greenhouse Greenhouse coolling on a budget

SentencedToBurn

SentencedToBurn

This is my attempt at getting my greenhouse ready for summer as I've been told by a bunch of people to sort this out before things warm up. I'll keep adding pics once it's finished in case this actually works, and if it ends up being a fail - this didn't cost me much anyway.
 
My greenhouse is 6'x10' and is about 6' high at the highest point. I looked through the cooling calculators online and it looks like ideally I'd need just over 400cfm of extraction fans.
 
After weighing up my options I ended up going with a bunch of 12V 120mm PC case fans. One of the reasons is that each of these fans are apparently rated at 44cfm while requiring only 0.1A @12V which makes them use 1.2W each. so 8 fans all up gives me 352cfm @ 9.6W of power (apparently). I am using an old PC power supply to run them and it looks like the PSU is taking 0.07 of an amp so that comes to about 17W all up that's being used up (we're on 240V). All up this panel is about 550mm by 260mm.
 
2014_09_16_16_45_42.jpg

 
Anyway, they all seem to run nicely, not sure about 350cfm, it doesnt seem to feel that full on but it's definitely pumping some air through thats for sure. I think I'll be able to tell better once this is installed.
 
I'm yet to make a cover for the outside to shield the fans from the outside, I'm also making a set of louvres to draw the air in from the other side of the greenhouse.
 
 
 
Dude that's awesome. Very good job at using what have on hand.

Remember to keep the inlet area in a nice shaded spot.

:cheers:
 
Hey thanks yeah I have a spot that sits close to the fence and never has any sun on it, plus its in one of the lower panels. And I'll mount the fans as high as possible so hopefully will help remove the hot air first.
 
good handywork bro, i commend you.
but id suggest maby a cheap gable vent insted.

no offense or anything, but using those tiny fans is sorta hopless no? i mean unless your greenhouse is way small.

here in the states you can buy a 1/6" HP axial gable vent for about 50 bucks at the local home depot.

they come with a thermostat too, so they kick on and off, altho in a crude manner.

what i did... was buy said gable vent, and whats called a DUOstat... its a crude membrane based humidistat AND a cheap crude bimetal thermostat.

when the humidity gets high, OR the temperature gets high... the vent powers on.

only issue is, you will need to frame it into place with some 2x4's or 2x2's, tho judging by your handywork here it shouldnt be a problem?

this is an example of what im talking about.

http://www.ebay.com/itm/Air-Vent-Attic-Aire-1050-CFM-Gable-Mount-Power-Fan-53315-/400305962688?pt=LH_DefaultDomain_0&hash=item5d34183ec0

i got the 1600cfm version for like 30 bucks shipped on ebay... im not sure if the same deal is still available tho, and if it is... probably not in new zeland...

anyway it might be worth a look around locally.

ONLY downside is that they spin around 1200 rpm, and are quite loud.
like half a lawnmower loud.
 
Hey yeah I'm not sure it'll be enough but i figured I'd try anyway. That fan you posted looks awesome, 1050CFM will be plenty for what I need, looks like the shipping charges to NZ are a bit more than the actual fan though lol. But I'll have to have a look at something if this doesnt work for sure.
 
I also thought of using a 12V powered radiator fan, they draw up to about 10amps which is easily achievable by this budget PSU I'm using. And they're a dime a dozen. I've checked and even small 10-11" radiator fans give you 650CFM as a minimum, most go up to 1000cfm. So I'll play around with these fans this weekend and will see if there is any benefit in using them or if I should just get a radiator fan to get a decent amount of air movement.
 
Its worth a go for the money especially as its not a big greenhouse. I doubt the array will have enough ummph to get the greenhouse down to the outdoor ambient temperature (the best you can do with exhausting) but it should outperform passive vents.
I went for the unconventional approach in my 150sqft greenhouse which can drop the internal air temp 20F-30F below outdoor ambient on a hot day and raise it 10-15F above outdoor ambient on a cold one.
 
I decided to test it out again after reading your guys posts - it definitely hasn't got enough power. And then I remembered that we had an old house ventilation system that was too gutless to pump heat throughout the house so it was left sitting in the roof for the last couple of years.
 
So that's what I'm gonna be using, its got 2 600cfm fans which draw air through both of those diagonal pipes - I'll mount this thing close to the top of the greenhouse, the exhaust is at the top which I'll run back down under one of the greenhouse walls so I don't have to cut holes in panels. And the intake will be the square louvres thing which I'll run underneath the other side of the greenhouse so the intake is right at the bottom plus that area is always shaded. Will mount it all up this weekend and will post pics. I reckon this will work spot on.
 
2014_09_17_15_23_59.jpg
 
Nice.Should keep things nice and cool.
Are you hooking it up to a thermostat?I got one for $60 from easy grow.   :)
Also get one of those small oscillating fans from Bunnings for $10.That will help keep the greenhouse and even temp all round. 
 
Swampy_NZ said:
Nice.Should keep things nice and cool.
Are you hooking it up to a thermostat?I got one for $60 from easy grow.   :)
Also get one of those small oscillating fans from Bunnings for $10.That will help keep the greenhouse and even temp all round. 
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Hey yeah nah dude I'm gonna get one of these here: http://www.trademe.co.nz/building-renovation/heating-cooling/other/auction-778923888.htm - it just closes the circuit and all sorted. I bougth one a while ago but turns out it was for 110V so just about to get one with the right voltage lol. But for now I'll mount this whole thing up and will just see how quickly it moves things around.
 
 
Nova said:
Yup, that will work!
 
I still like the original panel of fans though. Thing looks cool as.
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haha thanks man. I'll keep that panel for my grow cupboard to move the air around. So far I only had 1 of those fans but it wasnt quite enough. 8 of them will definitely be sufficient.
 
SentencedToBurn said:
Hey yeah I'm not sure it'll be enough but i figured I'd try anyway. That fan you posted looks awesome, 1050CFM will be plenty for what I need, looks like the shipping charges to NZ are a bit more than the actual fan though lol. But I'll have to have a look at something if this doesnt work for sure.
 
I also thought of using a 12V powered radiator fan, they draw up to about 10amps which is easily achievable by this budget PSU I'm using. And they're a dime a dozen. I've checked and even small 10-11" radiator fans give you 650CFM as a minimum, most go up to 1000cfm. So I'll play around with these fans this weekend and will see if there is any benefit in using them or if I should just get a radiator fan to get a decent amount of air movement.
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yea, i figured as much, regarding shipping.

but do you folks have home improvement stores etc? these things are super super common for any unconditioned attic space... with a gabled roof.

the radiator fan is another good idea, very good infact, considering they would probably be designed to tolerate moisture more so that that gable fan.

because of the moisture concern, i had my gable fan set to draw air out, not blow it in. i was worried it would suck in rain etc, during operation.
your radiatior fan, would not merit this concern i imagine.
 
queequeg152 said:
yea, i figured as much, regarding shipping.

but do you folks have home improvement stores etc? these things are super super common for any unconditioned attic space... with a gabled roof.

the radiator fan is another good idea, very good infact, considering they would probably be designed to tolerate moisture more so that that gable fan.

because of the moisture concern, i had my gable fan set to draw air out, not blow it in. i was worried it would suck in rain etc, during operation.
your radiatior fan, would not merit this concern i imagine.
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Hey yeah definitely have a ton of home improvement shops, a few large chains. I actually decided not to go with these fans - have a look above, i found an old heat transfer system that we bought a few years ago but it was too small for my house, so I'm using it for the greenhouse. Will hopefully have it all setup this weekend and will update here.
 
Looks awesome, the only thing I might recommend is a rough-high flow filter on the intake. It isn't necessary but cuts down on dust/insects.
 
A good read over, though it sounds like you've already been researching.
http://edis.ifas.ufl.edu/ae030
 
Sort of back and forth on thermostat controlled fans myself, a lot of fan load in the heat of summer. Though I've no idea about your local conditions. The shade cloth and oscillators already mentioned are a great idea.
 
miguelovic said:
Looks awesome, the only thing I might recommend is a rough-high flow filter on the intake. It isn't necessary but cuts down on dust/insects.
 
A good read over, though it sounds like you've already been researching.
http://edis.ifas.ufl.edu/ae030
 
Sort of back and forth on thermostat controlled fans myself, a lot of fan load in the heat of summer. Though I've no idea about your local conditions. The shade cloth and oscillators already mentioned are a great idea.
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Hey thanks for that yup that makes perfect sense, I'm gonna get that sorted for sure. From what i read it definitely extends the life of the fans so hopefully will last for a few seasons.
 
The stc-1000 is a reliable thermostat, i have a couple and they havent let me down yet. They`ve not got an IP rating (ingress protection) so be sure its well protected from any liquids including condensation. I have mine in a nice dry shed near the greenhouse but it could be a lot further away as the sensor lead can be extended upto a maximum 200ft.
 
Tank said:
The stc-1000 is a reliable thermostat, i have a couple and they havent let me down yet. They`ve not got an IP rating (ingress protection) so be sure its well protected from any liquids including condensation. I have mine in a nice dry shed near the greenhouse but it could be a lot further away as the sensor lead can be extended upto a maximum 200ft.
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Sweet thanks mate. Yup im making up a case that'll hold all the electrical stuff, itll have its own cover just incase condensation drips from the ceiling of the greenhouse, etc. So itll be pretty sweet. Glad they are good thermostats they seem to be pretty cheap over here.
 
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