greenhouse control system?

I'm looking for some greenhouse automation.
Initially, I need to cycle exhaust fan to control humidity (if humidity is high, exhaust fan on for 2 minutes, wait 30 minutes, check again).
This means reading a humidistat and driving 240V relay.

I was thinking about doing it with ICs (I haven't done anything with electronics in about 20 years), but then I figured I'd want to expand the system to controlling watering, recording temp and humidity, etc.

The system would ultimately drive relays based on time and sensor data, and report activity / sensor data:
Activity would be exhaust, heater, and 10+ water valves.
Sensor data would be humidity, temp, sunlight and 10+ moisture sensors.

So I was thinking the best way would be a microcontroller - I ordered an Arduino.
I know it doesn't have the capacity for 10+ water valves and sensors, but I figured it'd get me started with temp, humidity, exhaust, heat and 1-2 valves and moisture sensors.

As far as reporting - I figured I could have it post to a web server over ethernet.
I was considering just using a PC in the greenhouse to control everything, but I am hoping a microcontroller will be:
a lot less likely to crash
much more resistant to heat/humidity (I was hoping it could be sealed and not need active cooling)
maybe cheaper

Thoughts and recommendations?
Thanks

Which Arduino board did you buy? While far from an Arduino type we do have some people here who are really good with micro-controllers. I have only experimented with the Duemilinova board a little using ethernet shield.

Ron

You can get shelds with more I/O. Its a good place to start and its been done before;
https://gardenbot.org/about/
Andy

Cool link Andy.

Ron

Reloadron said:

Cool link Andy.

Ron

Click to expand...

How about a +1 for that one. Please

Reloadron said:

Which Arduino board did you buy? While far from an Arduino type we do have some people here who are really good with micro-controllers. I have only experimented with the Duemilinova board a little using ethernet shield.

Ron

Click to expand...

ATmega328

4pyros said:

You can get shelds with more I/O. Its a good place to start and its been done before;
https://gardenbot.org/about/
Andy

Click to expand...

Thanks!

Update:
Using 8A solid state relays for the 240v vents and fans - very easy to use, and seems to handle the load fine - fan as measured is greater than 10A starting (MAX recorded OL), I saw 5A, steady state is 1.66A. One vent (of two total) is 0.05A while opening, 0.075A while holding open.

I've got an Arduino Uno (atmega328) measuring temp and humidity (RHT-22), controlling the vents and fans. It has an lcd for displaying current state and adjusting settings.
I have a Arduino Mega2560 connected to it via I2C that logs its info every 10 seconds, answer web requests, and resets it if it stops responding. Both are running the built in watchdog as well.

I plan to replace them with a custom board once I see they are stable and I'm done adding to them.

A greenhouse control system can be a lot of fun. Be sure to provide a link back to a PC where you can log the data and graph energy use etc.

I played with this a while back. https://wx175.blogspot.com/

**broken link removed**