Drying Tent Air Exchange While Using AC

I'm looking for advice on how often I should exchange the air in my drying tent while pumping in cool air from a portable AC.

I am not allowed to change the climate in our basement says the other half. So I am only changing it inside the drying tent.
The climate in the basement is a constant 72° F and 46% RH.


I will be using a AC Infinity 5x5 tent. The AC Infinity humidifier is outside the tent keeping the RH at 60% inside the tent. The exhaust fan is a AC Infinity 6" inline and is outside on top of the tent. It draws from the vent at the top of the tent and air intake is through the passive vents at the bottom. I don't think I will need a dehumidifier since the lung room air is so dry. The portable AC unit is Hydrofarm Active Air 14k btu and sits outside of tent pumping cold air in through tent side vent. The AC exhaust will be blown into the cold air return.There is also a 6" AC Infinity circulation Fan inside the tent on the floor.

So how often should I exchange the air? I am confused since I lose the cool air each time I do.

BB Boomer said:

I'm looking for advice on how often I should exchange the air in my drying tent while pumping in cool air from a portable AC.

I am not allowed to change the climate in our basement says the other half. So I am only changing it inside the drying tent.
The climate in the basement is a constant 72° F and 46% RH.


I will be using a AC Infinity 5x5 tent. The AC Infinity humidifier is outside the tent keeping the RH at 60% inside the tent. The exhaust fan is a AC Infinity 6" inline and is outside on top of the tent. It draws from the vent at the top of the tent and air intake is through the passive vents at the bottom. I don't think I will need a dehumidifier since the lung room air is so dry. The portable AC unit is Hydrofarm Active Air 14k btu and sits outside of tent pumping cold air in through tent side vent. The AC exhaust will be blown into the cold air return.There is also a 6" AC Infinity circulation Fan inside the tent on the floor.

So how often should I exchange the air? I am confused since I lose the cool air each time I do.

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I looked into this a while ago and it really depends on who you want to believe. I have not come across any research on this but I did some Googling and came up with the following info. The first bit is copy and paste from the Excel document and then the links are below that.

The most important things is to manage stagnant air. The optimal is to dry slow in low temperature ideally 25C/60F , it's not as important to stay on top humidity if you can keep temperature down. I've dried passively many times during winter months, just some light fan moving the air around.

You want to slow down the drying process to preserve terpenes that are more sensitive than Cannabinoid when it comes to drying.
There's no set rule on how often you need to extract the air while drying.

You should have as little air exchange as possible when drying. just enough so you can manage humidity.
I used to have my extractor turn on for 5 min every 2-4 hours depending on how far in to the dry I was.
I guess you could use the VPD setting on the controller and have the minimum level set to 0 on the extractor.
There is this tread with great info regarding VPD and drying.

I really appreciate the good info. I will check out the links. Thank you

have the ac infinity controller set to turn on the exhaust when the humidity reaches 62% and switch off when it hits 58%, trust me I've been doing this for a long time, 16'c and 58-62% rh is good, colder is better. Your ac probably can't go lower than 16'c so just keep it at that.

my advice for this is try not to over complicate it too much, as time goes on you will get a natural feel for it. i only started using hygrometers and boveda packs in the past couple years before that i did everything by eye. it also doesn't hurt to pull a flower out and twist one up to see how it burns. each day of the harvest i mark on the line which day the flowers were hung as it sometimes takes me 5 days to clip all of my flowers by hand. you'll get a good feel for knowing when the flowers are dry even if your humidity in the dry room happens to be less than ideal say 45% the main thing is to make sure you get the flowers bucked off of the stems and into jars when the outside of the flowers feels dry that way you can get them into jars and the moisture that remains in the stems will travel to the outside of the flowers and essentially equalizes in the jar when its closed this will help you prevent over drying. dont forget to burp the jars once a day for an hour or so. continue to do that each day until the humidity on the hygrometer is sitting at 62 without having to burp the jar. its much easier to control the humidity inside a small jar with a hygrometer than it is to control a large room especially if you don't have any equipment to control the environment. you can grow great buds with just a light and a fan and some glass jars just need to be mindful and pay attention to the flowers as they dry.

I'm not growing something for 4 months to potentially f it up in dry bc someone who doesn't grow has placed a nonsensical restriction on the space during dry. Tell her be quiet, and get ur dry space in order. Respectfully, of course.

Yeah there's a range that you really can't avoid if you're going to dry the plants properly. 60 degreesF (or colder) and 58-62% RH is the ideal. If I had to choose between 57%RH and 63% RH, then I'd choose 57%. If I had to choose between 61 degreesF and 59 degreesF, then I'm choosing 59 degreesF. And I'd try to get a MINIMUM of 14 days of drying under those conditions....and more days, if needed.

72 degreesF and 42%RH isn't going to cut it.You're going to have to man up on this one, my friend!

As far as fans, I use a clip-on fan, lowest setting, set it in the bottom corner of the tent and point it at the floor.....just the minimum air flow as possible. I constantly monitor the conditions. Just as a safety precaution against mold, I also use a UVC sterilizing wand and wave it around the plants every so often -not long enough to degrade the THC, but long enough to kill any potential mld spores. I know it's probably not necessary, but it makes me feel better.

tstick said:

Yeah there's a range that you really can't avoid if you're going to dry the plants properly. 60 degreesF (or colder) and 58-62% RH is the ideal. If I had to choose between 57%RH and 63% RH, then I'd choose 57%. If I had to choose between 61 degreesF and 59 degreesF, then I'm choosing 59 degreesF. And I'd try to get a MINIMUM of 14 days of drying under those conditions....and more days, if needed.

72 degreesF and 42%RH isn't going to cut it.You're going to have to man up on this one, my friend!

As far as fans, I use a clip-on fan, lowest setting, set it in the bottom corner of the tent and point it at the floor.....just the minimum air flow as possible. I constantly monitor the conditions. Just as a safety precaution against mold, I also use a UVC sterilizing wand and wave it around the plants every so often -not long enough to degrade the THC, but long enough to kill any potential mld spores. I know it's probably not necessary, but it makes me feel better.

Click to expand...

This^^^^^

With your setup, you should exchange the air in your tent every 15-30 minutes, depending on the internal humidity level. During drying, maintaining stable RH (60%) is key while avoiding excessive circulation of cold air to prevent over-drying. Adjust and experiment to find the right balance.

ps.
I had a similar cooling issue because every tent opening messed with the temp. XD Check if your circulation fan at the bottom runs continuously – you might just need to reduce the number of air exchanges. If RH drops too quickly, shorten the intervals instead of stopping exchanges completely.