Shelly H&T vs ESP32 + DHT22

Hardware
#1

I’m comparing a Shelly H&T with a DHT22 connected to an ESP32.

There seems to be a constant difference between the two (ignoring the difference due to the difference in update intervals).

Screenshot 2022-08-02 at 21.32.02
Screenshot 2022-08-02 at 21.32.02928×470 9.09 KB

I’d like to know if anybody else has made a similar comparison and whether the result is the same.

What would be the best way to establish which one is correct? Should I get a mercury thermometer? That would depend on a manual reading though… Is there perhaps a good enough way to establish a reference temperature?

This is not for a serious application, but I’d still like to get it as close as possible to the truth.

#2

The Shelly is spec’d at ±1°C

The DHT22 is ±0.5°C

So worst case 1.5°C between the two. Your sensors appear to fall within this range.

A mercury thermometer will be no better than ±0.5°C, so won’t help much.

#3

Good thinking, thanks Tom. I didn’t consider the tolerances.

Interestingly, I have more than one Shelly H&T and they all report near identical readings. I wonder if they perform some calibration during manufacturing. I don’t have another DHT22 to compare against.

I also tried to find out which temp sensor they use, but couldn’t find the info (guess I could open one up).

#4

Hello, can you push the code with the connection beetwen ESP32 tp the Shelly H&T. I have problems with them ? You can help me a lot, thank you! Best regards

#5

I don’t understand what you’re asking. The original post was about comparing the different hardware.

The Shelly H&T is its own complete product and I run the stock Shelly firmware on it.

If you’re just looking for the ESPHome config for a DHT and an ESP32, it’s all on the ESPHome website.

#7

I need this issue fixed. How i can setup a ESP32 and connect it to a Shelly H&T wirelessly and then extract the data from the sensor. Thank you! I hope, you can help me.

#8