Brew fridge temperature

[Bocker Wright]

Hi. I've bit the bullet after a long time off brewing and got myself a fridge with an inkbird temp controller and a brew belt. I'm brewing a coopers lager (original series, not the European) and I've got the temp set at 19°C using the yeast that came with the kit but I rehydrated it first in 30°C water.
Does that sound about right with the temp or would it need to be a bit higher? Yeast went in about 5hrs ago. Cheers!

 

[RGeats]

Hi. I've bit the bullet after a long time off brewing and got myself a fridge with an inkbird temp controller and a brew belt. I'm brewing a coopers lager (original series, not the European) and I've got the temp set at 19°C using the yeast that came with the kit but I rehydrated it first in 30°C water.
Does that sound about right with the temp or would it need to be a bit higher? Yeast went in about 5hrs ago. Cheers!

Sounds perfect. Assuming it's an ale yeast which I'm guessing it is. The instructions should give you a temp range, but 19 sounds good to me

 

[Bocker Wright]

Yes I think its an ale yeast, from what I can gather it's code is 'AC' which is the same yeast in all the original series kits. Instructions say 21°C - 27°C. I know the high end of that spectrum is well off key but I wanted to check 19°C was ok

 

[foxbat]

My advice is to ditch the brew belt and replace with a free air heater such as a greenhouse heater or a ceramic vivarium bulb (what I use).

Tape the Inkbird sensor to the FV under a wad of folded kitchen roll to keep temperature swings to a minimum.

The problem with the brew belt is that it will have scorched your wort long before the increased temperature has reached the Inkbird sensor.

 

[Benfleet Brewery]

I created a second brew fridge a month or so ago. The first one I made uses a 60w tube heater but with this one I’ve just used a 7w reptile heat mat. The FV sits directly on it as it emits just gentle heat. I haven’t been able to test it fully as yet as we haven’t experienced outdoor temperatures lower than about 4-5 degrees but its working fine so far.

 

[Bocker Wright]

My advice is to ditch the brew belt and replace with a free air heater such as a greenhouse heater or a ceramic vivarium bulb (what I use).

Tape the Inkbird sensor to the FV under a wad of folded kitchen roll to keep temperature swings to a minimum.

The problem with the brew belt is that it will have scorched your wort long before the increased temperature has reached the Inkbird sensor.

Hi foxbat yeah I've seen the tube heaters which I plan on getting. I'm gonna need to get something better than a belt to bottle condition in the same fridge. I'm guessing a belt won't wrap around all the bottles.

Could a brew belt be used in some way where it would raise temps sufficiently without needing to be in contact with the fermenter and then bottles later? Such as just hanging in the fridge or heating a demijohn with just water in?

 

[The-Engineer-That-Brews]

My view on the positioning of temperature sensors with respect to heating elements, is that from a control engineering perspective you are almost always going to get the best results by putting the sensor as close as possible to the heating element.

Putting the sensor elsewhere introduces delay (‘lag’) into the system which is murder from a control perspective. It risks oscillations or temperature overshoot, especially of the part of the fluid adjacent to the element, unless you have a very overdamped system (i.e. low power heater compared to the volume of fluid).

Of course the flip side of just controlling well the temperature of the heater element, is that you can get a steady state error between its temperature and that of the thing you’re actually heating; but this is usually going to be best addressed by better heat insulation, or by just upping the set temperature by a degree or so.

 

[Bocker Wright]

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

 

[The-Engineer-That-Brews]

I‘d say the type of heater doesn’t matter nearly so much as the way you control it. For example I’d be perfectly happy using a brew belt around a fermenter, so long as I had it managed by a PID controller whose temperature sensor was in direct contact with the belt (and ideally a bit of blanket or something between it and the bucket, to avoid hot spots). That way you can not get scorching.

 

[Bocker Wright]

I see what you mean. I did think about hot spots. I thought about wrapping something conductive like tinfoil around the fermenter to help distribute the heat more evenly, but figured I'd need that much of if to make a difference I'd be circling it round and round like a mad Morris dancer. Plus there's a shortage of tinfoil from all the hats being made these days anyway.

 

[The-Engineer-That-Brews]

So I reckon your setup with an inkbird and a brew belt is fine: but just put the inkbird’s temp sensor in direct contact with the belt and monitor the temperature of the fermenter itself independently.
The way to look at it, is that so long as everything is reason well insulated from the environment (which it will be, in a brew fridge - basically an insulated box) then after an hour or two the temperature of the FV, the fluid in it, and indeed the air inside the fridge will equalise to that of the heater. So just manage the temperature of the heater and everything else will follow.
And in case you were wondering what would happen if the fermentation itself was exceptionally vigorous and generated significant quantities of its own heat, the outcome of this is that it will cause the temperature of the heating belt to rise above your set temperature point, causing the inkbird to reduce the electrical power going in.

 

[Bocker Wright]

Ah I see what you mean even more. Yes I can see how direct contact with the heating element wouldn't allow over heating. Only might take a bit longer to get the thermal mass to temp. That's probably the pay off though isn't it.

 

[The-Engineer-That-Brews]

Just for what it’s worth, incidentally, I’m not personally a great fan of managing the temperature of 25 litres of wort by applying heat to a square foot or so of the outside of the FV. To me that’s just not enough surface area, and leaves a big question mark over the temperature differences within the body of fluid itself. So I have fitted a coil of (sterilised!) plastic pipe inside my FV, through which I continuously pump temperature controlled water. I then measure the temperature of the water coming back from this heat exchanger coil as a good proxy for the average temp of the beer - a lot more accurate IMHO than just taking a reading at a single point.

 

[Drunkula]

I had a ceramic reptile bulb but it bust so now I use a 100w bulb and a computer fan and I've had no problems getting to 42c.

 

[The-Engineer-That-Brews]

Only might take a bit longer to get the thermal mass to temp.

Yes, however the ONLY way for the thermal mass to be brought up to temp faster [edit: without increasing the contact area], is if the surface temperature of the heater is hotter than the desired temperature. This is probably not good news for the parts of the fluid closest to the heater, if your process is sensitive to overheating.

 

[Tanglefoot]

I use a heat belt in my brew fridge.
Works fine, just like it did before I had the fridge.
If didn't already have one I would probably have bought a tube heater for my fridge though.

 

[The-Engineer-That-Brews]

Another way to think about this is in terms of energy input. Remember that Watts equals Joules per second, and temperature change equals energy divided by heat capacity. So all of the electrical power going into your insulated box is going to end up increasing the temperature of your beer - directly or indirectly. If you put a blanket between the heating belt and the bucket, then it won’t change the amount of energy going into the ‘fridge’...

 

[Bocker Wright]

I use a heat belt in my brew fridge.
Works fine, just like it did before I had the fridge.
If didn't already have one I would probably have bought a tube heater for my fridge though.

Hey Tanglefoot, great name, great drink
Yeah I'm just using what I already have for now. I read a bit before joining here but now I can ask the questions I couldn't find the answers to by just reading

 

[Richie_asg1]

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.

 

[Benfleet Brewery]

Hey Tanglefoot, great name, great drink
Yeah I'm just using what I already have for now. I read a bit before joining here but now I can ask the questions I couldn't find the answers to by just reading

Hmmm, not sure you’ll find actual “answers“ here either. There are so many variables with most things in brewing beer. You will, however, get plenty of opinions and from those be in a far better position decide what would best suit your needs.