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Post by Bess on Oct 21, 2014 15:56:06 GMT
I want to know what sort of heater I could safely use in my mini greenhouse? I didn't really need any heat this spring. I just stuck tea-lights in it some nights for a bit of warmth, which wasn't awfully safe with the fleece I was using too, but I tried to be careful! However I'm trying to over-winter some stuff this year, geraniums etc, and if it gets really cold I'd like to be prepared and not burn anything down. I don't need major heat. I'm a bit scared of Paraffin, and I remember the huge old heaters Mum had when I was a kid smelled awful. I can't use electric. What to dooo?! (I can't get hold of a proper air vent for my greenhouse either at the moment  will keep searching, don't want to poison my plants with no clean air.) |
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Post by lesley on Oct 21, 2014 17:50:55 GMT
Hi Bess, why can't you just bubble wrap it, geraniums don't need a lot of warmth you could always just lay newspaper over them if it's going to be really cold it's just to keep the frost out, good luck  |
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Post by daitheplant on Oct 21, 2014 18:54:07 GMT
Bess, I agree with Lesley 100%. No need for a heater, just keep it frost free.
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Post by Bess on Oct 21, 2014 23:57:00 GMT
Thank you Lesley, I thought geraniums needed more warmth than that (Mum always brought hers inside for houseplants over winter) so that's good to know.
What about ivy leafs and pelargoniums, please?
My mini greenhouse is an awkward beggar, but I will definitely take a look at the front panels and see if I can do something with bubble wrap.
I also have several Amaryllis, a chrysanth, and varying houseplants in there (plus stuff like callas/oriental lily bulbs that I know only need to keep frost free.) In early spring I'd like to grow all sorts of baby plants. I have no room in our flat (hoping to move, but it might be months) and I'd *like* to put a big cymbidium orchid in the greenhouse - it's a right nuisance indoors, but again, I'm not sure it'll be warm enough with just wrap.
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Post by lesley on Nov 2, 2014 17:54:59 GMT
Hi Bess, are the Amaryllis new ones or old ones ?? either way if you wont them to flower you really need to bring them in the warmth, re your cymbidium it should be alright in the G/h just put a piece of fleece over it if it gets to cold, mine last year lived out side next to the house and this year it has flowered for me, never had one before. All the rest should be alright. good luck
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Post by Bess on Nov 7, 2014 23:40:18 GMT
Ooh Ok thanks, I will definitely try that with the Cymbidium, the wretched thing is literally under my feet at the moment as I have nowhere sensible to keep it inside!
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Post by roofgardener on Dec 26, 2014 11:11:49 GMT
Can you get electricity to your mini-greenhouse Bess ?
There's something I'm going to experiment with in my polytunnel (2m x 3m). I'm running a cable from my flat into the PT (courtesy of a small window 'wot I can leave open), and am going to use one of these fan-blower electric heaters.
My thinking was that they have no naked flame per se, and that the heat is blown around the greenhouse, so it doesn't produce "hot spots", and hence there should be no chance of fires.
They don't produce fumes per se, and they are OK-ish for condensaton (not PERFECT, but not as bad as - say - a gas heater). I'm going to try using one of those cheap electrical timers so that in winter, it can turn on for 15 minute intervals, a couple-or-three times per night. This might be tricky, as most timers are VERY limited on the current they can handle, so the heater would have to be the sort that can be turned down to low power (600-800W tops).
I'll let you know how it goes.
****UPDATE****
Oh blast.... I didn't read your post properly Bess... you've already said that you can't use electricity.
Hmm... I wonder if something could be rigged up from a car battery ?
****UPDATE****
OK... it is possible to get small air-blowers designed to plug into a car ciggie lighter. So in principle, you could use a car battery to power one of these.
It is also possible to get 12V timer units, so you could arrange for the heater to turn on periodicly overnight ?
They tend to take about 200W or so. A car battery should last quite a long time if it is only turned on for 10 minutes or so, 3-4 times per night ?
Would that be a practical solution ? The battery and heater WOULD take up quite a bit of space ... and you WOULD have to recharge the battery every couple or three weeks.. which means lugging a heavy battery back and forth ?
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Post by daitheplant on Dec 26, 2014 19:31:31 GMT
Roofy, make sure you use a fan suitable for a greenhouse.
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Post by roofgardener on Dec 26, 2014 20:14:44 GMT
Meh... I'll just get a bog-standard house fan-heater from Wilko's. I mean.... what can go wrong ? Seriously ?
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Post by daitheplant on Dec 26, 2014 20:58:40 GMT
Polytunnels/greenhouses produce condensation, which equals moisture. Which equals, electrocution and death.
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Post by roofgardener on Dec 27, 2014 8:30:03 GMT
Meh.... you could hold a fan heater in one hand, and pour water into it with the other, and you are unlikely to get electrocuted .... providing you are not standing directly on the ground. I'll be standing on plastic matting, or sitting in the Comfy Plastic Chair. I'd be more concerned about fire. Water getting into a (running) fan heater could causeu the filament to shatter, sending red hot wire everywhere. Plus the timer switch could overload and melt. (which is why I'm going to put it at the PT end of the circuit, and not in the house end.) Electricity is safe, if you know what you are doing and anticipate the dangers. Heck, juggling running chainsaws is safe if you know what you are doing, as my friend Stuart "Stumpy" Johanson can attest to. Of course.. he can also attest to the dangers of complacency  |
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Post by daitheplant on Dec 28, 2014 19:17:46 GMT
Wearing wellies or standing on plastic, will not stop you from being electrocuted.  Apart from that, using a "bog standard fan from Wilko`s, continually, can cause overheating of said appliance, ergo, the possibility of combustion.  |
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Post by roofgardener on Dec 29, 2014 10:03:28 GMT
Both true, of course.
I'm hoping I'll be OK in terms of the overheating. Ultimately, I'd only be using the heater when I'm actually working in the greenhouse during the winter evenings, and I doubt I'd be therhe for more than an hour. The fan should be able to cope with that comfortably.
The other use would be to use the timer to 'pulse' the fan for 10 minutes at a time, three or four times a night, just to mitigate a little against extreme cold.
The danger of THAT is that the fan constitutes an inductive load. If the timer turns off with the fan at full power, it will create a back-EMF. However, this should be very small (a matter of a few volts ?), and very short lived (tenths of a second) as the fan is quite small. I'm hoping the timer will cope with this. Failing that, the circuit terminates in an RCCB at the consumer unit, which should offer additional protection.
I'm confident I can keep it safe for the next couple of months; it will be sitting on asphalt, with a "fire break" all around it. Once we get into Spring, I shouldn't be needing to use it. However, I will be looking to try and get an "official" greenhouse fan heater before we go into Autumn 2015.
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Post by daitheplant on Dec 29, 2014 19:24:20 GMT
Good plan Roofy. |
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Post by roofgardener on Jan 5, 2016 11:19:59 GMT
OK.. here's a thought for everybody...
Is it necessary to heat the entire greenhouse ? How will plants react if the greenhouse is very cold, BUT... the soil is warm ?
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will keep searching, don't want to poison my plants with no clean air.)
Apart from that, using a "bog standard fan from Wilko`s, continually, can cause overheating of said appliance, ergo, the possibility of combustion. 
