How to correctly measure temp of a Growbox?

Hi all,

I have a pc growbox that I had to make it to a minimum size, I'm actually struggling with temperature issues

Topic link: https://www.rollitup.org/grow-room-design-setup/330567-extremely-small-pc-growbox.html

So its obvious I can fit inside the pc growbox to take measurements from inside, and since its all sealed I cant put the probe inside as well...

So I'm taking measures from the air that comes out the outtakes the hottest one gets to max 90º F

Is that an valid way to measure will the inside temperature be the same as the air coming out?

Thanks u all

I wouldent have thought so as the cold air will be moving up and then getting heated and pushed out, but lookin at ya pics id go wiv 120mm fans as they make less noise and move more air if ya havin probs

Hi Essex,

Thanks for repply, I cant run 120mm fans on the back out take just there is no room for it, just on intake I'm able to run even 3 120mm but I dont think it will be usefull. I currently have total of 84cfm intake and 46 out take. People say that you gotta have more out take then intake but with just 46 in and 46 out before the temp was higher than it is now with more in then out...

I'm currently running tests to see the best set up, I will try using the stronger 80mm on the out take and see what I get...

The fucked up part is that my seeds are already showing the little white tail and I have nowhere to plant and they are my only seeds... Arrrrrrrrr!!!!!!!

How many lights are you running and what type? If you cant vent anymore to cool it down you might have to remove some bulbs. That or find a colder spot to put your growbox, on average your box will tend to be 15F or so above ambient, depending on the size and lights running...

There are 4 x 27W CFL's

I dunno the pc growcase its really small... I run tests with 3 and 4 lamps on and there is almost no diference, I get sometimes just 2º F less then with 4 lamps, it might be a cooler issue I'm currently running right now have tried some tests I've seen that if i take off the intake that blows air right in front of the lamps temperature goes to the 100's

Have you tried running both the fans on extraction? Normally a passive intake would suffice as the two fans extracting air will create an air flo anyway. 4 lamps in a PC case is quite a bit. Are they daylight (6500k) or warm whites (2700k)? Warm whites will always run warmer than daylight bulbs....

Hi Charmwah,

They are 3 6500k and 1 2700k, for veg then I will run the opposite for flowering.

Man... Crazy, I turned off all my intakes and I got better results then with any other experiment like just one intake or two or different positions and stuff... I let it on for the intire night and got 87 during the night and 92 max thats was after running it 10 hours and when it was 1pm so probably the hottest time of a day...

So the thing that most people say that out take works best its in fact true!!!

I will boost up more the out takes and see if I'm able to run with just the 2 better cfm exaust fans. Right now i have just taken one light off to see the results. If I'm able to lower to 80 i will start growing...

So whats the outlook then Maconha?

Charmwah,

I have make some changes on the PC Growbox, I took of a transformer, rectifier bridge and capacitor for the 12v of coolers, that I had inside so I could have just one wire coming out of the box. But transformers heat and they were one more source of heat inside, now I have a cellphone charger kind of thing and 2 wires coming out of the box and ended up that no intake fan just out takes 2 more powerfull then before 38CFM each so total of 76CFM ( I believe its more then enough for a box so small )

I'm currently getting 82 degrees inside the box running the 4 lights, I will run them and see if I notice any stress of the plants due to temperature I will take one off.

These are a Haze mix or something like that, that I got 2 years ago from seedsman, the right one was faster to seed just 2 days on paper towel thats why its bigger, the other one took about 4 days, they are total of 5 days old from seed to this.

I actually used 3 seeds, one still did not ''hatch''

On pictures the intake fans are still iside there thats because I will still do some tests with just one in the bottom, I actually had this done before but with the transformer inside. But in fact all the tests with different set ups of intake and out take, varying position intensity and number of intakes proved that intake fans actually rise up the temperature, the best way is no intake fans just outtakes, I want to remember that all the tests were made inside my room with half of the window open with a room temp of 76 F all the tests the thermometer probe was in the same spot, inside the box and the box was placed in the same place for all tests and for 15 minutes on ( Sometimes less I had tests that ran 108F in about 8 min so I just ended it before anything burned )

Well...

I HOPE I DONT MESS IT UP....

Is there anyway you can cool the temperature in the room that the grow box is in? I think you'll be fine at 82F, under 85F should be fine with no ill effects, but ultimately it pays to watch your plants and know what they're telling you.

I don't think its gonna be possible to cool the house temperature there is no AC, I live in the 6th floor, I open up the windows and that helps a little bit but I cant start opening all windows people might think its strange since I never done that... Basically the temp is just 10F abore room temperature which is normal to pc growboxes.

Veging its the most complicated because you have the lights on for so long I will let it 20/4.

On flowering I can leave the lights on the night period so outside temp is a lil lower from 8pm to 8am its gonna be a good and cool time to flower...

I wait and see how this all end up.

I'd remove a light. I think you're plenty good with just three lights. and with all the mylar you may be good with just three. I have 3 42w in my veg box and that's plenty with all the additional mylar.

But i'd find something to get your plants closer to the lights. DVD boxes work great for me cause they're only 1/2 inch tall and you can add and subtract when plants grow.

oh yeah, get a remote temp gauge from wal mart for 12 bucks. I drilled a pin-hole in my box and stuck a food thermometer in it and can read from the top.