My house is impervious to negative air pressure

L

Landing

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Okay, so I brought back my Can-Lite 800 filter and got a brand new one, just for the sake of finding out whether it's the filter being defective or not.

Apparently, it's not.

I have a Max Filter 1000 now and there is still smells. In fact, it's more than before.

You see, I set the fan to the highest settings (880 M3/h) and it started making a whining noise because there wasn't enough air coming into the room, forcing it to suck the air from small holes in the ceiling.

I put hand under these holes and it's like a vacuum, i.e. a ridiculous amount of negative pressure.

So, I decided to open up a medium sized opening to the rest of the house (about the size of a 5" duct), and now I find out that it smells in the rest of the house!

Meaning that wherever the air is COMING from, wherever there is NEGATIVE pressure, there is also positive pressure because my house is impervious to the laws of physics.

So, what does this mean and what do I do?

I could seal up every hole, but then what? I don't have a fan that can deliver 700 M3/h of intake, so the intake has to remain passive. But passive intake means that air comes out of the holes it's supposed to be going into!

No idea how to fix this..
 

MR1

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Pictures would help a lot.
 
L

Landing

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Pictures would help a lot.
Of what?

It's just a room with a ceiling that leads to an attic.

In the ceiling, there is an 8" hole where an 8" duct is installed and attached to an 8" fan connected to an 8" carbon filter.

There are numerous holes in the ceiling that are about 1-2" in diameter. The reason for the holes is that the ceiling is quite thin and the only way to hang anything off of it is to create two holes and run a zip-tie in between.

There is a ton of negative pressure from these holes, as you can imagine, and yet the smell persists..
 

MR1

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You should have those holes in the ceiling plugged. The only air entering the room should be from the bottom of the space opposite of the exhaust if possible. The intake vent should be the same or bigger than the exhaust. Make sure your ducting joints are airtight, and don't over power your filter, try different speed settings.
 

AluminumMonster

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Are you using solid ducting or flex ducting?

Solid ducting has seems all over it that should be taped over.
 

Joe420Camel

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IDK man...
It seems you understand the physics and logic behind all this
and
without being there, I'm not sure I can be much more help

I guess invest in a tent (or DIY something) is my best suggestion @ this point
anything to channel airflow over/through/past plants and then directly through a fan/filter

wish I had more ideas for ya

good luck
 
L

Landing

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Ok, pictures.



This is the aforementioned fan and filter, with the holes I drilled into the ceiling (which lead up to the attic) to mount them. There are two more holes to the right, off the picture. Basically, I drilled a series of holes in the ceiling to mount whatever it is I needed to mount as I went along. I didn't think this would be a problem, because the negative pressure in the room would pull the air out of them anyway and would provide some passive intake.



The duct exhausts into the attic as well. The attic extends over my apartment and into the stairway, where there are two large vents. I suspect this is where the smell in the stairway is coming from.



This is the vent that was previously sealed, but because the negative pressure in the room got so high I opened it up with the hopes of providing some more passive intake and aleviating the strain on the fan, which makes a whining noise under stress. That worked, but now some parts of my apartment smell, as I suspect this vent leads to other vents in the house (probably as part of my apartment's central air conditioning system). I just can't figure out HOW that is possible, considering the air should be coming out of them, not going in.



Some more holes in the ceiling, used to mount this light, which is above my plants.



The plants, all eight of them, are not sealed in a tent or anything, they simply sit in this corner of the 20 M3/h room.

Other points:
1.) The duct itself cannot have a leak, because it is insulated.
2.) I am positive that the smell is coming from us, because I conducted a short experiment in which I moved all the plants to the bedroom and shut the door. The entire apartment reeked, but the smell in the stairway positively vanished.
3.) It is not a defective filter, as I just returned the old one and bought another.
4.) The smell in the stairway is actually quite peculiar, in that it is one small spot only, and on the first floor, whereas I am on the third floor. There is never any smell right outside my front door, or anywhere else but in that one spot on the first floor. It's also harder to smell it when you're walking *down* the stairs, only when you go *up,* (I have no idea why) and though it is brief, it is distinctive and noticeable.

I am on my wit's end. I am considering getting some ONA gel (though it is expensive in my country) to provide a temporary fix while I figure out a permanent one, but I don't know how/if it would work in an entire room. Maybe if I place it inside the exhaust duct? Do I have any temporary options?
 

AluminumMonster

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I think you should put your fan at the other end of the ducting, just below where it vents in to the attic. Leave the filter where it is. Tape all joints in the ducting. Generally the setup goes: Filter--A/C Hood--Fan exhausting.
 

MR1

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I think you would have better odor control if you made some walls around the space so it is enclosed, or get a tent instead of filtering the whole room.
 
L

Landing

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I think you should put your fan at the other end of the ducting, just below where it vents in to the attic. Leave the filter where it is. Tape all joints in the ducting. Generally the setup goes: Filter--A/C Hood--Fan exhausting.
Why would placing my fan on the other end of the ducting change anything?

I think you would have better odor control if you made some walls around the space so it is enclosed, or get a tent instead of filtering the whole room.
But if I did that, the fan would blow it out like a bomb. That's an 880 M3/h fan in what would be a 3.5 M3/h area.
 

samarta

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Not familiar with your construction but I would jack that duct right to the bottom of a whirly bird on the roof and shoot it right out of the house. You may be pouring more into the attic than it can dissipate and naturally escape. If you are in an apartment you may have to grow less but more frequent. Just one possibility from someone trying to help.:confused2:
 

samarta

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If you open a nearby window, if just a crack, you will get flow, fresh flow, and leave open as those babes love the circulation. Especially with 8, I would be reluctant to close. If it is cold, you could close the door to that room.
 

AluminumMonster

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Why would placing my fan on the other end of the ducting change anything?
I don't know the exact physics of why pulling is better than pushing.... I do know my vacuum does a better job of cleaning than my leaf blower, it's the same principal. As it stands your setup is acting like a leaf blower and is blowing stinky air everywhere, now move that fan to the other end of the line and you're now vacuuming the stinky air. I can't explain it any simpler than that.

The four pictures below show, in order, how one of my fans is set up. Keep in mind that I have 33 flowering plants in that room and I can't smell anything outside of the room. I actually had cops (some punk was running away from them) standing 4' away from my exhaust and they didn't smell a thing.

Go ahead and leave it like it is.....if you want to go to jail.

View attachment SAM_1528.jpg

View attachment SAM_1529.jpg

View attachment SAM_1530.jpg

View attachment SAM_1531.jpg
 

samarta

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Quite elaborate Aluminum Monster. You look like a house rather than apartment, and that makes it a little easier. You're set up for the volume, and correctness is vital. IMHO 8 is too much for an apartment. You have shared attic space and I am surprised others are not smelling inside their apartments. Be careful Landing!!!!!!!!!!!!
 

MR1

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Why would it blow out like a bomb? you are supposed to be sucking air from the area not blowing in. Your fan is in the 400cfm range which is not that big, do you have a speed controller on your fan. The only way you will solve your problem is to give your plants their own space that you have better control of the environment.
But if I did that, the fan would blow it out like a bomb. That's an 880 M3/h fan in what would be a 3.5 M3/h area.
 

orangesunshine

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imo---seal up that vent and all the holes you drilled for hanging stuff pronto---make new passive intake air holes furthest distance from the new filter location---get rid of the ducting as it does not appear that u are even using air cooled lights/hoods---mount the filter/fan at the top location where the existing out take hole is---get urself a speed controller for the exhaust fan/filter---adjust the settings on the speed controller till u get a reasonable negative pressure that's not whistling or over working the fan and u should be good to go

so---1 end at ceiling level of the room has fan filtered out---all air leaks between it and the furthest point in the room are sealed---passive intake is at the opposite bottom end of the room requiring fresh air being sucked thru the passive intake on 1 end thru the room scrubbed and out the other end---pulling fresh air from 1 end---thru the entire room---and out the other end with no air leaks in between---1 way in and 1 way out at the farthest distances possible

u might also consider covering the passive intake with a cheap forced air filter/screen

looks like the way u are creating negative pressure now and not scrubbing all the air is because the fan/filter are scrubbing the air coming into the room from the holes directly above the location where the filter is hanging---its not actually exchanging all the air in the room and normal house drafts is why u have pockets of smelling herb in different locations

your house is not impervious to negative pressure---this set up will work without the speed controller---but it is a nice feature to have
 

Dman1234

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Somethings not right, this should be way easier for you, if you have true neg pressure any hole in the room will not matter at all, put your filter in your grow room and your fan in the attic and PULL air threw filter and out to attic, if your pushing it the fan is probably pushing more than the filter can handle and unfiltered air is escaping.
 
L

Landing

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I sealed up the holes in the ceiling. *sigh* It didn't work.

Until I figure this out, can someone please tell me how/if I can make use of ONA gel (this is the only form that is available to me, no blocks or sprays, etc.)? I have an entire 20 M3/h room, no tent. Can I just stick it next to the plants (yes, I know it is bad for them, but they're not flowering yet and this is a temp. fix) or should/could I put inside the duct that exhausts out into the attic?

I am pretty desperate at this point. My stress levels due to this whole issue are at an all time high. Nothing I've done has worked. What kind of sorcery is this?!
 

AluminumMonster

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Let me guess, you didn't move your fan yet?
I love how you came on here looking for advice but you won't take any of the advice given to you.
 

surfinc

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I know a guy that had a very similar issue in an apt building near by..they allowed pets..does your spot? If so ... Or maybe if not ...you can leave some poops in bags concealed in that area...small scent of **** crosses up most peoples senses...it worked for him until he could pull down..then the talk was of why does it stink like ****...maintannece not doing good job etc....he would just leave it around kinda hiding it for a few weeks....cheap and easy...and on the down low.....
 
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