Anyone recirculate active fermentation through a chiller?

[snowman_fs]

I'm fishing for feedback.

I have a thought/want to build an "inside-out" fermentation temperature control system. Using a temperature controller, peristaltic pump and either an air-to-liquid (it's winter) or liquid-to-liquid chiller for a loop that gently pumps the beer from the fermenter, to the chiller and back to the fermenter. Maybe only for the first 5-7 days of primary, until I typically transfer to a secondary/conditioning keg anyway. The fermenter jacket I have just seems too slow to drive temps down quickly and an interior coil seems like a CIP issue. Besides, I think I can use the same chiller for fermentation control as I do for wort chilling.

If I put the suction dip tube just under the liquid level and the return 1/4 of the way up from the bottom of the fermenter I figure it's worth some playing with. The return temperature (with variable flow rate) could be modulated to achieve either the chilled return temperature desired or the general fermenter setpoint I want. I'm thinking for the first few days I'd use the fermenter setpoint for control and a high flow recirculation rate but then switch to a return temperature control strategy when things slow down.

The risk of plugging seems minimal as I would use a full bore counterflow stainless interior coil, and I think there is a significant benefit to overall thermal control with a heat exchanger. I don't think sanitization and O2 exposure will be a problem since it's a sealed fermenter and I can PBW circ the whole setup prior to brew day and leave the chiller connected from boil to the end of primary fermentation.

Thoughts?

 

[3 Dawg Night]

I think you might clog your pump with all the solids drifting around in an active fermentation.

 

[PberBob]

That’s an interesting approach for temp control.

Just speculating here, but the pump shear is likely to drive off more CO2 than the unstirred fermentation. The result of that could be to allow the yeast to make more esters, for better or worse. On the other hand, more likely, it might not have any effect on the flavor.

 

[McMullan]

I often recirculate actively fermenting wort via an MP-15R pump to rouse yeast in a manner similar to a Yorkshire square fermentation.

I don’t think there are any practical issues with what you’re proposing here. I've never had the pump stall due to blockage. If I dry hop the hops are whole and contained in an SS mesh infuser. But why ‘inside-out’? It’s reasonable to assume it’s going to be more efficient than a typical ‘inside-in’ attemperator, but I wonder if it might actually be too efficient and shock the yeast as they pass through the chiller. Enough to push them away, metabolically speaking, from fermentation? I’d say give it go, but proceed with caution. Hopefully, you have a recipe and yeast strain you’re very familiar with so you can compare the fermentation performance and end product in a meaningful way. I wouldn’t want to compromise fermentation performance. It might increase it, though, which isn’t a bad thing. We won’t know until it's been tried, though. Nice to see people thinking outside the box.

 

[rgregoryirving]

I wonder if it might actually be too efficient and shock the yeast as they pass through the chiller.

This was my first thought.