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Thread: Evaporative Cooling.

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    Evaporative Cooling.

    Ok, I need some critiquing of my thought process here.
    I know that evaporative cooling (swamp cooler) needs low humidity to reduce the temperature; that it can only reduce the air to the wet bulb temperature, which is a deviation of the current temperature and humidity. For example, areas with lower humidity (areas like Arizona) work well with swamp coolers, while areas with high humidity (e.g. Florida), they do very little. So could a terrarium, which has a higher humidity than the surrounding room, be cooled by a evaporative cooler? The cooler would be outside the terrarium and blowing into it. For example, 40% room humidity, 80% terrarium. Would the swamp cooler reduce the terrarium temperature compared to the room temperature?
    Anybody doing this for their highland chambers? I get night temps in the low 60s from my basement, but would be interested in getting it lower to try more highland neps.

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    Admin- I'm growing CPs in the Desert of Tucson, Az. adnedarn's Avatar
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    Use the room's temperature and humidity to figure out what the cooler could do. But remember the more it blows into the terrarium, the more it will have to blow out of the terrarium and into the room. Depending on the air flow this could raise the humidity of the room making the cooler less effective over time.
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    Got it, so it will keep working until the humidity between the outside and inside balances? I'm assuming this can sink the humidity of the terrarium and wound need to be compensated for with a fogger?

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    Admin- I'm growing CPs in the Desert of Tucson, Az. adnedarn's Avatar
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    The difference in humidity between the inside of the terrarium and the outside of it (room) doesn't matter. The part to remember is the air that the cooler TAKES IN needs to be low humidity. And when you are sucking the air out of the room, cooling (thus humidifying it) and it escaping back into the room once it blows out of the terrarium, the room's humidity is bound to rise, unless you have something to keep it low (exchange with outside air, running a dehumidifier, AC running etc). And the more it goes up, the less the cooling effect will be.

    You mentioned in your original chart wet bulb, which makes me believe you've looked at the charts available online that show temperature and air intake humidity and what to expect for the temperature air coming out to be. At 40% (what you say the room is) and you want to further cool the tank when the room is low 60s, I don't think it's going to take it down much lower. The cooling effect happens due to evaporation, so the cooler the room/water/intake air is... The less evaporation is going to happen, and so the less cooling effect it's going to have. Some examples:
    At 75f and 30% humidity you can expect around 62f out 13f drop
    At 85f and 30% humidity you can expect around 70f out 15f drop
    At 105f and 30% humidity you can expect around 86f out 19f drop

    So I'm really not sure what the OUT temp would be if the IN temp is 60... the charts online just don't go that low. But with my explanation above, and following the trend above, it doesn't seem like it'd be much.

    Hope that helps!
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    Yes you can build a little cooler for a terrarium. I have one on my neglected Cephalotus tank. It's worked for years, albeit it is not pretty. It keeps the tank at around 75*F with a typical ambient room temp and 55% or better humidity. There is a little more to it than just humidity. Whenever air is compressed, it heats up, and whenever it expands, it cools. You can use these principles as well to create a cooler that will lower the temp even more than just a typical evaporative system. You can also use iced water in the cooler, a bubbler system with an aquarium cooler... there are plenty of ways to do it. Mine isn't that fancy, I manually refill it and just use tap water in it mostly. Here is my ugly cooler that combines all of these principles:

    That's a "mainstays" container from Walmart. They sell them with lids in packs of 4. Cheap, and perfect for my needs. It is powered with this, spliced onto the turbine fan, a switching DC/AC adapter. It makes the DC "computer" fans run on AC wall outlet power:

    The evaporative padding is humidifier padding for Vicks humidifier's, also from Walmart. It's by far the best thing I have found to wick up moisture and work as a cooler padding. Note that I have slits cut in all sides so that air can be brought in through the padding:

    And here is the proof it works, when wired into a temperature controller:




    Not pretty but it is effective. And cheap too. Most expensive part was the fan. That's pretty much the basics of a small swamp cooler.
    Last edited by Gigantea; 03-30-2016 at 09:08 AM.

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    Quote Originally Posted by Gigantea View Post
    Yes you can build a little cooler for a terrarium. I have one on my neglected Cephalotus tank. It's worked for years, albeit it is not pretty. It keeps the tank at around 75*F with a typical ambient room temp and 55% or better humidity. There is a little more to it than just humidity. Whenever air is compressed, it heats up, and whenever it expands, it cools. You can use these principles as well to create a cooler that will lower the temp even more than just a typical evaporative system. You can also use iced water in the cooler, a bubbler system with an aquarium cooler... there are plenty of ways to do it. Mine isn't that fancy, I manually refill it and just use tap water in it mostly. Here is my ugly cooler that combines all of these principles:

    That's a "mainstays" container from Walmart. They sell them with lids in packs of 4. Cheap, and perfect for my needs. It is powered with this, spliced onto the turbine fan, a switching DC/AC adapter. It makes the DC "computer" fans run on AC wall outlet power:

    The evaporative padding is humidifier padding for Vicks humidifier's, also from Walmart. It's by far the best thing I have found to wick up moisture and work as a cooler padding. Note that I have slits cut in all sides so that air can be brought in through the padding:

    And here is the proof it works, when wired into a temperature controller:




    Not pretty but it is effective. And cheap too. Most expensive part was the fan. That's pretty much the basics of a small swamp cooler.
    Hey what hygrometer is that? Is it accurate? I'm trying to find a good one for my greenhouse.

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    That's Zoo Med's Hygrotherm

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    It is, yes. Forgot to mention that. Yes, it works fine.

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