Setup for Johnson A419 Temperature Controller

[baron]

Just received this temperature controller from Northern Brewer.

Want to use it for controlling fermentation temps (for lagers and ales) and keg serving temperature.

Just testing it:
My Sanyo fridge has been off and the ambient temperature is 70 F.
I have the Johnson controller setpoint (SP) set for 60 F.
It is in cooling mode , cut-in.

dIF is at 1 degree.
ASd is set at 1 minute.
OFS = 0.
SF = 1.

I was perodically watching it and ensuring the relay was turning on/off and noticed this morning the temp was at 54 degrees (6 degrees below setpoint).

Not sure why is is that far off.

I might try putting it in cut-out mode -- that way the output is energized at setpoint -- plus differential.

If anyone has any ideas or suggestions, please post.

Thanks,

Rick

 

[user 84304]

Depends on where in the fridge the probe is. The higher it is, the longer it takes for the cold air at the bottom to build enough to hit it at the top. This can cause the overcooling you're seeing. You have the probe immersed in anything? Taped to a fermenter? Open air?

 

[HopSong]

I'd put the probe in a glass of water.. the water will more accurately reflect the average temperature of the box..

 

[baron]

Depends on where in the fridge the probe is. The higher it is, the longer it takes for the cold air at the bottom to build enough to hit it at the top. This can cause the overcooling you're seeing. You have the probe immersed in anything? Taped to a fermenter? Open air?

I've got the probe inside a 6.5 gallon carboy (plastic)-- no liquid, just open air.

Hanging about 1/4 way down carboy

I'll probably tape it to carboy when I am actually fermenting

 

[baron]

I'd put the probe in a glass of water.. the water will more accurately reflect the average temperature of the box..

Ok -- il give it a shot

 

[baron]

I set the controller to cut-out.

Seems to have helped-- I'll know for sure when I am controlling fermentation temperature.