Slightly OT: Wine fridge temperature hysteresis?

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/
Reply to
Joerg
Loading thread data ...

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
Reply to
Adrian Jansen

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

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.

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.

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/
Reply to
Joerg

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

Reply to
Lasse Langwadt Christensen

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.

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/
Reply to
Joerg

ed

py

m,

t,

to

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

Reply to
Lasse Langwadt Christensen

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

...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
 Click to see the full signature
Reply to
Jim Thompson

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

Reply to
dcaster

Yup, throw out the existing controller and put in something that does proper PID.

--
Regards, 

Adrian Jansen
Reply to
Adrian Jansen

Most older fridges I have come across have the capillary bulb or sensor next to the cooling radiator, such that any hysteresis was reduced.

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:

formatting link

--
Mike Perkins 
Video Solutions Ltd 
 Click to see the full signature
Reply to
Mike Perkins

Several years ago I bought a STC-1000 after reading about how homebrewers were using it with success.

I have it wired up in a box with a duplex outlet with separately wired sockets, one for heating one for cooling.

Mikek

--
This email has been checked for viruses by Avast antivirus software. 
https://www.avast.com/antivirus
Reply to
amdx

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

Reply to
makolber

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/
Reply to
Joerg

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/
Reply to
Joerg

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.

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/
Reply to
Joerg

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/
Reply to
Joerg

This one is electronic. The sensor does sit next to the cooling exchanger but the uC in the electronic sets the hysteresis.

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

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

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/
Reply to
Joerg

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).

Reply to
Dave Platt

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.

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/
Reply to
Joerg

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.