Is it a good idea to cycle the exhaust fan to maintain a higher temperature in a grow tent when lights are off?

Hi,

The temperature in my grow tent is dropping to about 13 C at night.

I've tried to do a bit of reading on ventilation but most articles/books/threads talk about ventilation for the purpose of removing heat where as here I need to conserve heat.

Am I right to assume that I can cycle the exhaust fan off then on every 15 minutes while the lights are off in order to keep it a bit warmer in there? Or is it a better idea to let it get a little colder but keep the ventilation. 15 minutes intervals are as small as I can get with my socket timers for the moment although I'm looking at getting one which can do 5 mins on, 5 mins off etc. For reference I have a 2.4 x 1.2 x 2m grow tent and I'm only growing one plant in there with a fan blowing on the plant to circulate the air and make it's branches stronger.

Thanks for any help

Plebschmo

That's fine as long as your humidity doesn't go too high

Gemtree said:

That's fine as long as your humidity doesn't go too high

Click to expand...

Thanks mate, is it OK to do in flowering as well as veg?

.

Plebschmo you need a temperature / humidity switch for your exhaust fan - comes on at say 85 F for LED and off at 75 F to repeat the cycle.

Works like magic.



HT-2 Humidity Temp Controller
By Grozone

.

Hobbes said:

.

Plebschmo you need a temperature / humidity switch for your exhaust fan - comes on at say 85 F for LED and off at 75 F to repeat the cycle.

Works like magic.

View attachment 4576942

HT-2 Humidity Temp Controller
By Grozone

.

Click to expand...

Cheers mate,

I just got a Ubibot which is pretty cool and gives me graphs of my temp and humidity. Trying to use info this to automate temperature with analog socket timers which I already have (on the fan) and a temperature switch which I use on an oil fin heater.

Temps get up to about 25 in the peak of the day, then drop to about 14 at night when lights are off.

13 is a bit cold. I would run a small space heater to keep it up to at least 17 or 18

JoeBlow5823 said:

13 is a bit cold. I would run a small space heater to keep it up to at least 17 or 18

Click to expand...

Thats what I'm doing but it isn't powerful enough to maintain anything above 14 degrees on a cold night with the exhaust fan on. I've just set the exhaust fan to cycle on and off every 15 minutes while lights are off and we'll see how that goes. I was just worried that I would be starving my plant of CO2 or something If i turned the exhaust fan off but I'm starting to think the exhaust fan is much more about temp/humidity control than it is about getting fresh CO2 to your plants...

plebschmo said:

Thats what I'm doing but it isn't powerful enough to maintain anything above 14 degrees on a cold night with the exhaust fan on. I've just set the exhaust fan to cycle on and off every 15 minutes while lights are off and we'll see how that goes. I was just worried that I would be starving my plant of CO2 or something If i turned the exhaust fan off but I'm starting to think the exhaust fan is much more about temp/humidity control than it is about getting fresh CO2 to your pants...

Click to expand...

Where is your exhaust fan exhausting to?

I do this in my main room using my T6 fan.
It's set up to run the fan when either the temp or humidity exceeds a set point.
Works like a charm

Run lights during night and off during hottest part of day. Will help balance the high/low temps.

thanks for the advice guys!

So no one really thinks that they need constant exhaust fan for fresh CO2? I

JoeBlow5823 said:

Where is your exhaust fan exhausting to?

Click to expand...

Its exhausting into a much larger room which is about as cold as outside...

plebschmo said:

thanks for the advice guys!

So no one really thinks that they need constant exhaust fan for fresh CO2? I



Its exhausting into a much larger room which is about as cold as outside...

Click to expand...

More to do with stopping smell leaking out like it can when fan goes off and keeping rh from spiking.

A temp controlled speed controller will kick your fan to an idol speed lights off and ramp it back up when lights come on.

I just realised I have a temperature switch which will allow me to turn the heater on under a certain temperature (say 25 C) and the exhaust fan on over that temperature. Do you think it is a good idea to set this up to keep the temp a bit higher (atm its around 17 with 15 minute cycling) or is it better to run exhaust fan on while lights are going?

Cheers

Thoughts on using a temperature switch to turn exhaust fan on when it goes above 25 degrees and turn the heater on when it goes below 25 degrees?