Slightly OT: Wine fridge temperature hysteresis?

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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.

--  
Regards, Joerg

http://www.analogconsultants.com/

Re: Slightly OT: Wine fridge temperature hysteresis?
On 6/03/2017 5:31 AM, Joerg wrote:
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Air temp in a fridge is notoriously variable, both in temp due to  
hysteresis, as you observe, and also in location inside the chamber.

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

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.

So put more beer in !

--  
Regards,

Adrian Jansen

Re: Slightly OT: Wine fridge temperature hysteresis?
On 2017-03-05 13:46, Adrian Jansen wrote:
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It's measured at the walls, not air. That changes very slowly, takes hours.


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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.


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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.


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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/

Re: Slightly OT: Wine fridge temperature hysteresis?
On 6/03/2017 8:43 AM, Joerg wrote:
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Yup, throw out the existing controller and put in something that does  
proper PID.

--  
Regards,

Adrian Jansen

Re: Slightly OT: Wine fridge temperature hysteresis?
On 2017-03-05 17:23, Adrian Jansen wrote:
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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/

Re: Slightly OT: Wine fridge temperature hysteresis?

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What's the typical cycle-on-and-off period, in your installation, with
the existing 5-degree hysteresis?

I suspect that trying for a tighter hysteresis might have required the
compressor to cycle on and off rather frequently.  This can be
destructive - refrigerator and airco systems need some "idle time"
after shutting off, for the pressure in the loop to equalize.  The
compressor usually has a timer on it, to prevent attempts at a rapid
restart.

Keeping the hysteresis tighter, while still maintaining a safe cycle
period for the compressor, might have required better insulation
(which is bulky and/or costly).


Re: Slightly OT: Wine fridge temperature hysteresis?
On 2017-03-06 11:41, Dave Platt wrote:
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Can't say for cooling because it is too cold right now. So heat only.  
With the 21W heater that I made each cycle is more than 20 hours. In  
part because it has a hard time to crank out the last degree.


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When I test ran it in the garage, setting it to 45F, the cycle times  
were hours so that doesn't seem to be the problem. Right now I can't  
test cooling anymore because I've got four beer fermenters in it and if  
I'd cool the fermentation would stall.

Considering that it has a >13A compressor all this seems overkill.

--  
Regards, Joerg

http://www.analogconsultants.com/

Re: Slightly OT: Wine fridge temperature hysteresis?

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maybe it is just that you don't want the compressor (or heating relay) to
  
cycle on and off all the time

heating with a solidstate switch you could make the hysteresis ~0

-Lasse




Re: Slightly OT: Wine fridge temperature hysteresis?
On 2017-03-05 14:52, Lasse Langwadt Christensen wrote:

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That can be maintained otherwise and actually is. They programmed a  
delay into it so if someone changes the temperatures back and forth very  
fast on the control panel it waits a long time to turn on the  
compressor. This avoids short-cycling.


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Unfortunately I can't. It is a Samsung uC with hard to decipher P/N,  
could be 1708B. Next to impossible to change the code in there.

--  
Regards, Joerg

http://www.analogconsultants.com/

Re: Slightly OT: Wine fridge temperature hysteresis?
Den mandag den 6. marts 2017 kl. 00.43.37 UTC+1 skrev Joerg:
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ed
py
m,
t,
to
  
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sure but there is a limit to how tight you can make it if you also want a
  
say +10 minute wait period between starts to limit wear on the compressor



Re: Slightly OT: Wine fridge temperature hysteresis?
On 2017-03-05 16:15, Lasse Langwadt Christensen wrote:
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The simple on-off controller on the old fridge ran on a 2F hysteresis  
just fine. Even less than 1F worked but I kept it set at 2F. Insulation  
and thus time lag on both fridges is similar.

--  
Regards, Joerg

http://www.analogconsultants.com/

Re: Slightly OT: Wine fridge temperature hysteresis?
On Sunday, March 5, 2017 at 6:43:37 PM UTC-5, Joerg wrote:

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Do  a search on aliexpress and Ebay for  W1209.  It is a cheap temp controler.  Will work for either heating or cooling, but not both at the same time.

                                       Dan

Re: Slightly OT: Wine fridge temperature hysteresis?
On 3/5/2017 7:10 PM, snipped-for-privacy@krl.org wrote:
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  Several years ago I bought a STC-1000 after reading about how  
homebrewers were using it with success.
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I have it wired up in a box with a duplex outlet with separately
wired sockets, one for heating one for cooling.

                                 Mikek

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Re: Slightly OT: Wine fridge temperature hysteresis?
You could mount a small heater next to the sensor and trick it into having less hysteresis..

no change to the code needed


Google "anticipator"


mark

Re: Slightly OT: Wine fridge temperature hysteresis?
On 2017-03-06 04:14, amdx wrote:
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I already have a Willhi controller from China, works great. However, it  
needs mains power and I wanted to make things more neat and integrated  
in this larger wine fridge. Inside there's only 5V at a few tens of mA  
available.

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Check out the Inkbird controllers. They come with cool/heat  
simultaneously. I found this not to be necessary though because we don't  
have wild climate swings out here.

--  
Regards, Joerg

http://www.analogconsultants.com/

Re: Slightly OT: Wine fridge temperature hysteresis?
wrote:

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for an engineer to watch >:-}  But doesn't seem to hurt the wine at
all.

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                                        ...Jim Thompson
--  
| James E.Thompson                                 |    mens     |
| Analog Innovations                               |     et      |
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Re: Slightly OT: Wine fridge temperature hysteresis?
On 2017-03-05 16:53, Jim Thompson wrote:
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Ah, so then 5F would be almost normal in the market. I wonder why they  
do that.

I'll see what the fermentation process says to that. If not happy I'll  
build my own controller. It's already on the schematic, just a lot of  
soldering. This would also allow me to strap a LM35-based sensor pod  
directly to a fermenter.

[...]

--  
Regards, Joerg

http://www.analogconsultants.com/

Re: Slightly OT: Wine fridge temperature hysteresis?
On 2017-03-06 08:02, Joerg wrote:
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BTW, I don't know much about wine but with beer there are a few types  
such as Pilsener and some Belgian ales where a difference of 5F can  
definitely matter. It can be the difference between ideal drinking  
temperature and too cold where yuo'd lose som flavors.

Anyhow, another project just reared its ugly head. The main pool pump  
goes TUNGGGG or sometimes just "tick" when it is supposed to come on but  
the motor won't turn. Shaft spins though. And it's raining, of course.  
Oh man ...

Since the sweep pump operates via timer that one might already have  
committed suicide because its design is suboptimal in that it can't run  
dry for long :-(

--  
Regards, Joerg

http://www.analogconsultants.com/

Re: Slightly OT: Wine fridge temperature hysteresis?
On 05/03/2017 19:31, Joerg wrote:
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Most older fridges I have come across have the capillary bulb or sensor  
next to the cooling radiator, such that any hysteresis was reduced.

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Not so long ago our central heating (bimetal) thermostats would have a  
resistor that would heat the bimetal strip when the thermostat demanded  
heat.  That, in a crude way, reduced the hysteresis.

Look for accelerator in:
   http://www.flameport.com/electric/central_heating/room_thermostat.cs4


--  
Mike Perkins
Video Solutions Ltd
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Re: Slightly OT: Wine fridge temperature hysteresis?
On 2017-03-05 18:12, Mike Perkins wrote:
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This one is electronic. The sensor does sit next to the cooling  
exchanger but the uC in the electronic sets the hysteresis.


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Crude but it works. With electronics this is no longer necessary though.

--  
Regards, Joerg

http://www.analogconsultants.com/

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