Pressure fermenting and temperature control

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I am doing two things for the first time today - fermenting under pressure, and using my now-fully-set-up brew fridge. The fridge is controlled with an Inkbird and has a tube heater in the bottom. My plan was to ferment at 15C under 10PSI, but the issue I am seeing is that, given I could only cool the wort down to 25 due to the warmer-than-normal mains water temperature, the fridge is turning off when the temperature of the air inside is at (I guess) 4C - at this rate, it's going to take days to cool the wort down it seems because whille the inkbird is telling the fridge to be on, of course the fridge thinks it is at the right temperature due to the aire temperature cooling down relatively quickly.
Two questions:

1. Have I missed something when it comes to setting up the brew fridge?
2. Do I need to go as low as 15C as I am fermenting under pressure?

Any help gratefully received.
(Brewing a lager using saflager-189)

 

[Cheshire Cat]

You need to have your temperature probe against the fermenter but then insulated from the air . I use bubble wrap and gorilla tape.

 

[AnimatedGIF]

You need to have your temperature probe against the fermenter but then insulated from the air . I use bubble wrap and gorilla tape.

Thanks. The temperature sensor for the inkbird is reading as it should (currently 24C) - the issue is the built-in controls on the fridge that are turning it off when the air temp reaches whatever the normal fridge temp is.

 

[Cheshire Cat]

Are you sure? Is the fridge connected to the cooling socket on the inkbird. I once had it in the heating socket.

 

[Baldbrewer]

Is your fridge’s internal control (dial?) set to its most cold setting?

 

[AnimatedGIF]

Are you sure? Is the fridge connected to the cooling socket on the inkbird. I once had it in the heating socket.

Yes, as the fridge does come on infrequently as the wort in the FV gradually warms the air inside

Is your fridge’s internal control (dial?) set to its most cold setting?

Yes - is this the correct setting?

 

[hoppyscotty]

What you brewing? when I've done pressure fermenting I'm running temperatures far higher than 15C - more like 25 - 35 C depending on the yeast. Is it a lager maybe?

Thanks. The temperature sensor for the inkbird is reading as it should (currently 24C) - the issue is the built-in controls on the fridge that are turning it off when the air temp reaches whatever the normal fridge temp is.

What do you mean by this? is your probe attached to the side of your fermenter and insulated? Maybe you could use a second thermometer to confirm the temp of the fridge to confirm if the fridge thermostat is cutting it out. Most fridges when the stat is turned upto the max it usually runs the fridge continuously and not under thermostatic control. So definitely turn the thermostat to the max.

 

[AnimatedGIF]

What you brewing? when I've done pressure fermenting I'm running temperatures far higher than 15C - more like 25 - 35 C depending on the yeast. Is it a lager maybe?

What do you mean by this? is your probe attached to the side of your fermenter and insulated? Maybe you could use a second thermometer to confirm the temp of the fridge to confirm if the fridge thermostat is cutting it out. Most fridges when the stat is turned upto the max it usually runs the fridge continuously and not under thermostatic control. So definitely turn the thermostat to the max.

I'm brewing a light lager using Saflager 189 yeast.
I'm not too sure how to explain in another way. The inkbird probe is in a thermowell which is itself in the FV.
When the temp of the air in the fridge gets cold (like I say, I am guessing 3 or 4 degrees) the frige turns itself off (as would be expected) - at this point, the inkbird is still powering the fridge, as indicated by the cooling light being on. This doesn't surprise me as it would be just like having a fridge plugged in normally - when it gets to 3 degrees or so, it turns off so as not to freze the food inside. It's just something I hadn't thought about when using for fermenting.

 

[tigertim]

Even at it's "coldest" setting, the built in thermostat would cut out at about 2-3C as a safety precaution - all refrigeration devices have design temperatures for normal operation (both ambient and interior) and it's generally not a good idea to try and force a refrigerator down to freezing temperatures or beyond, which some brewers like to do by bypassing the internal thermostat entirely.

The refrigerant enters the evaporator (the cold part in the refrigerator) as a liquid and needs to boil off to gas (absorbing heat from the compartment) by the time it gets back to the compressor. If the compartment is too cold, there won't necessarily be enough heat to boil the refrigerant off sufficiently and you can end up with liquid refrigerant returning to the compressor (known as liquid slugging) - this is usually exceptionally bad, like taking water into a car engine.

 

[AnimatedGIF]

Even at it's "coldest" setting, the built in thermostat would cut out at about 2-3C as a safety precaution - all refrigeration devices have design temperatures for normal operation (both ambient and interior) and it's generally not a good idea to try and force a refrigerator down to freezing temperatures or beyond, which some brewers like to do by bypassing the internal thermostat entirely.

The refrigerant enters the evaporator (the cold part in the refrigerator) as a liquid and needs to boil off to gas (absorbing heat from the compartment) by the time it gets back to the compressor. If the compartment is too cold, there won't necessarily be enough heat to boil the refrigerant off sufficiently and you can end up with liquid refrigerant returning to the compressor (known as liquid slugging) - this is usually exceptionally bad, like taking water into a car engine.

That is very useful information, thank you for taking the time to explain it to me.

Happily, the wort was down to 15C before I went to bed, so was able to pitch. Pleased I don't need to/shouldn't make any further modification to the fermenting fridge.

 

[tigertim]

thank you for taking the time to explain it to me

Not at all, it's what I love about this forum!

Essentially, the slight drawback with fermentation fridges is that they rely on air to transfer the heat out of the wort/beer and, as an insulator, it's not particularly good at it! Fermentation fridges regulate temperature well enough and can generally also stay on top of bursts of metabolic heat generated by the yeast, but shedding heat quickly from a large volume of wort is something they will struggle with.

Commercial breweries and some home-brew equipment employs liquid cooling, where chilled water is circulated directly through the fermenter, either through pipes or a cooling jacket. Heat removal is far more efficient this way, but it comes at a cost considerably greater than a £25 fridge off eBay So whilst fermentation fridges have limitations which it's good to understand, they are exceptional value for money and sufficient in almost all situations.

 

[AnimatedGIF]

Not at all, it's what I love about this forum!

Essentially, the slight drawback with fermentation fridges is that they rely on air to transfer the heat out of the wort/beer and, as an insulator, it's not particularly good at it! Fermentation fridges regulate temperature well enough and can generally also stay on top of bursts of metabolic heat generated by the yeast, but shedding heat quickly from a large volume of wort is something they will struggle with.

Commercial breweries and some home-brew equipment employs liquid cooling, where chilled water is circulated directly through the fermenter, either through pipes or a cooling jacket. Heat removal is far more efficient this way, but it comes at a cost considerably greater than a £25 fridge off eBay So whilst fermentation fridges have limitations which it's good to understand, they are exceptional value for money and sufficient in almost all situations.

Sums it up nicely!

I like also that if I need a fridge for "emergency use" (like family staying at Christmas), I can simply plug the fridge in to the wall socket and we suddenly have all the space we need to store the turkey etc

 

[hoppyscotty]

Ahh ok, the fact the fridge turns off when the air inside its cabinet hits 2 - 3C is irrelevant, its the heat transfer from the warm wort to the cooler surrounding air as has been said above already, so I wouldn't worry about that since you're just trying to cool your wort/beer down to 15 degrees C....it just takes longer the greater the temp difference. The main thing is you have the probe in a thermowell in the wort/beer. Just leave as is and let it ride...pateince is the biggest lesson I've had to learn since I started brewing....some things just take time.

Personally I find that my fermentation fridge can quite easily manage the temp of my 20 litre batches well even when cold crashing down to 1 degree or so from 18 - 20 degrees. Takes a few hours but thats fine. If I get bored when cooling wort before transfer into the fermenter and just transfer at high 20's degrees C I'll pop in the fermentation fridge to continue to cool down to pitching temperatures and it takes about an hour or so to cool 20 litres of wort from say 28 degrees C to 19 degrees C or so then I'm ready to pitch.

I do have a pretty good fridge though - it's a full size larder fridge. Managed to wangle it for free from a mate. its actually a better fridge than I have in my own kitchen.

 

[RoomWithABrew]

I got a fridge freezer with a top freezer, I packed this out with more insulation on the inside and cut a hole in the floor of the freezer. I fitted some flexible ducting from the fan in the freezer down the hole.
When cooling / crashing it works really fast. When I'm hot fermenting kveik brews I bung the freezer hole up so the space is smaller to keep warm.
There aren't lines in the bottom of the freezer section for this hack.

 

[foxy]

For those who are into pressure fermenting, be careful. In the best Michael Cane voice over., "It wasn't supposed to blow the bloody door off"

 

[Weizenberg]

Chilling wort to lager pitch temperatures (mine is at 5 Celsius), is challenging.

There are numerous ways of doing this. Many will involve ice cubes in water.

I was lucky enough getting hold of a Cornelius Maxi 310 from ebay for about £90 (in 2010).

The resulting setup ended up being a rather large swimming pool heat exchanger (another find on ebay), cooling the wort with tap water. Initially this is recirculated into the kettle.

An analog temperature dial on the exit of the HE tells me when it is in the range to run through the chiller (via a 3-way valve), usually in the 12-16Celsius range.

At this stage it goes via the chiller straight to the fermenter. Usually, the temperature it ends up with is 5 Celsius.

Takes about 20 minutes for the entire run. My brew length is 50 litres.

Others have good results recirculating through ice baths. A stainless steel coil is a good idea here.

You can try fridges or chest freezers, but I would bring the temperature as close as possible to the one of your municipal water supply first.

PS: if you use a HE, make sure you have a filter before. Stripping and cleaning them takes half a day - if you can. Otherwise you need to replace it (expensive). It's surprising how much debris collects in there.