How to lower the temperature

Lately it has been getting up to 95 degrees in my greenhouse. I have a large blower on one side, a ceiling fan overhead, and another fan that sits in my bathroom window that blows air into the greenhouse. So I was thinking about putting in some sort of misting system to lower the temperature. Can someone tell me about this and how you might be using it in your greenhouse. And also maybe you can give me some ideas in keeping the temperature down in the greenhouse. Thanks for your help.

Jesse

When you say "large blower," what do you mean exactly?
When it is 95F in the GH, what is the outside temp?
Do you have shade cloth?

Most of us cool with a combination of shade cloth, ventilation, and mist/fog.

Here is a little light reading on cooling ;-) http://www.igcusa.com/greenhouse_cooling_information.htm

I have been watching Nautical's GH weather data site, and in zone 7 he is keeping GH temps at or just below outside temps with adequate exhaust and misting, without shade cloth, I believe. The pic is a screen shot, I hope it comes out.

Here is some of our past discussion: http://local.davesgarden.com/forums/t/702633/

Can someone explain to me how to set up a misting system in my greenhouse? I think that is the way that I would like to do it but do not know very much about it.

Jesse

I purchased misting nozzles from a GH supplier. There are many places that sell kits. If you have adequate water pressure, they will work quite well without the need of a booster pump. I have city water and the pressure is around 65-70psi, most of the time.

I have the misters up in the peak area of the GH at the opposite end from the exhaust fan. As the temp in the GH rises, the humidity drops, which is important if you are to get any cooling effect from the misters.

I am having some problems with too much humidity, but it has been very humid outside here and I have not started looking for a solution to that yet. My concern is too much humidity may cause some plant issues. I saw what I think I have identified as "grey mold" on the surface of the soil on a couple of the plants I have out there. I need to read up on it more and see what I need to do about it. I welcome any suggestions and all suggestions. :)

Still very new to this, but am just loving it. Hard to get anything else done now, forever out in the GH "putzing" around.

Nautical

Plantcrazii:

http://www.amazon.com/o/ASIN/B0009NES3S/ref=s9_asin_title_1-serq_g1/103-7245592-9713418?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-1&pf_rd_r=1BSPYXJCR1YBP40SYJ0A&pf_rd_t=101&pf_rd_p=278240701&pf_rd_i=507846

Installing a mist system can be very complex. Here is a simple way to get mist that will lower the temp in your greenhouse (so you can stand to work in there). You really dont need a lot of expensive equipment if what you mainly want to do is lower the temperature. You do want to get mist, and not waste water. I have a fairly large hoop house and I don't have electricity. You didn't say what size your green house is. This system you can easily expand by adding more ordinary garden hoses from a multi-hose outlet.

(1) you need a multi-outlet from your water supply so you can use it one hose, and still have another to supply the mist.
(2) you need a light weight 5/8 in or 1/2 in garden hose with standard 3/4 " fittings. Attach it to one of the outlets on your multi outlet fitting. You may want to string this overhead to keep it out of the way.
(3) you need a "mist nozzle". Some standard hose- end nozzles have a mist setting. You can get them at the dollar store. Usually the cheaper ones are better. There may be a simple wire loop prop to hold the hand held nozzle to ON. Set it at the mist setting.
Or, there are screw on brass superfine mist nozzles that you can just attach to your hose instead of the hose-end sprayer nozzle.
(4) Position the mist wherever you want it, usually quite high and over plants that would enjoy the mist. If you have overhead rigging you can drop a chain and hang the hose nozzle from a long S hook plant-hanger. I have a fiberglass ladder, and I just hang the S hook from the ladder, and hook the S hook around the nozzle to keep it at the right position.
(5) You can save water, and also help to avoid fungal problems by using intermittent mist. The link above is to a Melnor intermittent water timer, that is not too expensive, and it does not require electricity.

Today I installed a 2nd hanging mist nozzle, (from a 2nd hose) because I have a lot of drought-stressed plants that needed the extra area of mist. I have one nozzle shooting east accross the width of the the greenhouse, and another opposite it and about 5 ft away from it shooting mist in the other direction.

You could put all of this on a 24 hour timer if you are not working in the greenhouse to turn it on and off.

Good luck. It sure is hot. We have had essentially no rain this spring in West Alabama.

http://www.amleo.com/index/item.cgi?cmd=view&Words=fog

These are the mist nozzles I am using. Dramm Fogg-it solid brass nozzles. They fit a standard hose fitting. You can use click-on fittings. Don't forget to use teflon tape on all screw threads.

This message was edited Jun 13, 2007 5:50 PM

Nautical: The intermittent timer above (or a fancier one) could help with your mold problems. Also make sure you don't have any drips. Use the teflon tape on all screw threads. The plants should not stay permanently wet. Ideally the mist will be a dry "fog" that does not leave water droplets on your plants. I turn my mist on about 10 or 11 a.m. and off and 3 or 4 p.m. This lets the plants dry so that there is less fungus. I just cut back on my mist time, because I am getting mushrooms growing in my plants. No mold though.

Whether you use teflon tape or not may depend on the type of mister system you have. My brass mister nozzles do not leak without the teflon tape, and if teflon tape is used, it cracks the saddles.

stressbaby: Thats interesting information. Some of the vendors recommend using teflon tape even on the plastic specialized mist heads (the kind you punch into 1/4 in tubing). Are the saddles made of plastic? I mean you are threading brass into plastic?

My saddles are PVC. I tried using even just a minimal amount of tape, they still cracked. I don't know what the manufacturer recommends, I got them from Hummert.

Gloria, I have added a cycle timer to the system and it is working much better.

SB - I had the same problem. I experimented with a couple different misting systems. My GH kit from ACH came with a "free" misting system. It also used PVC saddles and brass nozzles. I cracked the first one I tried, with 2 or 3 wraps of tape. I just assumed that I overtightend. I have also learned over the years that not all teflon tape is created equal. :)

Nautical