Seeking feedback/advice for temperature controlled sanke fermenter

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?

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

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

P-J said:

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

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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).

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.

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.

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.

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.

Sub'd

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?

I think I'm just going to put the carboy with the fermentation in a bucket with water and a fish tank heater. Dirt simple, dirt cheap, and probably at least nearly as effective as fermwrap + controller + temperature well.

heckels said:

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?

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Yeah, I thought about that but I wanted to keep the freezer as intact as possible.

6lluv6lu said:

I think I'm just going to put the carboy with the fermentation in a bucket with water and a fish tank heater. Dirt simple, dirt cheap, and probably at least nearly as effective as fermwrap + controller + temperature well.

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Yes, if I was just doing heating there would be better options than Flexwatt.

USCDiver said:

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.

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I made up some boards with hooks bent out of steel flat stock that hook to the bottom of the keg and are c-clamped at the top of my kettle. I could then use wooden wedges to hold the copper tubing tightly against the vessel until the epoxy (JB Industroweld) cured. I got a good bond between the copper tube and the keg and I think the thermal bond will be adequate.

I am going to be following this thread. I am curious how you seal the top of your Sankes and vent? I have a sanke and am wanting to come up with a way to convert it to a fermenter. Keep us posted.

I'm guessing you could have soldered that coil to the keg also.

You have my interest, I will be following.

I tried silver-brazing the copper tube on the lower skirt which is thicker SS and it worked. I had already done the finish work inside the kettle on those welds and didn't want to have to do it again after brazing or soldering so I went with the cold, epoxy method instead.

The clamping arrangement worked well, but it's a time-consuming process with epoxy because of mixing small amounts and a short working time.

Gonefishin said:

I am going to be following this thread. I am curious how you seal the top of your Sankes and vent? I have a sanke and am wanting to come up with a way to convert it to a fermenter. Keep us posted.

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If you aren't looking to do temperature control, you can use one of these to turn your sanke into a fermenter.

Here's the latest update on this project. I'm still not convinced it will work, but it is coming together more or less as I had planned.

I built a relatively standard, simple slip on collar using 2x4 and 1x6.


I drilled a couple of holes to hold 4" nipples (I think they are 3/8"). This allows me to hook up hose on the inside and outside separately. Not sure why I did this, but it seemed like a good idea at the time. Best I can tell it just cost me a few extra hose clamps, but what the hell.



I used compression fittings on the end of my copper so that I could attach ball valves. I got tired of the water and/or glycol leaking everywhere whenever I moved things around.


Here's the keg with 50' of 3/8" copper coiled around it and 4' of 3" FlexWatt heating strip in the middle.


And last but not least, here is my ghetto STC-1000.



I just used a cheap 3 gang box instead of some fancy project box. The controller sticks out a little bit and I had to trim the opening on the faceplate to get it in, but otherwise this was pretty straight forward wiring. Left recepticle is cooling. The dimmer is wired in-line with the heating side of the recepticle as recommended by the FlexWatt folks. I get 100V when it is all the way up and 90V when it is all the way down, so not a huge range of control there. Honestly, I'm not sure it even matters since it isn't going to be burning any lizards. I guess you'd want to avoid creating a hot spot on the inside of the keg, that stainless probably doesn't dissipate the heat from that stuff too much.

First quick test, I was only able to cool about half a degree C in an hour, however I've only got 2 gallons of 50/50 glycol/water in the bucket (started at -10F and warmed up pretty quick). I'll go get another couple of gallons of glycol tomorrow and make 6 gallons of 50/50. There was good condensation on the first 4-5 coils, but I think the glycol warmed up pretty quickly before it got to the bottom coils. I would imagine brazing and insulating would help with that a good bit.