How much does your temp controller swing?

[Noetikon]

I just bought a Johnson A419 and was curious about how much of a temperature swing I should expect. I have it set as: cut-out, SP 68F, diff +1, and the probe is taped to the side of my glass carboy (covered by insulation). When it hits 69F the controller kicks the fridge on, cools it back down, then shuts it off when it gets back to 68F. However, because of the large thermal mass of 5 gallons, there is a bit of cooling 'momentum' so that it drifts passed 68F and ends up at 66F (since the fridge air is now colder from being on). I don't have one of the heating & cooling units, just cooling. So I'm worried about a 3F degree swing for fermentation purposes.

Is this kind of swing unavoidable or is there some trick to get the controller to keep fermentation temps more steady? For example, should I put the probe in a small bucket of water instead?

[forcera]

Check what your temperature differential is set to.

I have a ranco and my differential is set to 1 degree and it never cools past the temperature I set it to.

[Ozwald]

The A419 probe is not water resistant & you should not submerge them.

Personally I just control the air temp. With yeast activity it's going to be a little bit higher than that, as it dies down the difference won't be so much. I find it easy to compensate for.

[brewinhard]

I have a Ranco temp controller with a stopper/thermowell into my wort in my carboys for primary fermentation and I have also noticed a bit of swing. I have noticed that once the yeast kick in and are actively fermenting the wort, then the temp of the wort will typically hover right around the temps I am looking to ferment at as the fridge kicks on. I personally do not worry too much about the small temp swing, and if you are worried about it dropping too low, then set it for one degree higher than you normally would.

[Bad Goat Brewing]

I do worry about the temperature swing. I don't use any insulation between the probe and the fermenter, but I tape my probe to the side of the fermenter, completely covering it with 3" painters tape. I have not observed the controller over shooting the process value by more than 0.4 F°. Not using insulation does increase cycles, but I think your controller has an anti-short cycle setting.

[Jerz]

I use a thermowell and keep the liquid less than a half a degree... I used to tape the probe on the side of the carboy (insulating it with some packing foam) and I actually think that worked fine too but the temp taken there would swing up and down a degree but I really don't think the liquid inside of the carboy would swing that much.

https://brewbit.com/dashboard/devices/3 ... 8634e4634a

[Klickitat Jim]

Mine used to swing but I switched to briefs.

Anyone?

No?

[Henielma1]

Is this kind of swing unavoidable or is there some trick to get the controller to keep fermentation temps more steady? For example, should I put the probe in a small bucket of water instead?

The temperature of the wort does fluctuate a lot less then it ambient temperature. In my experience the swing becomes less when you mount the temperature sensor to the outside of the fermentation vessel and isolate the sensor a bit from the ambient but not to much.



In the Netherlands we often use a scourer to isolate the sensor a bit from the ambient. The trick is to have some isolation from the outside environment but not to much. A bit of feed forward in the control system is good to prevent to much overshoot. That is why you do not want too much isolation.