Quick fermentation fridge question - probe in wort or not?

[biggtime]

The usual dumb last minute questions from me, I'm afraid! Brewing at the mo, built a temp controlled brew fridge yesterday thanks to lots of useful info on this forum (cheers all!), and am now wondering whether it is a good idea to put the temp probe into the wort in the fermentation bin (which presumably means a loosely fitted lid) or whether stuck outside but in bubble wrap or a sponge to protect from fridge air temp is sufficient?

Obviously I'd sterilise the probe if going in the wort, but is that a step too far for most people? Seems the logical thing to do to get the most accurate temp reading, but don't want to risk infection.

 

[Underground Joe]

You'll get some people say to do it one way and others will swear that their way is best. I stick mine on the outside with a generous layer of insulation covering it.

 

[biggtime]

Cheers Joe. What's your choice of insulation?

 

[Titus A Duxass]

Not - I stick mine underneath the PB.

 

[biggtime]

Not - I stick mine underneath the PB.

Sorry, being a thickie here - what's the PB?

 

[nobyipa]

did an experiment a couple o months ago that answers the question about my set up
here goes

my ambient temperature is set to 20.4C
with A 0.3C tolerance
fact my wort is 19.8C
did this when took out my furstey ferret clone thingy into secondary to dry hop it
aiming for 20c
so thats my fridge TOTALLY calibrated
used me Comark thermometer to verify this

done this by taping polystyrene onto the fermenter and the sensor tucked inside it
:drink:

 

[Underground Joe]

Cheers Joe. What's your choice of insulation?

I use a big generous wad off kitchen or toilet roll stuck down with electrical tape so that there are no gaps around the edges for cool or warm air to seep through.

 

[mattyhall22]

PB is a Pressure Barrel
FV is a Fermenting vessel

:

 

[Vossy1]

I put mine in, as I'm only interested in the temp of the beer. If you do go that route you can buy a small cable gland for the lid from ebay for next to nothing, just check it's 'clamping' limits with he size of your probe lead. If the probe lead is the 'figure of 8' type it's best to glue a round section onto it as otherwise you won't get an airtight seal from the cable gland :thumb:

 

[Vossy1]

Moved to this section as more relevant :thumb:

 

[biggtime]

Thanks all. Think it will have to be probe insulated but external this time round as I'll be putting it in the fridge in the next hour, and don't have a means of put the probe securely through the FV lid. But longer term, it's the wort temp that I'd like to be measuring, so I'll probably take that approach next time.

 

[airymary]

I've read posts where the OP has put the sensor into a container of water, such as a plastic bottle with one of Vossy's cable glands or a small grommet in the lid. Whilst it's a smaller volume of liquid, the sensor is measuring liquid temperature, not air changes when you open the door. Has the simple virtue of a permanent solution - stick it in the fridge and forget!

Cheers,
Chris

 

[photek1000]

I haven't got a fridge yet, but to monitor temperature of my FV in the garage whilst it sits under it's insulating old curtain and Brew belt (It's a bit red neck at the moment) I have the probe under four squares of bubble wrap taped on with insulation tape towards the top of the FV, seems to give a close reading compared with the actual liquid temperature.

 

[Titch]

Personally I have an old coke bottle with water in it . On the same shelf as my beer,wire through the lid. And initially have videne in it. Works well enough

 

[biggtime]

I've read posts where the OP has put the sensor into a container of water, such as a plastic bottle with one of Vossy's cable glands or a small grommet in the lid. Whilst it's a smaller volume of liquid, the sensor is measuring liquid temperature, not air changes when you open the door. Has the simple virtue of a permanent solution - stick it in the fridge and forget!

Cheers,
Chris

The only thing I'd query with that is that fermentation itself causes heat to be generated, so the contents of the FV would likely be warmer than a bottle of non-fermenting liquid nearby. That said, in an insulated and confined space such as a fridge, there presumably wouldn't be too much difference in the end anyway.

 

[Wezzel]

I trap a wodge of folded up bubble wrap against the side of the vessel with a bungy cord and trap the probe in between. Works fine.

 

[Daveg]

I've been reading up about this for a while now and my new brew-fridge is ready for my brewday tomorrow.
With this hobby it's easy to get anal about tiny details and the devil's in them I suppose but considering I've been fermenting in my living room, the brew-fridge with it's the stable constant temperature is what will make all the difference to my beer hopefully. So whether the probe is insulated from the ambient temperature on the outside of the FV or dangling in the Wort/Beer I don't think matters that much as long as you're within the particular yeasts temperature range. That's my take on it anyway.

 

[nobyipa]

I've been reading up about this for a while now and my new brew-fridge is ready for my brewday tomorrow.
With this hobby it's easy to get anal about tiny details and the devil's in them I suppose but considering I've been fermenting in my living room, the brew-fridge with it's the stable constant temperature is what will make all the difference to my beer hopefully. So whether the probe is insulated from the ambient temperature on the outside of the FV or dangling in the Wort/Beer I don't think matters that much as long as you're within the particular yeasts temperature range. That's my take on it anyway.

its a bit of a science
eg
fermenting at different temperature gives different flavours etc
a 2 to 4 C difference in fermenting temperature of a Hefeweizen can make a clovey beer or banana aroma flavour

 

[Daveg]

I get that, but the people who stick the probe on the outside of the FV covered with some kind of insulation (including me) seem happy enough with the control it gives them. That's why there's an F4 temp calibration on a STC1000 or have I got that completely wrong?

 

[morethanworts]

NOT

The probe under two layers of bubblewrap on the outside, half way up the wort seems to work brilliantly (when compared to readings taken across the inside of the FV). In short, the insulation adds just enough thermal mass to avoid rapid swings as the air heats or cools, but without the lag in response of putting the probe in the middle of the wort. A bigger lag means the heater or cooler will stay on for longer than required in each phase, because of the delay in its effect reaching the probe, overshooting in whichever direction each time (after the control has reversed or gone into neutral).

If I could heat/cool all parts of the wort completely evenly, at the same time, then of course the best place for the probe would be in the wort.

It's not just the accuracy in measuring the wort temperature that matters, it is also how effective the control is able to maintain it.