WARM fermentation control?
This is the last post I could ever have imagined making, since I'm in Australia.
BUT, the first winter has proved troublesome for fermentation temperature control. Last week, I was fermentating an American Pale Ale, trying for some pretty high temps to get good esters and yeast characters (>20oC / 68oF). Unfortunately, it's winter here and the temp in the brewery was about 10oC during the day - the fermenting beer never made it above 19oC, and over a couple of cold nights, dropped down to 15oC and eventually 9oC. The fermentation started and stopped, and is dribbling on, now nearly at the FG.
By the way, I have jacketed and insulated cylindroconical unitanks, with a side cooling jacket, no cone cooling.
I was suspicious of the glycol solenoid, and ended up isolating it off completely - the temperature did rise a little, back up to 13oC or so, so I think it may have been passing a little.
However, I wanted to ask, is keeping the ferm temperature high enough ever a problem with you N Americans and Europeans? How do you ensure ferm temps are maintained when it's mid-winter? Do you have a warming circuit in parallel with your cooling circuit?
I was always under the impression that fermnation process was endothermic and thus would generate heat, thus only needing cooling control - but it didn't appear to generate enough in my case. I'm pretty sure the beer will be different in character to the last one, which was happy at about 21-22oC.
I'm also surprised that changes in ambient temperature appear to have so much influence on a liquid sitting in an insulated tank! Is it possible that the cold seeps into the tank where the thermowell penetrates the tank wall and where the sample valve pokes out of the manway, creating local cold spots that don't actually represent the bulk temp? But then, the sluggish fermentation still occurred. This is only the second time I have brewed this beer, so I don't have strong records yet to compare the ferm profile against the last one.
Any hints/tips/thoughts welcome!
Last edited by jipjanneke; 08-08-2005 at 07:56 PM.
You might slightly redesign your cooling plumbing so that there is an air gap at the top fitting for the cooling jacket. Depends if T-stat turns on pump or opens solenoid, but the idea is that if your jacket is full of coolant even when not flowing, it is much more heat conductive than when it is filled with wimpy air. So, if when no coolant is flowing, it drains the coolant back to the glycol tank, there will be more resistance for the heat to be lost thru the jacket into your cold "winter" atmospheric conditions.
Of course one can always temporaily replump the jacket to hot liquor and warm it up. (Don't let nasty glycol recirc back into hot liquor)
Last winter (Nov-March on our side of the globe), the temps in my place were at freezing much of the time, occasionally below as evidenced by the frozen water lines, and my frostbitten hands.
I've just got 3 fermenters (2-7bbl and a 15bbl), but they are fully jacketed and insulated on all sides except for the top. Even now that I've ramped up a bit, I still only operate the chiller and control the temp when needed - and any tank I'm not using is manually valved off in addition to the temp controller shutting the solenoid.
I had some concerns about my ability to keep the ferment warm enough, but there were no issues - started at 70F and it went up to 75-78 on it's own, then slowly dropped down a few degrees a day. About perfect actually. You might want to consider installing/operating a manual valve if you're getting a trickle chilling effect, which to me sounds like you are...
The one exception was when I left a valve open and took the temp on a new batch way down. DOH! Luckily, I had an empty fermenter that I could fill w/ hot water and run the glycol recirc pump a bit to warm the overchilled batch back to the right temp. Worked like a charm.
Sounds like your solenoids were passing a little glycol through - hold your hands on the fittings to see if they are ice cold next time. What was your knockout temp? You might try knocking out at a little above your temp you want to maintain when it's cold in the brewery, to let the yeast get going before it can cool down much.
Thanks everyone ... your hints and advice are good. We were getting about 24oC into the fermenter, perhaps a little warmer would help. I was interested to read in another post about the grainger strainers - perhaps the solenoid is blocked or just old, and passes...
Cheap solenoids, especially for irrigation seem to exactly be worth their price.