and greenhouses for reheating for a stronger rescue periodic frosts or plants against frost in spring and autumn. Another restriction is that you should not use gas heating in rooms below ground level because of the risk of explosion.

Heating furnace. Hardly a convenient solution for this reason that requires constant supervision and policing of fire sometimes at night when frosts are greatest.

Heating Duct. Such heating only pays to build a small greenhouse, because of the low cost of construction and low operating costs. Unfortunately, it requires constant heating time-consuming supervision. The furnace can be powered by waste from the garden.

Happy Growing!



#2 Earthman

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Posted 17 August 2011 - 10:35 AM

yo elektro nice work. which is the method you prefer?.

just a couple of things to add. as you mentioned about the floor of the green house, you can loose up to 25% of the heat through the floor, so if anyone is going to build a green house and are building a concrete base for it, then it would be a good idea to use some foam insulation borads, plus the concrete stores heat very well. to make this better you could use an underfloor heating system that would connect to your boiler with a seperat zone control system. efficient if used with combi-boiler

considering that Glass makes up the majority of the structure then it would be wise to buy the little bit more exspensive glass as the U-values (thermal transmittance) are lower and cause less heat transfer, there are also a few other factors such as R-values (thermal ressistance), K- values (thermal conductivity), emmissity and absorbtion, matirial/surface/airspace ressistance. there are many more that can be equated amongst these but i think you get the just of it

the best green house heating system that i have ever use was a old Victorian paraffin heater. for being over a hundred years old it totally blew me away as it had a sort of heat sensor built into it, it was controlled by how much of the wick was showing, and there was a seperate peice that sat outside the green house conected by an old cord hose. not really sure how it worked i only had it for few months and then had to give it back to my father, but by far it was the best i ever used.

anyways if you want any help on this just give me a shout man

all the best
peace

Go placidly amid the noise and haste, and remember what peace there may be in silence.

Earthman

#3 domnic0723

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Posted 26 July 2012 - 01:26 AM

what abou LED Grow Light?

best wishes

#4 Elektroski Justovski

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Posted 26 July 2012 - 09:06 AM

Is up to you i think. U can see many use leds now so maybe it's the way too.

#5 beronha

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Posted 10 October 2012 - 01:57 PM

Nice work ;)
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#6 BC farmer

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Posted 18 October 2012 - 05:25 AM

Great info, thanks for sharing.




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