Guy

Heater and fan advice please

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Afternoon all.

My new greenhouse has served me well during the summer.  The number of plants in it has increased hugely and, despite thinking differently when I started this hobby, there are now about 100 CPs, plus some cacti and succulents.  You said it would happen, and you were right!

Today, though, I've discovered a nasty attack of Botrytis on several of the plants.  I haven't allowed the plants to dry out, humidity has been at >95% and the temperature has been all over the place.  Down to 5°C, up to 22°C.  Perfect for Botrytis I've now discovered.  Stupid me.  Didn't think through winter care well enough.  I bought a small heater to keep the greenhouse frost free and didn't think beyond that.

So, a couple of questions.  Firstly, should the infected plants be thrown away, or is there any way of saving them?  Secondly, can anyone recommend a suitable fan and heater for my 6ft by 8ft greenhouse?  I'd like something where the fan can stay on all the time if I so choose, and the heating will come on and off as necessary.  

This lovely thing is on Amazon, but at £200 is a bit pricey and seems possibly too big for such a small greenhouse.  It does have the facility for an 'always on' fan with heating cutting in and out as necessary.

All advice gratefully received.

Thanks.

Guy

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Those are very nice heaters but also very overpriced. I have a 2nd hand propane version in my 2nd greenhouse at the bottom of the garden.

Look at something like  https://www.amazon.co.uk/dp/B01DW9ESL2/ref=cm_sw_r_other_apa_i_-u7fEbEFQ86H2

These are sold under a number of names but are simply and work in damp greenhouses (some of the smaller semi domestic units are not fit for use in such environments for more than a year or two). You can never have too much power either as long as it's on a thermostat!
 
You do need to think what you want to grow and what minimum to aim for. I used to heat to 5 to 10 min but mould is a menace. For the last decade I just aim to keep my 1st greenhouse frost free and my big fan heater is only for severe weather and back up. I use a thermostat tube heater 99% of the time. O or even a few degrees below for a short time seems to do minimal damage with the advantage of no more grey mould.
 
However, so far, this winter is a real pain as it's staying so warm and humid. All you can do is ventilate when you can.
 
Edited by Dunc

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Thanks Dunc

That's exactly the heater already sitting in my greenhouse!  It's great for keeping it frost free, but the fan in it only comes on when the heater is on.  What I'm looking for is something with a fan on all the time and the heating elements coming on as necessary.

Perhaps the simplest answer is to get an ordinary fan to continuously circulate the air and leave the current heater to keep the greenhouse frost free.

Guy

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Hi Guy

Maybe you have a slightly different model but the Amazon description from Dunc's link does state "Features continual fan operation to aid greenhouse airing, frost prevention and extending the life of the heating element."  Also, in answer to a question about the fan/heater, an Amazon user states "The fan stays on all the time but, the heating element turn off & on and keeps a stable temp."  So maybe you have a slightly different or older model as Dunc states they are sold under a number of different names.

Kind regards,  Rob

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Hi Rob

Very useful reply, and I think you're right!  Mine is exactly that model, but it's controlled with an Inkbird thermostat.  This gives very accurate temperature control and a nice digital read out.  But, of course, only supplies power to the unit when the Inkbird comes on.

Tomorrow, when it's light, I'll plug the heater straight into the mains and see what happens.

Thanks.

Guy

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Hi Guy

I have one of the Biogreen Phoenix heaters in my 12'x 8' cacti/succulent gh, I run it through a Biogreen thermostat to keep minimum temp around 5-6C or so, this is on the 1.8KW setting.  I found the built in stat temps to be a bit vague so went for the additional stat but this sacrifices the always on fan feature and of course adds to the cost.  In summer I put the Biogreen stat on "cooling".  Personally I think the fan is a bit underpowered although the Amazon page states it's 53W.  Anyway as a heater it seems to do the job OK but as you pointed out the price is rather high.  I've had it a number of trouble free years (hopefully not tempting fate there).  If it were to breakdown I don't think I'd be forking out another £200 and would probably try something like the Parasene Dunc mentioned.

In my 6' x 8' CP gh I have a tube heater (5' double tube, 80W/foot from memory).  This is on an Inkbird stat and again keeping minimum around5/6C, as the Inkbird has double outputs (1 each cooling and heating) I run a separate fan.  The tube heater seems adequate for the smaller greenhouse and I had it running for many years without problem.  Perhaps if we had another Winter like in 2010 I might need to put another one on (I have 2 spares) I seem to remember this was also not a cheap option although I can't recall the exact price.

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So Guy, it would seem that if you want to continue using your Inkbird thermostat for more precise temperature control, you need a separate ordinary fan - or another fan/heater like you have already but plugged directly into the mains and set to fan only - to keep the air moving.

Kind regards,  Rob

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Thanks for all the help and advice.  My heater must be a really old model, even though it was only bought last year.  The thermostat controls both the fan and the heating elements.  So, no continuous operation for the fan.

However, a bit of fiddling with the wires in the unit and the fan now runs continuously, plugged into a separate supply, and the heating elements are still controlled by the Inkbird.

The fan seems fairly weak, but I'm hoping some small air movement is better than none.

Guy

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