Having problems cold crashing with glycol

[BrewinSoldier]

Ok long story short, when I had my two SSbrewtech 7 gallon BME conicals, I had zero problems going from a 70°F diacetyl rest to 34°F cold crash. I also had a 8 gallon Brewers Hardware jacketed conical that also had zero problems cold crashing.

I've recently upgraded my batch sizes and bought a Spike CF15 and a Brewers Hardware 14 gallon NON jacketed conical. I can't get either one of them to drop below 39-40°. I have no idea why it's a problem all of a sudden with these?

I've had two batches in the Spike so far. First was a 6 gallon batch. I thought maybe there just wasn't enough wort in it for it to get to 34°(even though it's advertised to do 5 gallon batches). So now I've got 12 gallons in it and same deal. I had 12 gallons in the BH conical as well and it couldn't do it either.

What gives? This gylcol chiller is supposed to run this size conicals with ease. One thing I did notice is that the gylcol bath is reading 28° on the controller but is actually 30°.

Maybe it's time to change out the glycol but I don't think that would be the culprit behind the cold crash issue.

What do you guys think?

I did check the coils in the fermenters and they weren't frozen over so that is ruled out.

 

[ScrewyBrewer]

Sounds like the glycol unit is a bit undersized for the extra volume batches you're now brewing. And using a non-insulated conical will also be harder to cool down. If it were me I think a ~4F deficit in cooling is a fair trade-off for the extra capacity.

 

[mongoose33]

I've got a Spike CF10. And yes, it does do half batches. But it doesn't cool that half batch as efficiently as it cools a full batch.

The bigger unit provides more surface area to draw in outside heat. Especially if you're doing half-batches, you still have the same surface area, but only half the beer to provide thermal mass. It's just a larger heat load from the outside relative to the size of the batch.

Some of this depends on ambient temperature. If you're in a hot garage, there's a terrific heat load to overcome. Those conicals have all sorts of projections sticking out of them that absorb ambient heat. On my Spike it's....counting....11 things sticking out (handles, legs, ports, etc.), all of which are drawing in heat from ambient. Sort of like reverse radiators.

I have the neoprene jacket on mine, but it doesn't cover the lid, nor do anything with all the projections. I've done things like wrap the fermenter in a moving blanket and that helps. I haven't yet cut pipe insulation to fit around the legs, but I will. I also will drape a small blanket or towel over the top to provide it a little help.

If the area in which you have the conicals is at all warm, I would actually be surprised if you could get the unjacketed one down to crash temps.

How warm is ambient? And do you get a lot of condensation?

 

[etk29321]

100% agree with mongoose33. Uninsulated I could never get my conical down to 34F in my garage. Ambient temp there is typically in the high 80's during the summer. There would also be a puddle forming under it from humidity condensing. Insulating made a world of difference not just in what temps I could reach, but in how often they a/c unit that powers my chiller had to cycle.

 

[BrewinSoldier]

I guess I should have clarified a few things to help.

The BH non jacketed I insulated with towels. Not sure how much that helped but I kept the towels folded so I could have more insulation.

The room is usually between 78-80° ambient. It's in a spare bedroom. I don't get a ton of condensation but there is some on the parts that stick out and are uncovered.

As far as the gylcil unit being underpowered, it's rated to do up to 4 1/2BBL conicals at a time. So not sure if it's just not keeping up or what.

 

[mongoose33]

I guess I should have clarified a few things to help.

The BH non jacketed I insulated with towels. Not sure how much that helped but I kept the towels folded so I could have more insulation.

The room is usually between 78-80° ambient. It's in a spare bedroom. I don't get a ton of condensation but there is some on the parts that stick out and are uncovered.

As far as the gylcil unit being underpowered, it's rated to do up to 4 1/2BBL conicals at a time. So not sure if it's just not keeping up or what.

It may depend on what they're referring to as far as how many at a time. There's a glycol chiller at MoreBeer that says it can hold 4 fermenters at 75 degrees, but that's not the same as cold crashing.

 

[BrewinSoldier]

100% agree with mongoose33. Uninsulated I could never get my conical down to 34F in my garage. Ambient temp there is typically in the high 80's during the summer. There would also be a puddle forming under it from humidity condensing. Insulating made a world of difference not just in what temps I could reach, but in how often they a/c unit that powers my chiller had to cycle.

Just curious but what did you end up insulating it with?

So a quick update, i was finally able to get the Spike CF15 down to 35*(although it did take a long time). I called up the manufacture of my chiller and they walked me through how to get my controller to a lower set point. I set it to keep the glycol at 20* and with that, I was able to get to 35* in the fermenter so Ill leave it at that. Im going to see how often the chiller has to keep kicking on to keep it at that now that its got it there.

 

[mongoose33]

Just curious but what did you end up insulating it with?

So a quick update, i was finally able to get the Spike CF15 down to 35*(although it did take a long time). I called up the manufacture of my chiller and they walked me through how to get my controller to a lower set point. I set it to keep the glycol at 20* and with that, I was able to get to 35* in the fermenter so Ill leave it at that. Im going to see how often the chiller has to keep kicking on to keep it at that now that its got it there.

Watch out for beersicles forming on your chilling coil in the fermenter. When others have used really cold glycol, they'll get ice forming on the coil.

 

[BrewinSoldier]

Watch out for beersicles forming on your chilling coil in the fermenter. When others have used really cold glycol, they'll get ice forming on the coil.

Yeah I'll have to watch it. From what I've read, that only happens if you try to crash to quick. I think from now on with these bigger batches, I will step down the temp from diacetyl rest to cold crash 5-10° at a time, let it rest until the pump quite kicking on and off and settles in, then knock it down another 5-10° until I get to 34.

 

[matt_m]

I recently started using BrewPi controllers on my Chrnoicals. I'd had trouble the first first couple batches since I got the Chronicals getting below about 42. I never saw ice but didn't want to keep opening fermenters. With the BrewPis, I put a logging probe in my glycol which showed with the chiller setpoint at 28 it was getting as low as 26 in the bottom of the reservoir. I turned the chiller setpoint up 2 degrees and now have a beer sitting at 37 which is probably the limit of what heat the chiller can remove vs what the 7gal Chronical with the neoprene jacket absorbs in my basement in the low-mid 70's. I suspect the ice forms when the pump is running and quickly melts when they stop since the beer surrounding was a good 10 degrees warmer.

 

[etk29321]

Just curious but what did you end up insulating it with?

I just used a couple wraps of reflective insulation (https://www.lowes.com/pd/Reflectix-50-sq-ft-Reflective-Roll-Insulation-24-in-W-x-25-ft-L/3011904). Since theres a fair chance of it getting wet, I didn't want to pick something that could become waterlogged. It's enough to do the job for me. The key is covering every square inch and sealing the seems with al tape.