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PreciousGreen

Help for newbie! Major heat issues for loft grow!

Hi all;

Initially posted this on General Growing questions section of the site, but advised its sits better here (so aplogies for duplication).

So I'm brand new to this growing lark and having some issues with my first grow that I'd appreciate some help with as there seems to be so much conflicting advice out there! I'm still learning and reading as much as I can, so please be gentle!

I've established a loft grow for stealth reasons.

I've built a grow box approx 80x80x120cm high from timber, clad in ply with glass wool insulation.

This is lined with Mylar to reflect the lights.

Exhaust ventilation is via a SwiftAir 4" carbon filter attached to a TT100 inline fan.

Lighting is 8x 30w CFL bulbs which are suspended a few inches above the 4 girls in 12" pots on a 20/4 cycle.

To reduce heat issues, the 4 sleep hours are 11-3 in what should be the warmest part of the day.

I'm growing autoflower Lowryder EasyRyder (fem) strains as these were recommended for a first timer.

Initially I went with 2 x 4" passive intakes and a SwiftAir 4" inline fan (Amazon purchase) as the exhaust, but temperatures in the growbox were hitting 40C! I should point out that loft temperatures in this heatwave are hitting the mid thirties which I understand is way too high.

My local Hydro store advised using the SWiftAir fan (pretty crappy, you get what you pay for!) as an active intake and adding the more powerful TT100 as the exhaust. The intake fan has a length of ducting bringing cooler air from the eaves which is noticably cooler when I place my hand over the fan outlet (this to try and combat th ehigh ambient loft temperatures).

However, temperatures in the box are still hitting 32/33C at peak :eek:

I've even tried a diy swamp cooler of wet sponges in a shallow water-filled dish in front of the intake fan which has brought humidity up (36% from 25% without), and now at a loss as to what to do next.

Will my girls be badly effected by this heat? Does anyone have any solutions to the problems?

I'v ebeen advised I may be better off ditching the CFL's and going for a dual band HPS 250w - will thsi produce less heat?

Really appreciate your advice (Here's hoping)!

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33°C doesn't sound too crazy for a loft grow in the middle of summer. From seeing other loft-growers' diaries here, the key to controlling extremes of temps over the seasons seems to be to build a room within a room. Jon Clobert did a good one a couple of years back...

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Find somewhere else to grow that is not so hot I have had to stop in my loft from the end of June till end of August cos its impossible to control the heat. It's not just that its the girls drink more which has caused me all sorts of issues. Add mite into the mix and lofts are bloody nightmare probably not what you want to hear but thats my 2 p :stoned:

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In my loft I have just a 1.2x1.2x2m tent but have a 6" thermostatic extractor fan with a 4" flexy pipe intake going into a cupboard in the house. The house has a vastly more steady temp and has more co2. I have a cool tube just now as well and temps haven't gone over 29c even with outside temps being 25c.

Also the hottest part of the day is actually 3-6pm ;)

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@@PreciousGreen Everything LJH has said rings true for me. I was having the exact same issues as you were before I upped my exhaust to a 6" and used my 4" as an active intake. As mentioned, if at all possible, intaking from the house is best as it has a fairly static temperature - excellent for the winter too.

As for the light, i have no doubt that a 250w hps would be significantly hotter than whatever your cfls are throwing out. I use a 600w with a cooltube and my plants can manage the heat at about a foots distance. So certainly youre gonna have to bring your temps down before you consider that - Im sure it was suggested not to help with temps but because by all accounts cfls arent great for growing high yielding plants.

Is your loft insulated? Mine isnt (or barely), which works well for me as i just exhaust into the attic and intake from the house. If youre exhausting into an insulated loft Id imagine you would have issues with heat retention. My room itself is insulated with 25mm kingspan-esque insulation board, although 50mm is ideal. Depending on thickness glass wool should work well enough too, but board is what you want if youve got the money. If you go down this route go to a local merchants or buy from ebay, whatever you do stay out of b&q.

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I'm in me loft and the max temp I've had so far is 28s but then I live up north and it's always raining and cowld! I love it even Rome to the shops in me short and t-shirt pissing down

Hec

Ps as a side note forget the cool tube m8 grab yourself a parabolic shade they are the absolute bolloxs I've got two 600w bulbs up there in two 1m shades and my temps are at 23 and that's with one of my extraction fans off just running the 6" fan and rhino at the mo but if and when I do run in to heat problems I can wack my 5" can an fan on

Hec

Edited by hector 1804

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was using 1x400hps last week was hitting 86f max, this week i have the 2x400 up and running just 82f max.

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On 8/4/2014 at 11:11 PM, hector 1804 said:

I've got two 600w bulbs up there in two 1m shades and my temps are at 23

I dont know how you do that, I joined two 1m parabolics together to get a dual bulb shade with 2 x 600s and my loft is 33-34 in this current weather. I have a 6 inch L1 outtake, and 6 inch A1 intake. 

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On 7/21/2014 at 10:53 PM, PreciousGreen said:

Exhaust ventilation is via a SwiftAir 4" carbon filter attached to a TT100 inline fan.

 

Either increase these numbers or get an AC unit but that would be noisy.

 

An oversize fan connected to a speed controller will move more air and make less noise than a smaller fan running at full speed.

 

Then if it gets hot you have the choice to turn it up.

 

EDIT :

 

Also, FYI, ideal temps are 26c day 22c night.

Edited by MicroDoser

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