Keezer powered external fermentation chamber

Alright, looking for some thoughts before I go cutting holes and gluing foam together.

I have a keezer (14cu ft) that I'm hoping could provide some "cooling power" to a fermentation chamber. Now, I'm not in a position to go tracking down some old craigslist fridge or freezer and not wanting to try a swamp cooler, so bear with me with this idea

As you can see from the attached diagram, I'm wanting to cut a hole in my freezer and use a high speed PC fan connected to a temp controller to provide cool air to the fermentation chamber. The room where this is located typically won't get above 68 for the next few months. I'm mostly wanting to keep it around ale fermentation temps, but would hopefully be able to get down to lower temps to start a lager (which would then be transferred to the keezer for lagering).

I keep the keezer around 35 degrees. Do you all think this would provide enough cooling? I'm thinking it should, especially with the mass of all the kegs. I may add some fans inside the cooler for extra circulation.

Thanks in advance!

Kosch

I am very interested in input on this concept as well, since I have been thinking about the same project. Here are some of my recent thoughts...

New air problem:
I figure that the best efficiency for such a system will be an air recirculating path, so that you are not pulling ambient air unto your freezer, chilling it, then pushing it out through the fermentation chamber. This means two ducts, or a duct with a duct. You may have thought of this already, I just don't see it in your drawing.

Air flow:
(1)Since your freezer transfers heat on the inside to the outside, it is important that the area around the freezer has good air flow so that you are not inadvertently heating one side of your fermentation chamber.
(2) depending on the size of your chamber, freezer, and the dead spaces in each, you will need to asses the air flow characteristics and air flow requirements. If you are serving beer from taps on freezer, you may not want warm air from the chamber return duct blowing directly on your tap lines ( you may even want to independent insulate them).

Accessibility:
The fermentation chamber should be air tight (much like your keezer). The opening/door is the most important part. A combination of something like weatherstripping and rare earth magnets might work well.

To address your primary question:
Will this work? Yes.
The design and efficiency of the setup will determine how hard your freezer has to work to keep the magic happening.

Not that I have ANY experience or knowledge in this department, but won't circulating the air eventually cause the fermentation chamber to be the same temperature as the keezer, and therefore be too cold?

I am using my keezer to cool my fermenter as well - but not with air.

I have 5 gallons of glycol sitting in a plastic container in the keezer, and a pond pump sitting in that tank.
On demand from the thermal sensor in the fermentation bath, (carboy sitting in water), the pump turns on and pumps cold glycol thru tubing, which has a heat exchanger sitting in the fermenter bath. the return glycol dumps back into the same tank - which is why I had to have at least 5 gallons for it to work. Since I use a collar on my keezer, no holes were drilled in the freezer. When desired temp is reached, pump shuts off.

(heat exchanger = new transmission oil cooler)

Hang Glider said:

I am using my keezer to cool my fermenter as well - but not with air.

I have 5 gallons of glycol sitting in a plastic container in the keezer, and a pond pump sitting in that tank.
On demand from the thermal sensor in the fermentation bath, (carboy sitting in water), the pump turns on and pumps cold glycol thru tubing, which has a heat exchanger sitting in the fermenter bath. the return glycol dumps back into the same tank - which is why I had to have at least 5 gallons for it to work. Since I use a collar on my keezer, no holes were drilled in the freezer. When desired temp is reached, pump shuts off.

(heat exchanger = new transmission oil cooler)

Click to expand...

This is an interesting concept. Not sure I want to dedicate a whole cornie to glycol though.

I do not know how well it would work with a big freezer but I put my fermenter in my little 7 cf freezer and add a gallon of ice every day in a milk jug set on top of the hump. So far it has kept it at a even 60 degrees.

I had a temp control on it but the thermostat on the fridge in the kitchen went out and you know where the wife deemed she wanted cooling :cross:

I would put a collar on the keezer (may already be there but it appeared your air line would be coming from the lid). Then get a temp controller to control the fan where the probe is in the ferm chamber. Make sure the ferm chamber is sealed tighter than a frogs butt, and insulate the hell out of the in line. An out line would be helpful too, but I don't think it's necessary.

You need some sort of 1 way check valve so you don't get cold air creeping into the ferm chamber or vice versa that only opens when the fan runs.

Brewmech said:

I would put a collar on the keezer (may already be there but it appeared your air line would be coming from the lid). Then get a temp controller to control the fan where the probe is in the ferm chamber. Make sure the ferm chamber is sealed tighter than a frogs butt, and insulate the hell out of the in line. An out line would be helpful too, but I don't think it's necessary.

You need some sort of 1 way check valve so you don't get cold air creeping into the ferm chamber or vice versa that only opens when the fan runs.

Click to expand...

I think this is the way to go. Adding a collar will prevent you from trashing your freezer lid, so you could always restore it to it's former glory if needed.

I'd add the out line. The controller could turn on 2 fans. One would pull air into the chamber, the other would push it out into the freezer. When the right temp is reached it would shut off.

If the ferm chamber is sealed and insulated I wouldn't worry too much about a check valve, though it's a good idea. Since cool air will sink into the freezer the collar shouldn't leak too much cold air when everything is off.

I've done this same thing but with two freezers, one works as a freezer and the other one is dead so I use the working freezer to cool the dead one.



I found out that pulling cold air out of the freezer and cool air back in is a bad idea, you get a LOT of condensation in the freezer which turns to ice. I solved this problem by using vent duct which gets cold and transfers that into the dead freezer.





With the vent tube going trough the freezer I can keep my kegs @ 50 - 55 degrees with the fans running all the time.

Greels said:

Not that I have ANY experience or knowledge in this department, but won't circulating the air eventually cause the fermentation chamber to be the same temperature as the keezer, and therefore be too cold?

Click to expand...

If you run fans all the time, the the external chamber will be within a few degrees of the freezer. To hit a specific temperature, the fans need to run off a temp controller (and the target temp needs to be warmer than the freezer set temp).

Well sorry I disappeared for a bit there lol. Okay so, lots of good information here!

freelunch: I had thought about the return air, but not enough to actually plan for it apparently! Good call on the return air not blowing on the tap lines too.

Brewmech/b-boy: I was originally planning on going through the lid since I will be eventually be building a bar and coffin for taps on the top. BUT, after seeing the need for the return air, a collar would make it WAY easier.

Hang Glider: I'd love to do that idea, and would like to do that in the future, the budget right now doesn't allow for it though.

Everyone, thanks for all the info! I think I'm going to go for it. I'll install a collar, have the keezer->chamber air blowing in to the top of the chamber. The return air will come from the bottom of the chamber, and have ducting in the keezer going to the floor to prevent it from warming the tap lines. I'll use a fan going each way. I suppose I could rig up another fan bringing in outside air in case I need to warm it up, somehow I doubt I'll need to though.

I'm hoping it should work pretty well. If not I guess the holes in the collar will be pretty easy to plug

Cheers all, I'll post back when it's complete!

Kosch