Tent Air Exchange: How Much?

[CharlieWaffles]

Hi All
Thanks in advance for your help. I have a 4 x 4 tent with a 6 inch exhaust fan and multiple fans and a heater running inside the tent and fresh air coming in all the time. My question is this; especially during the winter, where my tent is in my shed, I find that too much of the heat is getting sucked out too quickly using my 6 inch exhaust fan. I have decided to try the exhaust fan on a timer, only having it come on for one hour every three hours. This does make it significantly more humid and warm during that time in the tent which I think is great and that is my goal. Does anybody see an issue with not having air circulating near as much throughout the tent during those three hours? I’ve been doing this for about two weeks and so far so good but I’d hate for something to dramatically change one day overnight and all my plants suddenly either be shrivelled up or much too heavy with moisture. Any help and suggestions is greatly appreciated!

 

[Rexer]

Hey Charlie!

Two small purchases can save you a lot of troubles.
The first is a fan speed controller (fairly cheap) they look something like this:

And the second would be a temp controller. Inkbird makes some great ones that are reasonably priced (I got the WiFi model- love it!).


But to answer your question, I don't think you'll have any issues with three hours of fans off. Keep an eye for RH spikes.

 

[Phytoplankton]

Shouldn't be a problem, I do the same thing, and here's how they look.

 

[CharlieWaffles]

Hey Charlie!

Two small purchases can save you a lot of troubles.
The first is a fan speed controller (fairly cheap) they look something like this:

And the second would be a temp controller. Inkbird makes some great ones that are reasonably priced (I got the WiFi model- love it!).


But to answer your question, I don't think you'll have any issues with three hours of fans off. Keep an eye for RH spikes.

Excellent thanks @Rexer ! And I have that exact fan speed controller in my tent and it still sucks out so much air and heat even on the lowest setting. In hindsight I wish I had bought a 4 inch exhaust fan instead of a 6 inch.

 

[CharlieWaffles]

Shouldn't be a problem, I do the same thing, and here's how they look.

Perfect. That’s what I wanted to hear!

 

[Rexer]

Excellent thanks @Rexer ! And I have that exact fan speed controller in my tent and it still sucks out so much air and heat even on the lowest setting. In hindsight I wish I had bought a 4 inch exhaust fan instead of a 6 inch.

No problem! If you have lots of room, put a bend(s) in the ducting, it'll reduce the efficiency and it'll pull less air.

Honestly though, if your loosing that much heat- a Inkbird temp controller will probably pay for itself within a grow, and they last years (that being said- I know what it's like to try and stretch a budget).

Anyhow- best of luck!!!

 

[CharlieWaffles]

S

No problem! If you have lots of room, put a bend(s) in the ducting, it'll reduce the efficiency and it'll pull less air.

Honestly though, if your loosing that much heat- a Inkbird temp controller will probably pay for itself within a grow, and they last years (that being said- I know what it's like to try and stretch a budget).

Anyhow- best of luck!!!

So far the on off method for the fan seems to be A++. Certainly not near as big of a deal in the summer when it’s warm, but in the winter when the heater has to be on all of the time at high wattage to keep the temp above 20 Celsius, I thin k it was really driving up my electricity usage Fingers crossed this method works. If not I will certainly try your method of putting a few more bends in the pipe, unfortunately I’d have to buy another section of pipe and that crap is not cheap for what it is.

 

[iffey]

How much light do you have in there? 6" in 4x4 for years did ok w 1K HPS. Ambient room temps 77F.

EDIT: just thought how big a 6" fan do you have (CFM)?

 

[Doctor Trevor]

Does the exhaust blow outside the shed? If so, change it so it blows inside. Let the air recycle; it'll stay warmer this way.

Is the shed insulated?

 

[Stormblessed]

I think u will b good as long as the humidity swings aren’t to dramatic, to big of swings is a good environment for powder mildew

 

[bluter]

a temp or time control will work fine. the temp control will probably work a touch better. i've only ever used timers if i run in to this as they were cheap.

Does the exhaust blow outside the shed? If so, change it so it blows inside. Let the air recycle; it'll stay warmer this way.

Is the shed insulated?

never do this. best way to get mold, pm, bud rot, ever. always exhaust to outdoor if you can. it's the moisture you are controlling more than the heat.



edit : standard graphic for tent or grow space ventilation set up

the first set up with the filter in the tent is better, either are acceptable. the green line represents an external wall.

 

[Doctor Trevor]

Charlie mentioned a heater in the tent. Wouldn't that would dry the air out? Maybe even too much?

 

[Camaro1691]

Hi All
Thanks in advance for your help. I have a 4 x 4 tent with a 6 inch exhaust fan and multiple fans and a heater running inside the tent and fresh air coming in all the time. My question is this; especially during the winter, where my tent is in my shed, I find that too much of the heat is getting sucked out too quickly using my 6 inch exhaust fan. I have decided to try the exhaust fan on a timer, only having it come on for one hour every three hours. This does make it significantly more humid and warm during that time in the tent which I think is great and that is my goal. Does anybody see an issue with not having air circulating near as much throughout the tent during those three hours? I’ve been doing this for about two weeks and so far so good but I’d hate for something to dramatically change one day overnight and all my plants suddenly either be shrivelled up or much too heavy with moisture. Any help and suggestions is greatly appreciated!

As long as your cycling the air out of the room every couple hours and not letting the humidity get above 70% when it’s hot you should be fine for the most part, more ideal RH would be around 60-50% and around 70 degrees F. Pickup a speed controller and turn the fan speed down to keep more heat in and then you can leave the fan on to keep things more constant, you want to avoid swings in temp and RH if possible.

Shouldn't be a problem, I do the same thing, and here's how they look.

Plants look fairly healthy although looking like you have some heat and/or light stress going on. What type of light are you using?

 

[bluter]

Charlie mentioned a heater in the tent. Wouldn't that would dry the air out? Maybe even too much?

it really depends how heat challenged he is. and whether he is in a dry or wet climate. i can get away with a bit more here as it's super dry in winter, but i still vent my flower room to outdoor.

it's the moisture that primarily holds the heat. loads of times all a heater does is warm up the wet air.

 

[Phytoplankton]

As long as your cycling the air out of the room every couple hours and not letting the humidity get above 70% when it’s hot you should be fine for the most part, more ideal RH would be around 60-50% and around 70 degrees F. Pickup a speed controller and turn the fan speed down to keep more heat in and then you can leave the fan on to keep things more constant, you want to avoid swings in temp and RH if possible.

Plants look fairly healthy although looking like you have some heat and/or light stress going on. What type of light are you using?

Two 2000W Bestva (385w draw ea.) RH is about 50%, temps from 65-80. Lights are about 18" above the plants. Those pics were taken about a day after I did a major flush and soil re-set. I was starting to get a lockout. Buds are coming along great. About 7-8 weeks in flower now, starting to really swell. The buds are big enough I can only get my hand around them half-way.

 

[Camaro1691]

it really depends how heat challenged he is. and whether he is in a dry or wet climate. i can get away with a bit more here as it's super dry in winter, but i still vent my flower room to outdoor.

it's the moisture that primarily holds the heat. loads of times all a heater does is warm up the wet air.

I second this, during the winter months when it’s really dry for me I can easily and comfortably run my room around 100+ Degrees F. and show very little if any heat stress, when it’s humid though, as soon as I start holding high heat, I run into PM issues big time.. @charliewaffles what do your night time temps get down to? Something to also consider if you can, is having your lights on time at night, the sun during the day will help hold temps up and the lights on at night will help when the sun isn’t out, also many times your electric rates will vary between night and day, when it’s night rates are often lower as theres not as much industrial use on the grid, soo the power companies will dump power off cheaper at night trying to sell more as to not waste energy they’re producing, soo you’ll help hold your temps up and cost slightly less at the same time

 

[CharlieWaffles]

Does the exhaust blow outside the shed? If so, change it so it blows inside. Let the air recycle; it'll stay warmer this way.

Is the shed insulated?

I can’t blow inside. I need it to blow outside so there’s no smell. Yes the shed is insulated and heated.

 

[732002]

Dealing with similar grow, cabinet in garage.

Small heater on low, thermostat set to 75F,
lights on 75+ lights off mid 60's.

Exhaust fan on low speed 15min on 45 min off.
I prefer to have shorter fan cycles because I feel
it keeps temp and humidity more constant. The fan
is at the lowest setting.

 

[bluter]

i run a heater on it's own thermostat for the veg space. it does well.

 

[CharlieWaffles]

Dealing with similar grow, cabinet in garage.

Small heater on low, thermostat set to 75F,
lights on 75+ lights off mid 60's.

Exhaust fan on low speed 15min on 45 min off.
I prefer to have shorter fan cycles because I feel
it keeps temp and humidity more constant. The fan
is at the lowest setting