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Why extract from the top?

extract fans heat airflow with farty bits

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#91 Enzyme303

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Posted 08 July 2018 - 07:50 PM

Ive gone and looked for cheapish thermal imaging handhelds you can get chinese flir kockoffs on ebay for round 100,my comment above with the piping was to use step downs wherever you want to slow air flow.


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#92 Anonymiss

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Posted 08 July 2018 - 07:51 PM

Can that bottom extraction point be raised up Missy? I'm assuming that's why you used flexible ducting...

 
It can, but that's only part of the reason for using flexible rather than rigid.

In an ideal world it would probably be rigid with a flexible end but the distance between the outlet vent and the corner pole of the tent precludes the use of solid duct, unless it were to just hang there with no support.
 

Nice idea with the T piece running straight through to the bottom exit point & having the top one off at an angle... Not sure if you thought about it, but that's how I would have done it if I was trying this idea out... So the top one isn't dominant ;)

 
It was indeed the plan, but it wouldn't be possible to orient a T-piece the other way around anyway, because the outlet vent is too close to the edges of the tent.
  
A 3-way corner might fit though.
 

Seems to eliminate the need for a reciprocating fan cool idea :)

 
It may, and it'll be nice if it does, but there's not really all that much in the way of a breeze coming out of those inlets.

Although the intake vents do have fans I'd hesitate to call them 'active' - 'assisted' might be closer.

They're PC case fans rated at 100 m³/hr and although they produce a stiffish breeze in free air, in this situation they do little more than overcome the impedance of the duct and produce only a very gentle draft at the outlets when there's no negative pressure to help.

The original plan was to put the duct the other way up, with the round->square adapters at the bottom and facing inward with the fans blowing directly towards the middle, but that raises concerns about wind burn and dessication from the constant draft.
 

You could probably regulate air flow rates for the T point and lowers with step down pipe sizing depending on where needed

 
Air regulation will probably be achieved by adding or removing a layer or two of dust screen from the outlet vents as required (or by stuffing them with rolled-up socks!)
 

it also would be handy to look at this on a flir for thermal imaging ,i have heard of thermal imaging apps but may have to buy hardware to use,you could also rent a flir to take a look if inclined .

 
That'd definitely be a nice-to-have, but there's no 'smart' phone available so it would require either a phone or some other hardware and a computer, neither of which is very likely to happen.
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#93 Enzyme303

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Posted 08 July 2018 - 08:37 PM

@Anonymiss i kinda guessed the flir cameras and co would be a stretch, it was because of this thread i discovered the cheaper ones, i now i want one for myself  ill just add it to the never ending list.

 

Atb :)


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#94 Anonymiss

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Posted 15 August 2018 - 06:57 PM

Seems to eliminate the need for a reciprocating fan cool idea :)

 
So we went back to Plan A and moved the round->square adapters to the bottom of the duct and placed the fans on the inside, blowing across the top of the plant.

The breeze is minimal with only a small (but sufficient) amount of leaf flutter so it looks like it'll be OK, but we'll see in a week or two.

No picture (flat battery in the camera) but I'll get one next time.
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#95 Budgie

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Posted 24 January 2019 - 12:34 AM

How did it work out @Anonymiss?
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#96 Anonymiss

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Posted 24 January 2019 - 06:57 PM

Very well, @Budgie :)

The temperature difference between tops and bottoms of the plants was never more than 2°C to 3°C, and the bud level sat pretty stable at the target of 4°C to 5°C above ambient, although above the lamp was obviously considerably warmer.

Humidity was better than before, as evidenced by no wet patches on leaves or buds, let alone any mould or rot, but I have no way of measuring it properly.

There were other problems, mind, not least that the space is an unusual size (for a grow tent) and is a bit too big for 250 Watts but too small for 400.

I think it would work well with a scrog, but there won't be anything going on in there for probably four or five weeks now.
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#97 Budgie

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Posted 24 January 2019 - 07:15 PM

Good, glad to hear it all came to a successful conclusion @Anonymiss :bong:

Ive not looked in a while but a dimmable 400 ballast could be in order if your friend wants to max the yield a bit more, or an led if funds permit and we have a warm spring/summer :sun:
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#98 Anonymiss

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Posted 25 January 2019 - 12:28 AM

I can't see any money being spent on it, @Budgie, but a screen will probably sort it.

The space is 1 m x 0.5 m, but leaving a bit of room for the duct and fans at the ends would make it make more like 70 cm x 50 cm, which is in the 250-Watt-lamp-sized bracket :)
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#99 Solo Quin

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Posted 29 January 2019 - 06:58 PM

Is it not the reason why the filter sits above is that humidity rises upwards, it would seem like the obvious place to put it.


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#100 jimmi2scoops

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Posted 29 January 2019 - 07:26 PM

Cus that`s where loft is and hole in ceiling :)


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