Heating the greenhouse.

[cefa@]

Hello everyone :)

I am the owner of a 2,5 m x 3 m x 2,5 m (height) greenhouse, covered with PVC panels. I would like to heat it at about 13°C or 15°C during the Winter in order to grow a larger variety of plants, especially highland Nepenthes and Heliamphora, but I fear it would be extremely expensive. I live in Northern Italy and temperatures in Winter can be as low as -5°C... electricity is definitely unaffordable here I think, so I was thinking about using a small pellet stove... do you have idea?

[S Krelbourn]

In the past I heated a similar sized greenhouse to grow cool orchids at about 10 - 12 degrees,using a combination of mainly parrafin with electric to boost in particularly cold weather. Suffice to say I now grow sarracenia which need no winter heat. I think the key to reduce heating is in the basic design of the greenhouse, sinking as much of the body of the greenhouse  beneath ground level in an effort to make the most of the ground heat and using well insulated polycarbonate sheeting as glazing. Good luck with the pellet heater idea, I too would like to know if it is a viable proposition.

regards

 

Phil

[cefa@]

2 hours ago, S Krelbourn said:

In the past I heated a similar sized greenhouse to grow cool orchids at about 10 - 12 degrees,using a combination of mainly parrafin with electric to boost in particularly cold weather. Suffice to say I now grow sarracenia which need no winter heat. I think the key to reduce heating is in the basic design of the greenhouse, sinking as much of the body of the greenhouse  beneath ground level in an effort to make the most of the ground heat and using well insulated polycarbonate sheeting as glazing. Good luck with the pellet heater idea, I too would like to know if it is a viable proposition.

regards

 

Phil

Thanks for your opinion!

[manders]

Most highland nepenthes will be happy with 10C, which will be much cheaper than 13 or 15C to heat to, some highland neps are ok with lower temperatures, especially if daytime temps are higher, but 10C is safer.

can you add extra insulation, maybe multiwall polycarbonate?

at a guess you are looking at somewhere between 10-20 kWh per day, on average, in winter, depending on how good your insulation is.

[cefa@]

13 hours ago, manders said:

Most highland nepenthes will be happy with 10C, which will be much cheaper than 13 or 15C to heat to, some highland neps are ok with lower temperatures, especially if daytime temps are higher, but 10C is safer.

can you add extra insulation, maybe multiwall polycarbonate?

at a guess you are looking at somewhere between 10-20 kWh per day, on average, in winter, depending on how good your insulation is.

I gotta try with bubblewrap applied from the inside

[manders]

Try and get proper greenhouse insulation bubblewrap, with big bubbles and two layers.

[cefa@]

23 hours ago, manders said:

Try and get proper greenhouse insulation bubblewrap, with big bubbles and two layers.

I dpn't know where to find it here but i'll try

[Martin7bergen]

You could also consider using floor heating mats in combination with covering the plants with bubblewrap during cold spells. This decreases the volume to be heated, but only works if your plants are not too high. This floor heaters are often used in campers/caravans and generally you need a transformator to get 12V.


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[S Krelbourn]

4 hours ago, Martin7bergen said:

h. This floor heaters are often used in campers/caravans and generally you need a transformator to get 12V.

Would it be possible to run these off a solar panel/ 12v battery combo? Could be handy / green if you've no mains electric in the greenhouse.

 

Phil

[manders]

Solar Panel/battery probably won't be big enough, but you could use mains as backup, it might reduce the overall cost.

[cefa@]

Thanks for all the replies! I don't think mats could be enough, also as usual the cost of electricity would be way too high

[Martin7bergen]

Yes, probably. You could use it as additional heating though. Advantage is the good heat distribution with this method.
Another option is a greenhouse gasheater on butane/propane bottles. Downside there is that you need some ventilation, which will cause heat loss.


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[cefa@]

On 9/1/2017 at 4:14 PM, Martin7bergen said:

Yes, probably. You could use it as additional heating though. Advantage is the good heat distribution with this method.
Another option is a greenhouse gasheater on butane/propane bottles. Downside there is that you need some ventilation, which will cause heat loss.


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I fear that propane and so on would be less cheap

[manders]

We just had discussion on Ebay about this, in the UK bottled propane is more expensive than electricity.

[Martin7bergen]

Here in Holland I saw a company selling bottles which can be filled with LPG (car fuel). The bottles were quite expensive, but the fuel is much cheaper if you fill them at the gas station. Check out https://www.gaswinkel.com/_uk/catalogus/lpg_gas_vapor_tanks


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[manders]

~10p per kwh

Edited January 27, 2017 by manders

[cefa@]

On 27/1/2017 at 8:15 PM, Martin7bergen said:

Here in Holland I saw a company selling bottles which can be filled with LPG (car fuel). The bottles were quite expensive, but the fuel is much cheaper if you fill them at the gas station. Check out https://www.gaswinkel.com/_uk/catalogus/lpg_gas_vapor_tanks


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Personally I've begun to thnk that this topic might have very different answers depending on where the grower comes from... for example Ive seen that in France many enthusiasts heat their ghs with electricity but my goodness here it'd be like spending a pint and a hlf of blood a day! In Italy everything is kinda expensive, I think that pellet here would be the best option for a small gh like mine, but heh, probably in France or in the UK propane or gas work better

[manders]

Your power price is a bit higher than ours.

natural gas here would be about 1/3 of electricity, but the idea of running a natural gas pipe down the garden is a bit scary from a safety point of view, not to mention expensive.

 

[Richard]

Here in the West Midlands UK it's costing me around £30 per month to heat my 10 x 6 greenhouse to a minimum of 5*c.

I have bubble wrapped the greenhouse and electricity here is just short of 11p per kwh.


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[manders]

20 hours ago, Richard said:

Here in the West Midlands UK it's costing me around £30 per month to heat my 10 x 6 greenhouse to a minimum of 5*c.

I have bubble wrapped the greenhouse and electricity here is just short of 11p per kwh.


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Thats the problem with aluminium greenhouses, the heat just goes straight out, bubblewrap only helps a small bit.

[corky]

I wonder how much it would cost if we had a proper winter , been one of the mildest , when I was a nipper it would freeze solid for weeks:-)

[manders]

I heat mine to 13C, 18x10ft, costs about 50£/month in winter.  Currently looking at ways to reduce that to about 8£/month, might work out/might not.

[cefa@]

I intended to heat mine at about 13°C or so too... I think the only way to see if it works it's trying, unfortunately it's damn hard to make predictions in this case

[Richard]

Manders, what is your greenhouse made of? Is it timber framed or aluminium?

[manders]

Richard, its wooden framed, some lower wooden parts (north, east, weat lower sides) are insulated with celotex building insulation, the glass parts lined with 25mm polycarbonate.  The poly is expensive to buy but saves on electric so pays back pretty quick, wouldnt be worth it if you only want a minimum of 5C, but with a minimum of 13C or so the heater works most days, sometimes even in summer.

i used to have a 10x8 aluminium lined with bubblewrap and min 10C, heating costs were about the same as the new wooden 18x10 @13C.