air circulation

hey guys

So I am at an impasse with my current build.

I am building an HID system in a cupboard so heat extraction and general air circulation are the main problem areas.

I am thinking of the current setup for circulating air, basically connecting the grow room exhaust to the intake of the air cooled reflector, is this okay? Would "stuff" float into the reflector and possibly damage the bulb? I am hesitant of placing a flammable filter near the bulb.

Before I commit to drilling holes in my cupboard I would appreciate some feedback. I will be using two 4" Xpelair extractor fans and the total area requiring extraction is approximately 0.9m3.

Not using a Carbon filter ? I find one essential myself.

My growroom (approx 3m^3) has 1x4" inline fan and it's plenty - even dialled down with the fan speed controller. How do you plan on dealing with the fan noise ? A combination of insulated ducting, fan speed controller and mdf box and noise insulation around the fan itself worked for me.

With 2 fans, you don't necessarily need to connect the grow room exhaust to the air cooled light. What wattage of light will you use and what are the dimensions of the box ?

Where is everything venting to ?

thanks for all the feedback, I didn't want to dump all the details of the grow room here as I have another thread open in the newbies section here https://www.rollitup.org/t/starting-with-my-new-grow-room.828844/#post-10504070

The carbon filters are pretty pricey for me at this stage, this is essentially a budget build I'm trying to do under $300-400 and a carbon filter will take up half of that budget. I've already spent just under $150 in total.

The fan is quiet, I have tested it and I barely know its on until I feel for air or look at it. As you can see in the pic I do have insulated ducting which I will be using. If we are going to be talking noise, its the noise from the HID magnetic Ballast that I'm most concerned about, it will be extremely annoying to listen to for three months.

I will be using a 400w HID system, so to assist with the cooling of the aircooled reflector I thought using the exhaust of the grow room will assist with air flow through the reflector. The dimensions of the box is 550mm * 620mm * 1700mm. The dimensions of the reflector is also 550mm* 620mm but around 210mm in height.

I will be venting into my bathroom which has an extractor in the ceiling as well.

I had to make a hole somewhere, so I did so this afternoon and dry fitted the exhaust fan for the reflector.

ah you're using extractor fans... My inline fan sounded like a jet engine before I made some mods. I can't see any insulated ducting in the pics. Your plan looks good. The advantage of what you propose is no light leaks from the passive intake to the light. You just need to construct a light-proof passive intake in base of the grow room. (3x90 degree pvc elbows fitted together and inside spray-painted black works for me).

I haven't bought the ducting yet, as I require things I buy them so I do not waste on things if I decide to change my mind.

I drilled all three holes since you didn't bring up any issues. Hole saws are dangerous! My third hole the hole saw actually jammed and the drill flew out the hole I sort of hurt my thumb (nothing serious), I suppose I was over confident after I did the first two holes with no problem.

I connected the fan to the power and tested it, its reasonably quiet, the magnetic ballast is much louder. Thanks for the tip on the passive intake, with the three bends suggestion I actually have a neat trick that I will do once I get to that stage. I think that ends this topic, I will revert back to my original thread when I have more updates. Now that I successfully installed the extractor fan I will mount the bulb, seal the reflector and then do a test run to see if it remains cool inside the reflector (under 50 degrees celsius).

those fans will have ALOT of trouble cooling a 400hps! You cant hear them because there not moving enough air. A good inline fan is what you should have bought! Remember your intake needs to be 2x the size of your exhaust for passive intake to work properly.

Like some one else mentioned, be careful with light leaks from the passive intakes, that is the biggest problem I find using them. Also, your absolutely going to need an inline fan, and I would recommend getting the highest rated CFM 4" fan you can find, especially with that wicked 180degree bend in the ducting. Trust me, your probably going to wish you bought a 6" fan to be honest. Make sure it is at least 200cfm-I would personally go with a 400cfm 6" fan and put it on a speed controller. Also, I would seriously consider planning your design to accomadate a carbon filter. I know you said money was an issue so save for one and plan on adding it later. It's going to smell more then you can imagine!

Your set up would work fine. When I first got started using 4x4 tents I used 1 fan to cool my lights and act as my main exhaust fan. I would hang my carbon fliter in the back corner of my tent, then I'd put the fan after the carbon filter and that would blow through my air cooled hood and out my tent.

So, carbon filter>duct>fan>duct>air cooled hood>duct

There are a few disadvantages using just one fan. The first being control. I like to have my fans on speed controlers so I can adjust my exhaust. When it's hooked up to the light it need to always be on full blast, and sometimes I don't always want or need that. Sometimes my humidity gets a tad too low and I need to slow my exhaust fan down a tiny bit.

That being said I used 1 fan on full speed for my exhaust and hood for a long time. It's definitely doable.

Do yourself a favor and wait till you can afford a cool tube or air cooled reflector and the proper fans. If not, I would SERIOUSLY consider using CFLs until you can afford to go the HID route.

I have a 4x4 tent that sits in a basement room that stays 50-70degrees year round. Using a 200cfm fan just for my air cooled hood, and another 450cfm fan for my exhaust, my temps will still climb into the low 80s on hot days.

Your temps shouldn't be over 85, and preferably they should be more like 70-75. I don't think that fan will pull in enough fresh air let alone suck enough heat out. All you can do is test your cab to see how well it works. If I were you I would test it asap. I'm not trying to burst your bubble but I've seen so many people try similar things and it just doesn't work.

Now, if you used CFLs you might be able to get away with your set up. The bud also doesn't stink as much grown under them. The only thing with using CFLs is by the time you buy and set up enough of them you may as well just of bought a better inline exhaust fan.

Grab one of those hyper inline fans. They run quiet and are powerful. That will really help cool those lights.

Hey guys thanks for the all the inputs.

Just like to make some general comments as I think some thoughts were missed.

I already had one CFL grow, I'm now trying the HID grow- it was even more low budget than this one.

I made my own air cooled reflector, it is still in the building stage and its basically around the reflector that I needed input.

The fan is specifically for the air cooled reflector and by essentially having two four inch fans on the air cooled reflector (active intake and active exhaust) I think it should be sufficient to keep temperatures in the reflector down. One fan runs at just under 80m3/ hour, given that the area in the air cooled reflector is well under 0.3m3 I really think I will be fine especially once I purchase the other fan. Just as an aside I did see another 4" fan that runs at 86m3/hour, so maybe I will purchase that one.

Also in terms of a 6" fan, the 6" fan would not have fitted in the reflector, the 4" one just about makes it. The hole saw for the 6" hole was also prohibitively expensive, around R450.

As for the noise of the fan, as I said compared to the magnetic ballast that I have the fan runs much quieter, it might make a noise in absolute terms but with the magnetic ballast on you can barely hear the fan.

I will be venting into my bathroom which has an extractor going into the building's extractor system (I live in a 48m2 flat), the ducting will basically go straight to that exhaust so I'm hoping that will minimise any smell concerns, also I will only be growing one plant.

I can always make the intake of the grow area active if it is a problem, its not a train smash.

I intend to do a dry run on the reflector this week with one fan. Basically connect the bulb in the reflector and run it for 20 hours to see what the temperatures are like. Incase anyone is wondering I will be sealing the air cooled reflector once I am happy with everything.

The back wall of my grow area is concrete and its quite cold (its winter in Cape Town) so that too may assist with cooling.

okay first dry run, very rudimentary but I was excited when I managed to get everything so I had to light it up.

Its been running for an hour, amazing how the heat penetrates the glass, its warm but not hot, I can get the plant pretty close to the bulb which I'm happy about.

The reflector, made of stainless steel, its surprisingly cool, its warm but not as hot when I ran the bulb with no ventilation.



You can see the ballast on the right, I will be moving it out of the room.



Pic of the bulb and extraction fan in the home made air cooled reflector.



The back part of where the bulb is mounted together with the exhaust of the grow room which will also act as an active intake for the air cooled reflector. I still have to purchase the fan.