Negative Tent Pressure - Growroom Designs & Equipment - International Cannagraphic Magazine Forums

Zeez · 07-16-2017, 05:21 PM

Hi Everyone, I need some advice. This is a 5x9 tent with two carbon filters, one recirculates, and one exhausts. They run on re-cycle timers. The portable 10,000 btu a/c and dehumidifier vent hot air outdoors. There is a third fan on full time that pulls outside air into the tent.

The problem is that there is always negative pressure in the tent and there is concern that the a/c and dehumidifier will not get adequate cooling from short supply of air. Should I just add another fan pushing air into the tent? Or, is there a better way to get this done? Thanks.

bigganjabud · 07-16-2017, 06:23 PM

Wtf a recirculation carbon filter?
What gave you that idea

ALL that aside all tents are supposed to have negative pressure as it stops botritis and also means the smell is getting taken out quickly rather than just stagnant air and odour mate

The recirculation carbon filter is a waste id swap with a desk fan

I ain't roasting you man

Seriously I'd do a bit more research if I was you bro look in the grow room design section

bigganjabud · 07-16-2017, 06:24 PM

Oh and from the diagram I'd swap the side the extract is on aswell

Ie opposite the intake

Zeez · 07-16-2017, 06:40 PM

The recirc fan through the second filter goes on for 20 minutes ever two hours. It keeps the smell down when exhausting through the other filter. It was pretty stinky outside until doing this and the ac exhausts unfiltered air. It works. A room with a mini split eliminates all this I know. Maybe some day.

GOT_BUD? · 07-16-2017, 09:25 PM

Quote:

Originally Posted by bigganjabud

Wtf a recirculation carbon filter?
What gave you that idea

ALL that aside all tents are supposed to have negative pressure as it stops botritis and also means the smell is getting taken out quickly rather than just stagnant air and odour mate

The recirculation carbon filter is a waste id swap with a desk fan

I ain't roasting you man

Seriously I'd do a bit more research if I was you bro look in the grow room design section

Recirculating carbon scrubbers are fairly common, especially in a closed system.

sdd420 · 07-16-2017, 10:54 PM

Negative pressure is good

Chunkypigs · 07-16-2017, 10:57 PM

Quote:

Originally Posted by Zeez

View Image

Hi Everyone, I need some advice. This is a 5x9 tent with two carbon filters, one recirculates, and one exhausts. They run on re-cycle timers. The portable 10,000 btu a/c and dehumidifier vent hot air outdoors. There is a third fan on full time that pulls outside air into the tent.

The problem is that there is always negative pressure in the tent and there is concern that the a/c and dehumidifier will not get adequate cooling from short supply of air. Should I just add another fan pushing air into the tent? Or, is there a better way to get this done? Thanks.

it shouldn't hurt your appliances in there, if the pressure goes positive then you are forcing unfiltered air out of the tent.

why are you stressing on the smell now that we are legal here?
my house is a dank festival with 2 lights just harvested and drying.

Zeez · 07-16-2017, 11:13 PM

Quote:

Originally Posted by Chunkypigs

it shouldn't hurt your appliances in there, if the pressure goes positive then you are forcing unfiltered air out of the tent.

why are you stressing on the smell now that we are legal here?
my house is a dank festival with 2 lights just harvested and drying.

No stress really, keeping it on the down low. There was plenty of house dank here. Drying tent helped allot too.

Raho · 07-24-2017, 05:58 AM

Have a speed controller on the exhaust fan and adjust it until you have just the right amount of negative pressure you need, no more. Problem solved.

I love the hyperfan line, comes with it's own controller, cheap, light, quiet and powerful.

Fitered recirc is smart. Well done Zeez.
Cops aren't the only people interested in a house of dank.
Being discrete is always a good idea.

Doesn't your exhaust from the dehu send out "dirty" air?
Seems you'd be better letting your AC handle that heat.

Unrelated question, but have you built a filter box on your intake air to keep out mold spores, insects and other undesirables?

Zeez · 07-24-2017, 01:18 PM

I think you nailed it. Throttling air being pushed in to get the right amount of negative pressure would be optimal. All fans used so far get flat spots and are reliable only on full speed, a better controller or fan would fix that.

The recirc scrubber is the only way to go. It works. I have used several big filters on exhaust fans that do nothing more than share the dank. Both the dehu and a/c exhaust unfiltered air but the scrubber covers it. The hope was that a/c would handle the dehu job too, but a separate dehu was needed. Had to exhaust the dehu heat with the a/c heat. Maybe taking the exhaust carbon filter and making it a second recirc scrubber would be cool. There's plenty of exhaust with the Dehu and a/c.

On the intake air, I get a forced air furnace filter at Depot (dust and pollen) and cut pieces that get taped over the tube.

07-16-2017, 05:21 PM	#1
Zeez Going Deep Join Date: May 2016 Posts: 722	Negative Tent Pressure Hi Everyone, I need some advice. This is a 5x9 tent with two carbon filters, one recirculates, and one exhausts. They run on re-cycle timers. The portable 10,000 btu a/c and dehumidifier vent hot air outdoors. There is a third fan on full time that pulls outside air into the tent. The problem is that there is always negative pressure in the tent and there is concern that the a/c and dehumidifier will not get adequate cooling from short supply of air. Should I just add another fan pushing air into the tent? Or, is there a better way to get this done? Thanks.
	Quote 1 members found this post helpful.

07-16-2017, 06:23 PM	#2
bigganjabud Senior Member Join Date: Sep 2014 Location: In the land of the giants Posts: 3,312	Wtf a recirculation carbon filter? What gave you that idea ALL that aside all tents are supposed to have negative pressure as it stops botritis and also means the smell is getting taken out quickly rather than just stagnant air and odour mate The recirculation carbon filter is a waste id swap with a desk fan I ain't roasting you man Seriously I'd do a bit more research if I was you bro look in the grow room design section
	Quote 3 members found this post helpful.

07-16-2017, 06:40 PM	#4
Zeez Going Deep Join Date: May 2016 Posts: 722	The recirc fan through the second filter goes on for 20 minutes ever two hours. It keeps the smell down when exhausting through the other filter. It was pretty stinky outside until doing this and the ac exhausts unfiltered air. It works. A room with a mini split eliminates all this I know. Maybe some day. Last edited by Zeez; 07-16-2017 at 07:03 PM..
	Quote 2 members found this post helpful.

07-16-2017, 10:54 PM	#6
sdd420 Senior Member Join Date: Sep 2009 Location: Norcal 707 Posts: 1,512	Negative pressure is good __________________ Gypsy is free! dont count the days make the days count Legal medical patient _________ “Make the most you can of the Indian hemp seed and sow it everywhere.” – George Washington "Some of my finest hours have been spent on my back veranda, smoking hemp and observing as far as my eye can see." - Thomas Jefferson "Two of my favorite things are sitting on my front porch smoking a pipe of sweet hemp, and playing my Hohner harmonica.” – Abraham Lincoln
	Quote 1 members found this post helpful.

07-24-2017, 05:58 AM	#9
Raho Member Join Date: Mar 2013 Posts: 464	Have a speed controller on the exhaust fan and adjust it until you have just the right amount of negative pressure you need, no more. Problem solved. I love the hyperfan line, comes with it's own controller, cheap, light, quiet and powerful. Fitered recirc is smart. Well done Zeez. Cops aren't the only people interested in a house of dank. Being discrete is always a good idea. Doesn't your exhaust from the dehu send out "dirty" air? Seems you'd be better letting your AC handle that heat. Unrelated question, but have you built a filter box on your intake air to keep out mold spores, insects and other undesirables? __________________ Raho Everything x oBoy
	Quote 1 members found this post helpful.

07-16-2017, 06:24 PM	#3
bigganjabud Senior Member Join Date: Sep 2014 Location: In the land of the giants Posts: 3,312	Oh and from the diagram I'd swap the side the extract is on aswell Ie opposite the intake
	Quote

07-24-2017, 01:18 PM	#10
Zeez Going Deep Join Date: May 2016 Posts: 722	I think you nailed it. Throttling air being pushed in to get the right amount of negative pressure would be optimal. All fans used so far get flat spots and are reliable only on full speed, a better controller or fan would fix that. The recirc scrubber is the only way to go. It works. I have used several big filters on exhaust fans that do nothing more than share the dank. Both the dehu and a/c exhaust unfiltered air but the scrubber covers it. The hope was that a/c would handle the dehu job too, but a separate dehu was needed. Had to exhaust the dehu heat with the a/c heat. Maybe taking the exhaust carbon filter and making it a second recirc scrubber would be cool. There's plenty of exhaust with the Dehu and a/c. On the intake air, I get a forced air furnace filter at Depot (dust and pollen) and cut pieces that get taped over the tube. Last edited by Zeez; 07-24-2017 at 02:22 PM..
	Quote