Ambient temperature

[Lovemebeer]

Hi all,

I am fermenting in a small wine fridge with a glass door, ( good for keeping temp as you don't need to open up the door each time to have a peek) using a temperature control set at 18degrees. Does anyone know the difference between ambient and actual temp inside the fermenter?

 

[michaeld16]

Its all just a guess unless your measuring the temp of the wort, tape a thermometer to side of ya fv its quite surprising how much heat is generated the ambient temp of the fridge might be at 18 but your wort could be fermenting away at 24c. Also what are you using for an fermenter? The glass door while handy for looking through the light going through wont be good for the beer

 

[Lovemebeer]

Yea I taped the probe to the fv with an old sock to the outside to stop the ambient temp being to much of a contributing factor, but I usually come home to find the duct tape falls of and probe is dangling inside fridge. My fridge is in a dark space

 

[Benn]

I reckon residual Sodium Perc causes tape to not stick, I give the area a once over with a wet wipe and there's no more dramas.

 

[Ducatiboy stu]

Fermentation causes more heat than most think, so you do need to measure the temp of the wort directly

Plastic ferms do have an insulating effect so wont give you a true reading

 

[Lovemebeer]

So is there a known difference between inside and outside? Or is it different each brew?

 

[Ducatiboy stu]

Depends on the yeast and amb temps

 

[Lovemebeer]

So how do more advanced brewers measure the temp inside the fv?

 

[Ducatiboy stu]

So how do more advanced brewers measure the temp inside the fv?

With a thermometer

 

[manticle]

Even taking a sample straight into a hydrometer tube in a room temperature room will give you an indication.

I have measured an average of 2.5 deg C difference but as suggested, different yeasts and different brews may be different in heat generation. Higher gravity will often burn quite hot for example.

 

[Ducatiboy stu]

Generally the faster/quicker/bigger the ferment the more heat produced

Ales will make more heat than Lagers

 

[Lovemebeer]

Even taking a sample straight into a hydrometer tube in a room temperature room will give you an indication.

I have measured an average of 2.5 deg C but as suggestd, different yeadts and different brews may be diffrent in heat generation. Higher gravity will often burn quite hot for example.

Thanks mate, so would you usually set your fermenting fridge temp 2-3 degrees lower than desired?

 

[manticle]

At least. I always start cool, then towards the end of fermentation raise it a little. Essentially if a yeast's lower end of the range is around 18, I'll set the fridge at 15-16.

General rule, mostly for ales. Similar with lagers but I start them at 4 or 5, yeast fependent and slowly raise a degree a day during main ferment.

Main point is fermentation generates heat - measure it in some way and consider it a major factor in setting temp.

 

[Rocker1986]

I tape my probe to the side of the FV insulated underneath packing foam and set the temperature to the temp I want to ferment at. Every time I have measured hydrometer samples they have been within 0.5C of what the controller is reading. The controller I calibrate against my thermometer every 2-3 batches as well.

That is close enough for rock n' roll for me. It doesn't have to be precise to within a bee's dick, consistent temperature is the aim of it. As long as it isn't consistently way too high, it's fine.

 

[Mr B]

Yea I taped the probe to the fv with an old sock to the outside to stop the ambient temp being to much of a contributing factor, but I usually come home to find the duct tape falls of and probe is dangling inside fridge. My fridge is in a dark space

Old sock? Lash out and use a non stinky sock

I use a big bit of elastic to go round fermentor and hold the probe to it with a bit of insulation foam over it.

 

[danestead]

Stc 1000 or similar is your friend. Search for it here on ahb.

 

[Benn]

Can the out of the box STC-1000 probe go straight into the wort? Or will submersing it in liquid wreck it?

 

[Tex083]

STC1000 probe should be waterproof, I had one in my HLT measuring sparge water temp in the water.
If you search for NTC probe you can find stainless probes for the STC1000

 

[Kingy]

Craftbrewer sell the stainless probe. I just tape the cable to the side of the fermenter so the probe is submersed about half way. Then glad wrap on the fermenter with a ring to hold it.
Also i write on the tape the beer name/style, sg, the date it went in, the date i dry hopped, cold chilled etc. Then when its finished i can transfer all the info to my notes.

 

[Benn]

No worries, been thinking of probing the wort in the FV for a while. I'll track down an NTC probe.

 

[klangers]

Fermentation produces a set amount of heat per molecule of alcohol produced. So, a faster ferment = higher heat power output over a shorter period of time. Slow ferment = less heat over a longer period.

Pro brewers use temperature probes mounted through the wall of their fermenters. These would be jacketed fermenters which allows a far more efficient heat transfer and thus more responsive and accurate control.

 

[Lovemebeer]

Fermentation produces a set amount of heat per molecule of alcohol produced. So, a faster ferment = higher heat power output over a shorter period of time. Slow ferment = less heat over a longer period.

Pro brewers use temperature probes mounted through the wall of their fermenters. These would be jacketed fermenters which allows a far more efficient heat transfer and thus more responsive and accurate control.

thanks mate. Since reading these responses I have taped the probe inside the rebated handle on my fv with foam over it and have taken a few samples and been within half a degree each time

 

[TheWiggman]

The beerbelly thermowells are a top unit if you already have an STC, and are longer than the probe discussed in this thread: http://aussiehomebrewer.com/topic/82130-temp-probe-outside-or-in-fermenter/?p=1262835
Lots of good info in that thread too.

I recently did an RIS with a set temp of 20°C. I didn't plug in the fridge because it was <10°C in the shed, and it managed to heat up to 22.7°C over the working day. Best advice I can give, as above, is to measure the temperature of the liquid with a thermowell. I've found the insulated strap-on approach is also very accurate (0.3°C difference between submersed) but it must be insulated on the outside.

 

[danestead]

thanks mate. Since reading these responses I have taped the probe inside the rebated handle on my fv with foam over it and have taken a few samples and been within half a degree each time

With foam over it?

You want it taped to either the outside or inside of the fermenter at the wort level so you are measuring the temp of the wort. The temp of the foam is insignificant.

 

[Rocker1986]

Maybe the wort comes up that high :unsure:

In any case, mine is taped to the outside about half way up the FV. The foam is only there to insulate it from the ambient. It's not perfect but it does a bloody good enough job for my satisfaction.

 

[danestead]

Maybe the wort comes up that high :unsure:

In any case, mine is taped to the outside about half way up the FV. The foam is only there to insulate it from the ambient. It's not perfect but it does a bloody good enough job for my satisfaction.

Ahh I thought he was referring to krausen as foam! Disregard!