Where to place the temp probe in my fermentation fridge

[David Woods]

I use a fridge with an Inkbird controller in my fermentation fridge and up to now I have the probe placed against the fermenter held in place with bubble wrap.

I have noticed that there are big temp changes given that the probe is measuring the outside of the vessel and it seems doesn't really react in a very smooth way enough.

I was wondering if it would be better to have the probe measuring the ambient temp of the fridge instead as maybe this would result in smaller adjustments in the temp - hopefully giving a more stable and consistent reading.

What do you prefer - it does seem that the wort needs to cool down or heat up a lot to affect an Inkbird change and then the reading seem a bit extreme.

I would be very interested in what would give the best results. I use a Tilt and it does show some wild swings in temp.

Cheers

 

[RichardM]

The usual advice is to do what you are doing.
An alternative would be a thermowell so you are measuring the temperature nearer the centre of the fermenter.

I don't see large temperature swings with the probe taped to the fermenter with bubble wrap over it. What are using for heating?

 

[fury_tea]

I measure the outside of the fermenter, same as you, you can get thermowells that measure the temp of the liquid a bit more accurately but honestly I don't think you really need them, I have one and I never use it.

You shouldn't be getting temp swings though, you might need a bit more insulation on there. Ambient temp.will swing more wildly and not be anywhere near as accurate.

 

[MashBag]

You can get temp swings, if the heating or cooling is creating a lag.

Ie heater too big. Cooling to much. So the probe detects the temp correctly (if positioned right) but the juggernaut is still rolling.

 

[Leon103]

You are doing it right. Changes in temp are due to fermentation taking place and it is all natutal

 

[RichardM]

You are doing it right. Changes in temp are due to fermentation taking place and it is all natutal

It would be interesting to know what the temperature changes are.
Cooler to warmer or vice versa? Over what time period?

 

[Dazzelknight]

I sanitise the probe and put it through the hole with the airlock, it sits directly in the wort,, been doing that years and never had an issue

 

[An Ankoù]

I have the probe placed against the fermenter held in place with bubble wrap.

I have noticed that there are big temp changes

I would suspect the measuring equipment. It would be difficult to get big temperature swings as it takes quite a lot of energy to shift a body of (say 20 litres) of liquid to change even 1 degree. Heating the wort to boiling required several kilowatts of energy for how long? No way that's going to happen even during the first flush of fermentation. But it all depends on what you mean by big temperature changes.

I sanitise the probe and put it through the hole with the airlock, it sits directly in the wort,,

Is the probe and it's connecting wire intended to sit in an acidic medium for such a long time? I'm surprised it doesn't corrode.

 

[Paulus]

I find that if you set the temperature to slightly lower (0.5-1C) than you want fermentation, the thermocouple should be anywhere near the height of the wort (nearer the top better). This leads to a general temperature in the cabinet. The wort will assume this temperature over time.

The problem with chilling/heating is that unless the heat/cool device is in the wort and you are measuring the wort temperature in the fermenter, as people above have written, there is a large time lag in changing the temperature of 20 or more liters of fluid. In that time the temperature in the fermentation cabinet will raise/fall massively before the temperature controller responds which is expensive in power and will cause temperature swings in the wort.

When fermenting, the wort temperature will rise but controlling the cabinet temperature will ensure it doesn't go too far. I use an Ink Bird to control a freezer or heat pad usually with just the heating or cooling plugged in at a time (a cycle of overshoot and undershoot could happen with both in). The cooling is set to kick in at set+0.5 and the heating at set -1.5.

The only thing is to know your cooling/heating is powerful enough to cope. However, if you are using a fridge or freezer then there is no problem.

I do keep a close eye on the temperature to start as the wort may need warming before pitching and then swap to cooling once the yeast gets going. I also use a rapt pil in the fermenter to back up. The pil feedback always is always within setpoint +-0.5C once things get started.

I have used a few different devices for temperature insulation: duvet, cooling bags (using chilled water) and finally now 2 chest freezers. Cabinet temperature control is the most efficient, cheapest (if you can buy the fridge/freezer 2nd hand) and works well in my view. I have made much better tasting kits from this method than from before (less stressful as well)