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Question about highland cooling system


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#1 Greg Allan

 
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Posted 01 January 2012 - 18:12 PM

I'm aware that there are several threads relating to this topic, but as my knowledge of electronics and the principles of heat transfer is nil, they are basically incomprehensible to me. I therefore want to set up a very simple cooling system. I currently use a mini greenhouse indoors as a highland terrarium, the sort with a metal frame and a plastic transparent cover which fits over the frame. If I purchase a wine cooler, and remove its door and make a large hole in the side of the greenhouse so that the fridge directly opens into the greenhouse, is this likely significantly (and safely) cool the interior of the greenhouse (i.e. by at least 5deg C) if the cooler is switched on at night?

Any advice would be greatly appreciated.

Cheers,

Greg

#2 mobile

 
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Posted 01 January 2012 - 19:37 PM

A wine coolers refrigeration system will be sizes for cooling the volume of the cooler, i.e. if you significantly increase the volume then the cooler will not cool it sufficiently and the compressor will be running constantly.

Perhaps the simplest way of reducing the temperature is to use a fan to draw in air from outdoors, as this will typically be cooler than the greenhouse. A basic thermostat could be used to switch off the fan when the required temperature is reached. Of course, cooling will be less effective during summer nights.

#3 corky

 
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Posted 01 January 2012 - 21:10 PM

i was thinking of doing something similar to what mobile is suggesting,i also thought if i ran the ducting through a large container of water with those ice packs for cool boxes it should cool the air in hot summer nights,what do you think just an idea

#4 Peter Hewitt

 
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Posted 01 January 2012 - 22:44 PM

There have been many threads and many failures with trying to create a cool growing chamber for Ultra-Highland Nepenthes. There are many challenges which are not easily overcome.
Jeff Shafer came up with the easiest and most economical way. Take a look at the link below for instructions for adapting a chest freezer for cool Nepenthes growing.
http://www.carnivoro...v32n1p20_23.pdf

Edited by Peter Hewitt, 01 January 2012 - 22:45 PM.


#5 Martin Hingst

 
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Posted 03 January 2012 - 14:23 PM

I would say there is no easy and overall satisfying way for cooling a tank.

Either - it is cheap and simple - then you have plenty of work with maintenance (e.g. replacing cooling accus)
or - it is extensive and / or expensive in contructing.

The maybe easiest way is a cool cellar - when heating during the day is aceived by the waste heat of the artificial lighting.

#6 mobile

 
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Posted 03 January 2012 - 15:06 PM

Or move to North Scotland, where it's always cool :lol:

#7 Greg Allan

 
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Posted 09 January 2012 - 19:27 PM

Thanks for all of the replies. It's extraordinary how difficult the apparently simple aim of cooling a terrarium can be. Mobile- I have thought about your idea of simply using cool air- after all the average low temperature in Birmingham is 10 deg C during the warmest part of the year. The problem is that I suspect that making a hole in the wall of my house would be an expensive rigmarole, and leaving a window open all summer would have implications as far as my home insurance is concerned. I have had another idea, though. What about making a hole in a floorboard and using a fan and a tube to draw air from under floor of the house? I think that the air under the floorboards should be pretty cool for most of the year, especially as there appears to be a vent in the side of the wall that allows air circulation under the floorboards. What do you think?

#8 mobile

 
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Posted 09 January 2012 - 20:21 PM

Perhaps you could put a min/max thermometer under the floorboards to verify the temperature ranges?

#9 billynomates666

 
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Posted 11 January 2012 - 13:50 PM

Hi Greg

Can I ask how big is your mini greenhouse is and forgive me for asking (but the summation of my in depth knowledge of nepenthes you could happily tattoo on a gnats left knee cap with a red hot poker and still have room to spare) what sort of temperatures are you looking for? Ventilation will probably give you the 5C differential you are looking for most of the year, but it is a balance of heat gain to the space (lights, conduction etc) verses external ambient conditions as to the required volume of air needed. As previously suggested a fan on a thermostat should provide your requirements without too much trouble.

The max min thermometer under the floorboards will give a very general indication of the temperatures you will experience under there as, as soon as you introduce a fan, the dynamics of the space change, in as much as you will probably be drawing in more air from outside via the airbricks than would normally occur by natural ventilation alone, leading to (in cold weather) a lowering of the base temperature measured. Other things that may be noteworthy are, are the floorboards a reasonable fit/seal, otherwise air could be drawn from the warm rooms rather than outside and do you really want to increase the airflow under the floor as this may well end up increasing the heat loss through the floor and or create draughts, depending on the fit of the boards, air quantity required etc.

As to other methods, I have seen the effective use of home made evaporative coolers (a fan in a 100 tube drawing air over a wick standing in water) to cool spaces but this will give high space humidity and the cooling effect will depend on the original room air temperature, for instance air at 20C and 50% saturation can be cooled to give a supply temp of 15C and 90% saturation by such a method.

Hope this helps.
Cheers
Steve

#10 Greg Allan

 
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Posted 03 February 2012 - 21:40 PM

Hi Steve,

a (belated) thanks for your very detailed reply. The greenhouse is about 2 ft square x 3 ft in height. I am looking for night temps to get down to about 15 deg ideally (10 deg would be even better, but very expensive to achieve, I suspect). The lows last summer were often somewhere in the region of 18-19 (with a fan being used), so a 3-4 deg drop is what is required. The home made evaoprative cooler seems like a good idea, but I cannot envisage how it is created- I will look online.

Cheers,

Greg

#11 Gareth Davies

 
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Posted 04 February 2012 - 08:51 AM

Greg- what species are you trying to grow?

Bit of a controversial idea here- so everyone is free to jump in with their objections- but in the uk, I reckon most highland Neps are ok in the house without any special cooling systems.

In my quest for the perfect Nep growing conditions, I've tried pretty much everything, and found that mot species are tougher than we give them credit for.

If 18C nights are the warmest nights that they experience, I don't think you'll have any problems at all.
I have a theory that what stresses highlanders out in the short term are hot days in the greenhouse (over 30C)- although I agree that 18C nights all year round will stress them out in the long term (they "burn out" and die.)
But in the uk, if you have lower night temperatures from Autumn through to Spring- like you'd get in an unheated spare bedroom- your plants would still be happy for most of the year.

I've found that a spare bedroom with a couple of electric propagators and cheap T5 lights on timer works miracles for even the most demanding species (currently nights are 14, days 22.)
This works nicely even for small villosa plants, although I understand that villosa gets more demanding as it gets older.... but then I think growing a decent villosa is a lifetime's work and not to be embarked upon lightly....

#12 Greg Allan

 
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Posted 04 February 2012 - 09:49 AM

Hi Gareth,

Thanks for your post. Yes, night temps are low at the moment (10-14C) and, as you say,it is only in the warmer months that temperatures are higher. I think that the very warm Autumn that we had in 2011 probably made me worry more than necessary about temps as the lows were often as high as 17 until the end of October. I've got N maxima, inermis, glabrata, talangensis, dubia, jamban and jacqueliniae in the mini-greenhouse. I realise that the Sumatran highlandlanders are not the esaiest species, but having grown Drosera, Byblis and Pings for many years, I am becoming obsessed with the Neps which have viscous fluid and act as flypaper traps.

Greg

Edited by Greg Allan, 04 February 2012 - 09:53 AM.


#13 manders

 
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Posted 04 February 2012 - 10:33 AM

I have certainly grown many of those in a cold windowsill for a while, long term i started to have trouble with talangensis and some others, (e.g. vogellii, mira) both started to flower prematurely and nearly committed suicide, (talangensis seems prone to suicide by flowering in any event). I think in all cases it was due to being too warm for too long (a couple of years).

I brought my dubia in out of a cold conservatory and put in a windowsill (unheated room) it was dead inside a month, but moving it may have been the issue. Glabratas really hate hot weather. Maxima and jacqulineae should be fine wherever you put them.

#14 Gareth Davies

 
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Posted 04 February 2012 - 13:04 PM

Mark- I've really struggled with vogellii at highland temperatures and it was only when I moved it to more intermediate conditions that I got it to grow at all.

Random observations on the other species:

N talangensis always did best for me on a windowsill- in the greenhouse, it has occasional flushes of pitchers but nothing you could call reliable.

N maxima is indestructible and would thrive anywhere.

I haven't really got to grips with the rest of these species myself, but maybe that's because I've only had them for about 18 months, and it's only been recently that they've started to take off for me.... jamban seems to have suddenly taken off with no special treatment...

I've got some seedlings of jacq, inermis and glabrata that weren't happy until I got the temperatures UP to 14 at night/ 22 by day (they really weren't happy with 12 at night, 18 by day.)

I've been trying to grow some dubia from seeds, and I was trying my usual germination temperatures in the mid-20s, where I got only one seedling. I move it, in its pot of ungerminated seeds, to the 14 nights/ 22 days and got a sudden synchronised set of 6 more germinating.

I take my cue from an expert grower whose collection makes me weep with envy, who gave me some of his wisdom and suggested a pragmatic approach, that you can grow most things pretty well in a wide range of temperatures.
In the uk, I think cool indoor temperatures work for a lot of things, a lot of the time, without having to resort to converting chest freezers.

#15 manders

 
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Posted 04 February 2012 - 13:35 PM

Completely agree Gareth windowsills work well most of the time for highlanders/intermediates. Also agree refrigeration shouldnt be neccessary most of the time. With highlanders, things like vogellii, talangensis, you really need warm daytime and cold nights for it to grow well long term, but that might mean just mean opening a window in summer to let cool air in. 15 night 25 daytime is normal highland climate and warmer daytime if they are in direct sun, if you can provide those temps night and day, every day, growth will be much faster and healthier, but here in the uk getting close that ideal temp variation can be a challenge, thats why i think there is some temptation in being able to control temperatures properly for the tricky highland/ultrahighland species, with heating and/or refrigeration.

Mind you, the talangensis clones in cultivation may just have suicidal tendencies anyway and its nothing to do with climate, fun isnt it?

#16 Gareth Davies

 
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Posted 04 February 2012 - 14:46 PM

Mark, we pretty much agree on this...
Personally, I just can't be bothered with complicated technological solutions to Nep growing.
I'm tending towards greenhouses in a shady spot (to prevent summertime overheating) and an array of £10 fan heaters, a couple of £60 thermostats and a timer switch (£3.50).
And, at the moment, a cleared space in the garden in the sun for the future lowland house.

#17 manders

 
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Posted 04 February 2012 - 15:05 PM

Mark, we pretty much agree on this...
Personally, I just can't be bothered with complicated technological solutions to Nep growing.
I'm tending towards greenhouses in a shady spot (to prevent summertime overheating) and an array of £10 fan heaters, a couple of £60 thermostats and a timer switch (£3.50).
And, at the moment, a cleared space in the garden in the sun for the future lowland house.



Pretty much the same here, havent sorted out my summer greenhouse overheating issues yet though.

#18 Gareth Davies

 
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Posted 04 February 2012 - 15:32 PM

Wandering well off topic now- I think everyone who runs a highland greenhouse has the same issue- with any sun in the uk, a greenhouse will overheat... so you can add autovents, and then humidity plummets whenever they open.

I think that Nep growing, if anyone wants to get into it as a hobby, is actually very, very hard...
It's no problem to grow scores of the easier ones, but once you realise that you NEED a decent rajah, villosa and a bicalcarata, then it's a massive challenge...