German Brewing

Has anyone evaluated various types of chillers for how much DO they introduce? I'm considering a Therminator, but it seems it could introduce a lot, even if flushed with CO2.

There's two issues with chillers:

1) Introduction of oxygen via trapped air. This is most likely to be an issue with plate chillers, less likely with counterflow chillers as long as your purge them first. To be honest, I really love my immersion chiller.

2) Leeching of metals capable of participating in Fenton reactions. These are primarily transition metals which have multiple oxidation states, and the three you're most likely to encounter in the brewing process are iron, copper, and manganese. Stainless steel is the best material to use because it is protected by an extraordinarily stable oxide layer, so as long as the surface is passivated, it won't leech anything into the wort. Copper, on the other hand, is protected by an oxide layer which is far less stable than stainless' and can leech into wort. This is a source of free oxygen AND copper ions which will act as oxidation accelerants via the Fenton process. However, if you rinse the oxide layer off first (like with an acid wash such as star san) then you've just exposed all of the copper underneath to your wort. You won't get the oxygen from the oxide layer this way, but you will get far more copper leeching.

How big is your system? My 13 liter batches are well served with a 25' stainless immersion chiller. I use a utility pump to recirculate ice water through it.

It depends on the chiller and is hard to say. You are probably alright.

You can always run half the wort through the plate chiller and the other half chill with an IC. Compare the two, and see if the wort that went through the plate chiller got darker and/or lost flavor.

Is it a cost thing preventing everyone from just grabbing SS ICs?

I've priced them out and you can get a 3/8" x 50' chiller for $60 if you find the right deal.


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I'm fine with an immersion chiller except for the measures I have to take to keep chilling times acceptably (to me) low. I either have to use a pre-chiller (cumbersome) or I have to put the wort in motion relative to the chiller (introduces oxygen?). Otherwise I like the idea since I already use an IC to chill the strike water after pre-boiling.

I would think if you kept your return below the wort and inserted your mash cap that chilling with recirc wouldn't be any different than recirc'ing during the mash.

That may be shortsighted on my part so I'll defer to the more experienced guys on this one for clarification.

I don't have a mash cap for my boil kettle, but I suppose I could make one! Didn't think of that.

I would not use my mash cap in the whirlpool for fear of contamination - but making something that could be sterilized and sit just above the boil makes sense. I use my whirlpool arm to circulate during chilling. it returns about 14" below the wort level of a 12 gallon batch, but I need to throttle it or it will increase the surface area of the wort during chilling.

I have been searching for a stainless counterflow chiller. Just popped on a 50" stainless immersion chiller - which will work well for the HLT, and the boil until I can find that CFC.

I guess the trick would be making sure the IC is low-profile enough that it's always covered by wort (else there would be a gap between the cap and the wort). And if you had a return-to-boil manifold under the cap (like Loc-Line), there would need to be enough clearance for it.

I don't know of a stainless CFC, but the Therminator is all stainless, and it behaves kind of like a CFC. Expensive, though.