# Tin Benders..Theoretically speaking



## NorCalHal (Sep 23, 2009)

Say you have a room that is 17' x 14' and you are going to throw up 9, 1000w lights. 8" Aircooled. The light string would be in a U shape around the edges of the room.

My initial thoughts were to place a Can 8" Max fan on each end, one blowing thru the lights at one end, and the other pulling on the other end and the exhausting out of the room.
So, it would be one loop, with 2 fans , one pushing, one pulling ,both with the same CFM rating. Would it work, and work well?

OR...I have seen plenums built along the edge of the room, one for air intake, and one for air exhaust. Then, the lights are tied into the plenum, with about 3-4 lights in one string. If this was done, I could get str8 lines "I think" for all the lights cooling ductwork.

I am just looking for ideas from Tinbenders, or anyone that has some input. I have never built a "plenum", but with a little help reading and asking questions, I should be able to figure it out if I go that route.


Ideas?


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## greenfriend (Sep 23, 2009)

One thing I know doesnt work is having long loops of 8" aircooled hoods i.e. 8 lights.  With an 8" fan and 8" duct booster, there wasnt enough airflow.  But when I used a 12" inline, it was too much, just crushed the ducting.  

Your plenum idea sounds like it would work - 3-4 lights in a string, though i havent tried it.


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## NorCalHal (Sep 24, 2009)

Thanks Green, I think I have a plan.

I love theory!


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## StoneyBud (Sep 24, 2009)

NorCalHal said:
			
		

> Say you have a room that is 17' x 14' and you are going to throw up 9, 1000w lights. 8" Aircooled. The light string would be in a U shape around the edges of the room.
> 
> My initial thoughts were to place a Can 8" Max fan on each end, one blowing thru the lights at one end, and the other pulling on the other end and the exhausting out of the room.
> So, it would be one loop, with 2 fans , one pushing, one pulling ,both with the same CFM rating. Would it work, and work well?
> ...


 
The idea is to have one even temperature throughout the grow area. To do that, you have to have one or both of two methods;

1. Air intakes from several locations in the room that cause air movement that equalizes ALL the air in the room.

2. Rapidly moving air in the room that causes ALL the air in the room to be equalized in terms of temperature. Then, any exhaust will do.

Picture a colored air flow like what they use on aircraft and cars when testing in a wind tunnel.

Using directional venting from a plenum would *mix* the air if used in sufficient flow, but I think a more practical method would be to just use standard vent duct along one side of the room at ceiling level and another set of vents at the floor level on the opposite side of the room.

Four vents spaced evenly across each side would create and even air flow across the room, especially if the vents were aimed in a crossing pattern on the delivery side.

One fan on the intake, one of equal size on the exhaust.

You wouldn't need the direct connection to the lights. The room air would move sufficiently to keep the temperature constant. That would save some on the costs as well, as lower priced reflectors could be used.

Is this something like what you're thinking of Hal?


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## meds4me (Sep 24, 2009)

NorCalHal: Okay lets think about this folks from a "tinners" point of view. 

In your home Therer is typicaly 1 or 2 return air vents along with #  of supply vents. In therory the air is being drawn from the cieling ( being the warmest) and the floor level ( being the coolest) Thermostat at chest level. As the air circulates thru the duct work both warm and cool air are mixed and ( If a/c  is optional) and then cooled mechanically  then return to the living quarters at either floor or cieling level. 

The plan from what I gather it would be best if : A) 8" or 12" inline fan to pull the heated air from the lights to the exterior ( thru scrubberrs if needed). This will get rid of excess heat. Timed of course 5 min intervals.
B) Make-up air can be "pre-heated or tempered" prior to the room the better. Simple old elec htr works best for this w/ addition of time delays to "delay" certain elements for room size . 
C) oscillating fans to "mix" room air for even growth and stem developement. 

hope this helps PM me if need more ideas...


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## NorCalHal (Sep 25, 2009)

Thanks fellas.

Some great ideas Stoney, and ya, I was thinking of something like that. I usually have just one passive air intake,but I want to do it a little diferent this time.

Thanks Meds, that gives me a bit more to think about.


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## Tater (Sep 25, 2009)

I'm no hvac expert but stoney seems to have a good grasp on this.  The amount of turbulence you would create by running air through that many hoods would be enormous even if you used cool tubes to minimize this effect.  You fans would need to be pretty heavy duty to stand up to a load like that because as the resitance increases the load on the fan increases reducing its efficiency and literally causing it to burn up. 

I would either go stoneys route or reduce the amount of lights on a line and increase the number of fans but I can't see your original idea working to well so its a good thing you have decided to theorize before putting it into practice.

Also nice to "see" you again man, I've been gone for a while.


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## OldSkool (Sep 25, 2009)

NorCalHal, lets say you suspended a DWV pipe above the lights, say 6'' or 8'' dia with an inline fan blowing OUT of the pipe to exhaust the hot gasses. The other end would be fixed with a 6'' or 8'' adjustable damper for a wood stove to regulate airflow (if needed). 
Cheap enough and slip-fit to boot! Might want to try two pipes, one on each side of the room above the lights. Since heat rises, this seems logical to me. Also provide for multi-source inlet air as Stoneybud recommended. Cool air in from the bottom and out the top.
This setup would draw heated air in from the ceiling along the light path without having to push it. Vacuum like discharge, better flow, less pressure.
But I am a millwright and a welder tho, not a tinman! Just my thoughts bud.


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## Tater (Sep 26, 2009)

Just a quick question that I hope is on topic enough to not be considered thread jacking but when you have a main vent with multiple off shoots and are using it to pull air from multiple points in the room will the same amount of air be pulled from each vent or will more be pulled from the vents closest to the fan?  HVAC is one part of home construction I have never tackled and I am quite ignorant on the subject.  The reason I ask is because I am building 2 4x4 sealed rooms and plan on using a port box to pull air from each with a similar setup to what stoney has described and just want to be sure each box will be given the same cooling power.

Sorry NorCal if this is out of place in this thread, if so I will gladly repost the question in another thread.


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## StoneyBud (Sep 26, 2009)

Tater said:
			
		

> ...when you have a main vent with multiple off shoots and are using it to pull air from multiple points in the room will the same amount of air be pulled from each vent or will more be pulled from the vents closest to the fan? HVAC is one part of home construction I have never tackled and I am quite ignorant on the subject. The reason I ask is because I am building 2 4x4 sealed rooms and plan on using a port box to pull air from each with a similar setup to what stoney has described and just want to be sure each box will be given the same cooling power.


You're right on target with your thoughts, Tater. The vents closer to the supply line will always have a stronger flow. That effect is minimized with the use of a manifold system that delivers to several branches of vents and by increasing the volume and amount of air delivered to each branch. Doing that will minimize the effect and in a small application such as this, make it seem to be the same because of the lessened effect. If the supply creates a slight back pressure at the vent, the result would be a more even distribution of the pressure.


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## NorCalHal (Sep 26, 2009)

Thanks alot fellas, I have a lot to think about.
I am taking the weekend off and just chillin', but I will be back on the project Monday. The equipment was ordered yesterday, so I should get it wensday, and friday is construction day.I am really leaning twords Stoneys idea of having a plenu,m on the ceiling for air exhaust and one on the floor for intake, and plugging into those. If I was any good at drawing, I would scetch something up, maybe I will tonight, I do have a scanner so I could post up the pic.

More to come.


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## StoneyBud (Sep 26, 2009)

NorCalHal said:
			
		

> Thanks alot fellas, I have a lot to think about.
> I am taking the weekend off and just chillin', but I will be back on the project Monday. The equipment was ordered yesterday, so I should get it wensday, and friday is construction day.I am really leaning twords Stoneys idea of having a plenu,m on the ceiling for air exhaust and one on the floor for intake, and plugging into those. If I was any good at drawing, I would scetch something up, maybe I will tonight, I do have a scanner so I could post up the pic.
> 
> More to come.


The cool thing with using HVAC stuff is no one looks twice at you when you buy it. It's reasonably priced too.

Just to be clear, you mean air suppy at the ceiling and air exhaust/return at the floor, right?

Taking the weekend OFF??? You slacker! hehe

Enjoy it man!


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## Tater (Sep 26, 2009)

Stoney:  As I outlined above I want to build a port box with the ability for expanding the number of rooms to tie into it, using a plenum (i think that means a big tube with little tubes coming off of it to where you want to pull/push air kinda like a manifold?).  Would it be best to place the fan that was responsible for the exhaust in the in the middle of the plenum

===={fan}====
[]---[]---[]---[]

[] denotes exhaust ports

or should I place it on the end?

If I place it in the middle would I need to create a baffle so that it doesn't just suck air from the ones directly below it?


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## StoneyBud (Sep 26, 2009)

Tater said:
			
		

> Stoney: As I outlined above I want to build a port box with the ability for expanding the number of rooms to tie into it, using a plenum (i think that means a big tube with little tubes coming off of it to where you want to pull/push air kinda like a manifold?). Would it be best to place the fan that was responsible for the exhaust in the in the middle of the plenum
> 
> ===={fan}====
> []---[]---[]---[]
> ...


The primary difference between a manifold and a plenum is a manifold joins several units to one without regard to the mix. A plenum takes the mix into consideration.

The best way to accomplish a balanced draw would be to use vents that total the needed intake size when compared to the fan draw. That way, no one vent can out-perform the others by much. It will take the entire set to make the flow match the draw. If that is done, then it would make little difference where the fan was placed.


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## Tater (Sep 26, 2009)

Ahhhhhhh man a light just came on in my brain, I think I am grasping what you are saying.  Essentially you need to space the intakes out in relation to the exhaust ports so that it creates a sort of choke limiting the amount of air that can be drawn from one single vent and sort of forcing an even air flow based on limiting the intake.

Is that kinda the general idea?


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## StoneyBud (Sep 26, 2009)

Tater said:
			
		

> Ahhhhhhh man a light just came on in my brain, I think I am grasping what you are saying. Essentially you need to space the intakes out in relation to the exhaust ports so that it creates a sort of choke limiting the amount of air that can be drawn from one single vent and sort of forcing an even air flow based on limiting the intake.
> 
> Is that kinda the general idea?


That's it! If you make the vents huge, then like you say, the first one will take all the air and the rest would dribble.


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## NorCalHal (Oct 2, 2009)

OK Fellas, I have the plan of attack.

The room I am "theoreticaly" usuing has a small bathroom that we will be usuing as an exhaust room. This meaning that all hot air from lights and room will be exhausted in that room.
We took off the door to the bathroom and installed a 24,000 btu AC and framed it in the doorway, and sealed off the bottom of the door under the AC. The bottom is actually a "smaller door" to allow me to get in the small exhaust room to ensure no issues and to do anywork that needs to be done.
In that "exhaust" room, there is a Can125 filter with a CanMax 10" fan for exhaust.

The light strings will be seperated into 2 strings, one with 4 lights, one with 5, both being cooled by a 8" can fan. One fan tied into one plenum pulling air thru the lights.

The air intake will be a "vent" system like Stoney described. Hung from ceiling and multiple vents being sized smaller to larger from the blower side.

The Air intake for the lights will also be supplied from a "plenum" type box.

I may have to play around with some Speed controllers to balance out the air flow into the exhaust room, but that is the only issue I see, so far.

Construction starts today. The Home depot trip was fun, let me tell you. 2k in random parts with every Home Depot employee asking" watcha buildin'?"
When I am asked this by random employees' I always tell them we are building a Dominatrix Sex Room, and that usually shuts them up quick, which it did. The guy looked at us really weird, being I was with my buddy who is 6'5" str8 okie with a handle bar mustache. lol.
I wonder what he thought we would use the 3 intermatic Spa timers for?


Thanks EVERYONE for thier input and thoughts. This will be the first build usuing a different type of intake and exhaust that I normally do, so it will be interesting.


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## ozzydiodude (Oct 2, 2009)

Green Mojo to help get the room off on the right foot


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## meds4me (Oct 2, 2009)

StoneyBud said:
			
		

> The primary difference between a manifold and a plenum is a manifold joins several units to one without regard to the mix. A plenum takes the mix into consideration.
> 
> The best way to accomplish a balanced draw would be to use vents that total the needed intake size when compared to the fan draw. That way, no one vent can out-perform the others by much. It will take the entire set to make the flow match the draw. If that is done, then it would make little difference where the fan was placed.


 
True to a point as you design youre duct work try to accomplish two things. 
1st ) duct work should be of "equal  length" as possible.this insures the same cfm caan be drawn the the ducting to a plenum for exhaust purposes. 
2nd) Give youre self +15% over the load for sizing the fan . IF the fan was centered and ducting relatively the same the flow will be consistant and less static pressure. IF the fan was off set and ducting wasnt the same then higher static will occur in some branches of the ducting.Thus an un-even draw of air.


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## greenfriend (Oct 2, 2009)

geez sounds too complicated for my mind to comprehend this early, but im sure you've got it under control.  maybe you can give me a few pointers, im going to attempt kinda the same things w/ 12-14lites


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## meds4me (Oct 2, 2009)

Green friend: Thats what we all are doing here ! I'll do what i can and feel free to drop a pm Peace ~


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## NorCalHal (Nov 8, 2009)

Theoretically, it is all fired up and running like a champ. 72 degrees with lights on. Thanks for all the input everyone!


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## greenfriend (Nov 8, 2009)

So are you using Co2 with this setup?  and how many inline fans are you using?


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