Growroom Thermal Dynamics

Hey All,

I've been thinking a lot about room temps in my flowering room. What I have noticed is the following:

I've got 3 thermometers permanently monitoring several areas, one is the aircon's thermostat, then a wall-mounted thermometer and hygrometer, then another permanently monitoring my canopy. I've got a passive inlet on the far side of the room, opposite to the aircon, and an exhaust fan with intake right above my gullwing type reflectors.

So, to get a canopy temp of 25 C, the aircon with it's intake on the ground reads as low as 19 and the wall-mounted one will read 22. Here's the interesting bit, if I suspend one from the ceiling, it'll read a degree or two LOWER than the wall-mounted one.

Any of you got some pointers as to some reading I can do to help me understand what is happening in there? I've got all my hottest air in the middle, and a cold layer above and below. Or is this merely the radiation off the lamps? I did shade the thermometer, it's got a aluminium backing I faced up too.

Any and all insights massively appreciated, come summer down here things like this become the main problem, temps...

There will always be fluctuations when using different thermometers, air flow--hot air rises and cold air falls--combine that with fans blowing, and things like grow space dimensions and your plants locations.. and like you stated (heat emitted from the equipment) etc etc

It seems overkill to me, but hey, if you want to take readings from every which angle-- that is totally up to you

I would just concentrate on the wall mounted thermometer --IMHO , as long as your not keeping the lights too close to the canopy, its really not practical to monitor the temps up there-- unless you want to for research purposes

I have been described as a 'research addict' and an 'encyclopedia for USELESS information' so your comment just suits my personality to a tee haw haw haw...

OK fair enough, I guess it's one of those things I'll just keep jotting down in the little ol' notebook to keep myself busy hehehe... So far I've been focusing on canopy temp, you reckon the wall-mounted thermometer (it's about halfway up the wall) is enough to keep my mind at ease? Excellent news that.

KushKrew said:

I have been described as a 'research addict' and an 'encyclopedia for USELESS information' so your comment just suits my personality to a tee haw haw haw...

OK fair enough, I guess it's one of those things I'll just keep jotting down in the little ol' notebook to keep myself busy hehehe... So far I've been focusing on canopy temp, you reckon the wall-mounted thermometer (it's about halfway up the wall) is enough to keep my mind at ease? Excellent news that.

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Your not alone in the "cannabis research addict" department Its not useless, maybe you will find something worth sharing to the rest of us~

I think you would make things a bit easier if you just concentrated on the wall mounted thermometer~ Don't worry, there are other variables in your grow room to keep you busy, (EX: what temp are the mediums.. etc etc) hehe

Weeeeeelll I just ended up raiding the medical box, and now have a little mercury therm stuck in a pot... Alarms set so I'm there in time for the flood haw haw haw... Happy to report nice LOW res temps, they're going to stay clean with so little effort this run

cannawizard said:

(EX: what temp are the mediums.. etc etc) hehe

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I have a hygrometer with the outdoor probe stuck between pots.

I like to keep an eye on root zone temps. as well as canopy temps.

my lights are on movers tho and pretty close to the canopy

Hey Joe! (I love saying that, always get the Jimi song stuck in my head hehehehe)...

I've been thinking about light movers also. I have a few pretty small spaces available, limited as far as height goes, so I have actually been wondering how much closer a mover allows you to keep your lights. Seeing as you actually measure I figure you're a good guy to ask. Any idea how much closer I can bring them and keep the same AVERAGE canopy temp? I am assuming that as far as heat goes, it will be best to run at approximately the same distance as I'd place two lamps keeping in mind the overlap, am I correct in assuming this?

Heard a lot of guesses on the topic from mates, but we are talking about people that have run their rooms at 46 degrees C come summertime and wondered why the nugs were fluffy...

I'm within 15" frequently w/a 1kw bulb

Wow that's damn close... Excellent. Time for a test or two.

air cooled hood though

Yeah if I use the small spaces air-cooled hoods are a MUST. Also thinking I need to upgrade the gullwings in the current space...

If you want to get decent measurements of multiple points in the grow you're really best off getting a single unit that can have multiple probes hooked up to it. Ideally this also controls the cooling system. One day I'll get to make a grow room that's built how I would design a lab.

Hehehe you speak my language, Sir I'm calling my current setup my 'training rooms' and the goal is to eventually have everything, including climate, automated and mechanically/digitally maintained as far as possible. And if I can monitor things remotely, that would be a HUGE plus. Not only is it something to burn my excess energy on, but my day-job is as a musician and music promoter which requires insane amounts of travel. Right now I've got a few months at home on my hands thanks to a spinal op so I'm trying to 'cash in' on the downtime as much as possible, and keeping sane.

So definitely on the cards is a muti-output and input thermostat. I'd love to find one that works with voltages AND has on/off style outputs that isn't meant for electric kilns or other hardcore process control, they cost quite a bundle. But once I know exactly what I want, I'm gutting this rig and starting brand-new, new climate control the works. Most of the nice gear I'll need to import and our taxman is pretty brutal at customs. So I want to make sure I buy RIGHT, I really don't want to buy twice!

Man I'm glad I don't have the tax man running customs here. Unless they let me import whatever the fuck I wanted so long as I paid them. Then they could be in charge of it.
What you're looking for is a PID controller. I don't know if there is a decent ready to go off the shelf unit for a smaller applications. When I worked in R&D we had people who could fabricate all of that based on drawings or even vague descriptions and a few probing questions. God I wish I could get those guys involved in setting up a grow.

Get a lazer pointer thermometer. I got one for $14 USD on ebay. Point and shoot to get the temp instantly in one spot. I found many micro climates in my grow.

joe macclennan said:

I'm within 15" frequently w/a 1kw bulb

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My leaves bleach if I am under 12" with my 600 watt hps.

MrEDuck said:

Man I'm glad I don't have the tax man running customs here. Unless they let me import whatever the fuck I wanted so long as I paid them. Then they could be in charge of it.

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There is only ONE upside to that, and that is as long as a price is declared on a package it's pretty much guaranteed to make it through. But man, they can nail you pretty hard, all depending on what you import too. Musical instruments, no tax, high-end electronics up to 30 percent. Add shipping and yeah you want to make sure about the right choices!

A custom unit sounds SWEET, most of my amplifiers etc are custom and hand-built, so I have that soft spot for 'boutique' gear. I'm not half bad with a soldering iron myself but I think I'll have a talk with a mate in electrical engineering instead. When in doubt, hire a pro, a philosophy that's always worked for me.

Hey Trousers, I am SOOOOO getting one, thanks bro!! I can see the hours melt away already. Bored boys need toys.

When you are done checking the temp in about 457 spots in your grow room, you can check every thing in your house.

The ir thermometers are awesome and the only way to really map canopy temps.

Guys sometimes it REALLY pays off being a propa NERD Let's just say I annoyed the rest of the house soooo much with this topic, I got given access to the room I really wanted, I've now got a whole 1.6 METRES extra height! I've also just gained at least 10 square metres of floor-space. I find this incredibly exciting, the room has ceiling fan so circulation is going to be SUCH a treat.
That and my back can't handle the midget-sized space I was using any longer. What took me out was the usual PH tweaking after adding some Mineral Magic to the res last night. Ended up stuck and having to call for help to get back upright.
This move is going to save me a LOT on climate control I can add another 600w hood and flood table to the mix now too...

Thanks for your input on this topic guys, looking forward to an easier and more forgiving space for me to continue my experiments with!!

Nice, short spaces are no fun to work in. I grew in a crawlspace area that was like 1.5m. It sucked.