My house as an unconditioned mechanical closet with 170 deg. F. boiler and two 3KW solar inverters -- it gets HOT in the summer! I would use your devices as a home automation server, monitoring the inverters, boiler, heating zones, etc.
This would be a neat challenge. It sounds like the heat is pretty intense and sustained. But using Linux to monitor a home automation system is a great idea. And having a server that itself was judicial in electricity usage would make sense. There's no way to lower the temperature in the mechanical closet or just have the sensors report across a network to the main server?