Glycol Fridge Fermenter Mod/Build

So for several years now, I've always fermented in heavily modified fridge to control temperatures. After getting spoiled by the conicals at the local microbrewery I help with I decided that I too needed to upgrade my fermenting situation and bought a plasticmart 15 gal conical.

This led to a few issues:
1. The new conical required partially dismantling the fridge to get it in or out.
2. With the thick plastic on the conical, the thermal transfer was pretty poor.
3. Because of #2, crash cooling didn't work that great anymore.

Besides that, the fridge had really seen it's better days...

Fit in the old fridge:




So something new was needed.

Some of the requirements I had:
1. It needed to be insulated, as the fridge lives in my garage, and it gets to 110/120 in the summers sometimes....and still get to lager temps.
2. It needs to fit 2 conicals, with flexibility on type (my next one may be a brewhemoth, which is taller)
3. The two conicals need to have independent temp control.
4. It needs to be able to cool 15 gallons of wort 20 degrees within an hour for summertime.
5. Optionally, it should be able to function as a fridge if need be.

So the plan is to build a large insulated box, and a glycol chiller. I built a large glycol chiller system for the brewery, and it works quite well, although it would be pretty oversized for this system. I also want to get rid of the two fridges I had been using for fermenters, and gain some room in the garge.

For making the glycol chiller, I could either use a window a/c like i did for the brewery, or tear apart the first fridge. I decided to repurpose the fridge since I didn't have a use for it, and it had been sufficiently modified to not have many other uses anymore. The second fridge I gave away to a friend to return to its prior life as a kegerator.

In retrospect, a 5,000 BTU/hr window unit would probably have been easier and with higher capacity, although there might be issues with short duty cycle times.

Removing the cooling system from the fridge:




Test to figure out the cooling capacity:
To find out, take a known quantity of water, and run the chiller in it and measure the temp drop over time. 1 BTU = 1 degree per pound of water. I used a small pond pump to stir the water to get a more consistent reading.


It calculated out to approximatly 1500BTU/hr...or about what I expected.

it pulls about 300-400 watts doing so, which makes it somewhat ineffecient, I'd probably get about double the efficiency with a newer unit or newer window a/c.

Next up, I needed to build the boxes for everything.

The plan was to have a base that housed all the chilling equipment, and then the top insulated box to house the conicals.

I built a wooden base and started to fit things in:


Because the evaporater was 27" wide, I wasn't able to find any plastic tubs to fit it in...so I decided to make one. This part turned out to be an annoying PITA

The start of the glycol chamber.

The initial plan was make a mold and use spray foam insulation...sortof like is done inside coolers.
This was a horrible failure.





so well after the supposed cure time, and a day or two after I had removed the formed. It shrunk. A lot. As in about 20% in every direction.

So I put in 2 more inches of rigid foam


I was debating on how to make it water tight, I thought about using a pond liner and even bought some vinyl sheeting that I didn't use (I was concerned about poking holes in it)...when it dawned on me to just use fiberglass and make a tub.

A couple notes...the fiberglass resin does melt through rigid foam (thankfully the rigid foam mixing board alerted me to this) Fiberglass resin jelly also does, although at a much slower rate, and effectively will harden before dissolving very much.

I coated then inside with some neoprene stuff I had for laying tile and made the fiberglass tub in place

After a few gel coats, and time to cure, we deemed it water tight...which a quick fill with water confirmed. It also worked out to being 12 gallons in capacity...which should work well for cooling purposes.



The Chamber itself is basically just a plywood box, primered with 2" rigid insulation added.





and the box fits on top of the chiller base.

At this point, I was in a rush to temp put it together so I could brew a batch of beer...so I don't have pictures right now. I've temporaily hooked it up for 10 gallons of CDA, so once that beer finishes, I should have the rest of the parts in and I'll continue the build portion of the thread and show the control, and chilling portions better.

Still to do:
-Build doors
-Set up the glycol system to control multiple conicals, (solenoids etc)
-Re-do the airflow over the compressor (just using a bunch of fans right now)
-clean up the wiring and possible add better controllers (fermtroller or bcs-460 or similar)
-Add the thermowell to the conical.

As for performance, it seems to work pretty well. The thermowell didn't arrive in time for the brew session, so I taped the temp controller probe to the outside and puts some foam insulation over it. The system chills the batch down faster than the controller can respond...so I see ~4-6 degrees of wort temp drop by the time the controller registers 1 degree...a thermowell will really help here.

I haven't had a chance to check pull-down performance but the first few degrees come off in under a minute. This won't scale as it warms up the glycol resevoir, but it looks like I should be able to drop down to lager temps within the hour even in the summer with 70degree wort coming off the chiller.

Action shots!:


Chiller coil in conical



More to come!

Very cool! Looking forward to seeing the rest of this build. When/if you add another (stainless) conical, are you intending to wrap the chiller lines around the outside, or submerge them as it appears you are now with the plastic model?

depends on what I get, but most likely I'll submerge. If I go with the brewhemoth, they'll sell a chiller that will attach to the top 4" triclover

So an update
Instead of make progress on it the past few weeks, I brewed beer instead and got some performance numbers.

I did a 10 gallon lager prior to finishing the doors, and off the plate chiller I got 70 degree wort. With the glycol bath prechilled to 29 degrees, I was able to get the conical down to 50 degrees in ~35 minutes. The glycol had warmed to 37 degrees by this point.

It held temps during the primary, despite the weather getting warmer than expected, and after a diacetyl rest, I was able to pull it from 68 to 40 in a couple hours.

I've got doors on it now, a new ethernet based controller (not installed) and a brewhemoth on the way. I'll post the pics soon, and info on the controller setup for multiple conicals.

Any updates on this?

benbradford said:

Any updates on this?

Click to expand...

I've got some updates for it, just been busy lately.

Great build, love how neat the setup is, it looks much better than the bastardized cooler setup. Looking forward to more info!

I love this idea! But could the coils ice over at any point?

bloodonblood said:

I love this idea! But could the coils ice over at any point?

Click to expand...

they could, but I did two things to prevent it. one, there's glycol added to lower the freezing point, so it primarily just slush.

Second, I added a small pond pump to circulate the fluid. That seems to effective.

I'm having to redo the chiller system - the evaporator I was using was made from aluminum, and it looks like an area where the defrost heater used to be killed the anodized coating...and it corroded through and died. I'm replacing it with a dehumdifier core.

I'm also cleaning the inside up and will get pics of the electronics and how the glycol is pumped and controlled.

But for now, here it is with the doors mounted and the brewhemoth sitting in it.

Any updates on this? I'm curious how you pumped the glycol?

pickles said:

Any updates on this? I'm curious how you pumped the glycol?

Click to expand...

Yes, actually I have several updates for it! I've just been really busy lately (haven't even brewed since new years )

for the glycol pump I'm using a 1 gpm 12v diaphragm pump. This pump has an internal pressure switch that kicks it off around 40-50psi. When the controller needs glycol, it opens a solenoid that allows glycol to flow through the chiller coils. the drop in pressure makes the pump kick on.

here's the pump i'm using: http://www.northerntool.com/shop/tools/product_357081_357081

they are also used in rv's for the water supply

Does that pump stay primed or are diaphragm pumps self priming? I'm training to figure out the best way to cool my Brehemoth that should arrive in a few weeks. How do you like yours?

they are self priming.

I like the brewhemoth, I wish the cooling coils were larger, as it doesn't work as well as my other fermentors, but in reality it works fine and I can still lager with it. the capacity is nice as well as how well it seals up.