i made this ambiental sensor using arduino uno and arduino lcd 16x2 shield(with analog buttons). The sensor i used is DHT11 but it works with all DHT sensors.
It has 2 outputs that can connect to an arduino relay shield or other types of relays. The first output is used for temp control and the second output is used for humidity control.
From the buttons you can select the temp point and the humidity point after the outputs are switched to ON state.
On the main screen you will see the curent temp and humidity marked with T-temp. and H-humidity, and another feature called Tvar wich is the variation of the temperature from min to max, basically an arithmetic mean.
Step 1: Sensor Connection
The DHT sensor has 4 pins but only 3 are used.
As you can see in the picture, facing sensor with the label towards you, the pins are from left to right:
-NC (not connected)
-Data (conected to pin 2 digital on arduino)
The output pins for the relay are:
-Output 1 pin 3 digital from arduino
-Output 2 pin 13 digital from arduino
Step 2: Case
I've used an IP56 120mmx120mm plastic case for mounting the arduino, the temp sensor can be glued on the case (externally) and the switching relay can pe connected through holes with a lan cable or other 4 pin cable.
Step 3: Arduino Code
This is Arduino code, it contains the software you need to write it inside your Arduino uno. The code can be modified for any other Arduino. I've used a "diagnostic mode" on serial port, if you have problems with the project you can always connect to the usb port and run the serial monitor from Arduino codeing software, and you will se if you have sensor reading or the relay output is working.