[time-nuts] Temp/Humidity control systems?
scott.j.stobbe at gmail.com
Wed Oct 26 17:31:31 EDT 2016
If your instruments/clocks were insensitive to variations in line voltage
you could vary your rooms line voltage with a variable auto transformer
(end up being a heater with tons of surface area). Or pack enough OCXOs in
there so they end up thermally servoing the room.
On Wednesday, 26 October 2016, jimlux <jimlux at earthlink.net> wrote:
> On 10/26/16 10:58 AM, John Ackermann N8UR wrote:
>> On 10/26/2016 1:00 PM, Richard (Rick) Karlquist wrote:
>>> On 10/26/2016 8:59 AM, John Ackermann N8UR wrote:
>>>> I may have the opportunity to build a small "clock room" and am
>>>> considering whether I could make it an environmentally controlled space.
>>>> I'd like to learn about the options for doing this.
>>>> The space would probably be 6x8 feet or so, in a basement with one
>>>> outside wall.
>>> I'm lost with the basic concept here. Help me understand this.
>> This room would be a large closet in my basement where two racks of
>> various OCXO, Rb, Cs live. There wouldn't be a lot of in-and-out
>> traffic. I'm not looking for 0.01 degree regulation -- <1 degree C and a
>> few percent humidity throughout the year seems a reasonable goal.
> Heating is easy (proportional control of a resistive heater)
> 1C is going to be very tough unless you have some way to variably mix cold
> dry air from your cooler with room air. Air conditioners don't like being
> short cycled.
> The challenge is that "cold" is usually available in a bang/bang way, so
> you need something to low pass filter it.
> If you had a large source of cold water, you could use a proportional
> control valve and some sort of radiator with a fan.
> Or, have a massive thermal sink between your "controlled space" and "where
> the ac unit is".. If you imagine a meter thick slab of, say, Gold (good
> conductivity, very high density), it would act as a very effective low pass
> filter between the cycling of your AC unit and your controlled space.
> I started my control system by putting a 5 gallon bucket of water in a
> refrigerator, and then using a variable speed pump into a radiator in the
> chamber. This worked quite well, but you run into all the problems with a
> liquid loop system: stuff grows in the water, water corrodes stuff, it
> leaks, etc.
> What I envisioned was a very small heat pump or other heating/air-con
>> unit coupled with some sort of proportional control. I just don't know
>> where to start looking for that, or what other issues to be thinking
>> (I know the way time-nuts think, and I recall the great ideas posted
>> here in the past about using an old refrigerator, or burying standards
>> in a deep hole -- but this would be wrapped into a bigger construction
>> project that I'm going to be managing from a distance, so I need to keep
>> it fairly straight-forward.)
>> Thanks, all!
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