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HELP!:heat and humidity problems

This is a discussion on HELP!:heat and humidity problems within the New Growers: Ask the Senior Members forums, part of the New Growers category; I am very new to this site and not too clear on how to use ...

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  1. #1
    Bard is offline Junior Member
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    Default HELP!:heat and humidity problems

    I am very new to this site and not too clear on how to use it to best advantage. I posted part of what follows on another thread and have received no responses for 3 days. I am very discouraged and in need of advise. In addition the problem is more serious than I thought at the time. Some background: I have just completed an orchid growing case 18w x 42H x 35W. It has a humidity tray on the bottom and a 24" 4 tube t5 fixture on top ( 8000 lumens) the back wall and right hand side wall are solid plastic board painted off white while the front and left end are 1/4 plexi, The front panels are on sliding tracks for access,. Ventilation is provided by 6 - 6"x1/2" ports just above the hum. tray and 4 small doors in the top that can be adjusted ( no fans yet). The combination of bottom ports and top vents give a chimney effect and provide a constant and adjustable updraft. This arrangement ,sans fans, works very well in my first case but, in the new, bigger case, I am having trouble achieving the humidity levels I want:60-80% and the heat from the lights is excessive. It burned the leaves on a catt. 3" away and the temp exceeds 82f 16" below the bulbs. On the humidity front, noting that some orchidariums use an aquarium bubbler and air pump, I added an air pump and a 30" of perforated bubbler pipe but it made very little difference, perhaps 10-15% RH improvement. I have also considered a small muffin fan mounted just above the Hum. tray to speed evaporation. Perhaps there is a better option or things will improve if I can draw off the heat, but I would prefer to avoid a humidifier or mister. Interestingly my first case (see photo)is identical in design but only 15" x 15" x 22" and maintains 70% RH at 70f most of the time. Being too small for more, it only has 18 watts of light so heat is not a problem. Fearing more damage to my plants, I have emptied the new case, cramming all the occupants in the old case or onto the windowsill. The case stands ready for badly needed modification but of what sort? Some of the things I have considered are a sheet of glass below the lights but that will cut the light and I only have 8000 lumens, a fan or fans near the top vent doors to increase circulation and pull off some of the heat. Obviously several variables are at work and I really need help sorting them out. Otherwise I will just continue to shoot in the dark, wasting money on things that don't work and getting more and more frustrated. Your thoughts will be deeply appreciated. PS:I tried twice to add photos but they are gone when I revisit the site.
    Last edited by Bard; February 25th, 2008 at 10:42 AM. Reason: adding photos

  2. #2
    hcubed's Avatar
    hcubed is offline Senior Member
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    Default

    Unfortunately, I certainly can't help you since I am a strictly windowsill grower myself. But I didn't want to go on uncommented.

    Just as a side note, that is an awful lot of information in there bundled very tightly. It might help some of the other members give you advice if you try and pose the question a little more clearly....I'm just having trouble identifying the troubling issue from all of the background information. But maybe that's just me.

    Sorry I can't help more!

  3. #3
    cindiras's Avatar
    cindiras is offline Senior Member
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    8000 lumens sounds like a high light situation to me. If you do put glass between your lamps and the plants, how much differance will this make in temperature and in lumen reduction?

  4. #4
    Bard is offline Junior Member
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    Default

    Good question. going by figures I have seen for foot candle reduction of sun-light through glass it should be a lot but I guess I should get some and see. I hooked up a 36 cfm dc fan blowing across the lights today and it looks like it may be a direction to explore also.
    A friend of mine who used to build grow chambers for Cornell U Plant Science is currently stumped by my problem too but I have hope that between Orchid Forum and him the problem can be worked out. In the meantime my orchids are back where they used to be.

  5. #5
    Bard is offline Junior Member
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    Default Here is a photo of my new case


  6. #6
    ischel1's Avatar
    ischel1 is offline Senior Member
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    Wow, sounds to me like you have too much light in the case. Just a thought, but have you tried to reduce the lighting. That seems to be the root of the problem and the causative factor in generating all that heat.

  7. #7
    jfrizz743 is offline Senior Member
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    Geoffrey Melton
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    I'm afraid I'm not much help on this, but I did want to say that that is a very nice looking case you've built. I'm impressed...

  8. #8
    Bard is offline Junior Member
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    Default Thanks +update

    Thanks for the kind words. It has cost $350. so far but if I can get it running right it should be cheaper than the commercial alternatives. I had the wood, white cedar, which probably saved $100.
    I have been continuously playing with the ventilation ports and have achieved an average of 50% RH at 78f. 78f may be a bit high for a winter intermediate temp but it gives me an almost a 20f day/night temp and it beats the 84f I started with. variable which is good and the 1.8v. DC fan has almost completely evened temp /RH stratification. I am looking for a water holding fiber mat for the back wall that I can spray daily to increase humidity some more. Any suggestions?

  9. #9
    Bard is offline Junior Member
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    Default Update "...humidity problems" gone

    I thought I'd update those who responded to my plea for help. After digesting the comments from you all and re-reading William Cullina's description of his first growing case I decided to throw caution to the wind and try a fan blowing across the water in my humidity tray instead of a water wall or blanket. I got a DC transformer and a 3" DC fan and set it up. With the lights off it produced a clear spike in humidity. Encouraged I took the next step. I separated the lights from the case with a sheet of plexi and mounted 2 more fans, purchased on the web at $12.90 for 10, to the light chamber, 1 blowing across the lights and 1 exhausting the warm air. This reduced the case temp to a max of 74f., down from 85f. I replaced the first fan blowing over the H tray ( it was too loud ) with 2 0f the $1,29 models and the humidity rose to 75%. Although it drops to 58-65 in the 5/ 6 days between waterings, it goes right up to the mid to high 70s when I water. Interestingly the water level in the 14 x 30" tray only drops about .25" in a week. I'm excited! Now that I have a proper environment with some size my next step is to get a phrag or 2 and try semi hydro growing.
    Cheers,
    Bard

  10. #10
    jfrizz743 is offline Senior Member
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    Geoffrey Melton
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    Well, let me be the first to say congratulations, sounds like you got everything sorted out. By the way, did you read that about William Cullina's first case in Understanding Orchids?

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