Is this possible?

Hi guys,

Ok so I currently have a standard size shed in my garden which houses creepy crawlys and a few computers (strange mix I know), and due to this I therefore cannot let it get to hot or to cold!

So my question is this, i want a small setup using my current Arduino Uno board which reads the temp every so often (5 mins) and then if it gets above 30 dgrees c or below 5 degrees c, the arduino board will then either text or email me?? Is this possible? Is it easy? Is it expensive? And what other hardware is required?

Thanks!

It is very much possible. You will need some kind of temperature measuring device, which you can pick up for under $20. The emailing part my be slightly tricky, as you will need a (wireless, I am assuming) eithernet shield for about $80, and then you will need to work the code for some time to get it to gain access to your mail server.

My question is to you, why do it that way, and not just control the heater itself? Simply using the temperature device and running your loop to check the temp, if it falls too low you could turn on a pin, that switches a relay, that allows your AC to power your heater, and vice a versa for an AC unit. This way would be cheaper and much less complicated.

a simple sensor like this will do Temperature Sensor - TMP36 - SEN-10988 - SparkFun Electronics
and there is a tutorial on page 26 of this book http://www.sparkfun.com/tutorial/AIK/ARDX-EG-SPAR-PRINT-85-REV-10.pdf

Are any of the computers in the shed running all the time and do they have internet access? If so, you can just use the arduino to provide the temp to a program running on the PC and let it worry about contacting you. The idea of the arduino turning on heat or opening a window is more appealing though.

and if you don't want to play with high voltages and put it relays just rig up a cheap servo to flick the switch

You don't need an Arduino for that - there are standard USB temperature monitors available which you simply stick into one of the PCs and alarm you when the temperature is too high or too low. (Choose one that supports the type of alarm you want.)

Hey everyone, thanks very much for all the ideas and advice. The problem with the thermostat idea is that I do not have windows that open in the shed, nor a heater. I should have made it more clear that the heater is in fact a reptile mat which is only the size of a place mat.

As for the emailing idea I cannot really have a computer on all the time but also it would not have to be a wireless Ethernet as I have my router in my shed so an Ethernet would easily reach to that. Where is the best place to buy one of these however?