Temp/humidity gauge issue?

[pakman91]

Hey guys, Pakman here.

I've got one of the temp/humidity guages with a probe on lead. It has an in/out reading.

I've been having a bit of trouble keeping temps up in the box with this cold weather (7am lights on 4 hours, 13°c)...but I've since realised that the 'in' is actually for the gauge, 'out' is the probe. This means that it's not actually 13°c, it's about 35°c.

Is my gauge stuffed, because I'm only running cfls and I could hold my hand on the globes without worry until the end of time.

The escaping heat wave from opening the door makes me think temps are quite high, but 35+, shouldn't they all be withered away to a crisp?

Thanks for any input guys.

 

[Nightmask]

I'm not really sure what you're saying. Are you saying you got confused on the temp reading for the unit and the probe, and your inside box temp is 35 degrees while your outside the box is 13?

For the probe try to hang it around mid box at around the height of your plants so you know what the temp is like at plant level otherwise your readings could be off.

To keep your temps down inside the box stick in a fan. I've got a small 2x2x4 tent with some small plants in and the temp was running around 31-33°c. I've since put a big standing fan in the room (outside the box) because I don't yet have the small ones and aimed it towards the vents to blow some air in and my temps in there are now around 23-25°c. Now I just need to find a way to keep it warm inside the tent during lights out as it drops to around 13-17°c currently and will only get colder (winter has just started here). I saw someone (can't remember who) get like a metal baking tin with a lid and they drilled some holes in the lid and put in a few of them small tea lights to keep the tent warm so I might have to look into that idea.

 

[pakman91]

Yeah sorry that post didn't come out very clearly.

It's a unit with a probe on a lead. The unit is external to the box, the probe is sitting in the middle/top of the plant canopy.

I assumed 'in' would be the measure for the probe, not the unit itself.

This means that after the lights have been on for 4 hours in the start of winter, the box which isn't closed on the front is hitting 35°c rather than 13°c.

I have a clip on fan blowing between the canopy and the lights for air circulation, but I am not currently using the exhaust fan as I can't close the door due to the clip on fan.

When I fully open the door a lot of heat escapes, which makes me believe it is 35°c in there, but I held my hand right at the lights (closer than the plant tops and probe) for a good 5 minutes, and nothing, not a single bit of discomfort.

I understand that 8x cfl(24w) ballasts can create a decent amount of heat, but why can't I feel it?

Which leads me to thinking that there is an issue with the temp gauge, but the heat that escapes when opening the door is definitely hotter than 13°c.

 

[pakman91]

Also, for your issue have you considered having lights off in the hottest part of the day, and on during the coldest.

 

[Nightmask]

Yeah sorry that post didn't come out very clearly.

It's a unit with a probe on a lead. The unit is external to the box, the probe is sitting in the middle/top of the plant canopy.

I assumed 'in' would be the measure for the probe, not the unit itself.

This means that after the lights have been on for 4 hours in the start of winter, the box which isn't closed on the front is hitting 35°c rather than 13°c.

I have a clip on fan blowing between the canopy and the lights for air circulation, but I am not currently using the exhaust fan as I can't close the door due to the clip on fan.

When I fully open the door a lot of heat escapes, which makes me believe it is 35°c in there, but I held my hand right at the lights (closer than the plant tops and probe) for a good 5 minutes, and nothing, not a single bit of discomfort.

I understand that 8x cfl(24w) ballasts can create a decent amount of heat, but why can't I feel it?

Which leads me to thinking that there is an issue with the temp gauge, but the heat that escapes when opening the door is definitely hotter than 13°c.

Pushing air around your grow box will only do so much if you don't have a way to vent some of that air and get fresh air in. Maybe clip the fan to another part of the box, even if you have to put something else in there to clip it too so you can have the exhaust fan going aswell. Or even try turning off the clip fan and turning on the exhaust fan and see if that helps with temp. My tent didn't feel like 33 degrees but the temp meter says it was, and when I added the fan the temps did go down, but I also have vent flaps open to cycle in/out air.

As for my own heating issues I'll have to consider what to do when I actually get everything set up properly. I have my small 2x2 veg tent but haven't got my 3x3 flower tent yet or all the other stuff to go with it (exhaust fan, carbon filter, ducting, etc), so when I get everything set up I'll figure out what to do then when it's working properly. Right now the small tent is keeping my seedlings in light but it's not at all positioned where I want it. I had considered turning the lights on at night and off during the middle of the day to help with temp issues but I'm also concerned about the power usage in the middle of the night and if it would raise any red flags. I don't wanna get busted because of some increased night time power usage. But as I mentioned I'll wait till I get everything set up properly and then I'll figure out what I'll do. Oh, and right now I don't have any timers either so it's all manually turning off and on the lights (I currently turn off between about 6:30pm and 12:30am so that's atleast part of the night).

 

[pakman91]

The exhaust fan I have is far to loud unfortunately, and with a small diy carbon filter it can't perform enough to lower temps. I removed the filter as only vegging at that point and fitted a fan speed controller, but I couldn't find a good enough noiseerformance ratio for it to be useful.

I bought a clip fan (didn't realise how big it was...) so it has to be on the front. The door is closed about 95% though.

I am looking at starting a new setup, but in the mean time I'm concerned I can't feel the massive amount of heat?
EDIT: I was sweating in shorts and a shirt in an industrial freezer set at -48°c, I should have some discomfort from 35+


I'm not sure at what point you are at in setup, but fyi Bunnings sell twin packs of digital 24/7 timers for $15-$20.

I don't think you mentioned which lights you are using, but let's just say a 600w hps, and the ballast will draw power as well, so that's roughly 700w. Assuming your in a house, a wall mount electric heater rates on average 2.4kw. This time of year in aus, it's not unusual for people to leave heaters running over night.

If your only running overnight in the cooler months, I think it will be less of a red flag, so long as there's no other tell tale signs of what's going on.