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  1. #801
    Robert Oliver's Avatar
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    negative pressure, from what I understand means exhaust is pulled from the room via an intake......

    positive pressure is where you push air out of the room.

  2. #802
    ROL
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    Quote Originally Posted by Robert Oliver View Post
    I am using a 300cfm negative pressure system... sucking air through two 14x14 inch air filters. it will be easy to upgrade the fan if I decide I need more air flow. The space is also hooked into the central ac / furnace.
    Looks like you're having fun. When I built, I was cautioned by the HVAC professionals NOT to hook into the house AC, even though that would have been by far the easiest to do. Unless your AC capacity is overbuilt for the house (mine wasn't) and your DR is well insulated (mine is), you will overtax the entire AC system. Then there is the problem of introducing forced air dust into the DR from the house.

    I ended up with the smallest available "split system" heat pump which serves only the DR. There is no air communication to the outside (no light leaks), as it recycles room air (I have separate outside fresh air by negative pressure exhaust). It is very efficient and effective for both heating and cooling as well as dehumidifying (really, cooling). I cannot recommend these systems highly enough. They are used widely throughout the world and are beginning to replace forced air systems in the U.S. The unit cost for small units sufficient for small rooms is not much more than a stand alone cooling or window-type unit (actually the same as better units, ~$200-$400). The extra cost (either judged to be worth it or necessary) is in the installation, where it pays to obtain someone with experience in split systems.

  3. #803
    Robert Oliver's Avatar
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    I installed a bigger unit than needed with the thought of my future darkroom...

    I wish I would have known about heat pump system. It sounds really cool (literally ) and effecient.

  4. #804
    Nicholas Lindan's Avatar
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    Quote Originally Posted by Robert Oliver View Post
    negative pressure, from what I understand means exhaust is pulled from the room via an intake......positive pressure is where you push air out of the room.
    Hrrrrmmm. I think you are trying to say the right thing, just saying it backwards.

    Positive pressure: the pressure in the darkroom is greater than the surroundings; air is pushed into the darkroom with a fan; it escapes through a free-flow exhaust and/or cracks and leaks; you need to place an air filter on the fan that blows air into the darkroom, dust exits the darkroom through the exhaust and the cracks and leaks and is blown from the room when you open the door - thus positive pressure is the way to go for a dust-free darkroom.

    Negative pressure: the pressure in the darkroom is less than the surroundings; air is drawn from the darkroom with a fan; it enters through a free-flow vent and/or cracks and leaks in the room; you need to place air filters in the intake vent and the the cracks and leaks, however, you can never seal all the cracks and dust gets sucked into the darkroom every time you open the door - in general, negative pressure is a bad idea
    DARKROOM AUTOMATION
    f-Stop Timers - Enlarging Meters
    http://www.darkroomautomation.com/da-main.htm

  5. #805
    ic-racer's Avatar
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    Nicholas is right, you would want positve pressure for your darkroom. Negative pressure is for TB isolation

  6. #806
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    My last and final version of my darkroom with almost all the equipment I would ever need.
    Might be small and might not look as impressive as some glorious photographic halls pictured here, but its one of the very few dark rooms left in the country and possibly the best equipped.
    Attached Thumbnails Attached Thumbnails DSC_0220.JPG   DSC_0338.JPG   DSC_0317.JPG   DSC_0314.JPG   DSC_0374.JPG  

    DSC_0425.JPG   DSC_0428.JPG   DSC_0408.JPG  
    aristotelis grammatikakis
    www.arigram.gr
    Real photographs, created in camera, 100% organic,
    no digital additives and shit




  7. #807
    fotch's Avatar
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    Needs a "Darkroom sweet Darkroom" sign
    Items for sale or trade at www.Camera35.com

  8. #808
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    Looks great to me Ari. A lot bigger than mine! Is this from where your recent postings in the Gallery have originated? If so it looks like everything's working just fine.
    If I had been present at the creation, I would have given some useful hints for the better arrangement of the Universe.
    Alfonso the Wise, 1221-1284

  9. #809

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    Aristotelis,

    Your darkroom looks very tidy and well organized, an example I should follow...

    Tom

  10. #810
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    Of course it is the best equipped - it has Aristotelis using it.

    Really glad to see you posting again about photography/posting again in the gallery.

    Matt



 

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