Too Much Heat. Why?

[FirstTimer]

Hello,

I have a 4x4x7 cabinet with a 1000 watt light. I have one cage fan(265CFM) that blows air outside and it is connected to one end of my light on the other end of the light I have a 6" inline fan(300CFM). So I have two fans that suck the hot air off my light and blow it outside. I have one other cage fan(180CFM) that sucks air into the cabinet from the outside. All ducting is 4" dryer vent duct.

This all works fine but only if the temp outside is about 55 degrees or less. I am very worried about the heat in the summer. When I built the Cabinet I thought that I would only need to blow the hot air off the light and outside and that the room temperature air coming into the cabinet would be enough to cool it. I found out fast that it wasn't.

Am I crazy or does it seem like something is wrong with my venting system?
If there doesn't sound like there is anything wrong with my venting system how can I cool my cabinet in the summer months? Thanks for any advice!

FirstTimer.

 

[DankCloset]

flow through ventilation is the only way to go, you gotta have fresh air being dragged through your hood, so one in and one out. plus have your norm vent for your grow room as well. you want your exaust fans to cycle through air in under 2 mins i believe is the goal or it actually might even be 5 mins.

 

[Akornpatch]

You have plenty of air flow in total. Let me get his straight...180 CFM into the cabinet, 300 cfm into the light(?), and 265CFM from the light to outside? Is that correct? So it's all going in a straight line? Try switching places with the 300 and 265. And make sure that the exhaust end isn't plugged somehow.

As long as you have one fan into the light and the other out from the light it should be keeping it cool. Is your ballast outside the cab?

 

[FirstTimer]

The 300 cfm doesn't have any duct going to it, it just sucks air out of the cabinet and into the light. So it is sucking hot stale air into the light. No cooling. I should have cool fresh air coming in the other side of the light!? Is that where I went wrong!!??

Yes that is correct Akornpatch and yes the ballast is outside the cabinet. I am going to wait until my current crop is done before i make any changes. Still got 2 weeks. Just trying to get ideas now so if I need more parts or anything.

The first change I am going to make is to replace all the ducting in the cabinet with 6 inch duct. I also forgot to mention that I want to add a carbon filter to this set up for my next grow. So I will be losing exhaust flow that way. Which worries me even more. I am afraid I will have to add some kind of AC unit to my room and I really don't want to do that. Too much extra power. In the summer I could run the duct to the central air vent and at least vent some cooler air in when the ac turns on.

I will post some pics tomorrow if that would help.

Thank you for the help!!
FirstTimer.

 

[Urdedpal]

Your going to need a a/c unit to run that light in such a small space.
1000w HIDs are more for whole rooms and even then I have to run a a/c unit in the summer. All that air movement is great but your grow area is small and the heat from the bulb is reduced but the heat from the light and reflective areas is gonna stay real high. A 5000btu a/c unit would fix this, its the smallest window unit and they are pretty cheap. It would tack on a extra 15 to 40 bucks a month to the electric bill.

 

[FirstTimer]

Thanks Urdedpal! I guess I will end up investing in a cheap AC unit in the near future. Thankfully the window to my room is under my deck and not in view.

FirstTimer.

 

[MadameCrash]

Hey FirstTimer - you always want the fans sucking hot air out (not blowing). So I'd mount the 300cfm to some duct hose and hang it so it sucks heat out of the room, by pulling it through the reflector and then venting it outside the room.

Here's a cheap cheap way to drop your room temps like 8 - 10 degrees...

Change out all your 4" ducting to 6" ducting.... You don't need to change any of the flanges or anything. Just snip the wire at the end of the duct hose and sqeeze the ends together so they overlap. Then you can tape or zip-tie the 6" hose end onto the 4" connections and you should be all set.

Peace
MC

 

[FirstTimer]

Hey MC,

The 300CFM fan is sucking air out of the grow area and into the reflector and then it is pulled out by a cage fan. So I have two fans pulling air through the reflector and outside. Sorry if I didn't explain this very well before.

Thanks for the tip on the 6" duct. I will be doing that for sure.

FirstTimer.

 

[tazman1996]

just a thought.

I know I'm knew here, but do have a little experience growing. You've said that you have 3 fans(180,265,300cfm's) this equals 745cfm that these fans are moving. Your grow space is only 112cf total. This means that the air is changed 6+ times a minute. I would think this is overkill. Also look at the temp of air coming into grow room. If you could have it be colder than your grow room temp. This would help to. I would put the 180cfm fan and use that for the light. Drawing air from outside or a cooler place, striaght through the light and outside again. Then maybe get a controller to slow down the 265cfm. And use it for the air exchange of the room. This could help also with temp problems. Good luck with you ventures.

 

[greenmonkey]

ok, im really baked. had to get that off my chest.
your light is the highest source of heat in your room and to get rid of that you want fresh air blowing through and going out. the faster fan should be exhausting the air becausing if its blowing in then itll creates positive pressure which equals heat since its getting bottlenecked by the slower fan. that and a larger exhaust and intake will make the cab cooler. good luck with the heat, im still battling a 150w, cant imagine the heat off that 1000w.
must post pictures of marijuana, post nugglets!!

 

[Racefan]

I operate a 1000watt HPS in a 20sf room. I have no air conditioning and no heat problems. Proper set up of the fans and plenty of flow through ventilation is the key. I have a 600+cfm fan(elicent 200B) for room exhaust and a 265cfm fan to pull the heat from my light. The light fan draws air from a out of room source and through the light and out of my room to outdoors. The elicent is powerful enough to suck your hat off if under. I run a passive intake system which creates a vacuum in the room (negative pressure) which controls odor escaping the grow room. I have two 4" intake and two 3" intake openings. All down low and across the room from where the elicent draws its air from. This gives me a maximum air flow across the plants which maximizes natural c02 to the plants and its cooling effect. In my room is a 13" oscilating fan that runs with the light. There is another 13 inch fan across from the other one that comes on with the humidity/temp controller I have. So if it gets hotter than 78df or more humid than 50% a exhaust fan kicks on as well as a oscillating fan to help dissapate heat or humidity. The house is kept as close to 70df as possible but considering all of our heat and cooling comes from space heaters and window air conditioners we are pretty much fighting the temperature elements all year long indoors here. It's hard to keep it warm in the winter and cool in the summer with what we have to work with. I have to run my lights at night all year long.

 

[FirstTimer]

Thanks for your input guys, greatly appreciated!! I am going to make some changes once I harvest my current plants and I will let you know how it works out.

First Change will be moving from 4" to 6" ducting. Then I am going to draw air from outside the cabinet and through the light and then outside, using the 300cfm fan and the 265cfm fan. I also need to redo my duct work to make sure there isn't any leaks in it and tighten up all connections to flanges.

My cabinet isn't light/air tight because of my poor carpentry skills, could this make a difference in the cooling?

Thanks again,
FirstTimer.