-------- In message <837330db-2015-4ae5-8c9c-f444f569f...@n1k.org>, Bob Camp writes:
>Your “time cave” does not have a specific spec on temperature or on humidity. >You get to pick a number for either one. Anything in the “non condensing” >(let’s >call it < 80%) range for humidity is likely ok. Temperature up to 40C is >probably >ok for any gear that I can think of. As long as you *never* go in and out of >the >cave, comfort in the cave is a non-issue. Danger Will Robinson! Under no circumstances should your dewpoint be above the temperature on the other side of the door. If you have 40C at 80% humidity your dew-point temperature is 35C, which means that whenever you open the door your clock cave will fog up. If you run your clock cave at 40C, humidity needs to be well below 30% to hold the dewpoint below room tempreatyre. That is both hard, expensive and prone to electrostatic discharges. >Assuming the humidity in the basement is under control (if not, fix that), all >I need >to do for humidity in the closet is to exchange air with the basement. "fix that" is usually non-trivial, and from very to horribly expensive. The cardinal rule is that you should only exchange air (basement/outside, or cave/basement) when the air outside has lower *ABSOLUTE* humidity. And I keep stressing that it is *ABSOLUTE* humidity, because people simply don't pay it enough attention. 25C/40%RH air holds 9.2 g/m³ water ... as does 15C/72%RH air. This is why a lot of people in costal climates who ventilate their basement during summer "to dry out the basement" get the exact opposite result: The air outside is a lot wetter than on the inside. One would think that somebody had designed fans to measure this, but it is expensive: Cheap humidity sensors measure relative humidity and you need to correct for both temperature and pressure to get absolute humidity. And therefore, at the risk of repeating myself again: If you build your clock cave in the basement, it should be air-tight and you should manage the humidity in it separately from the rest of the basement. PS: Here is a good webcalculator: http://go.vaisala.com/humiditycalculator/5.0/ -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.