[tommymorris]

My fermentation chamber is a chest freezer with Johnson Controls temperature controller.  Although I have had it for 5+ years I have recently noticed it runs the temp lower than I would like before turning off.

I currently have it set at 67. Last night I saw it took the temp down to 65F. I used my thermometer and confirmed the wort was actually 65F. I can live with a 2F swing.

This morning I checked and the temp was 63F. I didn’t have time to measure the actual wort temp.

The temp probe is attached under a folded wash cloth to the side of the plastic fermenter.

One hypothesis I have is that the ASD (anti short circuit delay) is leaving the freezer own and taking the temp farther than I would like below the set point.  I just moved that setting  from 2 minutes down to 1.

Any other suggestions?

I am using cooling cut-in mode with 1* F differential. So, it should turn on at the set point run until the temp drop me 1* F and then turn off. Unless the ASD timer has not expired, in which case it will stay on until the timer expires.

Thoughts?


- formerly alestateyall.

[MDixon]

The differential should be at least 4F or more. Monitor the wort/fermenter temp and adjust the temp controller setting to achieve that temp. The temp probe for the temp controller should be in the air in the fermentation chamber, not tied to the fermenter.

[Robert]

The differential should be at least 4F or more. Monitor the wort/fermenter temp and adjust the temp controller setting to achieve that temp. The temp probe for the temp controller should be in the air in the fermentation chamber, not tied to the fermenter.

+1

[LWRhomeBrew]

The ASD should only come in to play with a power outage to the controller. If the controller is running past your set point, try to change the off set.  If you are using an A419 control, I believe it is OFS on the screen.  You can use this feature to move the differential to above the cut out. 
I run a ranco etc111000 with a 1 degree dif without issue.  It cuts out at the set point as opposed to below.  That's where the OFS feature on the 419 will help. 

Cheers,



Sent from my iPad using Tapatalk

[MDixon]

One day your chest freezer or fridge will die with a 1F differential if it exceeds the duty cycle.

[JT]

I have used 1° differential for years with the probe in the beer or taped to the fermenter.  ASD is set to max at 12. This lets the freezer rest for a least 12 minutes between cycling. 
Having the probe in the beer in a thermowell further delays cycling on and off, as it takes longer for all the liquid to change two degrees than it would for the air to warm two degrees. 

[yugamrap]

I have used 1° differential for years with the probe in the beer or taped to the fermenter.  ASD is set to max at 12. This lets the freezer rest for a least 12 minutes between cycling. 
Having the probe in the beer in a thermowell further delays cycling on and off, as it takes longer for all the liquid to change two degrees than it would for the air to warm two degrees.

This is close to what I do, but I use a 2° differential and 10-minute ASD.  You're trying to control the temperature of the fermenting beer - so using a thermowell is the best option for probe placement.  Before I had fermenters with thermowells, I taped the probe to the side of the bucket or carboy and covered it with some packing foam (the kinda soft kind used for electronics) so that the probe would mostly read the temperature of the vessel rather than the surrounding air.  I found that the probe typically would read within 2° of the actual beer temperature.