Closed cold crash in HDPE fermenter?

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Simon N

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For a range of reasons (space constraints, batch size, etc) I’m looking to start cold crashing in an old school HDPE fermenter with airlock and spigot. Current thinking is to switch out airlock for a gas disconnect, run as a blow off while fermenting, then keep closed/disconnected while gently lowering temp. My question is, has anyone tried gently topping up the headspace with co2 to offset the change in pressure? Would be a bit of a balancing act, and not sure what the margin for error is before the spigot blows, lid pops or something else disastrous.

I’ve seen similar experiments in cubes but just wondering if anyone has tried with an HDPE fermenter?
 

S.E

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Just use a long blow off tube. I use about 1.5 - 2 meters of tube into a glass of water on a 60L fermenter. The glass has never emptied or the water ever reached the fermenter. However I don’t normally chill below 10C -12C.

Or you could replace your airlock with a blow off when it’s ready to chill but fit a bag or balloon at the end and fill it with co2 if you want a bit of back pressure. You may need a small valve or maybe just squeeze the tube to stop the balloon or bag emptying as you connect it to the fermenter.
 

rizrah

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Hi Simon,

Yep i used to do exactly what you state all the time. but guesstimating the amount of pressure the HDPE could handle was tough.
i found it much easier to chill first and once the fermenter sides suck in, add the gas. then you have a clear visual indication of how much to add. i check it morning and night over the 3 day cold crash.

Previously i added *approx* 2psi of co2 before cold crash, but with a large co2 gauge, dialling in 2psi is very rough, i did overdo it once and the lid seal popped off, but was completely salvageable.
 

Simon N

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Thanks! Long blow off sounds like the low risk option. Rizrah glad it was the lid and not the spigot that gave way!
 
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dkril

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Sealed container 500ml-1L) in the middle of the blow off tube. Extra safe, and easier than miles of tube in your fermentation chamber.

IIRC there was a thread on this recently, but I'm on my phone and can't find it ATM.
 

S.E

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Thanks! Long blow off sounds like the lose risk option.
Long blow off is the simplest solution. Forgot to say, my blow of tube is 10mm diameter. If you use wider diameter you could use a shorter tube.

So long as the internal capacity of the tube can hold more than the water in the glass you cannot suck it back into the fermenter.

Worst thing that can happen is the glass will empty and you will start sucking a little air into the fermenter. That’s not really a problem though and was the norm a few years ago, it won’t kill your beer.
 

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