Ozymandias

I'm a little stuck on this one guys and any help would be hugely appreciated...

I've just set-up 4 air cooled lamps in a straight line, they have 150mm spigots and i have attached them to a 200mm fan via a reducer. There are a couple of bends and the fan is approx 50cm lower than the hoods (at the moment). When i switched the fan on no air came out of the end (the fan is on the correct way and should suck air through the lamps). I'm going to chop some bits out of the hoods to increase the air flow but i'm not sure it is going to be enough... i'm also going to add another 4 hoods on a T-Piece.

I have a spare 200mm fan which end should I put it on? The same end that the fan is already on so that more air is sucked through or should i place it on the other end so that air is blown through?

Any help from someone in the know would be a real help, thanks guys

CalicoJack

#1. I would certainly use other fan

#2. I would have one at the beginning blowing and the other at the end sucking through the hoods and blowing out the exhaust.

That's just my ,
I could be wrong, and am interested to see if I am doing it right

*fingers crossed*

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Ozymandias

Thought i should post plans for the two options for the system and see which one you guys would recommend...



Again, thanks for any help guys

JointVenture

how much air is the 200mm fan supposed to move? ... sure its working, wired correctly?

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preserve the spirit of resistance? Let them take arms. ...Thomas Jefferson

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Ozymandias

It is working correctly but i'm not sure how much air it's supposed to move. It's struggling to pull the air through the hoods 'cos there musn't be enough air flow; the ducting gets really hot straight away so air is making it through but it's not coming out of the other end of a fan. It's like when you cover the end of a vacumn cleaner, there is still suction but nothing comes out of the other end. There are no blockages in the system but it seems to be designed in a restrictive way so i'm going to attack it tomorrow but once i've added the other 4 hoods i think i will have the same problem.

What do you reckon? Thanks

JointVenture

if your hoods are sealed well, and the duct connections have good clear openings .... i would tend to push with both fans. reduce all sharp bends as much as you can too. by pushing through the hoods, the fans stay cool ... good for them



jv

__________________

Do not anticipate trouble, or worry about what may never happen. Keep in the Sunlight. ... Ben Franklin

What country can preserve its liberties if their rulers are not warned from time to time that their people
preserve the spirit of resistance? Let them take arms. ...Thomas Jefferson

Every reform movement has a lunatic fringe

Spirit of Bear

Eight lights on one fan is asking a lot of the fan (unless it’s a large Stanley, lol)…. You didn’t mention what type of fan you were running,,, so I’ll assume that it’s not an in line meant for what we do, but something that goes into ductwork to assist in moving air…. In that case you’re lost until you upgrade the fan……

If those lights are 1kw’s,,, you’re going to need at least 8”, and possibly 10” ducting on each row (I’d suggest 10”)…… If you are going to stay with 6” ducting,,, you will need to make a run to each light,,, even then you will need to go at least 10” on the exhaust…

I’d also suggest a plenum/manifold to help distribute the fans potential…. I’d run no more than two lights per run on an 8” system,,, and if you must hook four in line,,, I’d definitely go with at least 10” ducting……

It also matters whether you are in taking air through the lights, or drawing air from a fresh source and expending it outside without scrubbing…..

One last thing,,,,,, use insulated ducting,,, otherwise the heat you are trying to evacuate will just radiate right back into the room with un-insulated ducting…….

SOB

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Ozymandias

Thanks for all of the input guys. The fan is an inline but i'm not sure what brand it is as it's been fitted in it's own acoustic box type thing. It's good quality though and manages to blow a monsterous amount out of the other end. The spigots on the hoods are only 150mm so i can't use ducting that is any larger than 6 inches which is a shame and i've also not used insualted ducting but will upgrade if the room remains too hot.

I like to grow in sealed rooms so the air is being drawn from the room next door and being vented out of the chimney (eventually). I have to have two rows of four because of limitations with the size of the room, i think that this basically means that i either have to have more or bigger fans on the job... which is rubbish.

Ozymandias

i've just put a 250mm inline centrifugal pushing air into the system with only minimal impact... my tank heater has bitten the dust and both of my ph meters have broken in the past 2 days! I've had enough.

I think that i've got at least 1500m3 per hour on these two fans but nothing much is happening and i've GOT to put another 4 hoods on this set-up somehow.

So should i go for a 315mm Turbo fan that is 1800m3 and use that to blow air in (leaving the 200mm to suck air out) or am i going to need to get something more substantial... something outside of the hydro market. I'm trying to find suppliers of the next systemair inline range that go uptp 8000m3 out of a 315mm fan but i've no idea how much these babies are going to cost

Mr Burns

No1 I'd be pushing the air and not putting the fan bearings through such high temps by sucking air across it. Sure you can suck, bit I'd personally avoid raising fan 'bearing race' temps where possible

No2. Too much is being asked of the fans true capability.
With that many hoods on one fan it just ain't gonna work. For every hood 'port' it goes in and out of there will be turbulence, and with it a slowing or 'jamming' of air speed. This will happen with your first hood and increase as you go on down the line through each hood.
Fan ratings are all given as a 'free flow' figure, which to put it simple is what the amount of air the fan can pass through its veins with no ducting or any other attachment, just as it comes out of the box. Add just 3ft of ducting and you've already reduced its output so by adding each light the initial fan rating is being hammered down.

What spirit of bear said regarding a manifold (what we over here call a 'spigot box') would be a good start. If you mount the whole lighting system and ducting onto one ceiling hung rig that could be hired and lowered with rope (what I'm doing) then you only need worry about the single 'in' and single 'out' ducting when hiring or lowering the light platform. Making a lighting rig to fix it all to may seem a lot of planning & work, but anything to make the grow room more accessible at any stage of grow is paramount to me. Being able to hike the whole lighting and cooling rig up above head height with a few simple rope blocks and lines is heaven. You can even make a box section on the rig for spare lamps, scissors etc

I'd go for vortice fans blowing over a pair of lamps at a time....