HI

I would take a look at the “stuff” they make for wine cellars. It’s an application aimed
at the same sort of area size and done in much higher volume than an electronics
closet.

Bob

In message 5810D2D2.2070902@febo.com, John Ackermann N8UR writes:

You first need to decide what kind of clock room you want:

At one extreme you have a clock vault you never change anything in,
with incredibly stable temperature & humidity, but stabilization
times of days or weeks.

At the other end you have an environmental chamber which hits temperature
and humidity in a matter of minutes after you closed them.

If you want to do this low budget, consider getting a couple of old
fridges or freezers and run water of your chosen temperature
through their cooling loops.  That way you can have multiple different
climates and keep soom stuff stable while you play with other stuff.

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

In message CANy2iXrmyy2E9PBdgcqiUZgne_8rPL4KKuW2J4pDJLbJ+j1gXQ@mail.gmail.com
, "William H. Fite" writes:

And they come up on fleabay with surprising regularity.

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

In message 20161026210517.26c0fd397b1cae5ba9c12def@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.

Cinderblocks is a much better material for that scenario, because they
have both thermal mass and inertia (= heat capacity and heat impedance)

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

The nature of air is that when you heat it by one degree Celcius the humidity falls by 10%.
That does not change the moisture content of the air, just the activity of the same amount of
water vapour with regards to any material with an equilibrium moisture content.
So it is important to control temperature fluctuation if you are going to control relative humidity.
cheers,
Neville Michie

Hoi Poul-Henning,

On Thu, 27 Oct 2016 07:41:48 +0000
"Poul-Henning Kamp" phk@phk.freebsd.dk wrote:

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 Kinali

--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson

On 10/27/16 2:17 AM, David J Taylor wrote:

Indeed.. a large mass varies slowly.

(hence the suggestions in previous years for finding caves, digging a
mine shaft, etc)

On 10/27/16 2:43 AM, Neville Michie wrote:

In this particular case, I did do the calculation of "mass fraction of
water" from the data - the AC really does pull the water out of the air.
The "test article" in this case has relatively small air volume, and a
large surface area of wood.  Water goes out fast, comes in slow.

There might also be a surface condensation issue on the glass surfaces.

If you look at the wet bulb temperature, it runs a few degrees below the
air temperature, except when the AC is on, when it plunges several
degrees in seconds.

In message 20161027131226.0d5a72e62b2c91f2e13b637e@kinali.ch, Attila Kinali w
rites:

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@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.