keezer and fermenter

[swanwick]

I currently have a keezer with a 4 inch collar.

For those newer to the topic, that means I have placed two by four's between the lid and the body of a chest freezer. That provides extra height (to fit 5gal cornies) and it creates a place that is safe to drill through for power, thermoprobes, gas lines, etc.....

I use my keezer as dual duty for fermentation chamber, but that means my pre-existing beer is not cold while fermenting a new batch.

Have been thinking about building a custom fermentation chamber to house a 15gal conical and then putting a duct fan between the keezer and the fermentation chamber. So, the keezer could stay at good serving temp (via its temp controller), and the duct fan could kick on (via its own temp controller) when the fermentation needed some of that cool.

Do some of the experts here think that would work? Is there a certain strength fan that would be required? Is there a max distance that the duct could be?

 

[Zepth]

I have successfully made a couple of lagers (corny fermented) in my operational keezer. Worked out well enough for a low 50's ferment and still having all but one tap online. D-rest was just pulling it out of the keezer and an extended aging in place of cold lagering.

That said I can see you idea working out fine. I could also see it burning out the compressor due to a huge additional load that it wasn't intended for. If you've got a 4 cu ft keezer and want to add a 20 cu ft area it would probably not be up to the task; even though the ferm chamber wouldn't want to be as cold as the rest of the keezer. If you have a 15 cu ft one with 6+ kegs in it and want to add 5 cu ft for the ferm chamber it probably won't skip a beat. In both cases the keezer main controller is being kept significantly warmer (room temp -15C) than it was originally intended (room temp -35 or -40C). This may compensate for the former example.

All in all you're looking at turning your keezer into a side-by-side with custom fabrication. Side by side conversion may be of some help with ducting and baffles. Insulating the fermentation side will take a good deal of strain off the keezer side of things. A good thermal mass in the keezer would be your best friend.

Sounds like a perfectly viable option, I was considering something similar at one point myself. Then I acquired something to turn into a dedicated ferm chamber and that idea went out the window. At this point I'd like to ask a couple of questions. The first is pertaining to current keezer capacity. The second is a more precise (cu ft) size of the chamber you'd like to add. Ales or Lagers?

These fans are being used in a project of mine. They are powerful enough to open up the plastic baffles I used from the hardware store. A little louder than I'd like, but far quieter than other things in the setup. For example: compressor and its fan.

 

[swanwick]

Thanks so much for the reply.

My keezer is pretty big. To date I have only brewed ales, but would like to try lager. Could always resort to doing those in keezer itself.

Will definitely plan to insulate ferm chamber. Also, would probably get a fan more like this.

One thing I am worried about is the pressure. If I am pumping air out of the keezer and it is a closed system, it is not going to want to go through the duct. May need to put a hole in keezer collar that stays open when fermenting.

 

[Zepth]

Use 2 ducts. One as intake and one as exhaust. Exhaust goes back towards keezer. With a powerful enough fan you should be able to get away with only using one. Worst case scenario you may need one fan per duct to make it work.

Only reason I asked if you were doing ale or lager is because the external lager chamber could really put the hurt on the keezer if it were smaller. If it's large you shouldn't have a problem at all. Or even better do as I did and have the primary lager ferment in the serving keezer. One tap offline but you should survive.

I'd be interested in the build log and end result should this come to fruition.

 

[swanwick]

Good call on the return duct. The fermentation chamber will also be a closed system so it needs to be able to receive the new air without increasing pressure.

I'm not super psyched about punching two giant holes in the side of my keezer collar, but it seems like the right approach.

Does anyone here have a sense of what size ducting and what CFM fan is going to be required?

Does the return duct need to be the same size or can be smaller? Can they be side by side or will the output just push air that the input will immediately suck back in? ie. Its own little loop that barely grabs or pushes new air.

How much different does the duct length make? I haven't fully designed the ferm chamber, but I am probably going to put it in the corner of the room. If I put the keezer right next to it, that only leaves one other side for access. I am imagining that I will make one wall and the ceiling of the keezer removable in order to gain access.

This is a fairly long-term plan. I am going to have the space above my garage "finished" and when I do, will also get contractors to build the ferm chamber to my specs (I'm not very handy, unfortunately).

 

[Zepth]

Depends on how far you're planning on going. Air in ducts will have resistance just like beer in lines. Not sure if standard ducting will do the trick since your collar is 4" (I knew there was a reason I used a 2x12!), some 3" abs/pvc would probably be the largest I'd risk. The fan can mount directly to the collar with wood screws as long as the airflow is lined up with the pipe.

In theory a smaller return pipe would work as long as it carried a higher psi of air to compensate for the decreased surface area. "In theory, communism works." - Homer Simpson. Do yourself a favour and match it. If it works for placement to have the ducts side by side they'd likely have a small loop between them. Either a baffle to prevent the short loop or internal routing of the air duct to the opposite side should solve this.

For length I really don't know. Is it a question of "What is optimal?" Or is the question "What will work within my space requirements?" If it's going to be far away (10+ feet?) and built by contractors you might just be better off for them to install a "window" in the fermentation chamber and toss an air conditioner in it. Then a small space heater plugged into an outlet (and temp controller of course).

 

[Jbrown57]

It would be interesting to place a temp controller on the ferm chamber and control the fan based on temp.

 

[craigmw]

I currently have a keezer with a 4 inch collar.

For those newer to the topic, that means I have placed two by four's between the lid and the body of a chest freezer. That provides extra height (to fit 5gal cornies) and it creates a place that is safe to drill through for power, thermoprobes, gas lines, etc.....

I use my keezer as dual duty for fermentation chamber, but that means my pre-existing beer is not cold while fermenting a new batch.

Have been thinking about building a custom fermentation chamber to house a 15gal conical and then putting a duct fan between the keezer and the fermentation chamber. So, the keezer could stay at good serving temp (via its temp controller), and the duct fan could kick on (via its own temp controller) when the fermentation needed some of that cool.

Do some of the experts here think that would work? Is there a certain strength fan that would be required? Is there a max distance that the duct could be?

I have a 14.7 ft3 chest freezer that I purchased for using as a fermentation chamber, but realized that I could actually put some corny kegs in there at serving temp. I have rigged up some carboy "coozies" using Reflectix along with Fermwrap heaters that work very well in keeping my fermentation at the correct temps. My "keezer" is controlled by a BrewPi, but the carboys are controlled by a couple of STC1000+ units that switch the Fermwrap. The result is that my finished beer in the corny kegs is maintained at around 36F, while I can maintain ale or lager temps in the carboys. It works amazingly well, and even at ale temps (low to mid 60's), the Fermwrap is not activated all that often. I'll post a pic of the "coozie" design so you can see what I'm talking about.

 

[swanwick]

I have a 14.7 ft3 chest freezer that I purchased for using as a fermentation chamber, but realized that I could actually put some corny kegs in there at serving temp. I have rigged up some carboy "coozies" using Reflectix along with Fermwrap heaters that work very well in keeping my fermentation at the correct temps. My "keezer" is controlled by a BrewPi, but the carboys are controlled by a couple of STC1000+ units that switch the Fermwrap. The result is that my finished beer in the corny kegs is maintained at around 36F, while I can maintain ale or lager temps in the carboys. It works amazingly well, and even at ale temps (low to mid 60's), the Fermwrap is not activated all that often. I'll post a pic of the "coozie" design so you can see what I'm talking about.

Very interesting. I would have expected the two to fight each other. Where are you placing the thermoprobe for the fermentation? Are you using glass carboys?

 

[craigmw]

Very interesting. I would have expected the two to fight each other. Where are you placing the thermoprobe for the fermentation? Are you using glass carboys?

I'm using PET/Better Bottles now, not so fond of glass after a friend had an incident. The probe goes into a thermopile from Brewhardware.com, and it works great. The heater is on about 20% of the time with lager temps, and maybe 30% of the time with low ale temps (62-65). It turns out to work way more efficiently than I expected, certainly more efficiently than if I had a second fridge devoted to fermentation. The key is to use a couple of layers of Reflectix, and include 2 layers surrounding the top of the carboy. I'll try to post some pictures shortly.

 

[Zepth]

I think a better way to see if they're fighting each other would be to keep a log of compressor cycling for a day when you've got a couple batches fermenting and a couple days without.

Alternatively use the duty cycle of the fermwrap and it's heat output to find the wattage put into the unit. Then the power consumption and efficiency rating of the freezer to calculate how much longer it would need to run to neutralize that added heat from the fermwrap. But then there's mathing involved, method 1 may be easier.

 

[swanwick]

I know this is a bit of a DIY cop-out, but I think I am just going to go with a fermwrap and a fridge/freezer off of craigslist that is big enough to hold the conical. Seems to be the simplest and most energy efficient approach.

 

[KatoBaggins]

Swanwick, I think that is a wise call. Good luck, and post pictures.