MicroPython Forum (Archive)

Here's my little home IoT project based on Micropython.



https://github.com/jj-wohlgemuth/my-home-iot


[ micropython micropython-esp8266 synology synology-nas mqtt sql ftp python plotly dht22 dht11 dht ]

Here's a screenshot of the chart:

Interesting that the humidity readings in the kitchen correlate with the short term temperature variations. I suspect this happens on the other readings, but the temperature variation in the kitchen is more substantial so it's more evident. Or was something happening between those hours causing both temperature and RH to drop in sync? Cooking generally increases both...

I wonder if the device/device driver's temperature compensation is optimal? Mind you, I guess I'm splitting hairs here: an error of 10% RH is probably insignificant.

My impression was, that you open the window of the kitchen quite often, and that after having it closed again, the less dry air is causing a humidity drop. It would be interesting to see, if there is a slight time offset between the two figures.

I wondered about opening doors or windows. The air outside is colder and more humid. I would expect an exchange of air to cause a drop in temperature (as observed) and an increase in humidity. We see a decrease.

Hence my puzzlement.

When cold air warms up, the humidity decreases. That's why the indoor humidity usually drops in winter. And depending on the region and temperature, cold air can be very dry. But it is not yet cold enough here.

The drops occur when I open the door of the house which is about 3 meters away from the fridge (it's a 33m^2 studio appartment). The sensor sits under the fridge on the floor. Generally in winter I open the doors and windows at least once a day for 5-10 minutes to decrease the humidity inside.

https://de.m.wikipedia.org/wiki/L%C3%BC ... C3%BCftung

The bedroom sensor is about 6 meters away from the door and closer to the ceiling hence the inertia.

The outside sensor is close to the wall so it gets slighty warmed up by the house. It was probably actually a bit colder outside that day.

Roberthh wrote: ↑

Mon Oct 19, 2020 6:35 am

When cold air warms up, the humidity decreases...

Ah, OK. Vague memories from my schooldays are emerging. I need to do some revision

Nice project by the way

Thanks

I really love Micropython for standard stuff like this where it's just about parsing data from one protocol (the DHT22 serial protocol) to another (MQTT). No need to write hundreds of lines of C Code for it.