USCDiver

Recipes 

So I have a spare Sanke keg that I'm planning to turn into a temperature controlled fermenter. My current plan is to wrap a coil of copper tubing around the keg and circulate chilled glycol through it. I would like to put a bucket of glycol in my chest freezer with a submersible pond/fountain pump which would be controlled by a STC-1000. I might also use some Flex Watt For heat also controlled by the STC-1000. Once I have the kinks worked out, I'll probably wrap the whole shebang in Refletix.

I guess I'd like to know if anyone else has tried something similar. What size pump will I need? Will the glycol be too viscous for a pump designed to handle water? What size and length of copper line will be optimal? I was thinking 50' of 3/8" soft copper, but that might be overkill.

I don't want to turn the chest freezer into a keezer because we actually use it for food storage. Also, this plan would allow independent control of multiple fermenters just by adding an additional pump and STC to subsequent kegs.
Thoughts?

P-J

Recipes 

Sounds like an excellent plan to me. It is similar to a fermentation chamber that I built a few years ago. I wrapped 4 loops of 1/2" OD copper around the Sanke and then insulated it as you stated. I used heat sink "grease" to provide excellent heat transfer between the coil and the keg. I then used an Auber Instruments PID (SYL-2352) for temp control.

Works very well and I can maintain the temp spot on.

The difference is that I use a commercial 'liquid' refer unit instead of the 'keezer' plan.

Wishing you the best.

P-J

JoeyChopps

Recipes 

Dam you USCDiver now I want to build your awesome plan. Please include lots of pics

USCDiver

Recipes 

P-J, im guessing your commercial unit was one that both chilled and pumped the coolant, right? Do you a have any concerns about a basic fountain/pond pump getting the glycol moving? I was looking at a 200gph unit at Lowes today.

I'm also looking to do a dual stage heating and cooling controller because this thing is going to be sitting in my garage or basement which both have some cold temps in the winter.

The chest freezer we have right now doesn't have a collar on it. I don't really need the extra height, but I can't think of another way to have coolant and power lines running in and out of the freezer without drilling a hole in the side (which I know better than trying).

USCDiver

Recipes 

I picked up one of these fountain pumps as well as 50'x 3/8" OD soft copper and 20'x 3/8" ID vinyl tubing. I had to go to Tractor Supply for the propylene glycol, but it was $20 for a gallon of concentrated stuff. Diluted to 60% it won't freeze until something like -20degF so if this proof of concept works and I scale up to 5 gallons in my bucket, I would only need 3 gallons. Expensive but essentially doesn't run out. I've got the glycol sitting in the chest freezer now and I'll hook everything up tomorrow to see if it'll flow.

I'm worried the pump will be under powered, but I think a slow trickle may end up best for efficient heat transfer anyway. Ideally the glycol would be coming out at wort temps and there would be enough in the reservoir to keep a sub-freezing temp even when it is circulating for extended periods. I'm also concerned that the pump won't work well at sub-freezing temps. But that's why I got a cheaper model to test.

USCDiver

Recipes 

I don't know if anyone else is following along here but I'm going to keep documenting my trials and errors. So this little pump is definitely too small even for free flowing room temperature 50/50 glycol. I can only imagine it would be worse with increasing viscosity as the stuff cools down to -20*F. So I'm going to return it and get a bigger pump.

I'm starting to look at FlexWatt too but I'm concerned it will get too hot plugged directly into the STC. Anyone have any experience with the stuff? Best I can tell it gets up to a maximum of 110*F, but I'm not sure I want to have it running at full blast while the wort slowly comes up to set temp.

6lluv6lu

Recipes 

How did this work out for you with the FlexWatt and the STC 1000? Over here, http://www.beanfarm.com/heating/flexwatt_userinfo.pdf, it says that FlexWatt needs a proportional controller. The STC is just a switch right? If it does work, it seems like a relatively economical solution.

USCDiver

Recipes 

I actually just got back to working on this thing in the last week or so. Real life interfered for a few months. I will probably just get a rheostat from Lowe's and wire it into the heating circuit and dial it back to like 80%.

So far I've got the copper coiled around my keg but I haven't gotten it tight enough to transfer any heat. I've got a chest freezer but I couldn't find a reasonable way to route the tubing in and out of the freezer without building a collar, so I've been working on that the last few days. My Flexwatt from Bean Farm came earlier this week but I haven't messed with it yet.

So when I get home from the holidays, I should be able to test this thing out as soon as I get the copper tightly coiled, get my collar built and get the Flexwatt wired. I'll post updates when I get back.

stevej21

Recipes 

Sub'd

heckels

Recipes 

Instead of a collar, could you use a set of cam locks (or some other quick disconnects) and then a 90 elbow coming out of the top if the freezer?