Fermentation temperature spike....ignore or act?

A couple of months ago I finished my fermentation fridge build and after reading loads of threads on where to put the temp probe I settled for sticking it to the side of the fridge, following observations from Twostage and others who have put a lot of time and effort into comparing probe positions :thumb:

The fridge has worked well for last couple of brews, and on yesterdays brew I decided to tape and insulate an additional probe to the side of the FV to check that things were working as planned. The brew went in at 20 degrees about 18 hours ago.

The NBS West Coast ale yeast I'm using has a lower working temp of 17 degrees so I set the fridge for 16 in order to (attempt to!) compensate for the initial fermentation spike. My plan was to keep the brew at about 17-18 deg for about 5 days, and then raie it to 19-20 for the remainder.

7 hours later the brew was at 21 deg, and this morning it was up to 22.5 :-?. Whilst the fridge is happily sitting at 16 deg.

Does anyone set a temperature profile to deal with this initial spike?

Should I be dropping the temperature further to take the brew off the boil?

Thanks as always for any advice!

This is why I tape my probe to the FV with some bubble wrap over the top to insulate

I've tried both methods, didn't work out for me with the probe in the fridge as the temperature kept overshooting. The thermal mass of 23l of beer smoothed it all out nicely for my setup.

Thanks Graz

I guess the difference between the action of a kitchen fridge vs a fermentation fridge is that the wort creates its own heat.

I taped and insulated the probe to the FV yesterday and bingo - straight down to 18 degrees.

Once the initial fermentation reaction is finished then I assume a probe in the air would work fine, but I can't see how it can work whilst the wort is self-heating.

I'll have to post the question on some of the other probe-location threads....

You want to measure the internal temperature of the beer as best you can and not the air around it.

If you work with the same yeast a lot you cam predict when the spike will happen and change the temperature manually.

Yeasts will handle cooling in different ways too.

@donchihon -

A few questions -

What are you using to measure the temp of your wort ?
Is it the same as what you are using to measure the air temp ?
Are they calibrated against each other ?

It's possible that your wort probe is reading high (or high relative to the air measuring probe).

Wort generating a few degrees during the 'active' stage is to be expected and I personally prefer to let it do that so I can monitor fermentation progress than clamp it to an ideal temperature.

How well insulated is the probe when it is stuck to the side ? You can check this by openning the door and seeing if the probe temp drops. If it starts to drop you are actually measuring a combination of the fridge temp and the wort temp so you are not getting what you see.

By the way, I've learned a lot over the last few weeks programming a Raspberry Pi to do fermentation control. (Thanks to Robbo101 for sending me down this particular rabbit hole). In particular the need to overdrive either cooling or heating to ensure equalisation of the temperature through the wort. Must admit to being pleased with the final version that can cold crash without overshooting or heating being needed to correct it. Anyway that's off topic.

Anyway I would have probably left it. A compromise (if you are confident that the wort temp measurement was accurate when it was high) would have been to either reduce the fridge temp a bit to bring it down a bit or temporarily attached the fridge probe to the FV and then move it back when it had settled a bit.

Hi Twostage!

Twostage said:

What are you using to measure the temp of your wort ?

Is it the same as what you are using to measure the air temp ?
Are they calibrated against each other ?

It's possible that your wort probe is reading high (or high relative to the air measuring probe).

Wort generating a few degrees during the 'active' stage is to be expected and I personally prefer to let it do that so I can monitor fermentation progress than clamp it to an ideal temperature.

How well insulated is the probe when it is stuck to the side ? You can check this by openning the door and seeing if the probe temp drops. If it starts to drop you are actually measuring a combination of the fridge temp and the wort temp so you are not getting what you see.

Click to expand...

I'm using an Inkbird 310 and a reasonable unbranded thermometer. Both have now been used to check wort and air (as I swapped them yesterday). The Inkbird is callibrated, but I probably need to double check the other one. I was a bit surprised at a 6 degree difference between air and wort, so maybe a couple of degrees are down to the unbranded thermometer being uncalibrated. I'll check when I'm back tomorrow.

The FV probe insulation is about 6 sheets of bubble wrap interlined with foil and I've taped it down in two layers. I've done the door test and it remains stable.

Twostage said:

By the way, I've learned a lot over the last few weeks programming a Raspberry Pi to do fermentation control. (Thanks to Robbo101 for sending me down this particular rabbit hole). In particular the need to overdrive either cooling or heating to ensure equalisation of the temperature through the wort. Must admit to being pleased with the final version that can cold crash without overshooting or heating being needed to correct it. Anyway that's off topic.

Anyway I would have probably left it. A compromise (if you are confident that the wort temp measurement was accurate when it was high) would have been to either reduce the fridge temp a bit to bring it down a bit or temporarily attached the fridge probe to the FV and then move it back when it had settled a bit.

Click to expand...

I'm already down a number of rabbit holes which are currently threatening my marriage...so am going to rely on the research of others for guidance (Just reread that and should clarify that all are beer related :lol:)

I wasn't sure how okay it was to leave the wort self-heating above the 18 degree fridge setting. I had thought that the inital days of active fermentation would produce off-flavours if the wort got too warm.

My hope with a fermentation fridge was to be able to set it (and forget it!) to 18 for 5 days and then maybe around 20 for the remainder.

Like you suggest, maybe in order to achieve this I need to put the probe in the FV for the first few days and then move it into the air for the remainder when the brew is not generating large amounts of heat.