Multi-zone Freezer Fermentation Chamber

[jwynia]

So, a couple of months ago, I bought a freezer and put a 2 stage Ranco on it to use as a fermentation chamber with the temp probe just in the air. I fermented a couple of batches in it, using just the Ranco.

The last batch that went through it is a biere de garde, which I want to store for several months at 35F-45F. At the same time, I brewed on Sunday and want to ferment that batch at 65F.

My thought was to use my existing single-stage temp controller (the one I use to preheat my mash water with an electric bucket heater on a timer) and, with the overall freezer at 45F, heat the new batch to 65F.

I put a FermWrap (http://www.northernbrewer.com/shop/electric-fermentation-heater.html) around my stainless steel fermenter (http://www.dwbrewproducts.com/shop/product_info.php/gal-stainless-steel-carboy-p-65) with the probe taped to the fermenter and I set the temp controllers. The fermenter was at 74F when I pitched and put the fermenter into the freezer.

I went to bed and checked in on it the next morning only to find that the fermenter was at 57F. Clearly, the FermWrap can't keep up.

I also have a heat mat (had it plugged into the heat side of the Ranco intending it to handle the winter in my garage) (http://www.northernbrewer.com/shop/home-brew-heat-mat.html) that I put under the fermenter and plugged both it and the FermWrap into the single-stage, still set to 65F.

It helped a bit, but still couldn't make it to 65F.

Only when I raised the freezer temp to 50F can I keep the fermenter at 65F.

This is clearly not working well. So, I'm wondering a couple of things.

First, am I nuts to even be trying to do the 2 "zone" approach? I figured with the main probe in the air and the heated zone probe taped to the fermenter, the freezer would run more, but it should work.

Second, is there a way to better run the heated fermenter setup that will keep the fermenter at 65F+? Ideally, I'd like to use the freezer for long term lagering at 35F and still use it to ferment ales as well. Is that kind of differential just asking for trouble?

The obvious next step would probably be insulating the fermenter, but I'm also wondering about more powerful heaters anyone knows of.

 

[Fat_Maul]

You've put a heater inside a freezer and want both of them to run at the same time? Yeah you're going to need to isolate the warm fermenter from the rest of the box but generally speaking, you're just having a tug of war going on inside there

 

[FRS]

This is always going to be an imperfect solution, since you are heating and cooling the same space... I might worry about the longevity of the freezer compressor if it seems to run often.

That said I think you could make this work. I think the key will be insulating the warm area from the cool area as effectively as possible. I'm thinking a box of several layers of rigid foam insulation around the warm space. Once the fermenter is in place I'd fill the remaining space with an old comforter or something similar. That should minimize heating of the lagering space and reduce the need for the compressor to run.

 

[sasky7777]

It's been done. https://www.homebrewtalk.com/f51/3-temp-fermentation-controller-1-chamber-388549/

 

[Ramitt]

I use large chest freezer as a keezer and lager fermenter, I am sure it would work with ales but have a second chamber for the warmer ferments. I made a jacket out of reflectix and wrap my bucket with fermwrap. Works great and doesn't seem to stress the freezer much. I did make a lid for the jacket to keep the warm air in and allow the probe wire out.