Temp control approach with mult carboys.

[mwm5461]

Hello all! I have a problem that requires some advice from the community. This past year I moved to an apartment and switched to BIAB from a 3 vessel system. I also have switched from 5 gallon batches to 2.5 gallon batches with the goal to brew less and brew much more often. It has been great and my next goal is to have more control over fermentation temperature.

I was in the market for a 7 cubic feet chest freezer unit so I could fit more than one carboy in to ferment but then I would have to keep multiple fermenters at the same temperature. As I mentioned I'm in an apartment so I don't have tons of room. I built an STC-1000 controller and would like to hear people's opinions on the best approach to fermenting multiple carboys and what size chest freezer I should probably use. Is my only solution to two or more chest freezers with a controller for each?

I appreciate any advice!

 

[Bobby_M]

You could run one warmer within the freezer with a heat wrap and insulating. I would only do it if the target temp difference is a few degrees.

 

[mwm5461]

You could run one warmer within the freezer with a heat wrap and insulating. I would only do it if the target temp difference is a few degrees.

So have 1 fermentation chamber (like a 7cu ft chest freezer) and two STC-1000 controllers? I'd imagine I could just plug the chest freezer into the cold outlet for the ferment I want at the colder temperature and then only have a heat source for the second controller?

 

[mattdee1]

Yeah, having multiple fermentors in a chamber that is being controlled based on the temperature of just one of those fermentors is definitely a compromise.

I still do it, but usually only for split batches of the same base beer. I make sure:

- equal volume in each fermentor
- same "phase" of fermentation -- i.e., I would not add a second fermentor to a chamber that already contains vessels that have been going for a few days
- same starting temperature

The last point usually takes care of itself when doing split batches, but it may not if you're adding a warm steeped grain mixture to one of the buckets, which will cause that bucket to be warmer overall. When I've done that, I chill that bucket in the chamber until it is the same temperature as the other one, then pitch the yeast in both and start the fermentation cycle.

I guess doing same yeast would be another good idea, but that kind of spoils the fun of split batches, unless the only difference between them is different dry hops.

Luckily, ale yeasts have a range of temperatures where they are mostly OK. But I have experienced negative effects from having different sized fermentors in the temperature controlled chamber, which convinced me that you can't be too willy-nilly.

 

[helibrewer]

I do this with a controller for each fermenter. I have a large, 3 section cold box cooled with a window A/C unit. The middle section stays about 50-52F. For ales, I use FermWrap with insulation and set the controller on 68F, it works great. For lagers I do the same with the controller set at 55F....I can ferment these 2 beers side-by-side this way.

 

[Sadu]

https://www.homebrewtalk.com/showthread.php?t=590275
I solved this exact problem recently.
Keep the fermenters outside the fridge in swamp coolers. Each on their own STC-1000 with an aquarium heater and water pump. To cool the fermenters the water pump recirculates the swamp cooler water through the fridge.

This lets you run multiple fermenters at different temperatures, fully temp controlled for hot and cold. And 90% of the fridge is available for other uses.

 

[petrolSpice]

I tried this, brewed a 10 gallon batch that I split into 2 5 gallon carboys, but each got a different yeast. Needless to say, they did not ferment at the same rate. Beer A was blowing off within 1 day while Beer B had no activity yet. I put the temp probe on Beer A which caused the freezer to turn on more often, which caused Beer B to be too cold, further delaying its fermentation. Both were on the same heating circuit with fermwraps, and cooling circuit for that matter. During active fermentation the temps of the 2 beers can stray pretty far from one another if they are not fermenting at the same rate and you're only taking the temp of one of them.

My thought was to use 2 temp controllers. Each controls its own heater while both control the same freezer. I'm not sure if having 2 controllers controlling the same circuit would cause issues, electrically, or fry the controllers.

 

[augiedoggy]

https://www.homebrewtalk.com/showthread.php?t=590275
I solved this exact problem recently.
Keep the fermenters outside the fridge in swamp coolers. Each on their own STC-1000 with an aquarium heater and water pump. To cool the fermenters the water pump recirculates the swamp cooler water through the fridge.

This lets you run multiple fermenters at different temperatures, fully temp controlled for hot and cold. And 90% of the fridge is available for other uses.

This is similiar to what I do with my conicals only with a chiller and discharge hose wrapped around the outside of each conical as well as a heat strip to control temps.. I use one pump and 4 $3 solenoid valves to control which fermenter gets cooled and when. takes up very little room and with 2.5 g batches you could probable build something with a minifridge as the cooling unit resevoir. the heaters dont kick on much in my setup except in the winter months.