Groups > sci.electronics.design > #450452

Re: Slightly OT: Wine fridge temperature hysteresis?

From	Joerg <news@analogconsultants.com>
Newsgroups	sci.electronics.design
Subject	Re: Slightly OT: Wine fridge temperature hysteresis?
Date	2017-03-06 07:48 -0800
Message-ID	<ei5em5F8pumU1@mid.individual.net> (permalink)
References	<ei37ctFpvqkU1@mid.individual.net> <58bc8722$0$1604$c3e8da3$5496439d@news.astraweb.com> <ei3ik9Fs8otU1@mid.individual.net> <58bcba06$0$1587$c3e8da3$5496439d@news.astraweb.com>

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On 2017-03-05 17:23, Adrian Jansen wrote:
> On 6/03/2017 8:43 AM, Joerg wrote:
>> 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.
>>
> Yup, throw out the existing controller and put in something that does
> proper PID.
>

Doesn't need PID, just a smaller hysteresis will do fine. That's what I 
did with another fridge before, using an external controller. Worked 
nicely all summer last year. However, that fridge can only hold one 
fermenter. I might still use that on occasion if I want to brew a 
Pilsener or Bock which requires lagering for weeks at very low temperatures.

-- 
Regards, Joerg

http://www.analogconsultants.com/

Thread

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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