Home made swamp cooler for about $115.

orchidnickApril 15, 2014

Summer is coming and I need an additional swamp cooler for the warm greenhouse which on a 95F day tops way over 100F. I decided to build my own, here are the components needed:

1) Attic exhaust fan, HD $70
2) 110V to 24V transformer, Grainger $15
3) Electric (24V) sprinkler system valve HD $15
4) 3 Misting nozzles Charley's Greenhouse $15
5) Plywood, 2 x 4s and some PVC pipe

The attic fan has a thermostat. Electricity comes from the source to the thermostat which I set at 85F. From the thermostat it goes to the fan, I spliced into that line and sent one leg to the 110V/24V transformer. From there it goes to the 24V valve which in turn feeds the 3 misting nozzles. A rectangular box is built out of plywood and 2 x 4s, open at both ends. The exhaust fan sits in one end blowing air into the 2' x 2' x 4' box. Air comes from the outside of the greenhouse. The misting nozzles are on the inside just next to the fan. The other end of the box opens inside the greenhouse. The roof of the box slants down a little.

The thermostat needs to sit inside the greenhouse. That's the temperature we want to control. You can see that the line from the thermostat to the fan is only about 1' long. I'll cut that and make it 10' long as I want the thermostat to sit in the middle of the greenhouse close to the roof. That's where it gets the hottest. When it reaches 85F (inside the GH, not outside in the backyard) the fan goes on and the valve opens up to city water which feeds the nozzles. Moist cool air rushes into the greenhouse. The entire contraption sits on the ground and the roof slants down so that any unevaporated water ends up in the gravel instead of causing a grey film on the leaves.

The nozzles will clog with calcium and need to be cleaned every 6 month or so depending on the hardness of your water. They need to be placed in an accessible location with unions so the can be removed for cleaning.

Joe Parker from the Pleurothallis Alliance in San Francisco showed me the one he built, I built one last year for the cold greenhouse which works beautifully. Instead of buying a swamp cooler, I decided to build another one of these things, much cheaper and works just as well.

Here is a picture of the components, except the wood and the PVC pipe. You can follow the flow of electricity from the extreme right of the picture to it's targets. The only other thing missing is the motivation to slap it all together. Maybe that will come later today ----- or tomorrow ----- or the next day. Right now, a glass of wine, some cheese and catching some rays is in order. Its nice to be retired.

Nick

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orchidnick

The cheese/wine combination motivated me and I built the thing. It can easily be done in an afternoon if you have all the parts ready. It's sitting under a bench belching cool moist air into the warm greenhouse. It was not needed today, but the day will come when it will be very much appreciated.

Nick

    Bookmark   April 15, 2014 at 7:43PM
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ashes_of_the_fire(6B)

Very cool! Thanks Nick!

Pun not intended, but I'll go with it!

    Bookmark   April 16, 2014 at 7:31PM
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jane__ny(9-10)

Wish I were handy.

I can open a bottle of wine and cut a piece of cheese.

Jane

    Bookmark   April 16, 2014 at 9:40PM
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petrushka

can we see the pic of the connected working thing?
i've heard of swamp coolers in greenhouses in fl - and was wondering what they were.
now i know! this can be very handy in a lot of places - i am taking notes for the future :).
looks fairly easy jane! bet, you can do it too!

    Bookmark   April 16, 2014 at 10:10PM
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orchidnick

It's under a bench so I can't take a picture right now but I'm going to pull it out as 3 nozzles seem to be too much and I will reduce it to 2. I will take a picture then and post it.

This kind of gizmo works on the cooling effect of water evaporating. It does best in a low humidity environment which is why you pull warm, dry air from the outside rather than treat the humid air inside the greenhouse. It does not work well, or even work at all, in a high humidity situation. In Florida with the high humidity this thing would do poorly and is not recommended.

It uses much less electricity than an air conditioner so homeowners prefer it as it costs considerable less to stay comfortable than air conditioning. Yet in SOCAL you never see them close to the coast but they start popping up on the roofs of houses as you move inland. None visible in Long Beach, every house has one on the roof in Barstow (60 miles inland) where it is hot and dry. This is because of the coastal humidity which defeats it.

Nick

    Bookmark   April 18, 2014 at 9:33AM
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musaboru(Inland Calif.)

Awesome Nick! Cant wait to try this...

    Bookmark   April 18, 2014 at 6:15PM
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orchidnick

Great, I love conversions. The next time the Mormons come calling I'll tell them "Eat your heart out, I converted someone" .Keep in mind it is not the same as a swamp cooler. Both produce cool air but in the swamp cooler the water percolates thorough mesh and only cool air enters the greenhouse. With this thing tiny water droplets are part of the offering. I direct it to the ground so that any unevaporated water stays there. Hence sloping the roof a little downwards to the exit end.

I have had one in operation for a year and there is no evidence of grey residue on the leaves. The plants should not get wet in it's vicinity otherwise you'll experience the grey film. The ground in front of it is pretty wet but the plants on the bench above are not. I know someone in Palo Alto who uses only this for cooling and recommends it as I do.

If it's used often, the wood stays constantly wet so it will deteriorate over the years. It's easily replaced and if it develops a leak no problem, it's not in the living room. I also cover the entry with chicken wire, don't want possum hamburger.

Good luck. I should have some more pictures tomorrow as I feel a surge of motivation coming on to remove one of the misters.

Nick

    Bookmark   April 18, 2014 at 7:47PM
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orchidnick

More details for some one who actually wants to build one. The thermostat is mounted in a suitable location not in the line of fire of the cooler. This is not a thermostat I had to buy, it came with the attic fan.

Nick

    Bookmark   April 21, 2014 at 3:35PM
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orchidnick

Chicken wire covers the air intake to keep little animals out. I wish I could have made it to let rats in but that was not possible.

Nick

    Bookmark   April 21, 2014 at 3:38PM
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orchidnick

The position of the 3 misters. I blocked one of them as I thought they were delivering too much water.

Nick

    Bookmark   April 21, 2014 at 3:40PM
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orchidnick

The system is going with the lid off. If you look very carefully you can see a grey triangular shadow at the orifice of the top mister. The mist is very fine and cannot be seen on the photo except that one spot.

Nick

    Bookmark   April 21, 2014 at 3:45PM
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orchidnick

A view of the mechanical set up. The 110v comes from one of the brown lines and feeds the fan with the other brown line. There is a branch which goes to the 110V/24V transformer on the right. From there it goes to the 24V sprinkler nozzle which turns on the water the same time the fan goes on. The top has a 6" overhang which will keep all this dry. Water comes in from the right and goes to the misters inside the box.

Nick

    Bookmark   April 21, 2014 at 3:51PM
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orchidnick

Since I located this thing under a bench there was no convenient way to get access to the misters for biannual cleansing. I simple added a union so I can disconnect the water and pull the whole thing out.

Nick

    Bookmark   April 21, 2014 at 3:54PM
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orchidnick

It's located under a bench and shoots the cool air into an aisle.

Nick

    Bookmark   April 21, 2014 at 3:55PM
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orchidnick

Don't forget the 'Sun visor' or slant the roof. In any case make sure the plants don't get misted otherwise they'll get a grey film in time. Keeping the unevaporated water on the ground prevents that. The wood stays wet all the time and probably will fall apart somewhere between 5 and 10 years. I know of some one who built one out of plastic and fiberglass materials.

Can't take a picture of it but this thing is blasting out a stream of cool air that is just as good or better than any swamp cooler.

Das is alles, good luck building it.

Nick

    Bookmark   April 21, 2014 at 4:12PM
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orchidnick

A little false enthusiasm there, it is in no way better than a swap cooler which, with a 1/2 HP motor, does put out more air. It is however an inexpensive alternative that should work real well for modest seized greenhouses.

Nick

    Bookmark   April 22, 2014 at 1:49AM
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petrushka

thank you for posting the pics - now it's much clearer how it goes together.

    Bookmark   April 23, 2014 at 3:35PM
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orchidnick

Notice how the 'roof' extends over the left side where the valve etc is. This allows me to water the plants sitting on the bench and all that stuff stays dry.

Nick

    Bookmark   April 23, 2014 at 3:42PM
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