I took ceestyle's suggestions and rearranged the filter location (perpendicular for ease) and the curvature of the ducting (the bends in the ducting aren't as sharp as they look). As you can see in the photo I jerry-rigged a cardboard box as a "fan holder" as well as a 90 degree elbow. I used plenty of duct tape to try and make it air tight. Anyone think this will cause issues?

After running for an hour the temps were still at 86 degrees. I'm not sure what else to do...

All advice is greatly appreciated.

Thanks all for the help so far; it's already made a huge difference.

~GG

Out of curiosity, what are temps like with the door left open?

I might try removing the scrubber and placing the intake duct for the inline fan right at the bottom level/side of the hood. This would just be as an experiment to see what happens--obviously not a permanent solution.

Is the hood radiating a lot of heat off it's top surfaces? Maybe get another desk fan (or temporarily use the one you've got) and hang it right next to the hood so you can move air all over it to wick heat away. Perhaps direct the airflow as best as possible right at the intaking inline fan duct.

Also, I might try moving that desk fan to various locations and pointing it in various ways. I know when I first started and was using CFL's I had three fans I situated in various ways until I got a flow pattern that would suck in fresh air from one side and blow it out the other (sliding doors cracked open).

So, the closet is 2x4x8 = 64 cubic feet. I wonder if the 170cfm fan is just not large enough to evacuate heat from that space. Ya gotta figure that after ducting and the scrubber there are losses. How much loss? I don't know. Say you're actually moving 100cfm (wild guess). Seems like that should be enough for 64cubic feet but maybe not in the absence of air cooling the bulb??

I find the digital thermometers that have an "outdoor" probe on a wire (or wireless but I've found them to be less reliable) to be extremely useful. You can hang/stick/clamp the remote probe anywhere and keep the main unit outside the room to monitor ambient. Such a tool might be very useful for getting fast, accurate figures on temps in various locations around the closet.

I think I got this one at the Lowes for about $12 and it's great.

Attached Images

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BTW, how are you getting uploaded images into your posts without the thumbnails? I can't quite figure that out (doh!).

Hey Hawk,

What I do for the pictures is upload them into my photo album in "My Rollitup". Once loaded you open a picture and copy the BB code towards the bottom. Then simply paste the code into your reply box. PM me if you need more detailed instructions.

I really think you're right about the fan size. I mean a 10 degree temp increase from ambient is going to be hard to pull down by simply readjusting the fans and filter. I'm going to try running it with the door open for knowledge sake and I'll post the results on here in a bit.

If that doesn't give me some crazy drastic change I'm thinking about another solution. Let me know what you think:

1) Spend the extra cash and purchase an air cooled hood and a 4" (maybe 6"?) inline duct fan (the cheap kind).
2) Use the "duct fan" strictly for cooling the bulb and hood and vent that to the attic via the current (and only) exhaust port.
3) Place the current "vortex fan" and filter in a decent location (upper left?) and run only for the object of reducing smells. The vortex fan would just exhaust right back into the closet (maybe route the output somewhere for extra air flow)

I'm thinking that the air cooled hood will provide little resistance and should allow for the "duct fan" to pull a majority of the heat away.

Not really what I wanted to do ($$$) but I have a good feeling it will work. Anyone feel the same way?

Thanks again for the input!

~GG

I ran across something that might be applicable. It's a chart from this link: NMB Tech ......



In the following graph, the vertical axis represents the heat to be removed and the horizontal axis represents the airflow; both axes are logarithmic. The sloping lines define the temperature rise in °C. To use the graph, find the sloping line that represents the permitted temperature rise. Then, find the point on this line that corresponds to the heat to be removed. The horizontal position of this point shows the airflow required.




Lets assume you're actually evacuating 100cfm. Your ambient is at 24C (75F) and your in closet temps are 30C (86F). So that's a 6C spread. It's hard to find exactly 400w on that logarithmically scaled chart but it appears to approximately correspond to the 5C line at or maybe just past the 100cfm mark. Boy--you're data sure does seem to validate that chart.

Another thing to remember is that any wattage used inside the space is a heat source. Watts consumed = heat generated. Your inline fan is surely blowing it's heat out. But any other fans, while moving air, are also adding a little bit of heat. Probably not worth accounting for, but still.

It's very possible there are important variables I'm not taking into account or I'm not using the chart properly. The part I don't understand is where the size of the space is being accounted for. I can only assume that after you allow for heat saturation and average the heat input into each square foot of area, the total cubic feet of space is moot. Large space or small, if the heat is spread out among each cubic foot, the volume of the space is accounted for in cfm of airflow. In other words, small room = higher concentration of heat but each cubic foot is being exchanged that much faster. That explanation is just my speculative thoughts on the meaning of the chart.

Regardless, the chart seems to suggest that your 4" 170cfm fan just isn't going to cut it by simply exchanging the air in the room. By all means, continue to experiment and see if you can make it work (although not optimal, I think you CAN grow in 86F temps). But I'd think seriously about a sealed air cooled hood so you can isolate most of the heat and get rid of it before it can get into the rest of the closet.

Wow that is amazing how much it resembles my situation. I'm quite the math nerd so graphs and charts are always a big plus in my book

So I guess this means that it's time to make the purchase. I just can't bring myself to try growing my first crop under non-ideal conditions.

Hawk, with your seemingly deep knowledge in heat transfer, do you think this (sealed) hood with this fan would do the trick? Just FYI I would have to funnel the 6" into 4" at some point in the line.

Ah-ha! We were writing at the same time and came to the same conclusion, I think.

I think what you suggested is a good way to go. I'd bet a simple duct fan could be sufficient based on my experiments with speed controlling my fan and hood. I could turn my 6" fan WAY down and it still seemed to cool my 250 watter. Or, just use your current 4" inline. You might find you can use it to pull through a hood and your scrubber and be ok, maybe. I'd prolly get the hood before any other parts and only get additional components as needed. Once you can aircool the lamp there's all sorts of options for single or multiple exhaust fan usage.

For what it's worth, here's a thread on the cab design I was/am working on. That's not quite what my prototype cab is--I've only got one exhausting fan at the movement. I just needed something thrown together so I could start to flower: How's this cab design look?

Here's what I'm working with now.

DIY scrubber and humidifier


fan to help move air out of the top of the plant area and towards the scrubber


Outlet for the humidifier


ballast is sitting on shelf inside closet at the moment, pc fan keeps it cool (its heat makes a round about path into the cab and then through the scrubber and out to the attic

I'm a little weary of trying to pull through the scrubber and the lamp fixture with just the 4" fan. Since I'm using MoneyOrders things move slower so purchasing is better in bulk (plus saving on shipping) so I may just throw in the 6" duct fan (I have to buy Panda sheeting as well).

I love your cab setup in the link you posted. The remote fans seem absolutely wonderful! All you have to mess with is a few hoses. P.S. I like the first design best.

I can't figure out what the heck to do with my fan. How did you mount yours? The screws they provided with mine don't even fit into the two mounting holes (unless I'm supposed to apply an un-godly amount of force).

Looking at your design I'm wondering this one question for my situation: Is it absolutely necessary to exhaust my carbon scrubber outside of the cab?

Thanks again for all the help so far!

Don't kid yourself. My experience is limited.

"Knowledge is a process of piling up facts; wisdom lies in their simplification." - Martin Fischer

I'm great at researching. I make no claims about wisdom.


But anyway....I'm partial to the SuperSun 2 because that's what I chose. I saw some homegrown (no pun!) but credible testing done by a member of another board that first turned me on to the SS2. It had one of the best light spreads and some of the best features. It is well made and seals very well (I only found 3 very tiny air leaks in mine that took 2 minutes to permanently fix). The older versions had a slide-in glass cover while the newer ones are hinged with a rubber gasket. Super easy access for cleaning. In a fan > hood > scrubber setup I think it's important to eliminate air leaks so you don't have any air bypassing the filter. I don't want tape all over my hood to keep it sealed.

This outfit has the lowest price on this hood I could find anywhere. Super Sun 2 - 6 Inch Air Cooled Reflector I bought mine locally for I think $135 though. I wanted to buy my ballast locally in case I ran into any problems so I just bought the hood at the same time.




I've also seen a newer hood made by Maverick Sun, the Magnilume Pro, that reminds me very much of the SS2 except with even more features. I love the glass cover latches (SS2 has thumb screws) and the adjustable socket is nice. 250/400 bulbs really need a socket extension to center the bulb in the SS2 (not really a big deal though). The only thing I don't like is the cord runs out the vent hole. I've never seen one in person so I don't know about build quality. They're on Ebay for $100 with free shipping. That ain't bad at all.



What stands out in the picture of the HTG hood is the how much restriction there appears to be around the bulb socket. I don't like that one bit. I know on the SS2 they actually add a mild aerodynamic element on the back of the "socket holder" to aid flow. I don't know if it does much but I like that attention to detail.


Why the restriction of 4"? You going through a dryer or bathroom vent? My attic vents through large louvers near the roofline so I just blow straight into the attic--not out the roof.

But to your specific question, I bet that HTG hood and that fan would be satisfactory. I don't think that kind of fan (axial) handles negative or possitive pressures very well though (unlike a centrifugal like your current 4"). Going through that hood and then necked down to 4" I doubt you'd be getting anywhere close to it's rated cfm.

Another thought. Go with a 400+ cfm 6". Go scrubber > hood > fan > 4" neckdown. A high powered 6" centrifugal might have the power to handle all your cooling and exhausting needs with that arrangement. It's working for me with a 50" duct run and 250w. Yours would be hotter but I think you also wouldn't necessarily have to have your hood 8" away from the canopy like I have mine since you've got brighter light. I take temps from that spot. The 4" neckdown might be a troublesome bottleneck though.

I dunno. I like multi fan arrangements too and plan on using one after this first grow I'm in now.

I've got my fan mounted in a DIY sound isolation box. Don't think I have any pictures of it. It's basically a wooden box lined with soundboard, drywall, and fiberglass insulation. The box just rests on the floor of my attic. I messed up part of it's design and introduced some slight vibration into the outer, wooden layer of the box. Only that vibration was audible in my house. It was amazing how such a small vibration could travel through the studs and down into the house. It wasn't bad but not what I wanted. A couple layers of carpet padding under the box fixed it. I can only really detect any fan noise in 4am type house quietness. And even at that--you've got to be looking for it. Part of my overall goal was nearly 100% stealth. I want my computer and maybe a desk fan outside my closet to provide full camouflage. The current arrangement isn't quite there (I made the prototype cab too deep and one of the sliding doors won't even go on) but I think it will be fully stealth in it's final version.

My fan (6" EcoPlus) had some brackets welded onto the housing. Your fan must have a iffy bracket design, I'm guessing. I hear HTG has good customer service. Maybe call them for advice.

About exhausting the scrubber. What are you getting at with that? You thinking pull ducted air from outside the cab, through the hood, and into the ceiling? And then what to do with the scrubber and ventilating the air in the closet? I think you can recycle the closet air through a scrubber without actually venting it anywhere but I don't think that's an especially effective odor control method. And if you did that, where would the needed fresh air for the plants come from? I'd be worried about odor escaping it's way to the hood's intake.