My blizzard day

[xela]

Having decided yesterday I'd rather be snowed in at the Zocalo if I was going to be snowed in, that's exactly what I did.

Well, that and unpack and organize and re-arrange furniture and hang out with housemates and just generally have a relaxing day. Well, except for the part where I was awakened at 6:00 a.m. by my phone getting email that our machine room was overheating. (I slept through the first alarm at 5:00.) I shutdown some non-essential machines, decided that as long as it stayed below about 40C it wasn't worth anybody going in to the office in a raging blizzard, and went back to sleep. Early in the afternoon Robby, who lives much closer to work, decided it would be a scenic walk to go to the office — for which I am most grateful. So he went in and reset the A/C (which is the usual cause of these events.) One consequence of all this is that we have a classic graph of what happens in a computer room with closed but not airtight doors when the A/C goes down for a few hours, and is then restored. I find the shape interesting:

Comments

[alierak.livejournal.com]

Convection cooling or heating probably works exponentially. The A/C, when it works, is constantly replacing some volume of room air with cool air, and mixing it fairly well because the fan is always on. It's like trying to turn a can of black paint into white paint by pouring some out, topping it off with white paint, stirring and repeating. I think when the A/C malfunctions it actually heats the air.

The other machines in the room don't necessarily operate on constant volumes of air per unit time, and don't necessarily replace cool air with hot air at a specific temperature. They do probably add roughly constant amounts of heat energy to the room per unit time. Mathematical description is left as an exercise for the reader, but I will say that if you just turned off the A/C, or turned off the A/C and its fan, you'd get a very different graph :)