Need some help - fermentation temperature controller.

[Thefirebuilds]

Here's my setup:

Spike brewing CF5 (No jacket yet, it's coming today.)

I have their cooling coil with two 3/8" stems coming from the top.

From this I am drawing two 3/8" PVC lines into a small dorm fridge (retired kegerator)

Inside I have a small basin of water/propylene glycol (around a 5-10% mix of PG with 90% water)

A pond pump advances cool water from the basin through the conical, back into the reefer, and then through a heater core (some truck heater core I found for $20). The pond pump is triggered by the temperature probe in the conical thermowell (an old johnson controls controller)

The heater core sits in the "freezer" section of the refridgerator, and I have a PC fan exhausting air over it.

I have the temps in the conical about 20-25* below ambient (it's around 60-65 here in TX) and the reefer is showing 25* in the freezer section, but I cannot get the temps any lower than that. Trying to cold crash for 2-3 days and 48* is as low as I've seen.

How can I make this loop more efficient, or is that the best I can do? The jacket will be here soon but I have no condensation on the rig so I'm not sure how much it will help.

Here's some pics to explain:

https://imgur.com/gallery/xYkvZeu

beer temp - 48.3
thermowell - 48
ambient - 60
freezer - 29

 

[bracconiere]

looks like your wasting space in the freezer? how about something like this to fill it up:

http://rover.ebay.com/rover/1/711-5...0001&campid=5338413729&icep_item=183378127821

and some of pipe wrap for the lines also?

 

[Thefirebuilds]

Pipe wrap is a fine idea. I do need to figure out where the temperature losses are, but I'm guessing that giant stainless steel bell end is working as a very effective heat sink to keep the temps high. I thought this solution would be far more effective than it is though.

One thing I did change is that I was pre-cooling the liquid through the radiator before sending it to the conical. By cooling the liquid on return I got about a -3* change.

 

[mongoose33]

You almost certainly are picking up a lot of ambient heat through all the various "protuberances" extending from the fermenter. Legs, handles, sampling port, racking port, lower yeast dump, pressure manifold, top of fermenter where the coil is--all of these are bringing heat in, and your setup cannot overcome that.

Sort of the reverse of a radiator, in essence.

I have a spike CF10, and originally tried to use a glycol solution to crash it, running that out of a refrigerator's freezer. I went through many iterations to try to make it more effective, and in the end, i just wasn't able to get it down to where I wanted. It did work at holding temps above 45 degrees, but I couldn't get it to crash below about 40.

https://www.homebrewtalk.com/forum/threads/conical-cooling-conundrum-spike-cf10.650037/

That thread may give you some ideas. Or cause you to lose hope.

*******

OK, now the somewhat bad news. I eventually gave up on the freezer thing (in retrospect it actually worked fairly well) and bought a Penguin chiller thinking that would be the ticket. . That penguin is nuts, in that I have it set at 28 degrees and it rarely gets above 31 degrees (I have a 3-degree set point).

I was thinking that THIS would get me down to where I want crashing to end up--but even circulating 28-degree solution through the chilling coils I can't achieve that. There's just too much of a heat load.

I've tried insulating the fermenter with a moving blanket, and also with reflectix covering all the "protuberances." I even tried making a "closet" into which I directed cold air from a window air conditioner to reduce the ambient around the fermenter.



None of it mattered much. I have a theory that the blowing 50-degree air from the air conditioner served to warm up the fermenter once it dropped below 50, so only a still-air "closet" would likely work.

Even lately when ambient in the garage is 45 degrees I can't get the fermenter down below 36. It's just the limitations of the setup.

I've largely come to accept this, kind of wishing I hadn't dumped the money into the Penguin though i can see ways this will pay off in the future.

My last attempt to overcome this is to create an insulated "closet" from 2" thick foam board. Sections 2' x 4' will let me create a box inside which the fermenter can sit; cover the top and I have an insulated box. I think that probably would overcome the tendency of the unit to absorb heat.

I also could add a second pump in the Penguin (I have one) that would run chilled liquid through a coil sitting on top of the fermenter and add to the cooling effect. I'm pretty sure that would work.

*****

Some of this is just to prove to myself that I can make this work. I have tried so many different things that have failed to work that this now is almost my white whale.

 

[Thefirebuilds]

Hmm, maybe I'll modify the old dupont foamboard cabinet to a closet for my pretty conical

Thanks for the link, I searched a little and couldn't find any details.