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Re: Slightly OT: Wine fridge temperature hysteresis?

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On 2017-03-05 13:46, Adrian Jansen wrote:
> On 6/03/2017 5:31 AM, Joerg wrote:
>> What is normal for a temperature hysteresis (or "dead band") in a wine
>> fridge? I am seeing 5F and more. It is a Vinotemp VT182.
>>
>> Long story short I modified it to become a beer fermenting chamber and
>> added heating capability. Due to it being winter out here it is operated
>> in heat mode right now and the original controller is still used to
>> measure and regulate temps. I didn't hack the micro controller part of
>> it (yet ...).  Currently it is set to 65F. Heat came on at 63F or 64F
>> and now it's topped out at 69F, still heating. Since the heater is wimpy
>> that means it may be always on until it gets warmer outside. No problem,
>> just got me to wonder why the hysteresis is so large on these.
>>
>> In case someone wants to know what's currently in there: American Wheat,
>> Honey Porter, IPA and Pale Ale. It sure beats having all these buckets
>> standing around in the downstairs room and having to run the pellet
>> stove just for the fermenters.
>>
> Air temp in a fridge is notoriously variable, both in temp due to
> hysteresis, as you observe, and also in location inside the chamber.
>

It's measured at the walls, not air. That changes very slowly, takes hours.


> 5 deg for a typical fridge is pretty good, the controllers are not all
> that smart, in general.
>

Ok, but for a uC-based controller that seems a bit much. My external uC 
controller for another fridge is programmable in the hysteresis and 2F 
is max there.


> It is usually assumed that the liquids in the fridge hold at least the
> liquid at a relatively stable temp, due to the high heat capacity.
>

Not really. The two sensors at the walls take easily an hour to change 
by 1F and the large liquid bodies (5 gallons of 18 liters each) follow 
that with some lag. A 5F hysteresis makes the fermenter contents meander 
by 2-3F. That's ok but I wonder why they chose such a large hysteresis.


> So put more beer in !
>

It's already maxed out. After scrapping out a lot of stuff and building 
new shelves I was able to cram in four fermenters. So the total is 20 
gallons or 72 liters. That's a lotta beer.

Anyhow, I just switched it back to 64F because the top part was about to 
exceed 70F and that becomes borderline for some yeast strains. This 
unfortunately means it's likely going to drop to 63F before the heater 
kicks back on. Not very close to the lower borderline of 58F but this 
does slow down the fermentation unnecessarily.

Some day I may have to build a better controller.

-- 
Regards, Joerg

http://www.analogconsultants.com/

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Slightly OT: Wine fridge temperature hysteresis? Joerg <news@analogconsultants.com> - 2017-03-05 11:31 -0800
  Re: Slightly OT: Wine fridge temperature hysteresis? Adrian Jansen <adrian@qq.vv.net> - 2017-03-06 07:46 +1000
    Re: Slightly OT: Wine fridge temperature hysteresis? Joerg <news@analogconsultants.com> - 2017-03-05 14:43 -0800
      Re: Slightly OT: Wine fridge temperature hysteresis? Adrian Jansen <adrian@qq.vv.net> - 2017-03-06 11:23 +1000
        Re: Slightly OT: Wine fridge temperature hysteresis? Joerg <news@analogconsultants.com> - 2017-03-06 07:48 -0800
      Re: Slightly OT: Wine fridge temperature hysteresis? dplatt@coop.radagast.org (Dave Platt) - 2017-03-06 11:41 -0800
        Re: Slightly OT: Wine fridge temperature hysteresis? Joerg <news@analogconsultants.com> - 2017-03-06 12:04 -0800
  Re: Slightly OT: Wine fridge temperature hysteresis? Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-03-05 14:52 -0800
    Re: Slightly OT: Wine fridge temperature hysteresis? Joerg <news@analogconsultants.com> - 2017-03-05 15:43 -0800
      Re: Slightly OT: Wine fridge temperature hysteresis? Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-03-05 16:15 -0800
        Re: Slightly OT: Wine fridge temperature hysteresis? Joerg <news@analogconsultants.com> - 2017-03-06 07:49 -0800
      Re: Slightly OT: Wine fridge temperature hysteresis? "dcaster@krl.org" <dcaster@krl.org> - 2017-03-05 17:10 -0800
        Re: Slightly OT: Wine fridge temperature hysteresis? amdx <nojunk@knology.net> - 2017-03-06 06:14 -0600
          Re: Slightly OT: Wine fridge temperature hysteresis? makolber@yahoo.com - 2017-03-06 07:18 -0800
          Re: Slightly OT: Wine fridge temperature hysteresis? Joerg <news@analogconsultants.com> - 2017-03-06 07:53 -0800
    Re: Slightly OT: Wine fridge temperature hysteresis? jurb6006@gmail.com - 2017-03-05 16:26 -0800
      Re: Slightly OT: Wine fridge temperature hysteresis? Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-03-05 16:42 -0800
        Re: Slightly OT: Wine fridge temperature hysteresis? jurb6006@gmail.com - 2017-03-05 20:41 -0800
  Re: Slightly OT: Wine fridge temperature hysteresis? Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-03-05 17:53 -0700
    Re: Slightly OT: Wine fridge temperature hysteresis? Joerg <news@analogconsultants.com> - 2017-03-06 08:02 -0800
      Re: Slightly OT: Wine fridge temperature hysteresis? Joerg <news@analogconsultants.com> - 2017-03-06 10:19 -0800
  Re: Slightly OT: Wine fridge temperature hysteresis? Mike Perkins <spam@spam.com> - 2017-03-06 02:12 +0000
    Re: Slightly OT: Wine fridge temperature hysteresis? Joerg <news@analogconsultants.com> - 2017-03-06 08:06 -0800
      Re: Slightly OT: Wine fridge temperature hysteresis? Mike Perkins <spam@spam.com> - 2017-03-07 00:56 +0000
        Re: Slightly OT: Wine fridge temperature hysteresis? Joerg <news@analogconsultants.com> - 2017-03-07 07:32 -0800
          Re: Slightly OT: Wine fridge temperature hysteresis? makolber@yahoo.com - 2017-03-07 10:57 -0800
            Re: Slightly OT: Wine fridge temperature hysteresis? makolber@yahoo.com - 2017-03-07 10:59 -0800
              Re: Slightly OT: Wine fridge temperature hysteresis? Joerg <news@analogconsultants.com> - 2017-03-07 11:19 -0800

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