Brew fridge temperature

[foxy]

I haven't used an Inkbird TC but don't they heat as well as cool? I have the STC 1000 which I use for cooling as well as heating.
It is the temperature of the wort you are monitoring with the probe stuck on the side of the fermenter insulated with Blue tack you can safely assume there is a + 1 C temperature difference at the core of the fermenter. Taking the ambient temperature could be as much as 8 C difference. Better still make a thermowell with some silicone tubing sealed at the end and drop the probe into that.

 

[The-Engineer-That-Brews]

I put the sensor on the item with the highest thermal mass i.e. the side of the FV. full of 23 Litres of water. The heater and cooling system only affect the air temperature in there so is not directly coupled to it, so rapid air temperature changes knock the high thermal mass temperature up or down a degree or two.
Another thing is I'm only using a 40W bar heater so even on full power it takes a long time to have any effect. If I was using 2Kw heater it would easily overshoot.
Sitting a FV on a 7W reptile mat with a thermostat taped to the side of it should be ideal even without a brew fridge to even things out.

yes Indeed, this makes sense in a setup where your heater is air-coupled... effectively it’s just a massively over-damped system

 

[RGeats]

I have a practically new aquarium heater and I was going to use that in a water bath. Would that be a better option?

Not sure if anybody answered this question. Yes a water bath would work well in the winter. I've done that for a couple of years and it's effective and simple. Just set the water temp and it'll act as a heat sink or source depending on ambient and wort temp.

 

[Buffers brewery]

Seems I’ve been doing it “wrong”. My brew fridge is controlled by a STC 1000 and the probe is stuck to the side of the fridge next to the FV (not the back). I have a tube heater sitting on the fridge floor under a 10mm plywood shelf that supports the FV. The FV goes in at 20C for fermentation and the door isn’t opened for 7 days. Seems to ferment OK. After fermentation the temperature is turned down to 4C. It takes a day and a bit to get to 4C and is left alone for 5 days when the beer is then transferred to a PB for carbonation back in the fridge set at 20C. That seems to work too. The PB is then transferred to my Barrelator that is temperature controlled in exactly the same way, but no heater tube, set at 12C. Beer comes out of the taps refreshingly chilled, so that works too.
Can’t get over the fact that by doing it “wrong” I’m getting such good results!

 

[foxbat]

The problem I have with direct-contact-to-FV heating methods is that yeast will start producing off-flavours like fusels and the more undesirable esters in increasing amounts as the temperature increases beyond the manufacturer's recommended upper limit which is usually around 23-24C (not Kveik of course). That's not a high bar to breach and could mean that any yeast cells that happen to be just that few millimetres from where the heating element is are going to be subject to heat stress.

Given that a 20W ceramic vivarium bulb costs £3.89 and has no associated risk to the yeast I don't see the point of more expensive brew belts and heating mats. I too thought that the idea of heating the air and measuring the FV temperature from behind a wadded kitchen towel would be a recipe for overshoot but it's just not borne out in practice. I set my hot differential at 0.5C so the heat lamp doesn't have to come on for long and it never seems to exceed the 1C cold differential that I set for the fridge so there is no oscillation.

 

[The-Engineer-That-Brews]

Can’t get over the fact that by doing it “wrong” I’m getting such good results!

If it works, then it's not wrong is it

As i said above, when your system is 'air coupled' or separated from the heater by something like a plywood floor then I think putting the temp sensor directly on the FV is a good approach.
But where the heater is in direct contact with the FV (like a brew belt, which was the subject of the discussion) then I'd strongly argue for putting the temp sensor on the heater itself.

Hopefully clarifies?

 

[Buffers brewery]

Haha. My tongue was firmly in my cheek when I wrote my post!
I agree with you @The-Engineer-That-Brews about controlling direct contact heaters and not the surroundings.
I wouldn't describe the fermentation process as being particularly dynamic. Could be wrong. So prefer a more relaxed approach to heating/cooling that an air blanket provides.

 

[terrym]

I use a water bath like this.
https://www.thehomebrewforum.co.uk/threads/how-to-set-up-a-water-bath-for-your-fv.66407/Its cheap and effective and works for ale yeast fermentations except in sustained hot weather, and even then I can cool things down by using chilled water. In the winter months I can ferment lower as for lagers. When I have done with it I pack it all away.
Although I now use an Inkbird to control the temperature, which is probably an overkill, the original method which involves setting things up via the heater thermostat worked fine.
What I would not recommend however is maintaining the temperature of a brew using an aquarium heater immersed directly within it, which I have seen some people say they do. Cooking yeasty beer with a hot glass surface can't be that good can it?

 

[Banbeer]

I use a heat belt in my brew fridge.
Works fine, just like it did before I had the fridge.

I also use heat belts in two of my brew fridges and have had no problems at all.

 

[The-Engineer-That-Brews]

I also use heat belts in two of my brew fridges and have had no problems at all.

if it ain't broke... ;-)

 

[MattHudds]

Thanks all, interesting thread. I recently purchased an Inkbird, but yet to brew.

The brew belt I have heats up to well over the desired temperature in a few seconds, so I was initially intrigued by the suggestion to have this in direct contact with the probe.

Presumably the idea is that the belt will only be on for a few seconds, and toggle on and off quite a bit to begin?

My initial thought was that this wouldn't give enough heating to get the whole FV contents up to temperature, but now thinking over it more, it will over time right, as the belt will retain some heat after the relay turns it off, and the whole system eventually reaches equilibrium? It's just the first time I've read this advice, many other posts on the forum digest taping to the side of FV under some insulating material.

I don't have a fridge, so the FV will just be in the side in a quite cold garage. I'll still insulate from the ambient temperature with some sponge/bubble wrap. Looking forward to trying.

 

[Banbeer]

I have three FV's and have made thermowells for each of them so the temperature probe is measuring the temp of the wort. Instead of trying to explain click Here (link) this shows how to make one.

 

[The-Engineer-That-Brews]

My initial thought was that this wouldn't give enough heating to get the whole FV contents up to temperature, but now thinking over it more, it will over time right, as the belt will retain some heat after the relay turns it off, and the whole system eventually reaches equilibrium?

Yes you are on the right track.
Think of it in terms of energy transfer, instead of temperature, if you like... Basically your objective is to get enough energy (Joules) into your FV to raise its temperature the desired amount, but without scorching the part that is in contact with the heating element.
The risk arises if you have the kind of controller that is basically on/off control, and it only switches the heater OFF when the bulk of the FV has hit your desired temp. The problem being that well before that has occurred, the heater itself (and the localised part of the FV it's in contact with) may have got far TOO hot.
If you control the temperature of the heating element itself, then it prevents that effect occurring.
You are right that it also slows down the rate of energy transfer (ie.e.heating rate) but the end result in terms of the final temp of the FV is the same.
Whether you need to worry about this depends, as other have pointed out, whether your heater is sufficiently powerful to potentially cause a problem - and whether it is in direct contact with the FV.

 

[Bocker Wright]

First time using this set up so I don't know if this is meant to happen or the inkbird is faulty or what... but I just noticed that the temp had dropped to 18.7°C and as I have the temp control set up to brew at 19°C the inbird had rightfully kicked in the brew belt. Then suddenly the temp shot up to 19.9°c instantly without increments. The brew belt knocked off and simultaneously the fridge kicked in just for a split second and straight back off again as the temp reading went to 18.9°C. I have it set to run at 19°C with an equal high/low differential of 0.3° either way. Is this normal? Do I have the differentials set right?

 

[Banbeer]

I have my inkbird 308 set at 1°c either way so the compressor in the fridge isn't cycling too much, have you got the temp probe away from the brew belt?

 

[Bocker Wright]

I have my inkbird 308 set at 1°c either way so the compressor in the fridge isn't cycling too much, have you got the temp probe away from the brew belt?

I thought the setting 'pt' was the compressor delay? I have that set to 3 (minutes?). Both 'Hd' and 'Cd' (hot differential, cold differential?) are set to 0.3°C. I have the probe taped to the FV about 4 inches above the belt under a folded up sponge type thing which is taped on top of it.

 

[Banbeer]

The compressor delay is for when it's turned on (I have mine set to 2 minutes) and the differential is + or - temp, as said I have the diff set at 1°C as I don't want the fridge cycling too much (1°C won't make a difference either way) so if you set the temperature at 20°C and the diff at 1°C both ends the fridge will kick in at 21°C and the belt/heater will kick in at 19°C

 

[Bocker Wright]

With such a low differential I'd assume the compressor delay function would be used quite a lot on your set up? Or do you find it holds fairly steady? I'm still trying to understand this to be honest. Like are there any instances where your 2 minute delay is TOO long a wait for your fridge to kick back in? I'm guessing not as you'd have it on 1 minute

 

[The-Engineer-That-Brews]

I wouldn't worry too much about time delay... 24kg of beer will not change temperature quickly, whatever you do - especially if it's in a well insulated fridge

 

[Banbeer]

With such a low differential I'd assume the compressor delay function would be used quite a lot on your set up? Or do you find it holds fairly steady? I'm still trying to understand this to be honest. Like are there any instances where your 2 minute delay is TOO long a wait for your fridge to kick back in? I'm guessing not as you'd have it on 1 minute

You are getting the two mixed up, the 2 minute delay only works when you turn the inkbird on, after that it relies on the Hd & Cd as you call it to maintain the temperature and the way I have it set keeps the temp really steady (within a degree either side)