Where to pull intake air from?

[Fraggle Rock]

Currently I have 2 tents in an extra bedroom. Each tent has its own inline fan for exhaust that works great. I have some passive intakes in both my tents now...There is a lot of airflow that gets sucked through the sides of the bedroom door when I close that and it creates a small whistle noise...So I know I need to add an official intake vent in my bedroom.

Is it okay to add a vent to the bedroom and leave the passive intake vents on the tents open so they receive the fresh ambient air? I'm trying to avoid adding more ducting to each individual tent...

Now, I need to remain as stealth as possible per the agreement with my housemates...So I have done good so far and what I am thinking is that I can close off the central a/c vent since I will be using a portable a/c anyway and use that "natural" looking vent and use a small amount of ducting in the attic to connect it to the exhaust fan ducting that is used for the spare bath that we don't use...I would assume the intake would just pull air from the top of the house where that bath exhaust fan vents to now. I would also make sure there was a filter on all air coming in and out...

What do you all think? I basically need to keep the exhaust fans going and I am trying to also add some fresh air to keep the room fresh!! I am a little worried that once it gets hotter that I will just be pulling in hot as$ air, but I guess I would assume the portable a/c would handle that??? What do you all think??

Any advice and input is greatly appreciated!! Thanks again!!

 

[messn'n'gommin']

You might want to consider door vents/air return grills. If light is a concern, you might want to look at the light proof vents in ScrubNinja's thread:

“DIY A new angle on light proof vents,” by ScrubNinja
https://www.icmag.com/ic/showthread.php?t=135524

namaste

 

[Danseur]

If you are getting a whistle under your door adding some more intake surface area will reduce this. It seems you are only using the seams of the door as intake?

You can do a number of things, but all will depend on what you would prefer and feel comfortable with. First of all the exhaust should be run 24/7. So long as you keep the exhaust going to an alternate location than you receive your intake then you do not run a chance of radiant heat building up to the point of failure. Meaning if you are exhausting into the attic like you say, and your intake is not come from the attic you have nothing to worry about.

Using a portable a/c is another thing to consider, because they throw off heat also so be prepared to exhaust that away from the source of your intake also.

Now for the intake, you wonder how to get it and maintain stealth? Your idea about routing a duct line from the vent in your space to the vent in the bathroom is perfect. It will allow everything to look just fine and maintain your stealth. Just keep the door to the bathroom open or it might start to whistle too. lol Or if there is a window in the bathroom you can crack it.

Great for sharing your idea. You can always install another "dummy" a/c vent (used for your intake) in another portion of the flat if the bathroom fan location does not pan out. Perhaps in a hallway or somewhere with active air exchange and do the same thing you planned out. A place with the coolest ambient temps would be ideal. When I first read this I couldn't understand what you were talking about. Now I am all A+ this is badass. Great Post OP

 

[manitu]

Where do you exhaust to now? >If your exhaust goes trough the wall or a window... Have you considered reversing the airflow?? It should be more effective , exhausting over the roof.

.manitu

 

[Fraggle Rock]

You might want to consider door vents/air return grills. If light is a concern, you might want to look at the light proof vents in ScrubNinja's thread:

“DIY A new angle on light proof vents,” by ScrubNinja
https://www.icmag.com/ic/showthread.php?t=135524

namaste

Door vents would be by far the easiest thing to do, but the bedroom door would look odd next to the other doors without grills...We will see what I have to do though! Thanks for the advice and link!!

If you are getting a whistle under your door adding some more intake surface area will reduce this. It seems you are only using the seams of the door as intake?

You can do a number of things, but all will depend on what you would prefer and feel comfortable with. First of all the exhaust should be run 24/7. So long as you keep the exhaust going to an alternate location than you receive your intake then you do not run a chance of radiant heat building up to the point of failure. Meaning if you are exhausting into the attic like you say, and your intake is not come from the attic you have nothing to worry about.

Using a portable a/c is another thing to consider, because they throw off heat also so be prepared to exhaust that away from the source of your intake also.

Now for the intake, you wonder how to get it and maintain stealth? Your idea about routing a duct line from the vent in your space to the vent in the bathroom is perfect. It will allow everything to look just fine and maintain your stealth. Just keep the door to the bathroom open or it might start to whistle too. lol Or if there is a window in the bathroom you can crack it.

Great for sharing your idea. You can always install another "dummy" a/c vent (used for your intake) in another portion of the flat if the bathroom fan location does not pan out. Perhaps in a hallway or somewhere with active air exchange and do the same thing you planned out. A place with the coolest ambient temps would be ideal. When I first read this I couldn't understand what you were talking about. Now I am all A+ this is badass. Great Post OP

Greattttt!! Thanks for the information!! What I was thinking is that my spare bathroom exhaust fan is setup to exhaust straight out the top of the house, through the roof....So in theory if I plumbed into that for fresh air, I would be pulling fresh air for the roof area of the outside of the house....My exhaust fans run 24/7, are in the attic and dissipates the air naturally through the attic venting...

My issue with this is that when the summer temps hit, I will be pulling in fresh 100+ temp air. I guess fresh air intakes are only good in the winter??? If the portable ac was vented properly as well, I would hope it would cool that air. My exhaust fans are a 750cfm 8" used for 2-1k air cooled lights and the other is 450cfm 6" and that cools a small veg tent with a 8 bulb 4' T5. My temps are always in the mid 70's

I like the idea of using a vent from another spot of the house, but I would be a little worried that you would hear air whooshing into the vent. I think pulling air from outside on top of the house would be quiet, but as I mentioned it will be extremely hot soon...Thanks again for stopping by, anything else you want to add please feel free!!!!!

Where do you exhaust to now? >If your exhaust goes trough the wall or a window... Have you considered reversing the airflow?? It should be more effective , exhausting over the roof.

.manitu

Yup, exhaust currently goes into the attic space. The ambient air up there is about 150 in the summer. I am going to be adding some gable vents this year to help pump that air out. Thanks for the reply!!!

 

[Vindie$el]

If I were you I would just get a small room air conditioner and set it on 75F so the tent will always pull 75F air. Use your bathroom exhaust to exhaust the condenser heat if you use a portable. Drawing air from inside your climate controlled house is always the most stable option.

 

[messn'n'gommin']

What areas share the grow room's walls? You could still add air return grills on a wall that is long enough (about 12" and more) to draw cool air. A hallway would probably be the best place. Grill work for A/C ducting is supposed to be located on a wall! Even then, if light is a concern and with just a bit of handyman skills, ScrubNinja's DIY thread would serve you well.

 

[Fraggle Rock]

If I were you I would just get a small room air conditioner and set it on 75F so the tent will always pull 75F air. Use your bathroom exhaust to exhaust the condenser heat if you use a portable. Drawing air from inside your climate controlled house is always the most stable option.

Yea I am thinking the portable AC would be the best thing to use....and I didn't think that pulling air from outside the house was that good of an idea for the potential heat and humidity it could pull in....I can vent the ac into the attic and into the bathroom exhaust fan no problem....I am currently pulling air from the seams of the bedroom door when it is closed and it makes a whistle noise from the airflow. I am not sure if I use a a/c vent from another part of the house if it will make a whooshing noise from the air being pulled in. It's a small house and every noise needs to be considered....I have the fans and my air pumps in the attic now and its pretty quiet.

What areas share the grow room's walls? You could still add air return grills on a wall that is long enough (about 12" and more) to draw cool air. A hallway would probably be the best place. Grill work for A/C ducting is supposed to be located on a wall! Even then, if light is a concern and with just a bit of handyman skills, ScrubNinja's DIY thread would serve you well.

My room is in a corner of the house that backs up to the small hall closet and the master bedroom...I think I would need to use a dummy vent that is on the ceiling and pull air from another room of the house...

 

[Fraggle Rock]

Ok, so I was just thinking about using the central ac vent in the bedroom and hooking it up to a vent that I install in the garage!! The garage does get hot in the summer, but I also plan on doing some upgrades to ventilate and insulate the garage to keep it cooler this year. I wouldn't have to worry about a whooshing noise if there was one because the garage is all good for a little noise.

On a side note, does anyone know if it is a good idea to place a vent from the garage to the bedroom? At some point I thought I remember hearing that you want to keep the garage separate from the house for fire safety....At the time I think I was looking into adding a central ac vent in there to help cool it down....

 

[Danseur]

You will want to source that intake from somewhere with cooler ambient temperatures than the ambient temperature of the grow space. I wish you luck, but at this point each case is specific. IMO unless outside temperatures are suitable you might be stuck with pulling your new source of intake from somewhere in your dwelling that is being cooled by the central a/c, assuming the rest of the dwelling is being cooled. Chances are if the outside ambient air is too warm, the dwelling is being cooled by a/c. If the dwelling is in a climate where a/c is not needed, usually the outside ambient air temperatures are suitable for using as intake.

IMO do not bring in new intake unless it is cooler than the growspace. I thought you meant to take the air form the bathroom, through the bathroom vent, to your room where the tents are. I did not understand it as taking the attic air where you are already exhausting excess heat into.

Sorry for the confusion, I hope this can be of some assistance. The wooshing you mention is from a lack of surface, if you add one 2" vent likely that it will still woosh. The point from as you say "wooshing" to not wooshing air is dependant upon your unique set-up. What kind of cfm are you pulling with your exhaust fan? What size space is it exhausting? That will lead you to determine the adequate intake surface area, but the air moving always makes a sound. Smooth ducting or insulated ducting can help eliminate this sound within the ductwork itself but moving air will always make a sound. How loud is up to the amount of air being moved, and with what equipment and ducting.

 

[Fraggle Rock]

You will want to source that intake from somewhere with cooler ambient temperatures than the ambient temperature of the grow space. I wish you luck, but at this point each case is specific. IMO unless outside temperatures are suitable you might be stuck with pulling your new source of intake from somewhere in your dwelling that is being cooled by the central a/c, assuming the rest of the dwelling is being cooled. Chances are if the outside ambient air is too warm, the dwelling is being cooled by a/c. If the dwelling is in a climate where a/c is not needed, usually the outside ambient air temperatures are suitable for using as intake.

IMO do not bring in new intake unless it is cooler than the growspace. I thought you meant to take the air form the bathroom, through the bathroom vent, to your room where the tents are. I did not understand it as taking the attic air where you are already exhausting excess heat into.

Sorry for the confusion, I hope this can be of some assistance. The wooshing you mention is from a lack of surface, if you add one 2" vent likely that it will still woosh. The point from as you say "wooshing" to not wooshing air is dependant upon your unique set-up. What kind of cfm are you pulling with your exhaust fan? What size space is it exhausting? That will lead you to determine the adequate intake surface area, but the air moving always makes a sound. Smooth ducting or insulated ducting can help eliminate this sound within the ductwork itself but moving air will always make a sound. How loud is up to the amount of air being moved, and with what equipment and ducting.

Thanks for the quick reply! I appreciate the good advice!! I will find a way to pull air from another part of the house. I didn't think it would be a good idea to pull ambient air that is potentially hotter than the air in the grow space. I will use a dummy vent system I suppose. Thanks again!!

 

[NiteTiger]

Just remember, you'll never cool your grow below intake air temps without an a/c in the grow itself.

First thing I'd try, assuming you have no light leaks, is to shave about 2 inches off the bottom of that closet door. You'd be surprised how much air that will let in. A 2 inch by 36 inch intake is 72 square inches of intake area. That's a lot of intake! Plus, stealth to the max

 

[Fraggle Rock]

Just remember, you'll never cool your grow below intake air temps without an a/c in the grow itself.

First thing I'd try, assuming you have no light leaks, is to shave about 2 inches off the bottom of that closet door. You'd be surprised how much air that will let in. A 2 inch by 36 inch intake is 72 square inches of intake area. That's a lot of intake! Plus, stealth to the max

Yup, sounds like I will need to stick to pulling air from somewhere inside the house...I have my tents in an extra bedroom, so I wouldn't be able to shave down the door. I think I will use the central AC vent in there and attach that to another dummy vent in another part of the house and run the ducting.

 

[NiteTiger]

Yup, sounds like I will need to stick to pulling air from somewhere inside the house...I have my tents in an extra bedroom, so I wouldn't be able to shave down the door. I think I will use the central AC vent in there and attach that to another dummy vent in another part of the house and run the ducting.

I'm curious as to why you wouldn't be able to shave a couple of inches of the bedroom door? It wouldn't effect the operation of the door, nor be noticeable.

 

[Fraggle Rock]

I'm curious as to why you wouldn't be able to shave a couple of inches of the bedroom door? It wouldn't effect the operation of the door, nor be noticeable.

I just think you would seriously notice the bedroom door missing 2" off the bottom. 100% stealth is key here. Its a great idea if stealth wasn't an issue and/or this was in a closet.

 

[Fraggle Rock]

Just looked at the door and I think I could reasonably shave off about .5" and not notice the gap....anything more and I think you would....there are some other room doors next to this one in the hallway and I wouldn't want this one to look much different.

 

[NiteTiger]

I just think you would seriously notice the bedroom door missing 2" off the bottom. 100% stealth is key here. Its a great idea if stealth wasn't an issue and/or this was in a closet.

It's a great idea specifically because stealth is an issue Measure 2 inches on your door, and you'll see it really isn't noticeable at all. Hell, take an inch off the top and an inch of the bottom if you're that concerned

I'm speaking from experience here bro, and I'm telling you no one, not even the landlord, noticed.

I figured you'd want to try a simple, easy solution before you started cutting and splicing duct.

Although, I admit, I may be misunderstanding. I'm confused as to why you'd disconnect an active intake to your room (central air), to passively draw through longer (read more restrictive) passive intake from another room?

Is that what you're taking about, disconnecting a central air vent, and ducting it to another vent in another room, to draw air from that other room?

 

[Danseur]

I was wondering the same NT, if the vent is in the room already then it should providing intake. Unless the vent is always closed, I am perplexed at this whole scenario myself. Even if the central a/c is not on, if set to "fan only" it will provide much needed intake. Even without that setting and negative pressure within your room it should still pull from that vent anyways.

OP maybe you need even additional intake surface area to accomplish your goals. More than you think. What kind of fan and cfm are you working with? What is your area? What is the total amount of current intake surface area including the duct diameter of the vent in your room and the gaps in the doors.

Maybe your fan is a beast and one single a/c vent and some gap under the door is not enough. NT had a great idea about shaving some off the top or bottom (or both) of the door. I had never thought of that and indeed 2"x36" is a good source of additional intake.

 

[Fraggle Rock]

It's a great idea specifically because stealth is an issue Measure 2 inches on your door, and you'll see it really isn't noticeable at all. Hell, take an inch off the top and an inch of the bottom if you're that concerned

I'm speaking from experience here bro, and I'm telling you no one, not even the landlord, noticed.

I figured you'd want to try a simple, easy solution before you started cutting and splicing duct.

Although, I admit, I may be misunderstanding. I'm confused as to why you'd disconnect an active intake to your room (central air), to passively draw through longer (read more restrictive) passive intake from another room?

Is that what you're taking about, disconnecting a central air vent, and ducting it to another vent in another room, to draw air from that other room?

Ok, well my issue is that I have kept the central ac vent closed in the room, during the winter we have our heater on and I didn't want that to be blowing in hot air. During the summer when ac is on or at least the heater isn't on I can use that vent I suppose. I guess I thought if I used that vent it would mess up the balance of the HVAC system for the house....my 2 fans are 6" 450cfm and 8" 750cfm - So they would be pulling air pretty hard through that vent and taking it away from other parts of the house...I guess I can just open it and see what happens...

I was wondering the same NT, if the vent is in the room already then it should providing intake. Unless the vent is always closed, I am perplexed at this whole scenario myself. Even if the central a/c is not on, if set to "fan only" it will provide much needed intake. Even without that setting and negative pressure within your room it should still pull from that vent anyways.

OP maybe you need even additional intake surface area to accomplish your goals. More than you think. What kind of fan and cfm are you working with? What is your area? What is the total amount of current intake surface area including the duct diameter of the vent in your room and the gaps in the doors.

Maybe your fan is a beast and one single a/c vent and some gap under the door is not enough. NT had a great idea about shaving some off the top or bottom (or both) of the door. I had never thought of that and indeed 2"x36" is a good source of additional intake.

I guess I will just open the central HVAC vent and use that...

 

[NiteTiger]

Ok, well my issue is that I have kept the central ac vent closed in the room, during the winter we have our heater on and I didn't want that to be blowing in hot air. During the summer when ac is on or at least the heater isn't on I can use that vent I suppose. I guess I thought if I used that vent it would mess up the balance of the HVAC system for the house....my 2 fans are 6" 450cfm and 8" 750cfm - So they would be pulling air pretty hard through that vent and taking it away from other parts of the house...I guess I can just open it and see what happens...



I guess I will just open the central HVAC vent and use that...

Ok, let me clarify some things, just so you have them for reference. Most houses are set to around 70F year round. This means the ambient air you are drawing from the rest of the house, no matter the means, is around 70F.

That means that even if your temps are running a whopping 15 degrees above ambient, you're only at 85, which is perfectly fine for our favorite plant. With the amount of air those fans can move, you shouldn't be running anywhere near 15 degrees above ambient. As you stated, you're already running just a few degrees above ambient.

When I was running a similar setup, I used just a single 8" Vortex 747 cfm to cool 2 kw, and my only intake was the central air. Using just that, my temps were only 1-2 degrees F above ambient. By the way, a 6 inch fan for flouros, WOW

Also, as far as upsetting the balance of the system, you are severely underestimating the amount of air a central unit moves I can say, from experience, that it will not have any noticeable effect on the temperature of the rest of the house.

Hope that helps for a bit deeper understanding of what we're dealing with in temp control