DHT11 vs DHT22

I am in a slow process of setting up home automation. It was Domoticz at first but my colleague talked me into OpenHab and I never looked back. But this is about something else.

I am using NodeMCU with ESP Easy software and sending sensors readings using MQTT protocol to the Mosquitto broker. Results were quite good altough readings seemed very innacurate and rounded to the nearest integer. So you had either 19°C or 20°C but not the decimal part. It shouldn’t be any suprise to me because when I announced that I am playing with DHT11 I was immediately told to ditch it for DHT22.

So I ordered DHT22 (AM2303 in fact) and set up them both on the same NodeMCU and used InfluxDB to store the data and then graph it with Grafana. The orange line is DHT11 and the green one is DHT22.

Comparison: DHT11 vs DHT22

The difference is amazing. Humidity reading is about 10% – 15% higher on DHT22 than on DHT11. The temperature difference is a little more, but it comes from the integer only reading. In worst case it is almost 2°C. Also as you can see it is much smoother because it gives you decimal readings. The DHT11 is less than a dollar per one and DHT22 is about $2.50. The choice for me is quite clear.

Please nothe that I don’t have a good reference thermometer so I didn’t include absolute comparision. It was rather one sensor vs another. But for sake of completness I used standard home digital thermometer. It was showing 19.8°C while DHT11 had 19°C and DHT22 had 19.4°C.