Ambient temperature outside growtent

Thread starter #1
I got a problem keeping temperatures down in my growtent.

If I adjust my ambient lung room temp down to 17-18C, I get just below 27C at the canopy, all good.
If I adjust my ambient lung room tempt to 20C so that I dont need to run an extra heater inside the tent on a timer during night, my tent will go up to 27-29C at the canopy.

Ideal temp at canopy during day: 27C
Ideal temp at canopy during night: 20C

Its cold outside, so I got a heater in the lung room set to 20C, with the heater set to 20C my lung room keeps 19-20C day and night.

Tent: 120x240x200 (4x8)
Lights;1x 600W HPS + 2x 200W CREE 3590 (8x50w COB)
Exhaust fan: 552m³/h without filter, without any bends on the ducting
Active Intake fan: 320 m³/h without any bends on the ducting, blowing in 20C air
Passive intake; open ports in each end of the tent
Temperature taken from the canopy, approx. 40cm offset from the sweetspot of the HPS

All lights are installed 48cm above the canopy, I got the same problem both when exhausting from an open air cooled reflector, and when exhausting from the ceiling running an adjustawing reflector.

Is it possible to get the temp at the canopy to stay below 27C with this setup and a ambient temp of 20c? What am I doing wrong?

 
Thread starter #6
Your gonna need an a/c unit :48:
its 20 degrees Fahrenheit outside and no need for an AC :D
My problem is that if I warm the room outside the tent (the lung room) up to anything above 64 degrees Fahrenheit, the temp at the canopy rise to 82F or more. I got plenty of exhaust/intake ventilation and I dont get what im doing wrong.
 
Thread starter #8
Your doing nothing wrong. The light creates heat. It's as simple as that. As the ambient Temps rise the more heat the light produces.
Heat in the lungroom isnt the problem, if I turn off the heater the lungroom will freeze even with all lights on full blast. The problem is that I need to run the lungroom at 64F to keep the canopy under 82F.
 

Fuzzy Duck

Well-Known Member
Sounds like you are doing just fine :thumb:

I run my own grows very much like yours to be honest... apart from the lung room aka my spare bed room & passive intake / active exhaust.

In general base line intake temp is around 20c give or take a little depending on seasonal weather etc.

Average temp lights on 26c/27c is ideal but varies in summer months.

This is all in small tent btw way 90cm/90cm/180cm 400w open hood / 5" exhaust fan not sure on air flow rate ?


I would not be to concerned about 29c at best it may cause a bit of fox tailing strain dependent tho... if you really want to tame those temps you need to think about an air cooled hood set up !
 
Thread starter #12
Sounds like you are doing just fine :thumb:

I run my own grows very much like yours to be honest... apart from the lung room aka my spare bed room & passive intake / active exhaust.

In general base line intake temp is around 20c give or take a little depending on seasonal weather etc.

Average temp lights on 26c/27c is ideal but varies in summer months.

This is all in small tent btw way 90cm/90cm/180cm 400w open hood / 5" exhaust fan not sure on air flow rate ?


I would not be to concerned about 29c at best it may cause a bit of fox tailing strain dependent tho... if you really want to tame those temps you need to think about an air cooled hood set up !
20C intake air will give me 30-32C at the canopy, I need to keep my intake air 17-18C to manage 26.5-27C at the canopy.
This is a bizarre problem to have when its -10outside, its easier during summer when I just set the AC to keep the room at 18C.

Now Im battling outside temperatures varying from -10C to +10C, I spend like 10minutes watering my plants every 3rd day and I spend like all my waking hours watching the temps! :D

2 x 200W frost guard heaters inside the tent set to go off if the temp drops below 23C
1 x 2kw heater in one corner set to keep the room approx 17C (to help the smaller heater when temps drops below 17C)
1 x 500w heater in the other corner where I got my tent intake set to keep 18C
1 x 552m³/h extract fan from the tent set to go 30% when temps go below 23C
1 x 320m³/h intake fan set to go 30% when temps go below 23C
1 x 120m³/h room exhaust set to run 15min every hour (to replace co2)
1 x small passive intake into the lungroom (to replace co2)
 

Spitz

Well-Known Member
A cooltube (air cooled hood) will completely eliminate your tent/lung room deltaT. I have also 2x200W Cree 3590 (8x50W) that I want to run just like you are with HPS. I’ve had those damn lights for a year and haven’t tried them yet. Keep us posted.

Edit,,
A small fan blowing straight up from the bottom will change your temperature profile in your tent as well. Your total heat won’t change, but temperatures will be a little cooler toward the bottom and warmer at the top. Depending on canopy height, you may save a couple of degrees at your tops. Just don’t run the fan too hard.