regulation of humidity

hi to everybody,

this is my first try to work with Arduino and i need your help with few think about understanding.

i got one interesting project from my friend who had so much problems with high humidity in his basement ( basement is separated from house ).
until now he used some low cost solutions with manual switching. but now he wants to renovate complete basement and he needs something more standalone to work. so here is basic idea for hardware and functions.

functions : - arduino will mesure inside and outside temperature and humidity

  • depending of mesurments he will switch on/off FAN between basement and outside
  • arduino will show on display current in/out temperature and humidity and fan status (on/off)

optional functions : - arduino will make some logs on microSD card of all mesurments and fan status

  • check control over internet of logs and current status

hardware that we intended to use

  • Arduino Mega 2560 Rev.3
  • temperature/humidity sensor DHT11 2pcs
  • lcd display 3.5" ( looking for some tips )
  • relay for 220v fan
  • standard 110mm 220V fan single phase, maximum 50W

i have good knowledge of electronics, soldering, wiring, because i work with another banch of electronics, but i have low level of knowledge of coding (but i wants to learn that too ).

if somebody have some ideas about hardware/software please let me know. any suggestion is welcome.

in attachment is one my sketch how i imagine to make all that in general.

thank you all for any tips or help, and also for your time :slight_smile:

I would change the DHT11 sensor by at least a DHT22 and a DHT44 for the outside. DHT11 is a super-cheap part and not very reliable.

Ensure you have free run diodes on the relay and check that the switching current is not more than 20mA, otherwise you have to use a transistor to switch the current for the relay.

For the display I would choose a simple 2 line LCD display with a I2C interface, easy to connect and easy to use.

An Arduino UNO would be sufficient for this task as you don't need the additional pins and the additional memory of the Mega2560.