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greenhouse Greenhouse coolling on a budget
- Thread starter SentencedToBurn
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Yeah mate scroll down about half way on the 1st page - I found a replacement.willard3 said:
I just finished setting everything up, feels like its working quite well. The thermostat isnt hooked up yet but I'll sort that out once it arrives in the mail.
The twin fan extractor - the foil pipe is the intake which goes under the greenhouse to suck cold air in:
This is the pipe that goes under the greenhouse (I didn't want to make unnecessary holes in the greenhouse so dug a hole instead):
The intake, its filtered and is pointing down so shouldn't suck up any water. Plus its in a really sheltered spot and is about 2 inches off the ground.
Exhaust: this is on the other side of the greenhouse and is close enough to the top to vent out hot air.
Hopefully this will be enough to keep this from overheating during summer. I'll set the thermostat at about 28C and will see how effective this setup is.
The twin fan extractor - the foil pipe is the intake which goes under the greenhouse to suck cold air in:
This is the pipe that goes under the greenhouse (I didn't want to make unnecessary holes in the greenhouse so dug a hole instead):
The intake, its filtered and is pointing down so shouldn't suck up any water. Plus its in a really sheltered spot and is about 2 inches off the ground.
Exhaust: this is on the other side of the greenhouse and is close enough to the top to vent out hot air.
Hopefully this will be enough to keep this from overheating during summer. I'll set the thermostat at about 28C and will see how effective this setup is.
Im not sure dude. I did block off the intake with my hands and i could feel it sucking the air pretty full on. With the exhaust - I switched it on before I installed the vent and the sliding door actually bulged out slightly to let the excess air out. So it definitely has some push. Thats about all i can say.willard3 said:
tube axial fans tend to produce decent static pressure numbers.
i disagree that you need a fan capable of a half inch of static pressure btw.
half an inch static pressure is alot, its close to what a well designed duct system in a house would experience. this is with the evap coil, filter, and 10's of feet of trunk, and run out duct.
not necessary for a greenhouse.
this could be the case if you needed to move air through extensive duct work, or evap coolers, but just for a gable vent type of situation? most definatly do not need something rated at .5 w.g.
edit: your air intake deal is worrisome to me.
mostly because it looks ghetto, in an otherwise very cool and nice looking greenhouse, but also because it could condense moisture.
you basically made a u-trap, and placed it in contact with the ground, where temperatures could drop well below the dew point.
with that said, even in the case you collected any considerable amount of water, i cant see it doing anything more than smelling mildew-y i guess.
whynot place the fan exhaust onto the hole you cut out for the intake? then you would just leave the door open like 2-4" for the intake? you could also drop like 5' of duct. this will measurable increase the air flow.
i disagree that you need a fan capable of a half inch of static pressure btw.
half an inch static pressure is alot, its close to what a well designed duct system in a house would experience. this is with the evap coil, filter, and 10's of feet of trunk, and run out duct.
not necessary for a greenhouse.
this could be the case if you needed to move air through extensive duct work, or evap coolers, but just for a gable vent type of situation? most definatly do not need something rated at .5 w.g.
edit: your air intake deal is worrisome to me.
mostly because it looks ghetto, in an otherwise very cool and nice looking greenhouse, but also because it could condense moisture.
you basically made a u-trap, and placed it in contact with the ground, where temperatures could drop well below the dew point.
with that said, even in the case you collected any considerable amount of water, i cant see it doing anything more than smelling mildew-y i guess.
whynot place the fan exhaust onto the hole you cut out for the intake? then you would just leave the door open like 2-4" for the intake? you could also drop like 5' of duct. this will measurable increase the air flow.
maby in a wildly stratified environment, but it dosent matter appreciably in this case.Swampy_NZ said:If I read correctly you are sucking in cold air and letting the hot air exhaust passively?
You should always exhaust hot air with the fan and let the cold air come in passively.
otherwise looking good.
many greenhouses blow in fresh air via a polyfilm duct, whereby holes are cut to allow air to jet out sideways.
they are pumping cold air up and to the sides, whereby it convects, falls, mixes with hoter air, and equilibrates.
Hey thanks for the suggestions guys, yeah I'm still thinking whether to move things around while I'm waiting for the thermostat. I did do a trial run yesterday and the temperature dropped to the ambient temperature outside pretty quickly but I do agree the u-trap that I made running the pipe under ground might cause issues so I might cut a second hole and just set the intake up like that. But yeah will sort this out soon as the temperatures will be rising in the upcoming weeks.
10" fan eh? sounds like you have a monster greenhouse... got any pics you might wish to share?Tank said:
id love to see your setup.
yea flex is mad lossy.willard3 said:
but regarding the system effect on the open exhaust, its not necessarily going to exist.
the fan could be ok provided the fan itself is mounted like 1-2 cross sectional diameters away from the the end of the tube,Or atleast thats the rule of thumb i recall for tubeaxial fans. it looks like its mounted way back, behind the splitter...so yea the splitter itself will create some turbulence too.
anyway... it looks as tho its setup to exhaust across that nasty splitter.. so im guessing the system effect, if it is even measurable, is quite negligible in comparison.
damn, how do you keep the door from blowing off the hinges running a 10" fan? whats the HP on it?Tank said:Its not much of a monster with 150 sqft floor area
still would like to see some pics lul.
lol i was joking about the door.
so is this fan inflating the walls or what? or perhaps cooling some lights?
so is this fan inflating the walls or what? or perhaps cooling some lights?
interesting. ive seen geothermal systems like for homes, never a greenhouse tho.
A home geothermal system usually involves a heat pump for liquid filled ground loops, plus a heat exchanger and fan. The method i use isnt as complex and has more benefits for plants. The single fan provides greenhouse air cooling, humidity control and air circulation, rootzone heating/aeration/moisture and winter frost protection. I use passive venting to bring in fresh air year round and to help out with cooling towards the end of the season when the soil temperature is higher. Luckily, the sun isnt as powerful so the combination of the fan and passive venting is usually enough to keep up with it.queequeg152 said:
It has paid for itself several times over in the last 5 years thanks to relentless energy price rises.