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BudBag
Thanks Red. I am going ot have to go back to the drawing board. I need to come up with a new cab before my babies get to big!
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blueybong
Redgreenry ~ I've read this thread, but still need your input.
Here's my situation: I'm growing in a 4'X4'X7' tent, which is located inside a spare bedroom. I'll be using a 400W HPS vented hood to flower. I'll run a 6" duct from the vented hood to the exhaust fan(S&P TD-150). From the outside of the tent, I'll connect a 6" 90 degree elbow pointing down and I'll then run another lenght of 6" duct to a Can 33 filter sitting on the floor.
My intake is a 4" pvc pipe that goes through my floor down into the crawl space under my house. I have a 4" 90 degree elbow connected inside laying on the floor. I then connected a 6" inline fan:
http://www.homedepot.com/h_d1/N-5yc...splay?langId=-1&storeId=10051&catalogId=10053
to the elbow and then ran another 3' section of 4" pvc pipe into the bottom of the tent.
I read that the passive intake should be 2X the size of the exhaust, but I didn't want to cut that large of a hole into my floor. So I thought adding this booster fan to the intake would provide enough fresh/cool air to still have negative pressure inside the tent.
I don't have any temps to give at this time because I'm just getting this set-up running.
Any info that you can supply, I'd be grateful!!
Tks!
Here's my situation: I'm growing in a 4'X4'X7' tent, which is located inside a spare bedroom. I'll be using a 400W HPS vented hood to flower. I'll run a 6" duct from the vented hood to the exhaust fan(S&P TD-150). From the outside of the tent, I'll connect a 6" 90 degree elbow pointing down and I'll then run another lenght of 6" duct to a Can 33 filter sitting on the floor.
My intake is a 4" pvc pipe that goes through my floor down into the crawl space under my house. I have a 4" 90 degree elbow connected inside laying on the floor. I then connected a 6" inline fan:
http://www.homedepot.com/h_d1/N-5yc...splay?langId=-1&storeId=10051&catalogId=10053
to the elbow and then ran another 3' section of 4" pvc pipe into the bottom of the tent.
I read that the passive intake should be 2X the size of the exhaust, but I didn't want to cut that large of a hole into my floor. So I thought adding this booster fan to the intake would provide enough fresh/cool air to still have negative pressure inside the tent.
I don't have any temps to give at this time because I'm just getting this set-up running.
Any info that you can supply, I'd be grateful!!
Tks!
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BudBag
I would guess you don't need that intake fan, but I'll leave that to the experts. 
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blueybong
Red ~ here's a couple of pics of my fresh air intake.
Again, your input would be appreciated.
Again, your input would be appreciated.
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blueybong
Yep, I have negative pressure inside the tent. I installed the TD-150 on "high" with no ducting(using CFL's during veg), but will add the ducting once I flower with the vented hood. Then I turned on both the intake & the exhaust fans. The tent looked like it was holding its breath; way too strong. So I'll wire the TD-150 on low and leave the lower flaps of the tent opened. This should allow enough air in to relax the tent a bit 
I'm sure once the vented hood, then 3' of 6" ducting to the exhaust fan. Then out back via a 90 degree elbow, 6' of 6" ducting and finally the Can 33 carbon filter that the pressure will be greatly reduced.
Note: the 4" fresh air intake via the 6" inline fan @ 160CFM Max provides enough fresh air to keep those girls happy, even with pulling in some room air via the lower flaps.
Rock on!
I'm sure once the vented hood, then 3' of 6" ducting to the exhaust fan. Then out back via a 90 degree elbow, 6' of 6" ducting and finally the Can 33 carbon filter that the pressure will be greatly reduced.
Note: the 4" fresh air intake via the 6" inline fan @ 160CFM Max provides enough fresh air to keep those girls happy, even with pulling in some room air via the lower flaps.
Rock on!
Just a word of advise... you would be wise to take off the fan from the intake. If anything at all happens to your exhaust pressure, (fan kicks out, etc...) then the intake fan will instantly start creating a positive pressure situation, and all the funk will start finding every nook and cranny it can to come out...and it will. It only takes a few short minutes of a funky grow to smell up a whole house.
Best to suck through a filter, rather than push into it..but it works.
If your intake fan is an inline, you could stack it together in series with your other fan, and make the work easier. The fan at the intake isn't helping things near as much as it would if it were part of the exhaust.
Best to suck through a filter, rather than push into it..but it works.
If your intake fan is an inline, you could stack it together in series with your other fan, and make the work easier. The fan at the intake isn't helping things near as much as it would if it were part of the exhaust.
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blueybong
Hooiserdaddy ~ thanks for your input. I realize that sucking through the filter is the best method, but unfortunately this was the only safe way to use the Can 33 filter with my tent.
If my exhaust fan did quit working, I would remove the intake fan and use it for the exhaust. And since I'm here everyday, I would know there was a problem before the smell started to migrate outside. Plus a have a Ozone Jr as a back-up.
The main reason for bringing in outside air is to help cool the inside of the tent while flowering, plus adding natural CO2.
Again, thanks!
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guest 77721
The "standard" configuration with a scrubber/vented hood is to locate the scrubber inside the tent connected to the hood, then the exhaust fan. The intakes are passive sized 2x exhaust with the tent running on negative pressure.
Reducing the intake to a 4" duct will certainly reduce airflow so your intake booster fan will be needed.
When you bring in outside air, it has to go somewhere otherwise the room gets pressurized with the airflow being determined by cracks and leaks around doors ad windows. Adding a fan in a window or leaving a window open will complete the air exchange path.
On that thought it might be easier to set up the tent in a "standard" configuraton and mount your fan in a window with a passive floor intake just to change the air in the room.
When you get it assembled, take temperature readings of Intake (ambient), Grow area and Exhaust and we can see what your effective air flow really is.
Reducing the intake to a 4" duct will certainly reduce airflow so your intake booster fan will be needed.
When you bring in outside air, it has to go somewhere otherwise the room gets pressurized with the airflow being determined by cracks and leaks around doors ad windows. Adding a fan in a window or leaving a window open will complete the air exchange path.
On that thought it might be easier to set up the tent in a "standard" configuraton and mount your fan in a window with a passive floor intake just to change the air in the room.
When you get it assembled, take temperature readings of Intake (ambient), Grow area and Exhaust and we can see what your effective air flow really is.
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blueybong
Red ~ thanks for replying! Unfortunately I'm unable to put the Can 33 inside the tent. It' too heavy to mount from the upper supports or to my vented hood. I don't have enough room to put it on the floor of the tent because I'm growing six plants in 5 gallon buckets and there isn't enough floor space.
The reason I cut a hole in my floor to bring in fresh/cool air is because I'm unable to use my window(neighbor is too close), plus I'm using a sun blocking material to prevent any light leaks from inside going out while running my lights 24 hrs per day during the 4 week veg cycle.
Right now the temps inside the tent are 78 degrees. I'm running my AC @ 80 degrees, so the air under the house must be a few degrees cooler.
This isn't the best set-up, but it's what I have to deal with.
I'll get those temps for you this afternoon.
The reason I cut a hole in my floor to bring in fresh/cool air is because I'm unable to use my window(neighbor is too close), plus I'm using a sun blocking material to prevent any light leaks from inside going out while running my lights 24 hrs per day during the 4 week veg cycle.
Right now the temps inside the tent are 78 degrees. I'm running my AC @ 80 degrees, so the air under the house must be a few degrees cooler.
This isn't the best set-up, but it's what I have to deal with.
I'll get those temps for you this afternoon.
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blueybong
An idea came to me after I responded to Red's post.
Find an old window AC unit and completely remove the guts, leaving only the shell. Then I could exhaust out the window and the neighbors would think it's only the AC running.
Time to go to my local scrap yard for some treasure hunting.
Find an old window AC unit and completely remove the guts, leaving only the shell. Then I could exhaust out the window and the neighbors would think it's only the AC running.
Time to go to my local scrap yard for some treasure hunting.
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blueybong
Red ~ I forgot to mention that in another month or so I'll be able to open up the windows in my house. Leaving the grow room door open during the day allows for a some what even exchange. This is how I did my last grow over the winter and it worked well. But I didn't have a scrubber or a 293CFM exhaust. Hopefully all will work out.
Batboy
Member
Red - Maybe this is offtopic to blueybong's posts, but it is my understanding that the configuration to which you refer [filter-->light-->fan-->exhaust] is problematic insofar as odor control is concerned, and that filter-->fan-->light-->exhaust is preferable for ensuring that no odor can escape.
As it has been explained to me, the reason for this is as follows: after the scrubbed air leaves the filter, it must be sucked through duct, into the light and through more duct before it hits the fan and gets expelled. The suction of the fan will create negative pressure in the ductwork and will draw in dirty cab air through any tiny hole/gap/etc. in the ductwork, light and connections (and we all know that no air cooled light is 100% leak proof). By the time the air gets to the fan to be expelled, you have potentially mixed stinky air with the scrubbed air, and you will exhaust odor.
The better configuration, as it has been explained to me, is to position the fan as close as possible to the filter to minimize the chance of any stink being sucked in and mixed with the scrubbed air. After the fan, everything is being pushed through the ductwork (positive pressure), so any leaks in the duct/light/connections/etc. will simply result in some amount of clean air being vented back into the cab, but the air that is ultimately expelled will only be scrubbed, non-stinky air.
FYI - this is based off lots of research and conversations with experienced growers. I have no practical experience of my own with filtering/cooling/exhausting cabs, so I am genuinely interested in others' thoughts about this advice that I have been given.
Thanks
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guest 77721
Having the fan inside the growbox makes all the ductwork up to the filter pressurized. Any leaks in the ductwork will stink up the place. It's always better to suck than blow. When you are scrubbing air, it's sucking like a vacuum cleaner.
I didn't seal up my lightchamber on my first grow in the cabinet cause I was changing lights and such. It sucked air from the growchamber and I fooled my into thinking my filter needed changing.
I didn't seal up my lightchamber on my first grow in the cabinet cause I was changing lights and such. It sucked air from the growchamber and I fooled my into thinking my filter needed changing.
colonelcrackers
Active member
Hey Red,
Hola! I was hoping I could get your assistance. I'm trying to light-trap the intake for the light box in my Rubbermaid. I'm using 6x 23w CFLs, an 80mm computer case rated at 37cfm, with a 3" exhaust. My intake is a 3-1/4" x 4-1/4" rectangular cutout. My idea is this (please excuse my poor drawing)
This will be constructed out of 1/4" thick flat black foam board I found at a Big Box store. It will be approx 3-1/2" tall and 4-1/2" wide to accomodate the pre-cut hole without restricting it. My question is this...by placing the two 1-3/4" x 4-1/2" baffles inside the box to block the light, have I effectively halved the intake? I'm looking to light trap the intake without any restriction while maintaining a degree of stealth (no tissue boxes) and I have no room for a DIY light trap like Blue_Adept's.
I thought this would be a good solution as it would work on the same principle as the 4" darkroom louvers I have on the intakes for the grow area. I would like to place it inside the light box area and attach it to the intake cutout. Any thoughts? As of right now, my room temp is 89*, the exhaust air coming out is 102* and the grow chamber temp at approx 6" below the plexi is 92*. I figured worst case scenario if this does cause a restriction, I could create a box with a 90* bend in it similar to the 2x 3" 90* flat black painted PVC elbows I have attached to the exhaust fan for the light box, just rectangular instead of round.
Much appreciation for all the advice you have doled out here. It's complete awesomeness.
Hola! I was hoping I could get your assistance. I'm trying to light-trap the intake for the light box in my Rubbermaid. I'm using 6x 23w CFLs, an 80mm computer case rated at 37cfm, with a 3" exhaust. My intake is a 3-1/4" x 4-1/4" rectangular cutout. My idea is this (please excuse my poor drawing)
This will be constructed out of 1/4" thick flat black foam board I found at a Big Box store. It will be approx 3-1/2" tall and 4-1/2" wide to accomodate the pre-cut hole without restricting it. My question is this...by placing the two 1-3/4" x 4-1/2" baffles inside the box to block the light, have I effectively halved the intake? I'm looking to light trap the intake without any restriction while maintaining a degree of stealth (no tissue boxes) and I have no room for a DIY light trap like Blue_Adept's.
I thought this would be a good solution as it would work on the same principle as the 4" darkroom louvers I have on the intakes for the grow area. I would like to place it inside the light box area and attach it to the intake cutout. Any thoughts? As of right now, my room temp is 89*, the exhaust air coming out is 102* and the grow chamber temp at approx 6" below the plexi is 92*. I figured worst case scenario if this does cause a restriction, I could create a box with a 90* bend in it similar to the 2x 3" 90* flat black painted PVC elbows I have attached to the exhaust fan for the light box, just rectangular instead of round.
Much appreciation for all the advice you have doled out here. It's complete awesomeness.
G
guest 77721
Hey colonelcrackers!
First, let me tell you that you nailed the ventilation design of the tub. You're running +10*F ambient on the lightbox with +2*F on the growbox. Too bad it's 89*.
Blocking up the intakes with baffels will reduce the airflow somewhat. I have found with a cooltube/lightbox design that you can run the exhaust as high as +30*F without affecting the growbox.
I would try to build the intakes and see what happens. If you measure the temps as you have done you'll know right away.
If you want to do the intakes in PVC piping, make sure that the intake area is calculated right.
First, let me tell you that you nailed the ventilation design of the tub. You're running +10*F ambient on the lightbox with +2*F on the growbox. Too bad it's 89*.
Blocking up the intakes with baffels will reduce the airflow somewhat. I have found with a cooltube/lightbox design that you can run the exhaust as high as +30*F without affecting the growbox.
I would try to build the intakes and see what happens. If you measure the temps as you have done you'll know right away.
If you want to do the intakes in PVC piping, make sure that the intake area is calculated right.
Hey Red,
Hola! I was hoping I could get your assistance. I'm trying to light-trap the intake for the light box in my Rubbermaid. I'm using 6x 23w CFLs, an 80mm computer case rated at 37cfm, with a 3" exhaust. My intake is a 3-1/4" x 4-1/4" rectangular cutout. My idea is this (please excuse my poor drawing)
This will be constructed out of 1/4" thick flat black foam board I found at a Big Box store. It will be approx 3-1/2" tall and 4-1/2" wide to accomodate the pre-cut hole without restricting it. My question is this...by placing the two 1-3/4" x 4-1/2" baffles inside the box to block the light, have I effectively halved the intake? I'm looking to light trap the intake without any restriction while maintaining a degree of stealth (no tissue boxes) and I have no room for a DIY light trap like Blue_Adept's.
I thought this would be a good solution as it would work on the same principle as the 4" darkroom louvers I have on the intakes for the grow area. I would like to place it inside the light box area and attach it to the intake cutout. Any thoughts? As of right now, my room temp is 89*, the exhaust air coming out is 102* and the grow chamber temp at approx 6" below the plexi is 92*. I figured worst case scenario if this does cause a restriction, I could create a box with a 90* bend in it similar to the 2x 3" 90* flat black painted PVC elbows I have attached to the exhaust fan for the light box, just rectangular instead of round.
Much appreciation for all the advice you have doled out here. It's complete awesomeness.
colonelcrackers
Active member
Red,
Thanks for the compliment! I was hoping I had everything right. I took alot of info from your original R2D2 thread, and modified it to work with my location. Unfortunately here in the dirty dirty it gets pretty hot, not to mention that my box is stealth and placed in a room thats not air conditioned. To combat this I chose Mandala's genetics due to their heat resistance and ease of care. I am TOTALLY happy with how my White Satins turned out, and I've just started 3 Sadhus.
I'm running the box 20hrs on/4hrs off with the dark period during the hottest part of the day. When I go 12/12 I will probably run it overnight from 7pm-7am depending on what the ambient temps are like. I may be close to winter time by the time I get the plants cloned, sexed and all. So maybe I'll be able to run the box on during the day and see if I can get some colors out of them, as I've heard Sadhu can purple up in colder temps. Thanks again for the help! Hopefully you can pop in my Sadhu thread eventually (when I get it posted!)
G
guest 77721
One topic that get's left out of ventilation is the effect of light schedule on growbox temps.
A 24/7 schedule in the winter is fine for a basement grow in the winter but a 18/6 or even 16/8 to reduce temps in the summer works fine. Reduced hours means reduced growth rates.
You can grow a plant from seed under 12/12 light. It will mature when it's ready with no big issues. I did this on my last grow and had a great grow.
A 24/7 schedule in the winter is fine for a basement grow in the winter but a 18/6 or even 16/8 to reduce temps in the summer works fine. Reduced hours means reduced growth rates.
You can grow a plant from seed under 12/12 light. It will mature when it's ready with no big issues. I did this on my last grow and had a great grow.
M
MicroDude
vent question
vent question
Can I get a little advice on my ventilation? I am building a NGB style cab. I have a S&P TD-100
vent question
Can I get a little advice on my ventilation? I am building a NGB style cab. I have a S&P TD-100
- Item: Duct Fan
- Type: In-Line, 2 Speed Mixed Flow
- Fits Duct Dia. (In.): 4
- Inlet and Outlet Dia. (In.): 3 7/8
- CFM @ 0.000-In. SP: 101/97
- CFM @ 0.125-In. SP: 85/81
- CFM @ 0.250-In. SP: 57/51
- CFM @ 0.375-In. SP: 19/16
- Max. Inlet Temp. (Deg. F): 104
- Voltage: 115
- Hz: 60
- Phase: 1
- Max. Amps: 0.45
- Max. Wattage: 26/23
- Motor HP: 1/25
- Motor RPM: 2500/2450
- Motor Enclosure: Totally Enclosed
- Bearing Type: Ball
- Housing Dia. (In.): 5 7/16
- Length (In.): 6
- Flange Width (In.): 1
- Speed Control: 1DGV1
disfunktional
Member
iv got what might seem like a weird question. i know that if you put 2 fans side by side that you double the cfm, and if you stack 2 fans you reduce the static presure by half. so my question is what happens if you put 2 stacked fans next to 2 stacked fans? would you end up with twice the cfm with half the static presure? and 1 more question. if you put 3 fans side by side by side would you then triple the cfm? if it does work that way i may try smaller cfm fans. i know it sounds like alot but if it does work that way and i use that setup then you will understand why i want to try this when you see it. peace
