Heating my new greenhouse

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Cactusgirl
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Heating my new greenhouse

Post by Cactusgirl »

Well my greenhouse is almost ready just got to glaze and fit doors then it's ready for my spiky friends! Can anyone offer advice 're Heating? It's a 16x8 greenhouse on a concrete base. I only have about 100 plants at present so plan to put these all on the staging together and concentrate the heat at one end (opposite doors) . My electrician has wired in a separate fuse box for the greenhouse which is located about 4 metres away and I have armoured cable ready for the electrics. Just need the best heater for the job now! I'm keeping my Melocactus indoors but plan to have everything else outdoors so probably need over winter temp of 8-10 degrees maybe? Any advice 're type/make of electric heater Please? Thanks
Herts Mike
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Re: Heating my new greenhouse

Post by Herts Mike »

I'd be interested in this too as my Parwin heater is getting pretty old now.
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habanerocat
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Re: Heating my new greenhouse

Post by habanerocat »

If you google "Greenhouse heater with thermostat" you get some good hits at the top of the page.

I like the "Cultivar" range myself. The 2Kw model comes with or without a remote controller.

They are also on ebay and Amazon. Search "Palma Heater".

You may need two of these for your size of greenhouse. You'll have to do the maths.
2Kw or 4Kw maintaining 10 deg will give a hefty enough electricity bill if it gets cold.
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habanerocat
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Re: Heating my new greenhouse

Post by habanerocat »

Or a heater used with this simple controller with a timer and built in thermostat.

https://www.greenhousewarehouse.com/hea ... aters.html

As I believe that some succulents can tolerate cold for a limited time. For example you just enable your heaters between 8am -11am each day.

The usual warnings apply..................
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rodsmith
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Re: Heating my new greenhouse

Post by rodsmith »

I've always used a fan heater with separate thermostat set to about 5 or 6 degrees C. I have found that this ensures that overall temperature won't drop lower that 3 degrees C, which is tolerated by most cacti & succulents (but there are exceptions!).
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Diane
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Re: Heating my new greenhouse

Post by Diane »

I upgraded from a couple old Parwins to Biogreen Palma heaters a few years ago - excellent heaters when used with the external 'stat - https://www.greenhousepeople.co.uk/prod ... hermostat/
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Cidermanrolls
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Re: Heating my new greenhouse

Post by Cidermanrolls »

I use a 2.8KW BioGreen Phoenix fan heater in my 13x10 wooden greenhouse. Like Rod I also aim for about 5c. I've found this a much more reliable heater than all previous attempts. The first thing to go on cheap models is the thermostat and the ever increasing hysteresis on cheap models makes temperature control very unreliable. The BioGreen appears very good on this point.
Key must be insulation if you aim for such a high temperature. I've fixed twin wall polycarbonate sheet as permanent insulation/shade. I believe this is much more durable than bubble polythene and it's been up now for about 4 years with no obvious degradation. polycarbonate is not the cheap option but I find it so much better.
Nick_G
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Re: Heating my new greenhouse

Post by Nick_G »

Why heat it at all? Keeping a 16' X 8' greenhouse at a minimum of 6-8C won't be cheap.

I see you are in Clacton. I'm just down the road in Southend so our climates won't be that much different and I have found that most of the popularly grown genera are quite happy in an unheated greenhouse. This includes Turbinicarpus, Ariocarpus, Lophophora, Lobivia, Mammillaria, Gymnocalycium, Rebutia, Sulcorebutia, Lithops, Conophytum, Echeveria etc. etc. The lowest temperature I have recorded in my greenhouse is -6C and I hardly lost a thing. It's important to stop watering in September to allow the plants to desiccate a bit before the cold weather arrives though.
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ragamala
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Re: Heating my new greenhouse

Post by ragamala »

I can endorse the suggestion that an external thermostat is pretty essential. I tried to use 2kw heaters with supposedly built-in thermostats but they were extremely erratic. No way could they be relied on. But they are now working fine when controlled with a separate digital thermostat - Biogreen and Inkbird have been discussed elsewhere on the forum and in my experience both are good - I prefer the inkbird for its separate cooling oultelt.

As to whether a 2kw heater is adequate for a 16x8 greenhouse keeping it at 8-10 I would say probably not, although it will serve in the short term with a part-filled house provided the rest is plasticked off or otherwise so that heat loss is minimised. There are web-based calculators, which will help.

As to whether you need a minimum 8-10 for all your spiky friends that's another issue!
Herts Mike
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Re: Heating my new greenhouse

Post by Herts Mike »

I grow Stapeliads so need a minimum of 10c. Not brave enough to go any lower.
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