Best set points for STC-1000 to minimize cycle times on large fridge?

[cbehr]

I expanded the cooling area by nearly 2X on my edgestar kegerator. I can't seem to figure out the best setting to limit compressor cycles and keep the beer at a steady temp.

I found out hanging the probe is not the best, kicks on/off when you open the door etc and when the fans on it REALLY screws with the probe which I think is odd? I used a 12oz water bottle next but it seemed by the time the fridge kicked back on it had to work for an hour to bring the water temp back to my set point.

Any suggestion, have a small amount of water, decrease my set point so it kicks back on sooner? How soon is too soon where I worry about the compressor not resting enough?

 

[skunkfunk]

You could just set a really long compressor delay. Air temp won't be as steady but those beers are a pretty big sink, they don't move much over a few minutes.

 

[72hw]

FWIW - I tape my probe sandwiched between a thawed ice pack and the side of a keg. Seems to work for me and gives a much more accurate read than a bottle of water.

 

[cbehr]

FWIW - I tape my probe sandwiched between a thawed ice pack and the side of a keg. Seems to work for me and gives a much more accurate read than a bottle of water.

Wouldn't it take a really long time for the keg to warm up a degree or two then require the compressor to run for really long to cool the air and then begin to cool the keg again?

 

[jbb3]

I would go back to your 12oz water bottle and change the hysteresis setting to .5 degree. The default setting 1 degree which is allows too large of a temp swing before the STC calls for cooling.

Just know that when you open the kegerator to change kegs or whatever, it will take a few cycles to settle back down to a more constant temp.

 

[72hw]

Wouldn't it take a really long time for the keg to warm up a degree or two then require the compressor to run for really long to cool the air and then begin to cool the keg again?

Hmmm.... now that you mention it, I might have to pay more attention to that. I always cold crash my fermentor before kegging so it's already cold when it goes on gas in the fridge so I don't notice it running too long out of the gate.

I have my differential set to +/- 4 degrees I think with a 2 minute delay on the compressor, but yes, I think I will toss a datalogger in there to see exactly what's going on. Just need a way to log the Power On time now.

 

[RocketBrewer]

I'd decrease the hysteresis to .5 deg, increase the cooling delay to 10-15 min (you don't want the compressor short-cycling and burning up). Like mentioned before, tape the probe to the side of the fermenter with something over it so it doesn't just react to the air temp, but will still be affected by it. I've used folded paper towels or bubble wrap. You want to control the temp of your fermenting beer (which is generating a lot of heat), not a bottle of water. Your beer during active fermentation will likely be several degrees warmer than a bottle of water. keep experimenting and good luck!

 

[day_trippr]

fwiw...this is a plot of my keezer over the last 24 hours.

Currently the compressor is running for 45 minutes every ~5 hours and references the Keg probe, which is strapped to a keg under a ~4"x4" chunk of inch thick closed cell foam. There are six cornys in the keezer roughly half full on average. The effect of a stirring fan is shown between the Upper and Lower air temperature readings, while the Tower Air probe reflects a 40mm cooler doing the best it can.

The differential is set to 2°F and the beer temperature never strays outside that envelope. Meanwhile the air temperature swings are comparatively huge with an almost 20°F delta.

I could show a roughly similar plot of my fermentation fridge albeit with a much tighter differential (.5°F). My keezer and fridge controllers all use the same measurement technique: a heavily insulated probe strapped tight to the middle of the vessel, whether keg or carboy, taking advantage of that huge hysteresis effect to minimize compressor cycling...

Cheers!