Monday, April 12, 2010

Evap Cooling 101


I've been doing a little tinkering and jury rigging to come up with the first stage of a two stage evap cooler for the dungeon. I'm far from finished, but what I've done so far helps in here immensely as is. I'll probably add a stage II thread to this later on.

Most of you living in houses or Apartment more than likely have refrigerated air in them because it works anywhere. It can get expensive though because it uses a large compressor to pressure up freon and then meeter it through an expansion device going in to an evaporator coil inside where you live. An Evaporative cooler works about the same way with out having to use a compressor (Which draws high AMPS (Electrical current) which in turn runs the electric bill up. The evaporate cooler just blows air through a medium that is soaked with water. The water evaporates and cools the air without compression. It also operates much more cheaply because of that. Now there is a problem with this and that is if you live in a very humid area Evaporative cooling doesn't work and can also add insult to injury by adding even more humidity inside making it feel hotter than it really is. In areas where there is very little humidity an evaporative AC really shines. They can almost freeze you out even on a hot day. In the case of this one I've chosen to make it a pull through rather than forcing air through the cooling pad because I'm limited on space on the outside in case I ever want to close the dungeon doors and go out of town visiting. The way this work is by pulling air across the damp pad which works the same way and most of it will be inside rather than outside. The way I have this first part setup is that it also sucks the hot air off of the sealing and pushes it outside at the same time. (Hot air rises, cool air falls) So... the cool air being sucked through the dampened pad goes down and the hotter air goes up and is removed. On an Evaporative AC this is a must or the air just keeps getting more and more humid and the cooling effect drops off a bunch.

I've taken a cheap plastic mixing bowl and cut the bottom out of it to mount the fan where it will blow through it. I cut a hole through the upper part of the dungeon front (the part I built and without modifying the container in any way) for it to discharge through. This sucks fresh air through the blue pad (which is an evaprative cooler pad) which I dampen every so often. I used another cheap plastic mixing bowl on the outside with the side cut out of it and facing down to allow the discharged air to escape, to keep rain from coming through the hole and to keep direct wind from hampering the fan.

Next step will be to build an enclosure with a pan in the bottom to mount the evap cooling pad in and add a pump which will drip water through the top of the pad to keep it wet. Then it will run down through the pad and the water that doesn't evaporate will be cooled by the water that does. That cool water will be circulated through something like a car radiator and air will be drawn through it to further the cooling effect of the cooler.

I'll also be adding a second fan in front of the cooling pad and radiator to force more air through the system. For now this is running off of the solar battery charger only so it isn't draining any batteries or costing anything to run. At night and on cloudy days it will have to be switched to battery power. but the fans draw a very small amount of current so no big deal.

Hope I didn't loose anyone here?

UPDATE
  Had another neighbor visit today (Buddy Crawford) and he brought along a 55 gallon water barrel so my storage capacity just jumped by a bunch ! He said he has another one he will bring the next time he comes this way so that will make it even better. Buddy reads this and John's blogs, but I guess never posts. Thanks much Buddy!

27 comments:

  1. Looks good and glad it works well too! Your commentary followed real easy as well. Should make it much more comfortable when you have to be inside and for sleeping. Have a great one, Pepper goes to the Doc in the morning for shots and to be fixed, so hopefully you'll get her by the end of the month.
    Good night

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  2. brilliant!!! I so happen to have an extra pump just for that use its the eco 132 submersable pump that runs on 10 watts.

    Its extra and it didnt cost that much in the first place so give me your mailing adress and I'll send it to you.

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  3. I've also got a fountain pump that isn't being used, but I don't have the details here. I'll check it out this weekend when I get home and let you know. Nice writeup.

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  4. I appreciate the offer guys, but I need a low wattage 12 volt pump. Those are 120 volt pumps. I'm thinking along the lines of a generic windshield washer pump.

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  5. great Idea! I imagine their should be a few junk cars out there somewhere who wouldnt miss a windshield pump.

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  6. OGT, I'll probably have to wait until I go to Alpine next time and get a new one at AutoZone. The only place I've found down here with lots of vehicles has No Trespassing signs at the road to it and I don't want to get shot. I'm still having trouble finding scrap wards and junk yards down here.

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  7. BTW... first snake sighting of the season was yesterday by my neighbor down the hill. He said it wasn't a rattler, but he didn't know what kind. I'd figure a gofer snake. Of course if those are out the rattlers are probably out to.

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  8. Just updated the thread with a picture of my new water barrel. It can be used for drinking water and he said he would be bringing another one so I should have plenty of storage. I'll still want to get one of the 250 or + tanks for water catchment though.

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  9. Great to hear the news on the potable water barrels, will make it easier to look for a catch tank. I'm still hoping to be able to bring you one when we bring Pepper out, just need to find a food grade one local. Have a good day.

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  10. Don't know what a windshield washer pump costs (although I've heard they aren't great for sustained duty), but you might want to check out something like this, if the output is adequate:

    http://www.siliconsolar.com/replacement-12v-solar-pump-p-103.html

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  11. Dale, that should insure that both Pepper and I have plenty of drinking water. Speaking of Pepper I wonder how she will handle this place. Buddy said his two shepherds didn't even want to get out of the back of his PU when they got here.

    Rover, thanks for the link. Unfortunately they don't give the wattage on there anywhere that I can find. I don't know how well a windshield washer pump would hold up either.

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  12. Speaking of pumps I don't think the electric washer pump would flow much. Thinking outside the box maybe a generic electric FUEL pump would work and have a decent flow rate. Just a thought...

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  13. Really if you think about it, you don't need all that much flow, if all your intending to do is keep the pad damp. It wouldn't necessarily have to keep it completely saturated, would it?

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  14. Depending on the fuel pump they are high wattage and high pressure. Even the old style for non injected engines are power hogs. The wind shield pumps would do the trick for what I want to do at relatively low watts, but they probably aren't build for constant use so that probably wouldn't be a good choice either. The fountain pumps would probably work well, but I'd need to know the wattage they pull.

    When I have guest I could make them stand outside and spray the pad down with a spray bottle of water, but then I'd have to take that chore up when they left. I wonder if I could train Pepper to do that? ;)

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  15. Some reason I doubt that! Rhonda said she doing a good job of walking right now, she's got one of those funnels on to keep her from messing with anything. She's barely lifting her head up right now.

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  16. I can relate to that. I remember wearing a neck brace for 8 weeks and that thing nearly drove me crazy!

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  17. You explained that real well. Even I could follow it ;-) Thank you for taking the time.

    Buddy and Millie are First Rate folk. I am glad you got to meet Buddy. They also have a couple of yahoo groups where some of us go to chit chat.

    Kathleen

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  18. Good write up David. I like the way you use stuff that we all have lying around and give it a different spin.

    I am so glad you are getting to meet your neighbors and that they such nice people. There is nothing like having good neighbors.

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  19. Just a possibility but not sure though. someone told me that IRVIN has a few old junk cars and he let someone else go get something from them. I dont know if you know who I am talking about( guess he lives down the road from the kosmic place. but if you do you might ask him , and he might say yes to you grabbing a windshield washer pump off one of his cars. Just abounch of iffffs to go on. sorry I couldnt be a better help.

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  20. Kathleen, Yes Buddy is a great guy, but I haven't met his better half yet. I'm sure the same holds there to. When I get the chance I'll pay them a visit. I tried one of the Yahoo groups, but there was far too much bickering for me to deal with (especially by the Yahoo email) I only checked it every few days and would have hundreds of messages in my inbox. I may just start logging in and skimming through it though.

    MsB, Got to use what I have around here as much as I can. If it will do for what I need it to do then I'll use it. I can always get another pack of the mixing bowls when I go back to Alpine. Don't think a pack of 5 cost over $5. They can come in pretty handy for a lot of things besides what they were made for.

    OGT, I could use a 110 volt pump for starters, but that would mean running it off of an inverter which I don't really want to do because when I go on a power conservation kick I turn the inverter off when I don't need to be online and don't need the power. If I run everything dealing with the AC on 12 volts and low watts then a couple of the harbor freight solar battery chargers will take care of everything on sunny days and not much drain on the battery at night.

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  21. David....if I read your post right, you are gonna be pushing air through the pad. After 30+ years in the business, pulling (underline pulling) air through the pad is much more efficient for evaporative cooling. Hope ya got it up and running when I get there. Also, in your case, a reservoir above the drip tray with an electronic float switch to run the pump would save running the pump continuous.
    Just a thought.

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  22. The float switch in an upper resevoir with the switch wired into a small fountain pump is an excellent idea which would save on pump life as well as power use. The switches are easy to install and are found in many marine stores, as well as on EBay:

    http://www.opentip.com/product_info.php?products_id=1022685

    http://cgi.ebay.com/New-Liquid-Water-Level-Sensor-Horizontal-Float-Switch_W0QQitemZ390182527531QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item5ad8b0e22b


    http://cgi.ebay.com/ebaymotors/BILGE-PUMP-FLOAT-SWITCH-FOR-BOAT-20AMP_W0QQcmdZViewItemQQhashZitem3a59bdf1e1QQitemZ250613723617QQptZBoatQ5fPartsQ5fAccessoriesQ5fGear

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  23. BB, no you read me wrong. Both fans will be sucking through the pad. Only way to go for an evap (as you pointed out) Only difference is that the fan (In front of the coil/radiator) will be mounted on the AC its self where the other one will stay mounted where it is to exhaust the heat near the roof out. The idea about the float is a good one, but it wouldn't work when I add the second stage because that will require the pump to run continuously.

    Rover, see the above. I'll check the links for the heck of it.

    Now where I got the idea for the second stage isn't my idea and may or may not still be used on some high end evaporative coolers, but the problem when they first came out was that in areas with water with a lot of minerals in it they clogged up the second stage real quick and required a lot of maintenance because of that. The same will go for here (until I can get a water catchment setup) because rain water shouldn't cause that problem.

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  24. You know, you might want to look at a thicker ply tire and have that old bird ready for anything you throw at her. Drive train will take it for sure. She’s working now, being a sleeper don’t count no more.

    I think your evaporator cooler is going to be the cat’s meow for sure. You might not need to do nothing more than put a little timer on it just to drizzle a little water over it ever now and again. Moving damp air will make a great difference. I miss the old attic fans we use to use. That is about what your little discharge is doing. Great Stuff!

    Might think of them pallets for a gazebo over the door, could last a little longer than the tarp. You could always roll a tarp over it for full shade when the wind does stop. Just take it taller than the dungeon and put the corner post behind the door swing. Only problem might not be able to swing straight back 90 degrees. Might work, just a thought.

    We signed away 30 more years today. Let you know when I do a write up on it. Sure excited, it’s big!

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  25. Tigger, 30 more years? Wow! Glad I wasn't the one signing that mortgage! Hope it turns out good for you'll.

    Check list here complete because it looks like the bottom is going to drop out here. Sure wish I had water catchment setup! I'd probably be able to clean up if it keeps coming this way. I think I have everything rain proofed outside but the trike and it can deal with it the best if can. Didn't have anything left to cover it with. Robert (my neighbor) came up with a good idea on keeping the roof of this thing cooler back in hot weather. I was afraid the wind might blow pallets off and he suggested stacking rocks on top of them. I've got plenty of those, but figure on getting more blue board and putting rocks on top of it instead. I'll use the pallets for other stuff.

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  26. Thanks for the ideas on shade/overhead cooling. I was thinking - 5 pallets (one on each corner and one TDC) with a shade cloth or tarp over the top would provide both a nice shade and several inch air pocket for insulation on the roof. The corner pallets could be tied to the corners of the container with ropes. Sounds like you won't be doing this, but it should be great for my hootch. If you want to try it on your place, I can contribute the rope.

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  27. Just Me, in case you haven't heard we got slammed hard last night and I'd imagine everyone that has catchment made out like a bandit. Unfortunately I don't yet. We just got hit by another fast and furious wind/rain storm, but it didn't last long. Maybe 15 or 20 minutes. Maybe I'll talk over the pallets on the roof when you get down here again?

    The almost horizontal rain last night wiped out my only other 300 watt inverter and evidently power surges wiped out a lot of modems. My connection was down and so was the Legion so I'm just now getting access again.

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