DIY vented hood

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ginnzy

Active Member
Hey guys, just wanna share something im building. I am running 3-1000w hps lamps in my main bloom room, and 2 more in my smaller bloom room. I set up in march, and seeing how it was winter here, heat was no issue, well with summer on its way, i decided to vent my lights. originally i wanted to get the huge 4xxl hoods (or whatever their called), but at 275.00 each, they are too rich. So i decided to get the 24"x24" blue star reflectors, at 60.00 each, they are a great bargain. these are the non-vented hoods.

well, i know a glass guy, and he will cut me 24"x24" 1/8" tempered glass for 20.00 each, and i'll get 6" elbows, to add the vents to them, so for about 90.00 I will have 24"x24", 6" vented hoods, a very good price IMO! I'm going to run 435 cfm 6" stealth fan's on them, which should help keep my temps down. I'll post some pictures when im done.

I've also ordered two 120v relay's so i can build a 4 light flip box. Its not that i cant afford to buy this stuff, i just like building what i can. i get a kick out of it!

ginnzy!
 
bass1014

bass1014

Well-Known Member
just a hint on heat. run everything at night with the temps lowered in the evening u should get some relief ..
 
C

contraptionated

New Member
Using tempered glass to seal your hoods is a mistake. Even though some pre-packaged vented hoods will use the same glass that you plan on using for that same purpose it is still an error. Why? Regular tempered glass will severely filter the intended color spectrum of your lamps. The iron content of tempered glass is responsible for this distortion. It is for this reason that borosilicate glass is used for a proper cool tube , yet even that type of glass is wrong to put under the lamp because it too distorts the color spectrum. The only glass that should filter the arc tube is the borosilicate envelope, ie the bulb itself. Otherwise you will get the same mediocre results as any other noob. If you want to get the most heat extraction without distorting the light spectrum simply bring intake air through a raised perforated floor (passively, never forced intake) and locate the exhaust ports above the hoods (holes in the ceiling ) if possible. The air will flow from bottom to top, never giving the hotspot that surrounds the lamp a chance to expand eccentrically downward toward the canopy. The added super benefit of this technique is that fresh air will feed directly to the undersides of the leaves (stomata). By ventilating with this method, you will achieve perfectly even airflow distribution. No other method but a raised floor intake with above the fixture exhaust can achieve penultimate grow room ventilation. There is no better method. I challenge anyone to argue that.
 
G

ginnzy

Active Member
yeah, well I guarantee I will have excellent results at the end of the day, er, or at the end of 8-9 weeks. Pics to follow.
 
J

joe macclennan

Well-Known Member
contraptionated said:
Using tempered glass to seal your hoods is a mistake. Even though some pre-packaged vented hoods will use the same glass that you plan on using for that same purpose it is still an error. Why? Regular tempered glass will severely filter the intended color spectrum of your lamps. The iron content of tempered glass is responsible for this distortion. It is for this reason that borosilicate glass is used for a proper cool tube , yet even that type of glass is wrong to put under the lamp because it too distorts the color spectrum. The only glass that should filter the arc tube is the borosilicate envelope, ie the bulb itself. Otherwise you will get the same mediocre results as any other noob. If you want to get the most heat extraction without distorting the light spectrum simply bring intake air through a raised perforated floor (passively, never forced intake) and locate the exhaust ports above the hoods (holes in the ceiling ) if possible. The air will flow from bottom to top, never giving the hotspot that surrounds the lamp a chance to expand eccentrically downward toward the canopy. The added super benefit of this technique is that fresh air will feed directly to the undersides of the leaves (stomata). By ventilating with this method, you will achieve perfectly even airflow distribution. No other method but a raised floor intake with above the fixture exhaust can achieve penultimate grow room ventilation. There is no better method. I challenge anyone to argue that.
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while I won't argue that glass in the hood will reduce/distort the spectrum and intensity especially when it gets dirty, or your idea of a raised floor w/passive intake(I have done this it works great) I used to have a converted stealth refrigerator and this method was the only way I could keep temps down w/close to 500watts in it.

I will argue your assertion that good yields cannot be achieved w/cooled hoods. There are pics. all over here w/ ppl using cooled fixtures with great success.

I have ran both cooled and uncooled. I know for a fact that great yields can be pulled either way.

Also with your method co2 cannot be introduced. So obviously you claiming this method to be "best" has a bit of chest thumping bravado to it. No?
 
C

contraptionated

New Member
Maybe I shouldn't have said good yields couldn't be achieved. You got me there. Sorry for that assumption. Although, the yield can be higher without the glass while achieving the same amount of heat reduction. Instead of spreading the heat around with an oscillating fan one can poke holes (large ones) above the fixtures and through the ceiling . Fixtures can be strategically placed below the exhaust holes to eliminate light leaks and if the raised floor method is used, the room effectively becomes one big rectangular air duct with ideal bottom to top airflow. The exhaust fans are placed in the room above the grow room. The exhaust trunks can be kept horizontal and air may exit out the windows of the floor above the grow room.

In order to make this work the ceiling must move up and down with flex ducts connecting the holes of the foamboard adjustable ceiling to the holes of the floor above. It is actually easier than you think and it allows me to change a bulb from the room above. The foamboard adjustable ceiling squeezes tight against the foam board walls of the grow room and the entire light rig and moveable ceiling is connected together with 3/4" EMT and it adjusts from a central hub in that mechanical air handling room above the grow room.

The lights never touch the grow room by any chain, rope or fastener of any kind. You must be willing to use 2 floors to do this. It all sounds crazy as fuck but I am sure you understand it because you know how well it worked (not exactly the same way) in your refrigerator cabinet.
 
C

contraptionated

New Member
As for the "chest thumping bravado"... Compare yields of grow journals of sealed rooms with co2 and mini split ac units to those that are of the same scale (ie square footage and light intensity) as a grow that used a proper amount of "constant exhaust" ventilation with no co2 or ac unit. You will find that the yields are about the same or worse with the co2/ac method. There was no bravado in my claims. That declaration was made after years of reading grow journals of "co2/ac unit" grows that almost always yield between .45-.6 gpw. Those are noob yields and to top it off the over-contraptionated method defeats negative pressure and in turn leaks grow room odors. Negative pressure must always be maintained to assure that the neighbors don't figure out what's cookin' next door.


Even if there are some growers out there that do achieve nice gpw yields with ac/co2 they will still have odor leakage because you cannot use a carbon scrubber in a co2 grow (although many do) because carbon filters strip the co2 from the air ... completely. Sorry if that's a rude awakening for those who thought that carbon scrubbing would remedy the lack of negative pressure in their co2/ac grow. So now that we know that a grower can't avoid odor leakage with co2 , this method should only be reserved for those who have no fear of prison time.But seriously, if I can achieve .73 gpw with 50/50 mixed spectrum (3-600 Super HPS Hortilux and 3-600 watt Sunmaster MH conversion 3600 total watts) over a 8'x9' footprint with strains like reserva sour diesel and sour kush (low pressure aero) with nothing but passive intake and constant exhaust (with a few dampers here and there so temps don't get too low overnight) why would I bother with co2/ac to increase yields? I would just change out the MH conversion bulbs with 3 super hps and my yield would almost undoubtedly go to approximately .98-1 gpw.
Need I remind you that Heath Robinson (the undisputed Jesus of indoor pot grow ops) doesn't use co2, but instead employs the simplest means of ventilation without using cool tubes or glass enclosed hoods? His strains may be large yield producers to begin with but I've read through a few grow journals of those who grew his strains and didn't get the same yield because they either used a cool tube when they tried to emulate his vertical grow or they thought they could use co2 to match him. Nobody has been able to match him yet, but those that use cool tubes (borosilicate glass) in their vertical attempts to do so fall even harder (lower yields). You can confirm my thesis by googling "vertical grow or vert grow heath style or sealed room co2 grow". Trust me, I have nothing to gain by making these claims but quite the opposite. It is the open minded reader of this post that will gain high yields if they choose to use constant exhaust/passive intake with a few strategically placed dampers controlled by a lighting contactor and/or thermostat.All without wasting copious amounts of electricity and absolutely no odor leakage whatsoever.
 
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