Fermentation Temperature Vs Fridgemate

[clean brewer]

Hey,

After receiving some feedback from QABC in relation to some beers, a couple comments were made in relation to controlling my Fermentation? :unsure: I thought I did....

Anyhow, I have the probe for my Fridgemate attached to the side of the fermenter with a big wad of Blue Tack, now taking into consideration the temperature of the Fermenter(heat from fermentation)and the Ambient Temp of the fridge, could I be right in saying that if my Fridgemate is set to 18 degrees, the temp of the Wort/Beer could actually be higher????

A quote from Butters in another Topic...

Fermentation is an exothermic process, ie it creates it's own heat. So the actual wort temp will always be higher than the ambient temp, whilst fermentation is active.

edit: the specific temperature difference varies based on too many factors to worry about on a HB level; suffice it to say that it's usually ~ 2-3C difference. YMMV.

Should I maybe set the Fridgemate to 16 degrees for the Bulk of Fermentation and then raise to 18 degrees for the rest????

Obviously with the probe stuck to the side of the fermenter, its not giving an accurate reading of the core of the Wort???

:icon_cheers: CB

 

[glaab]

I cut in half a wet suit stubbie holder and tape it to the side of the fermenter with the probe under it,
it's about 1 degree out at worst compared to a probe in the middle of the wort, close enough for me. Sanitize your probe and drop it in you'll soon find out the diff.
If your at 18 - 20 that sounds pretty good, 20 might be better depending on what your brewing and your type of yeasties. :icon_cheers:

 

[dpadden]

Hey CB, have you calibrated the fridgemate against something a little more reliable? Be interesting to know how reliable it is

 

[Thirsty Boy]

IMHO - the temperature differnece between the wort and the side of teh fermenter is minimal. I did a few experiments where I measured wort temp with a thermometer inserted in the wort vs temperature read through the sides of the fermeter. They were always within 1C of each other - and thats inside the accuracy of my temp controller. Mind you, this is with a bare thermocouple sensor, not a chunky fridgemate probe.

Two things though - I always, tape the sensor onto the fermenter and then cover the probe with a double thick insulating square of camping mat. This shields the probe from the ambient temp in the fridge. I dont think a lump of blu-tack is a very good insulator.

Second - I don't think that when you are controlling the temp via turning the fridge on and off - that having the probe attached to the fermenter is the best place. Your fridgemate has a swing built in, you probably have it set to 1C?? So if the probe is stick to the fermenter, the fridge is slaved t the wort temp and therefore the wort temp must swing by the amount built into the fridgemate. Now on cooling... with a 1C diff set, the fridgemate will drop your wort to 1C below your set temp and then turn off... then it will let it warm up to 2C above the set temp before it kicks the fridge back in. so with a set temp of 18C ... your wort is actually being driven between 17 & 20 in a wave pattern. And swinging temp is bad for fermentation.

Now if you have the probe measuring ambient - its the temperature in the fridge that swings wildly... the wort temperature is much more stable. It might vary slightly, but nothing like it would with the fridgemate actually forcing it up and down. All you need to do, is stick on a bog standard HB temperature strip... set your fridge temp and see what the fermeter temp ends up at. Then you can calibrate the fridgemate so that the set temp reflects the average temp of the fermenting beer. I'd do the test with water, but as mentioned, the beer will probably be a little hotter during active fermentation.. so you might need to adjust the temp down a degree or so and put it back up once fermentation starts to slow down.

Thats the way I see it anyway, which is one of the reasons I dont control my temperatures like that - but I use PIDS and heaters and you dont need to hear about that. think moving your probe to measuring the fridge temp would give you much more stable fermentation temperatures. I'm sure others will have differing opinions.

Thirsty

 

[clean brewer]

Hey CB, have you calibrated the fridgemate against something a little more reliable? Be interesting to know how reliable it is

Ill do that this afternoon....

 

[BjornJ]

Two things though - I always, tape the sensor onto the fermenter and then cover the probe with a double thick insulating square of camping mat. This shields the probe from the ambient temp in the fridge. I dont think a lump of blu-tack is a very good insulator.

Second - I don't think that when you are controlling the temp via turning the fridge on and off - that having the probe attached to the fermenter is the best place. Your fridgemate has a swing built in, you probably have it set to 1C?? So if the probe is stick to the fermenter, the fridge is slaved t the wort temp and therefore the wort temp must swing by the amount built into the fridgemate. Now on cooling... with a 1C diff set, the fridgemate will drop your wort to 1C below your set temp and then turn off... then it will let it warm up to 2C above the set temp before it kicks the fridge back in. so with a set temp of 18C ... your wort is actually being driven between 17 & 20 in a wave pattern. And swinging temp is bad for fermentation.

Now if you have the probe measuring ambient - its the temperature in the fridge that swings wildly... the wort temperature is much more stable. It might vary slightly, but nothing like itwould with the fridgemate actually forcing it up and down. Thirsty

Brillaint timing!
Put my fridgemate together today and have now plugged the fridge in with a cube of tap water in it to simulate (!) the fermenter with the probe just taped on to it to test the fridgemate.
I have read with interest about this discussion before and never having tried it, two arguments both seem to make sense.

1: Bluetack to the side of the fermenter (or a more insulating material).
The temperature is measured on the wort which is what we care about, not the ambient air temp. When the fermentation kicks off and the wort temp goes up, the fridge will cut in "earlier" to control the temperature. Sounds clever.

2: Leave the probe hanging in the air.
Measuring the ambient air temperature of the fridge rather than the wort temperature makes great sense! As soon as the air temperature drops by a degree, the fridgemate will kick in, long before the wort temperature has dropped "by much". So the fridgemate controls the air temperature, leaving the wort temperature much more constant than if the temperature would be controlled by the wort temperature.

But I can't do both!

Side of the fermenter seems to cycle the entire wort temperature 17-19 degrees = bad?
Air temperature does not control the wort when fermentation increases temperature = bad?
Side of the fermenter can take into consideration the heat from fermentation = good
Air temperature measuring keeps wort temperature more constant = GOOD


Thirsty Boy seem to know how this works, but should we measure in the air or in the fermenter? The post above says that you do it on the fermenter, then the next point says in the air so I'm a bit confused (and haven't even had a beer yet, hehehe)

thanks
Bjorn

 

[niggles]

Yep, +1 to Thirsty Boy's input.

Check out a post I did a while back [post="411990"]here[/post].

I stick the controlling probe to a glass of water sitting next to the fermenter. Depending on fermentation activity, I've measured the temp in the beer to be ~1-1.5C higher than at the probe, so adjust the set point to suit. The difference between the beer and the side of the fermenter will be slightly lower, but I've found overshoot and long cycling less of an issue with the probe separated from the fermenter.

 

[clean brewer]

Yep, +1 to Thirsty Boy's input.

Check out a post I did a while back [post="411990"]here[/post].

I stick the controlling probe to a glass of water sitting next to the fermenter. Depending on fermentation activity, I've measured the temp in the beer to be ~1-1.5C higher than at the probe, so adjust the set point to suit. The difference between the beer and the side of the fermenter will be slightly lower, but I've found overshoot and long cycling less of an issue with the probe separated from the fermenter.

Cheers guys, this info is what im after and maybe why I have comments about my fermentation, its changing to much...

:icon_cheers: CB

 

[Screwtop]

Some findings of mine re fermentation control using fridgemates. Took a few stalled ferments before I began to become suspicious about what temp my wort was being maintained at in my fridges. Using a few finickety yeast strains I had ferments stall, after taking the temp of the wort using a quality thermometer I found that the wort was lower in temp than the Fridgemate setting by a couple of degrees and sometimes as much as 3.

The second time I dropped a beer to 1C after fermentation I left it for three days and then removed the fermenter to rack to keg and found the beer was frozen in the centre, the outer part was unfrozen. The beer was around 5% ABV and so should not have frozen at 0. Obviously there was some sort of overrun causing the problem, the probe taped on the side of the fermenter at mid wort depth with some foam insulation covering the probe. Had some thoughts that maybe the air/plastic fermenter wall interface has a greater transfer rate than the liquid and so the core of the liquid was amassing lower temps as the outer part near the fermenter wall warmed and the fridge switched on and again chilled the air in the cabinet.

Basically now I add 2 to all of my temps, so for fermenting at 18 the fridgemate is set at 20 and to drop out yeast at 1 the setting is 3C. Seems to work nicely using my fermentation fridge.

This may depend upon the size and/or efficiency of different fermenting fridges.

Screwy

 

[shonks69]

Hi all

I have recently set up a fermentation fridge using a sopac air-con thermostat to control my fermenting temp and use the original fridge thermostat to chill the wort via toggle switch (The sopac thermostat measures the air temp of the fridge). I also fitted an electronic aquarium thermometer to the fridge with its probe immersed in glycol measuring the temp inside the fridge, my fermenter also has a stick on thermometer on it.
I have now tried three brews in the fridge and all have stalled approx 4 days into fermentation at approx SG 1020. I have been targeting 18 deg fermentation temps using SAF-04 yeast and have maintained this temp with in +/- 1 deg.
I the pitch the yeast at 24 deg and leave fridge turned off until fermentation has started (overnight), I then drop the fermentation temp to 18 deg in the fridge (fermenter stick on thermometer colored scale reads a color gradation from 18 - 22 deg).
How accurate are the fermenter stick on thermometers and which gradation of the color scale is the actual temp?

Cheers
Shonks :icon_cheers:

 

[MarkBastard]

Thirsty Boy, that's why I like to stick the probe to the side of the fermenter with minimal insulation outside it.

That way it's measuring both the wort temperature AND the fridge temperature, and giving you something in between.

For example when I have my wort at 30 degrees or so and I haven't pitched yeast yet due to needing the fridge to cool the wort down first, the probe measures 30 degrees, even without insulation (I've tested this). But it does seem to cycle more and not let the wort temp drop down or go up before cutting in. It seems to be the perfect in between. I just use a bit of cardboard as insulation basically.

You're right though, I wouldn't control a fermenting fridge on wort temperature unless my thermostat had 0.1 degrees precision.

 

[King Brown]

If the fridge has reasonably efficient insulation on it and you dont open it too often wouldnt the temp swing be fairly minimal?

 

[QldKev]

If the fridge has reasonably efficient insulation on it and you dont open it too often wouldnt the temp swing be fairly minimal?

The problem is if the fridge controller is set to come on at 17 and turn off at 20, even with the best insulation your fridge will eventually heat until the 20, thermostat kicks in and drops the beer temp to 17 before kicking out.

Better fridge insulation will mean this just doesn't happen as often, but will still happen.

QldKev

 

[technocat]

Obviously with the probe stuck to the side of the fermenter, its not giving an accurate reading of the core of the Wort???

It won't, I have tried this and it gives an erroneous temperature to actual temps in the centre of the liquid being monitored. I found a thermowell in the centre of the liquid not withstanding layering differences was the only reliable way of monitoring near true temps.

cheers

 

[Thirsty Boy]

See, beernut finds this phenomenon to be exactly the opposite from me and some others.. but I bet he has a few people who agree with him too - this is why this is such a hard question/topic. I'm pretty sure that so far there has been a "this is the way to do it" AND a "what ever you do, don't do it this way..." for most of the permutations.

Its unfortunately one of those areas where you will just have to try a few different options and combine that with your idea of which brewer's argument makes the most "sense" to you. Basically you will be able to find someone who is making any and/or all of the different options work for them.

 

[clean brewer]

Ive now put a Jar full of water in my ferment fridge with the Probe attached to it, my Digital thermometer is reading 18 degrees at the moment as does the Temp gauge on the side of the Fermenter, fridgemate is set to 16 degrees... The wort temp should stay stable this way as the Fridgemate will only have to run to get the Jar of Water down to temp, not 23 litres of wort....

I think this will work much better...

Cheers for all your input guys, this is what I love about the Forum, so much advice and so many different ways, just gotta work out what works the best for you.....

:icon_chickcheers: CB

 

[schooey]

Some findings of mine re fermentation control using fridgemates. Took a few stalled ferments before I began to become suspicious about what temp my wort was being maintained at in my fridges. Using a few finickety yeast strains I had ferments stall, after taking the temp of the wort using a quality thermometer I found that the wort was lower in temp than the Fridgemate setting by a couple of degrees and sometimes as much as 3.

The second time I dropped a beer to 1C after fermentation I left it for three days and then removed the fermenter to rack to keg and found the beer was frozen in the centre, the outer part was unfrozen. The beer was around 5% ABV and so should not have frozen at 0. Obviously there was some sort of overrun causing the problem, the probe taped on the side of the fermenter at mid wort depth with some foam insulation covering the probe. Had some thoughts that maybe the air/plastic fermenter wall interface has a greater transfer rate than the liquid and so the core of the liquid was amassing lower temps as the outer part near the fermenter wall warmed and the fridge switched on and again chilled the air in the cabinet.

Basically now I add 2 to all of my temps, so for fermenting at 18 the fridgemate is set at 20 and to drop out yeast at 1 the setting is 3C. Seems to work nicely using my fermentation fridge.

This may depend upon the size and/or efficiency of different fermenting fridges.

Screwy

Probably a silly question, but have you ever calibrated your Fridgemate against your 'good quality' thermometer, Screwy, to see what the digital readout says against the actual temp in a glass of water?

 

[dicko]

Probably a silly question, but have you ever calibrated your Fridgemate against your 'good quality' thermometer, Screwy, to see what the digital readout says against the actual temp in a glass of water?

Mmmm!

I have recently found a Fridgemate to be 5 deg c out compared to a Digi Therm thermometer which is used to check fridge and air cond temps in the industry.
I re calibrated the Fridgemate over a period of a week with the unit controlling the temp of a small chest freezer by using the Digi Therm as the standard and now that set up is working just fine.
So; dont just rely on the controller to be the correct temp out of the box.

Cheers

 

[clean brewer]

Hey CB, have you calibrated the fridgemate against something a little more reliable? Be interesting to know how reliable it is

Paddo, yes I have just checked it yesterday and its spot on correct... So not a issue there...

:icon_cheers: CB

 

[Screwtop]

Probably a silly question, but have you ever calibrated your Fridgemate against your 'good quality' thermometer, Screwy, to see what the digital readout says against the actual temp in a glass of water?

Four years ago I probably would have been so anal as to to that. Now I basically use results as my yardstick, if a beer tastes like fermentation was too warm I make a note in the recipe to wind back the temp a little on the next batch, or if the yeast drops early the opposite.

Screwy