Lampshade for a temperature/humidity probe?

[Venturi]

It surprised me, too, when I came across it.

I’ve also found 2 easy ways to calibrate a digital thermometer that has a probe. They’re both rather obvious, and no one is going to dunk their Govee or digital controller in water. But, if you have a probe thermometer, you can calibrate that and then use it as a standard for calibrating the others.

It’s nice to have instruments that agree. After adjusting my probe and digital controller (as described above), I moved the probe and noticed later that its readings differed from the controller’s. When I placed them together, though, they gave identical readings again. Of course, agreement isn’t the same as accuracy, but it is a requirement (i.e., necessary but not sufficient) for accuracy.

[Low]

@Venturi

Hard to say whether those small differences are due to the hood. Can you move the hood to the other Govee and see if it then gives a cooler reading? (I can’t think of a reason your hood should affect the humidity reading.)

I agree with you, and I’m not ignoring your idea. Soon as I can I will swap hoods bro. Just haven’t had the time.

Here we are as of now.

Humidity is balanced with only a (almost) 1° temp shift. Zone 1 has the hood

Edit
@Venturi
The times weren’t synced here is the actual current reading

[Venturi]

Looks like the temperature difference is very small (0.6 - 0.8 degrees F) but stable over time. It’s reassuring to see the matching humidity values.

[Low]

Edited,

My bad the second meter was behind….

[Low]

Here is a week, and I just swapped hoods.

Zone 1 was hooded

Averages out to about the same over a week.

Just swapped to a hood on zone 2 instead

[Venturi]

@Low: Thanks for posting your results, which are especially convincing because your measurements were taken over long periods of time. Mine are similar.

I hung my probe 12" below one of my LED lights because 12" is the minimum height above the canopy I’ve seen recommended for lights. (It looks like more than 12" in the photo because of parallax.)

I put a black towel on the floor to simulate light absorption by the canopy and hung the lights 3 feet above the floor.

After zipping the tent up, I turned all 3 lights on full, along with my 4" inline exhaust fan and a 6" oscillating circulation fan. The lights’ built-in fans were off because I didn’t want the probe sitting directly in that airflow.

After the temperature reading stabilized, I recorded it, opened the tent, and installed the styrofoam lampshade while leaving the probe’s height unchanged. I punched the 8 airholes near the bottom at a 45-degree angle – that’s why they don’t appear to be open.

Results:

No lampshade - 99 degrees F in tent; 85 deg in room (14 degrees above ambient)
Lampshade - 101 degrees F in tent; 85 degrees in room (16 degrees above ambient)

Obviously, the lampshade didn’t reduce the probe’s temperature. In fact, it increased the temperature by 2 degrees F.

I got another surprise after turning the lights off and leaving both fans running, without opening the tent. My inline fan is rated 195 CFM at maximum RPM and AC Infinity has advised me that adding a carbon filter reduces an inline fan’s max CFM by 20 - 30%. My tent measures 2’ x 4’ x 6’11", which is a bit less than 76 cubic feet. So I should be getting (195 CFM x 0.7 / 76 CF =) 1.8 complete air exchanges per minute. Yet, it took a full hour for the temperature in the tent to drop to room temperature.

That means the tent and everything in it radiates heat long after the lights are turned off. So the styrofoam’s insulating property worked against me, instead of keeping the probe cooler. The good news is that a tent has “thermal momentum” that smooths out temperature fluctuations.

Combined with your results, I think we’ve demonstrated that a probe’s temperature isn’t affected discernibly by its location relative to the lighting, given that it’s at least 12" below the light.

This has been a fun and informative collaboration – thanks!

PS - My wife wanted to know why I was making holes in 3 stacked styrofoam cups and getting the debris all over my lap. I exclaimed “It’s a science experiment!” in my best Doc Brown voice.