[time-nuts] Temp/Humidity control systems?

Poul-Henning Kamp phk at phk.freebsd.dk
Thu Oct 27 13:28:43 UTC 2016


--------
In message <20161027131226.0d5a72e62b2c91f2e13b637e at kinali.ch>, Attila Kinali w
rites:

>> Stop!
>> 
>> Over insulating is a 100% sure-fire way to get unstable temperature inside,
>> because it amplifies the consequences of any change in power dissipation.
>> 
>> It is a classic mistake to build a 100mm insulated enclosure inside an
>> office-like enviroment and end up having less stable temperature on
>> the inside than the outside.
>
>No! Don't Stop! :-)
>
>That's why the next section I wrote described how to get rid of the
>excess heat in a controlled fashio. Of course, simply just insulating
>the room without giving it a lot of thermal mass or any form of control
>of the heat production/exchange will not stabilize the room.

Attila,  I did read that.

You are right in a certain set of circumstances, for instance in a
already climate-regulated office space.

But your model is a recipe for grief and disaster if you do it in
a typical basement, on about 2/3 of the inhabited area of the planet
where you cannot ignore the humidity.

In general in a basement, it is a better idea to set up a closed
space and manage the humidity inside it, than it is to move the
humidity in and out of it.


WRT to humidity, that's a very unlinear relationship, but you can
get far by remembering these five rules:

* Warm air holds more *absolute* humidity (ie: g/m³) than colder air.

* At the same temperture, wetter air is lighter than dryer air.

* The temperature is never the same.

* Condensation should be avoided, period.

* You cannot "feel" absolute humidity, always measure it.

And yes, go ahead and look up number two, it's true.  Dehumidifiers
belong on shelves under the ceiling, not on the floor.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at 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.



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