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liamtheloser
Advanced Idiot

Registered: 06/07/06
Posts: 1,453
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I don't know how big if an area you're planning to vent, or if you're going to be filtering it at all, but if it's just a straight duct of 8 feet it might be fine.
I'd say if you were going to suck through a house filter then blow through a duct and into a garbage can humidifier and then into your GH. Or if you want that to be an option in the future, go with a centrifugal fan.
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CAP_TURTLE
Adventurer



Registered: 03/11/05
Posts: 1,135
Last seen: 5 years, 8 months
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I have a seperate small fan for humidity. I'm just worried about the overall air exchanges. I could pump humid air in with it but I'd need just as powerful a fan to pump it out i'm guessing. A filter may be a possiblilty to filter spores going out but i'm not sure yet if that will be necessary. The ariea though is roughly 375 cubic feet. a 10x 7 greenhouse roughly 6'6" but arcing so its not completely cubed. One of hte 6" inline fans that run 400 some cfm should clear it out in a minute. I'm not sure how i will filter air coming in but it will come together i hope. Thats the reason for the thread
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drake89
Mushroom Magnate



Registered: 06/26/11
Posts: 4,168
Loc: TN
Last seen: 4 years, 11 months
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You could get a recycling timer for the larger fan, and one for your humidifier, or put them both on the same one. Here's some pics of my setup, nothing fancy, but maybe it will spark some ideas. The foggers and fans run 24/7 until I get everything dialed in.
air intake, with 12x12 air filters they sell at warmart, and hydrofarm 6" fan

 other side of the curtain, still working on the ducting, but there's 2 5 head pond foggers in there. I find it actually works better with the lid on the trash can off, but water sprays everywhere.
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nanncee



Registered: 12/01/12
Posts: 434
Loc: Utah
Last seen: 9 years, 2 months
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Re: Greenhouse [Re: drake89]
#18866635 - 09/20/13 08:36 AM (10 years, 5 months ago) |
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Quote:
liamtheloser said: You might end up being disappointed by a bilge fan if you're expecting it to move air through ducting. I'd go for one of the 100 dollar centrifugal fans. Just stay away from ones with words like 'value' or 'eco/economy' in them.
I had a 4x8x4 grow room at one time and it took a 4 inch centrifugal fan to have proper air exchange.
Why? Bilge fans work great for this. I have been running these in my two small rooms for a year with no problems. Although they will not last longer than 6 months or so if they are on 24/7. But at under $30 to purchase and under 30 minutes to install it's not a bad replacement when they do go out.
Not sure I would worry about filtering incoming air, i toyed with this idea for awhile but there just wasn't any benefit. RR and a few others advised against it as well. But if your outgoing air is being pushed into another room that people will be in and out of a filter may not be a bad idea. But be aware it will have to changed/cleaned frequently and it will increase the amount of positive pressure your fan has to overcome.
also you mentioned you have two fans, one for humidity one for air exchange. I don't know where you live but for example here in utah, I couldn't get away with having a fan blowing air straight in my rooms from outside. I have to send all air through my pond fogger box or my humidity would never be high enough with the amount of air exchange needed.
-------------------- I am a small scale farmer, come check out what we do. www.facebook.com/biocentricbros Check out our Youtube videos. www.youtube.com/biocentricbros
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liamtheloser
Advanced Idiot

Registered: 06/07/06
Posts: 1,453
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Re: Greenhouse [Re: nanncee]
#18866868 - 09/20/13 09:37 AM (10 years, 5 months ago) |
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Quote:
nanncee said:
Quote:
liamtheloser said: You might end up being disappointed by a bilge fan if you're expecting it to move air through ducting. I'd go for one of the 100 dollar centrifugal fans. Just stay away from ones with words like 'value' or 'eco/economy' in them.
I had a 4x8x4 grow room at one time and it took a 4 inch centrifugal fan to have proper air exchange.
Why? Bilge fans work great for this. I have been running these in my two small rooms for a year with no problems. Although they will not last longer than 6 months or so if they are on 24/7. But at under $30 to purchase and under 30 minutes to install it's not a bad replacement when they do go out.
Not sure I would worry about filtering incoming air, i toyed with this idea for awhile but there just wasn't any benefit. RR and a few others advised against it as well. But if your outgoing air is being pushed into another room that people will be in and out of a filter may not be a bad idea. But be aware it will have to changed/cleaned frequently and it will increase the amount of positive pressure your fan has to overcome.
also you mentioned you have two fans, one for humidity one for air exchange. I don't know where you live but for example here in utah, I couldn't get away with having a fan blowing air straight in my rooms from outside. I have to send all air through my pond fogger box or my humidity would never be high enough with the amount of air exchange needed.
So for the cost of 3 bilge fans (which are axial fans) you can have a nice centrifugal fan that is designed to work under pressure.
Axial fans, by design, are not good with any pressure.
And a good reason for a filter of some sort on the intake would be to limit bugs (filter in combination with positive pressure inside the greenhouse).
You don't need an intake fan and an exhaust fan either, just let the air escape in its own. Co2 is heavy so just letting air escape through the floor gap will clear it out faster anyway and still allow positive pressure (so that bugs and other baddies can't come in).
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CAP_TURTLE
Adventurer



Registered: 03/11/05
Posts: 1,135
Last seen: 5 years, 8 months
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Ok i'm gonna answer everyone together. I do have the air from the outside getting humidified. It goees from fan into an aquarium then the outlet is inside the gh itself. I'll take a picture eventually. As for letting the air come out on it's own that would mean the humid air would be released into my basement. Last thing I want is 5 full air exchanges of humid air or 120 a day being released into my basement. So it has to go outside. I don't mind air being sucked in from the basement just as long as it's not released down there. Plus for any accidental sporolation etc. i'd rather that go outside as well. I'm going to order a 6" fan since i can tone it down if needed and not hte bilge fan because replacing every 6 months wouldn't be something I'd want to do. Now if i could draw the air outside through passive exchange, that'd be awesome too. but for now to guarantee it goes outside and not inside the fan will be hooked up to the exhaust.
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liamtheloser
Advanced Idiot

Registered: 06/07/06
Posts: 1,453
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So for the exhaust you could do a couple things.
For passive exhaust, you'd have to make the exhaust duct larger, like very large, I don't now how sealed up your GH is, but air will take the path of least resistance. So, under the bottom.
For active exhaust, but still slightly pressurized, get a smaller fan for exhaust. You can find a cheap blower on Craigslist, either centrifugal or squirrel cage. Has to be less CFM than the intake or it'll start sucking dry air into the GH.
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ghiajake
Myco-Viking


Registered: 01/10/13
Posts: 3,864
Loc: Indiana
Last seen: 1 hour, 28 minutes
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I use this GH, www.amazon.com/gp/product/B00B8RAFHM/ref=oh_details_o09_s00_i00?ie=UTF8&psc=1, in my basement and it works perfect. I leave the door flap slightly unzipped and have a room air purifier bringing in fresh air from under the door flap. Cut a couple tiny holes above the door to vent air out.
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nanncee



Registered: 12/01/12
Posts: 434
Loc: Utah
Last seen: 9 years, 2 months
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Quote:
liamtheloser said:
Quote:
nanncee said:
Quote:
liamtheloser said: You might end up being disappointed by a bilge fan if you're expecting it to move air through ducting. I'd go for one of the 100 dollar centrifugal fans. Just stay away from ones with words like 'value' or 'eco/economy' in them.
I had a 4x8x4 grow room at one time and it took a 4 inch centrifugal fan to have proper air exchange.
Why? Bilge fans work great for this. I have been running these in my two small rooms for a year with no problems. Although they will not last longer than 6 months or so if they are on 24/7. But at under $30 to purchase and under 30 minutes to install it's not a bad replacement when they do go out.
Not sure I would worry about filtering incoming air, i toyed with this idea for awhile but there just wasn't any benefit. RR and a few others advised against it as well. But if your outgoing air is being pushed into another room that people will be in and out of a filter may not be a bad idea. But be aware it will have to changed/cleaned frequently and it will increase the amount of positive pressure your fan has to overcome.
also you mentioned you have two fans, one for humidity one for air exchange. I don't know where you live but for example here in utah, I couldn't get away with having a fan blowing air straight in my rooms from outside. I have to send all air through my pond fogger box or my humidity would never be high enough with the amount of air exchange needed.
So for the cost of 3 bilge fans (which are axial fans) you can have a nice centrifugal fan that is designed to work under pressure.
Axial fans, by design, are not good with any pressure.
And a good reason for a filter of some sort on the intake would be to limit bugs (filter in combination with positive pressure inside the greenhouse).
You don't need an intake fan and an exhaust fan either, just let the air escape in its own. Co2 is heavy so just letting air escape through the floor gap will clear it out faster anyway and still allow positive pressure (so that bugs and other baddies can't come in).
Those bilge fans are rated to 1psi according to the manufactures specs. I think the thing that usually kills it is water build up or calcium build up on the walls which causes the fans to scrape and wear out the bushings. i literally just replaced a fan and I believe that is what happened to it. Not everyones cup of tea but for someone with a bit of soldering experience they are a cheap route and locally available when they die.
you could very easily put a screen on your intake to keep bugs out.
I would agree there is no need for an exhaust fan, that is what positive pressure is for. Honestly that's why most peoples fan run 24/7 to keep positive pressure. As mentioned above anytime that fan turns of your going to have air coming back in through your exit. Positive pressure is a must in my opinion.
Definitely don't let that exhaust just dump into your basement. You want to keep that area out of your fruiting room as dry as possible. I see people on here all the time having no exhaust letting the air sit in their house and I just cringe and the thought of the nasty bits growing all over everything.
-------------------- I am a small scale farmer, come check out what we do. www.facebook.com/biocentricbros Check out our Youtube videos. www.youtube.com/biocentricbros
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CAP_TURTLE
Adventurer



Registered: 03/11/05
Posts: 1,135
Last seen: 5 years, 8 months
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Re: Greenhouse [Re: nanncee]
#18869515 - 09/20/13 08:39 PM (10 years, 5 months ago) |
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So if i ran a fan into the setup at a high enough flow to keep up with the air exchanges needed and set up an exhaust with no fan and the border of the greenhouse sealed to the ground, am I to expect that the air is going to be forced through the exhaust and out? Even if its 6 ft long and only 4-6" diameter? And as you say air is going to come back in when its off, so should I only get enough cfm to do 5 full exchanges in an hour while running 24/7? I was thinking there was a piece you can get that when there is no pressure it caps shut then rotates back open when pressure is added. Maybe it's used for chimneys or smoething. I can picture it but not sure what its called.
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liamtheloser
Advanced Idiot

Registered: 06/07/06
Posts: 1,453
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Use a louvered vent and it'll stop it from coming back through. Any dryer vent is louvered or has a flap preventing back flow.
Yes, if your tent is pressurized and sealed, an exhaust will not have to be powered.
An axial fan won't pressurize like that though, so you'd have to use a large centrifugal.
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CAP_TURTLE
Adventurer



Registered: 03/11/05
Posts: 1,135
Last seen: 5 years, 8 months
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Not sure what the difference in axial and centrifugal are. Would a hydro farm fan do the trick? it displaces the area of my greenhouse in a minute. Im still not totally against useing it as exhaust. Even though it could suck in dry air, it'd only run 5 mins out of the hour. It is already sometimes too moist in there so it might fix it.
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CAP_TURTLE
Adventurer



Registered: 03/11/05
Posts: 1,135
Last seen: 5 years, 8 months
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also another question if anyone sees it. The exhaust in the wall is at abnout 6 feet heighth. If using passive or active, would it be best to run the exhaust from floor level up or run it at an even height with wher i'd be running it out the wall?
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liamtheloser
Advanced Idiot

Registered: 06/07/06
Posts: 1,453
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Axial is a typical "fan shape". Meaning fan blades. A centrifugal fan is much different. It is impellers rotating around the center pipeline. Basically it creates a vortex that moves air instead of trying to chop the air up.
It won't matter what height on the wall you're exhausting at, because pressure will force the air through the path of least resistance. Either way the air has to travel up and out or straight out. It's the same.
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drake89
Mushroom Magnate



Registered: 06/26/11
Posts: 4,168
Loc: TN
Last seen: 4 years, 11 months
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Quote:
liamtheloser said: Use a louvered vent and it'll stop it from coming back through. Any dryer vent is louvered or has a flap preventing back flow.
Yes, if your tent is pressurized and sealed, an exhaust will not have to be powered.
An axial fan won't pressurize like that though, so you'd have to use a large centrifugal.
Quote:
CAP_TURTLE said: Not sure what the difference in axial and centrifugal are. Would a hydro farm fan do the trick? it displaces the area of my greenhouse in a minute. Im still not totally against useing it as exhaust. Even though it could suck in dry air, it'd only run 5 mins out of the hour. It is already sometimes too moist in there so it might fix it.
i use the 6" hydrofarm fan running 24/7 on a 2000cuft room. So maybe you should find one that has an appropriate rating to run all the time like you were saying? I run a 4" dryer duct out one of the walls to outside. Only thing is, you got to make sure you're not going to blow the cover off your greenhouse! I don't know how yours is put together.
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CAP_TURTLE
Adventurer



Registered: 03/11/05
Posts: 1,135
Last seen: 5 years, 8 months
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Re: Greenhouse [Re: drake89]
#18873697 - 09/21/13 08:22 PM (10 years, 5 months ago) |
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Is your duct from the bottom or top of the side of the greenhouse?
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CAP_TURTLE
Adventurer



Registered: 03/11/05
Posts: 1,135
Last seen: 5 years, 8 months
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I belive i've read that having drops and rises in humidity is good for initiating pinning and i know the 6" is only like 10 dollars more than the 4". So i may test running it one minute every ten minutes and if that doesnt work then adding a speed regulator on the fan. That way too if I later get a bigger greenhouse, i will still have something that does the trick.I'm also still debating on rather to run it as the air intake or exhaust. If I run it as the exhaust I'm guaranteed the air is going to go out the exhaust where as I run it as the intake I have every possible seam having pressure as a possible outlet along with the proper exhaust pipe. Is hydro farm the standard leader for affordable inline fans? Or is there any other brands at the same price considered superior.
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deadmandave
Slime


Registered: 02/16/10
Posts: 3,368
Loc:
Last seen: 2 days, 8 hours
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btw might i ask how you would regulate the fan speed?
my fan has a capacitor so i believe i should not use a rheostat; but i want to use less energy on the fan and keep it running 24/7 low speed. as it is right now i have it on a cycle timer.
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drake89
Mushroom Magnate



Registered: 06/26/11
Posts: 4,168
Loc: TN
Last seen: 4 years, 11 months
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Quote:
deadmandave said: btw might i ask how you would regulate the fan speed?
my fan has a capacitor so i believe i should not use a rheostat; but i want to use less energy on the fan and keep it running 24/7 low speed. as it is right now i have it on a cycle timer.
you need one of the expensive motor controllers. hydrofarm sells them, there may be a cheaper option. i think they operate on PWM (pulse width modulation) or something. You CAN use a light dimmer but it won't work well and it may fuck up your fan in the long run.
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nanncee



Registered: 12/01/12
Posts: 434
Loc: Utah
Last seen: 9 years, 2 months
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Quote:
liamtheloser said: Use a louvered vent and it'll stop it from coming back through. Any dryer vent is louvered or has a flap preventing back flow.
Yes, if your tent is pressurized and sealed, an exhaust will not have to be powered.
An axial fan won't pressurize like that though, so you'd have to use a large centrifugal.
I'll say this again, axial fans WILL allow positive pressure to build. Not that they are the right fit for this job, just don't spread misinformation.
Quote:
deadmandave said: btw might i ask how you would regulate the fan speed?
my fan has a capacitor so i believe i should not use a rheostat; but i want to use less energy on the fan and keep it running 24/7 low speed. as it is right now i have it on a cycle timer.
Check out these. Pulse Width Modulating Speed controller. It's what I use to controller my DC fans.
http://www.ebay.com/itm/12V-40V-10A-Pulse-Width-Modulator-PWM-DC-Motor-Speed-Control-Switch-Governor-New-/271281206593?pt=LH_DefaultDomain_0&hash=item3f299eb541
-------------------- I am a small scale farmer, come check out what we do. www.facebook.com/biocentricbros Check out our Youtube videos. www.youtube.com/biocentricbros
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