When trying to get the most accurate temperature reading should the stat be outside of the area lit by the light. When I leave the stat directly under the HID for 12 hours it always has some crazy number.

This morning it showed 100, despite the room only feeling mildy warm.

this is why you need fans.

__________________
Smoke Responsibly

Waffles.

Was that a YES you can get an accurate reading directly under the light ? AND a NO the light itself will not effect the temp reading on the stat ?

I leave mine sitting in a pot not covered by fan leaves. The closer to the light the better IMO. Its closer to what the plants are experiencing as opposed to having your your gauge above the light or off to the side.

When I set it in a pot with the plants...it reads about 82-84f. When I put it on the shelf above the light it reads about 79-80f.

Its the temp that the plants feel thats important. If you cant cut holes to vent....get a few GOOD fans. I have 3 to control the HPS temps in my closet. Not expensive fans....just good ones.

That'll be all that infra-red heat the HIDs pump out.

Temperature and humidity readings should always be taken in the shade about half way up your plant height.

It's the average temp you want, not the hottest at the top of the room nor the coolest at the bottom.

__________________
Mandala Seeds Kalichakra and Satori Grow
Holefillers 0.6gram per watt 64w Micro Grow

hense why you need fans to CIRCULATE the air to get an even reading... also just to move the co2 around off the floor...

__________________
Fruitopia Smoke Blueberry Mix It Wit Tha Purp Call It Cranberry

The cirulation is for the plants to breathe....and get more co2. I have 3. One oscilating blowing on plants/stems....one above on a shelf facing outward. Blowing hot air out of the closet....and another on the floor facing inward. Blowing cooler air into the closet.

Before the fans my temps were like 96f.....above the light. I could imagine what it was at plant level. Fans make my grow possible.