Yeah. You could probably replace the thing with a raspberry pi
$2M ? Someone's pork barrel overfloweth.
I think we're all forgetting that the HVAC system as a whole is that old. Pumps, valves, and compressors all have finite life spans. My first reaction was also to use some Rpi's at each location which could add up to under $200 per building I then considered the cost to forklift and upgrade the HVAC at each facility. This would be about right.
You are always doing something marginal when the boss drops by your desk.