Optimal Temperature for Internal SS Coil?

[lhommedieu]

I've DIY'd an internal cooling/heating coil for my Blichmann 14.5 G Fermenter and I've had success in the warmer months using chilled water and a pump. Basically the pump turns on when the fermentation temperature gets above a set point and turns off when it gets below a set point.

Question: is there an ideal temperature (or a formula for determining a temperature) at which the warm, circulating water should be set? The temperature in my uninsulated garage rarely dips below 32F and sits in the mid-40's most of the time. Since I brew lagers most of the time, the temperature of the wort inside the fermenter needs to be warmed 5F-20F
(but generally 5F-10F) above the ambient temperature in the garage.

 

[thekraken]

I don't have a real answer to your question. I'd assume IDEAL would be that the circulating liquid is exactly at the SP you want, but that would require more constant circulation.

I am curious about your setup. What are you using to control the temperature of the circulation fluid? What kind of controllers? You mentioned more of a thermostat control, have you thought about using PID?

 

[iijakii]

I've DIY'd an internal cooling/heating coil for my Blichmann 14.5 G Fermenter and I've had success in the warmer months using chilled water and a pump. Basically the pump turns on when the fermentation temperature gets above a set point and turns off when it gets below a set point.

Question: is there an ideal temperature (or a formula for determining a temperature) at which the warm, circulating water should be set? The temperature in my uninsulated garage rarely dips below 32F and sits in the mid-40's most of the time. Since I brew lagers most of the time, the temperature of the wort inside the fermenter needs to be warmed 5F-20F
(but generally 5F-10F) above the ambient temperature in the garage.

I don't think there's a good, easy answer here. It's entirely dependent on coil vs fermenter size, probe placement etc.

One thing Ive found with heating vs cooling is you have to be more weary of stratification, so don't go overboard with the setpoint or you might wind up with a hot top section.

 

[lhommedieu]

I've already run the gamut of lowering/raising ambient temperarure in a chest freezer using an STC-1000 and a paint can/light bulb with carboys, to fitting a SS fermenter with a heating pad and a Ranco controller (this worked fine until the pad developed a short and the fermenter developed a certain "buzzing" quality when touched), to heating the garage with a ceramic heater and Ranco controller (worked - but too cost prohibitive due to the fact that my garage is uninsulated). In each case the temperature probe was attached to the outside of the fermenter and insulated with bubble wrap; my new plan calls for a thermowell to be placed half-way down the fermenter.

So with these prior methods tried and to a large extent validated, I was thinking that a Ranco controller could be used to control the pump based on the thermowell temperature and the the water supply could remain at a constant temperature with another Ranco at its end. I understand the stratification issue, but until I can afford to place my fermenters in a walk-in refrigerator, an imperfect solution will have to do. And I'm not sure how imperfect the set up will be, given that the coil extends from almost near the top of the fermenter to almost to the bottom. If the warmer wort sits on top, then I guess the job is to keep both it and the cooler wort on the bottom, both within range of the best temperature for the yeast, with the lower temperature on the lower end of the fermetation temperature scale? Perhaps in this regard a couple of external thermometers insuluated with bubble wrap could provide some kind of back-up feature?

Perhaps the best thing to do is just to experiment with a few temperature setting to find where top and bottom ranges are produced? Say, 70F, 80F and 90F, when the ambient temperature in the garage remains fairly constant 32F - 42F, to hit a fermentation somewhere in the low 50's? This assumes that the pumps will not be harmed if they turn on and off every hour or so - but maybe I'm off-base and wrong here as well.

I am wondering if stratification may be an issue more germane to the cooler months, as convection occurs in the warmer months due to the cooler wort on the top sinking and the warmer wort on the top rising?

 

[wilserbrewer]

The critical time for temp control is when the yeast are quite active, and when the yeast are quite active stratification will likely not occur as the yeast create movement of the wort.

Just my observation and opinion on stratification.

Perfect can be impossible and take forever j/k