A/C hoods externally on top of cab

in Lighting Thu Jun 05, 2014 12:24 am
by zipflip | 57 Posts | 259 Points

just figuring ways to setin something new up here and I could go on forever why I hate and love A/C reflectros both all day but to put it simple ive been thru all the rigors of several failed attempts or even inneffecient ways to go bout sealing all the diff types of AC hoods ive had over ethe years but never does it work 100% for very long. I even went as far as siliconing up every single seam or rivet head or chord grommet etc and still got residual odor leaks. done foil tape all that. and even when im able to keep air/smell leaks at bay, there is then the whoel maintenance issue such as bulb changing and cleaning etc.. I know theres prolly a million an 1 other ways all u can think of settin something up but this is what im lookin at and wht im curious botu doin. but unsure if id be pretty much trapping more heat below lights among the canopy rather tan how would normally rise up around the lights and to the exhaust which is higher.
OR..... would this help heat more for whatever reason, u think? all I know is if I can do this hwile bein efficient then all my woes and stress will be solved for themoment anyway. LOL

of course I would be raising and lowering plants verses the lights. but ive always had setup where I did this anyways so no bother there to me. anytime id raise or lower lights id end up loosening up a leak and get odor thru the lights line so...
just weird hwo I can go extreme overkill of everything even simple dict connectiions and rigid duct etc etc and all is good and tight but soon as I get to runnin for few days things start to leak again. im startin to wonder if its due to the whoel temperature rise and fall and metal etc expanding and contracting to the temperatures, beings I hook everything up when at room temperature and fire up high wattage HID's and heat....?
I got 2 spare adjust a wings which I love dearly but never wanted to tear thinsg down to put em up and the chance that they wouldn't work and couldn't control heat wit open reflectors vs the usual A/c hoods Ive ran. 2-600's dimmed down to 75% with aircooled and room exhaust on separate lines versus one room exhaust and open adjustawing reflectore x2 @600watts both dimmed down to 75% in a 2.5'D x 5'W x 5'H exhaust size fan filter is no factor I can always get a bigger if need be. id rather make things work first and cry botu the money I spent later. but i'l still be smiling cuz its works LOL

oh I would of course have holes and framed opening of sorts for the reflector to set into without fallin to the grow space. id prolly make the glass part of the roof and simply set reflector on top the glass and build a big bok cabby or something around them for getting at em and wat not. I got it all down in my mind hw to do it just not sure the whoel heat dynamics of suck a setup and trappin heat more below than otherwise eiwt hoods inside the space. I just want more room to work inside here without havin to wear a dang helmet and face shield in fear of getting a dang wingnut in the side my skull or bashin head up into the glass of reflector or something.

Attached pictures:

Last edited Thu Jun 05, 2014 12:31 am | Scroll up


RE: A/C hoods externally on top of cab

in Lighting Thu Jun 05, 2014 12:02 pm
by umbra | 780 Posts | 4085 Points

yes it has everything to do with the temps...young's modulus...thermal coefficient for expansion of materials

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RE: A/C hoods externally on top of cab

in Lighting Sat Jun 07, 2014 11:34 am
by Justa420Friend | 633 Posts | 2284 Points


were the hoods warmer than the "inside the box" air temps or cooler?

assuming they were warmer, and you've now moved them outside the box, then "inside the box" temps should go down.

the radiant heat they were putting "into" the box is the same either way

or at lest that's the way I see it

I totally understand the smell frustration... the wife tells me often she can smell it and there have been times I could too but when I come downstairs I can't. I run all my air through a 4x20 carbon filter and have many many "odder eraser" containers sitting around the basement and yet I still catch a strong whiff upstairs every once in a while.


Your Experience is like Water
I am like Rockwool

Last edited Sat Jun 07, 2014 11:39 am | Scroll up


RE: A/C hoods externally on top of cab

in Lighting Sun Jun 08, 2014 2:04 pm
by zipflip | 57 Posts | 259 Points

4x20 filter .... tahs proly ur issue right there id bet. I started out very first filter a can33 thinkin it was adequate and was given the cfm ratings but wit all other factors in the equation like neg pressure drop and also flpw drop from intake prefilter and echaust prefilter plus tryin to max light a small space/high heat etc etc... and now ime up to usin a 8x39phresh or canlite wit 6inch fan and actually contemplating upping oine last time to a 10x39 and gettina n 8inch fan put on reducer to filter and usin my variac to run at half or less speed on the fan. the 6inch fan I got is prooly fine and dandy but given the volume of air it moves bein only 6inch ducting I almost have to run it full board and I cant stand when inline fans are past 3/4 spped. noise bout drives me insane. also why I got variacs vs cheapo speedsters. takes away that dang dimmed down humming whining sound them fans give off when turnin speed down on the sppedsters. jus sayin I prefer to get a fan sized according where I can run half speed and be kosher that way. hosestly don't need such big gear for my style of growin/setups, but id rather go big and dim down if applicable like with fans and balalsts.. love the flexibility to fiddle and fine tune things.
sorry went on ramble there. but I bet u get bigger filter I bet ud be better off. regardless of the size of ur grow. plus I absolutely never go by the cfms on the box when tryin to size a filter for my space/fan etc.. for instance the old canfilters have 3 ratings one for scrubbing and 2 for exhausting/single pass filtering(max and minimum ratuings for exhaust) I use the same principal when buyin into these new style light version filters. fir instance u take the initial listed cfm on the box and I assume it to be a simple scrubbing/recirculating cfm rating as if u were to have it setting in a room recirculating/scrubbing the air over and over within the room its in, as are with the old styel can filters ratings. and as far as single pass exhausting cfm rating I just simple divide the box listed cfm rating in half and I figure it to be the max cfm rating for exhausting on single pass. and if u really wanan get more efficient then I divide it again in half for the minimum rated cfm for single pass exhausting.
a 4x20 filter im assuming would be or is light version filter, no? if so then in all honesty and with my experience all them lil 4inch flanged filters are more for using wit them higher powered 4-6inch axial fans. if ur wanting single pass exhaust filtering. at least tahts what can/CFgroup told me to use wit my lil 4inch can lite and my old school can 9000(both prolly same as urs)
but for real tho on the air cooled hoods. im serious as a heart attack, man. u should see mine. ive had em for few years but they're a sight, that's for sure. . got the metal all dynamatted up and every single joint/weld/seam in the thing is silicone wit clear high temp 100% pure gasket silicone. even around the gasket foam where glass presses against. cant forget all the foil tape and duct tape along dynamat seams etc.. I even go to the extremes of using this stuff for the flange connections called silicone tape. u know how some times the duct doesn't snug tight around the flange and most just wrap flange wit taope or some other to make duct sleeve it tight/snug? well I use the silicone tape. its awesome stuff. it give a squishy base for duct to press into around the flange when u clamp it. my thinkin is that due to the whoel thermal expanding and contracting it would compensate for it by being squishy. squishy LOL sorry .
I even use the GOOD fantech brand neoprene duct clamps for beter clamp/wrap on the flanges as well. I don't use flex duct either and use only rigid/solid and I seal all elbow s the leaks at the swivel portions wit silicone and foil tapoe over that, then wrap the hell outta it wit good solid gorilla tape for extra extra. same wit those rigid duct connects too. filicone tape self tap screws foil tape silicone and neoprene duct clamps. hell, I even took my canfan for the lights and took it apat and silicones every single microscopic hole, crack etc in the thing, then foil taped and duct taped it tehn dynamatted the fan then did one the diy fan sound deadener boxes its in too. and after all this I STILL GET RESIDUAL ODOR THU IT! LOL. my lights would dump hot air in one place in the house totally away form the space/room the exhaust filter dumps into. and I get nothing in that area. only where comes out thue light exhaust. its been like this since I started growin a never ending battle and im bout sick an tired of fighting it and figurin eliminating the problem entirely either gonna hang open adjustawings and just amp up my exhaust fan and filter sizes, or make a lower ceiling on box/cab/closet whatever im gona fab up this time, and cut out squares the size of the reflector glass and set the reflectors on top and run fan/air thru lights that way, totally eliminating all possible chances whatsoever of any odor getting into the lights ventilation, no matter how sloppy or lose my duct conections or ducting are....
and in all honesty I don't recall my hoods ever actually really radiating off much heat other than what they threw down to the girls below them. I got the whoel dynamat wrap on them so it helps immensely wit radiating heat off the hoods for sure.. and cant forget how biug of a difference it makes in killin that air rumbling noise blastin thru the reflectors.
but no I aint even got it setup like this yet. I had a setup in closet but tore down to make a normal closet againa dn now workin on fabbin up a new deal. only I don't wanan have to break my balls building something again all just to have to deal with all the same hassles. I figure if im goin in and doin something I may as well do it right the first time. no sense in cutting my self short anywhere. im the only one whos to lose or gain by what I do so..
in theory, I too think it would be a hose a piece as far as heat goes but I ahev tendancy to split hairs on so much when comes to growing and the thinkin I had is the space around reflectors between them and walls etc allows heat to rise up and around them to the exhaust port that's up high. but not sure if being the exhaust port would now then have to be at a level lower then glass actually at same level, if it would create a whole new ballgame as far as the typical thinkin and figuring goes when workin wit ventilation etc.. and on the other hand im wondering if bein the exhaust bein at reflector glass l;evel right at canopy level pretty much it will be drawing air from intake directly over and between canopy and lights evenly all the way across vs havin exhaust up high above reflectors, assuming it comes in from intake and then sorta gradually angles up toward exi. port ...
jus don't wanan waste time building something to accommodate this accordingly unless I think it at the least, might work or have good educated feelin it will. and I think the more I hit this strawberry blue here and more I babble on bout it the more confident im feelin it'll work. LOL

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RE: A/C hoods externally on top of cab

in Lighting Sun Jun 08, 2014 3:08 pm
by Justa420Friend | 633 Posts | 2284 Points

brother, you and I are MUCH more alike than our (very) different writing styles may hint @


filter: Phresh 4 in. x 20 in. 125 CFM Lo-Pro Carbon Air Filter | 701004
fans: 2x (in parallel) 70 CFM bathroom vent (squirrel cage) fans
............/ ------fan---
filter -<
both fans ducted to filter with a "Y" so unfortunately, they draw against each other... I'm guessing about a net 90-100 CFM (advertised CFM, not real)

cant do it right now but I need to take and post 1 picture to tell the whole story

Your Experience is like Water
I am like Rockwool

Last edited Sun Jun 08, 2014 3:24 pm | Scroll up

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