Problem with temperature controller

[DPveritasGold]

Hello all,
I just fired up my chest freezer with a Johnson temperature controller for the first time today and currently have a yeast starter in there, and it's not working right. I set the temp to 65 deg F, with a diff of only 1. It kicks in at 65 and then cools it below 55 before cutting off. I've checked it several times and it's been reading anywhere between 65 and 54. What is going on? The temp should kick off when it hits 64 right?

Please help. If I'm having a temperature variance of over 10 degrees im not going to be able to ferment well.

Thanks!

 

[sandyeggoxj]

I'm not sure what is going on. But if you are just making a yeast starter then no harm pushing up towards 75ºF. It will finish out faster and won't harm anything. You are going to crash and decant the thing anyway.

 

[DPveritasGold]

I'm not sure what is going on. But if you are just making a yeast starter then no harm pushing up towards 75ºF. It will finish out faster and won't harm anything. You are going to crash and decant the thing anyway.

Let me clarify a bit. I'm not worried about the starter. But I am worried about the actual beer that I'm going to be brewing in about a day. If the temperature is jumping between 65 and 54 while the actual beer is fermenting that's going to greatly concern me.

 

[sandyeggoxj]

How do you have the temp probe on the starter? Is it insulated from the air? The air temps will swing a ton. That is just how it works. But the liquid is slow to change so you'll want to measure from that point. When I used a chest freezer and carboys I would use a thermowell and carboy cap. Worked great. Others just tape it on the side and get good results.

 

[DPveritasGold]

How do you have the temp probe on the starter? Is it insulated from the air? The air temps will swing a ton. That is just how it works. But the liquid is slow to change so you'll want to measure from that point. When I used a chest freezer and carboys I would use a thermowell and carboy cap. Worked great. Others just tape it on the side and get good results.

That could be the problem I'm having. Right now I have it dangling down so the that probe is suspended in the center of the freezer. During the actual fermentation I'll tape it to the side of the carboy and hopefully that will help.

I'm thinking what's happening is that it's coming on and running until the temperature hits the stop point at the probe, but then since the sides of the freezer are colder than the ambient temperature, even though it's off it's continuing to cool the freezer.

 

[Paradingbull]

I find the temp swings will be smaller with a full carboy inside. Plus the liquid temp will not swing as wide as the air temp does.

 

[Bobby_M]

First, clarify if you have a manual unit with a copper capillary tube or if you have the A419 digital. There will be a huge difference in how you will be advised to troubleshoot. In either case, the setting you have to work on is the offset. Even the manual/analog controllers have this as an adjustment. The A419 is just more controllable.

 

[DPveritasGold]

First, clarify if you have a manual unit with a copper capillary tube or if you have the A419 digital. There will be a huge difference in how you will be advised to troubleshoot. In either case, the setting you have to work on is the offset. Even the manual/analog controllers have this as an adjustment. The A419 is just more controllable.

Bobby,
I have the A419