Single Chamber - Multiple Fermentation Temps

Sorry, I'm reposting this on the DIY forum because I accidentally put it on the ferm and yeast one first and got no replies.

So I was thinking of using a large chest freezer as a fermentation chamber that would allow space for at least 3 buckets/carboys. My problem is that I'd like to be able to do this at a variety of temps(for ales+lagers temps) simultaneously without having to buy multiple freezers or setups. A one chamber system is ideal for me spacewise.

The best solution that I can think up right with is using 3 temp controllers with 3 probes and 2 brewbelts. One controller/probe combo would keep the freezer at an adequate temp for my lager(with probe in the lager). The other 2 would be simply heating the buckets/carboys individually.

I already have a johnson controller and I made one of the ebay aquarium controllers recently, so another(probably single stage) wouldn't be too hard.

I've also heard of people using arduino's to control something like this.

Does this sound feasible? is there an easier solution?

Thanks!

The easiest solution would be brew belts around your "warmer" ferments like ales or before you step down your lagers, and keep your freezer at the coolest temperature you need. I think this is what your thinking if I understand what you are describing. Other than that the "easiest" would be to brew/ferment like with like; do a string of ales and keep your freezer warmer, then when you do a stretch with lagers step your freezer down and do a few in a row.

I'm interested in doing something similar, one chamber, two carboys at different temps. I know I can do fridge always on and two brewbelts with temp controllers; however, I was hoping that there would be some way to power cycle the the fridge if it has lowered the temp below the bottom temp for both beers. One possible way is to run a dual stage and brewbelt on one (and this would be the beer fermenting at the cooler temperature). The other beer would have a brew belt to keep it warm. However, there is a chance that the second beer with only the brew belt could get hot enough before the second beer which is on the dual controller warms up. In this case, you'd want something like two dual stage controllers, both of which could provide a way to kick on the fridge.

I'm no electrician, but if someone knows how to build the electrical "OR"'ing of data between the two dual stage's upper temp value, that'd be a reasonable solution.

You're over thinking it.

Don't make things any harder than they have to be - trust me on this.

All you need is 3 probes and 3 controllers.

1: monitors keezer temp, powers keezer. Keep temp at X (lowest needed for all beer in cooler, powers cooler ON when temp goes above X)

2. monitors ferm1 temp, powers brewbelt. Keep ferm1 at Y (powers belt ON when temp goes below Y)

3. monitors ferm2 temp, powers brewbelt. Keep ferm2 at Z (powers belt ON when temp goes below Z)

That's it.

That'll work, however, the first controller is monitoring ambient temp of the chamber, not fermenting temp which means I'm back to calculating some lower level of temp below what I think it'll need to keep the beer below a max temp.

For example, my current one probe setup, I would set my ambient temp to 59 if I wanted to ferment at 65; and I'd have to watch it because as fermentation slowed down then 59 was too agressive. I now attach the probe to the side of the carboy and I don't have that delta anymore.

Now, with the heat belts, that'd keep it from going to low, so this method would be slightly better, but there is still the chance that the fridge is running against the brewbelts because one controller isn't getting all of the data to make the right decision.

To do this "right" (as in minimizing power consumption needed to keep two beers at two different ferm temps), we need a smarter controller: 2 temp inputs (one for each beer, thermowell/taped to the side), 2 ranges for each probe. Independent of the heat side (one belt per beer) and shared control of the freezer/fridge.

I'm googling around to see if anyone makes something like this.

I get what you're trying to do. The process you're describing would work for one fermenter in one chamber. Unfortunately it won't work for multiple fermenters in the same chamber. You'll end up averaging all the variables which means that in the best case scenario one fermenter is correct and the rest are wrong, and in the worst case scenario they're all wrong.

In this case you need one constant (chamber temp) to allow the other variables (fermenter temp) to be accurately managed.

The perceived inefficiency is actually minimal. In practice, the keezer runs like 5 minutes every hour to offset heat put out by the fermenters. The brewbelts run fairly constantly, but that's expected, and the power draw is negligable.

OK,

Thanks for the feedback. In the case where the fridge is maintaining a temp below the lowest level needed, do you suggest something like 10 to 15 degrees below the lowest? Or should I just not bother with a temp control on the fridge and just plug it in directly and let the brewbelts handle the right temp? I mean, I can hit something like 37 to 40 in the fridge via the normal coldness dial at the back; seems like a waste of a temp controller in that case.

5 to 10 works just fine for me.

Just put your probe in the largest container of water you can support in the cooler. It's how I control my DIY kegerator temp. It won't be the same from a thermal mass size but it should be better than air. Plus your belts and frig will cycle a lot more since the air temp will change faster.