Sorry just adding to this, if your equipment is critical you need a system that can email, sms and call. The reason I say this is we aren't always checking our emails, sms messages are sometimes not heard but a call will almost always get through.
I have our system setup on the following way
22 Degrees : Email and SMS (Warning)
25 Degrees : Email and SMS (Alert)
30 Degrees : SMS and Phone Call (Critical)
These alerts go to me and all of my staff. This solution has saved our equipment with the most recent episode being on the 24th of Dec after the fire alarm in one building was activated, when this happens are shuts down all cooling systems as not to "fan the fire" however when that was dealt with the cooling wasn't turned back on. I was able to remote in and restart the cooling system because the sensor alerted me to the fact it was starting to warm up in that area.
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