New Modular Wardian Case aka orchidarium

[HHTmom]

Hi all, have been reading posts on the Orchid board for about 2 years and recently joined. Anyway wanted to share my good news and ask a few questions. I am having my own modular wardian case built which is similar to the Grand Cayman only much larger. I plan to grow heat tolerant, moderate temperature, and cool temperature orchids in the case. My question is how to keep my masdevallias and draculas cool. I know that I need to keep them in the low end of the case, but does anyone have other suggestions?

Thanks

[Magnus A]

For a very large case the only viably way too cool it is by some sort of evaporation cooling. Or if you live in a cooler climate, take cold air from the outside via a ventilation tube and a fan connected to a thermostat. The two can be combined to keap the humidity up inside the case.

There are examples of this kind of setup on the internet but I do not have the links availibly right now.

/Magnus

[HHTmom]

Thanks for information. So my goal is to provide evaporative cooling to keep the heat in the case around 75-85 degrees, however, I am wondering if anyone who has a Grand Cayman can offer some information on how you vary the temperature from the higher level of the case where the temperature is the greatest, to the middle of the case, and then to the lower end of the case. It is my intention to keep all my chids inside the case which would require varying temperatures i.e. hot, warm, and cool.

[Discus]

In smaller cases (or even for sections of cases) you may also be able to use a large peltier cooler to chill down some air. A closed loop that passes over the peltier will probably work best. Remember the hot side probably wants to have a heatsink and a fan too! If you can keep heat out of the case, it will help (i.e. make sure things like lights aren't causing too much heat).

[HHTmom]

Thanks for the information. Where can I find a peltier cooler?

[Discus]

Try ebay, or just google around a bit
e.g. Awesome 400W Thermoelectric Peltier Cooler 12 VDC Tec | eBay
or somewhere like Thermoelectric cooling, coolers, modules, heat sinks, exchangers, Peltier coolers, devices - TE Technology

You'll have to do some construction work and some electrics to get it to do what you want, but if you are, or know someone who is, fairly handy it's not hard.

The simplest design will be to have something along the lines of two large heatsinks stuck (with thermal transfer glue) to each side of the peltier, with small fans blowing across them. The "hot" side obviously outside the case and the "cold" side inside the case. Some kind of ducting will make it more effective, particularly with regard to venting the hot air.
Ideally, you should put them on some sort of thermostat which triggers when your case gets too warm.

Reading around, the general consensus seems to be peltiers aren't all that efficient/workable, particularly for large volumes (they may well have been undersizing their peltiers or using them poorly).

A simpler/more effective system may be to use an aquarium chiller and pump this through a PC cooling system radiator inside your case. There is a thread on this technique somewhere on OB.
A chilling experiment
see also
cooling system
http://www.orchidboard.com/community...m-chiller.html
Serious cooling using a water chiller
Thermoelectric cooling



---------- Post added at 11:54 AM ---------- Previous post was at 11:51 AM ----------

Oh, I forgot to mention, if a single peltier isn't cold enough, you can "stack" them (i.e. cool a peltier with another peltier, making the second one colder, and then make whatever you want cold with the last coldest one). And of course, you can use more than one unit. The colder unit(s) should be a smaller wattage than the bigger, warmer one(s), because physics is annoying.

The more you cool the "hot" side, the colder the "cold" side can get.

Basically, the less heat (e.g. lights) you have warming things up, and the slower your room heats things up (i.e. insulation) the better cooling will work. If you have a lot of heat, you'll need more cooling.

---------- Post added at 12:00 PM ---------- Previous post was at 11:54 AM ----------

Also, particularly if you have adequate airflow inside the case, I don't think you'll successfully cater for warm, intermediate and cool growing orchids in a single case - you could have a single case that you partition (physically, with barriers made of e.g. perspex) into 3 separate growing zones with appropriate heating/cooling for each.

You need fans in a case, and that stirs up the air; cold air might sink, but fans will "stir" it up and negate the effect entirely.

If it were me, I'd do this with vertical barriers rather than horizontal ones, so you can change both light intensity (moving orchids up and down) as well as heat (move between the three section).

You *may* get away with "point cooling" a few orchids by having them in a stream of cooled air, but that seems like it will be problematic (particularly as cooling tends to result in drying, which you'll need to compensate for; cold, dry air will suck moisture right out of delicate plants). I really think either three separate climate zone cases, or one that is split into three internal zones will serve you rather better.