What functionality are you seeking from a micro-controller?

[Rparkera]

Hi - thanks BM, I see your point - that makes sense. I'll use the litre bottle in the new fridge. Have got an ATC 800+ ready to go

Cheers!

[troublebrewing]

Looking more closely at the controllers I have here, they do indeed have the ability to take the hysteresis below 1*c, all the way to 0.1 if necessary. But these are not the STC and ATC. I guess I might be offering both when my website get off its backside.

I'd be interested to hear from anyone who is interested in either, as I need to do some forward planning of purchases due to significant delays in the import of some of these controllers.

Thanks for the replies on the thread.

TB

[196osh]

The TC-10 controlller can go below zero and has a range set in 0.1c. If the probe is in a liquid the number of times the fridge and heater come on is reduced at least by half.

[boingy]

I have an alternative take. If you are controlling air temperature but monitoring the wort temperature you have an absolutely huge time lag which, as someone mentions above, can result in the air temperature in the fridge reaching very high values, certainly way above the temperatures that the fridge designers were thinking about. Maybe your heater over-temp will trip, maybe the fridge coolant will boil, maybe it will be ok, maybe the fridge will melt (OK, this one is unlikely...). And on the converse side, if the air temperature swings much below zero before the sensor in the middle of the wort hits the desired temperature then you could actually be freezing some bits of the wort or, at least, making some of the yeast pretty unhappy.

I am heating and cooling the air so I monitor the temperature of the air. I set the hysteresis to 2C and I set the target temperature to be 1 degree below the required fermentation temperature (fermentation is slightly exothermic). The sensor is mounted inside about a foot of copper pipe which helps to average out hot/cold spots in the air. In practice this means that the air temperature varies between 17C and 21C but the wort temperature is pretty constant at 20C. The thermal mass of the wort smooths out the air fluctuations and the 2C hysteresis stops the heat/cool circuit from ping-ponging around the place. I suspect a hysteresis of 1.5 C would be perfect for my set-up but my controller does not have that option.

if you want near-perfect temperature control then you need to heat and cool the wort directly, monitor its temperature directly and constantly circulate/agitate the wort to eliminate temperature gradients. It is really not necessary to go to these extremes for fermentation though...

The smaller bottle idea has some merit but is not as good as just controlling the air temperature imho.

Note that here I am talking about the "bang-bang" or "on-off" type of controller like the ATC-800. Any form of proportional controller, and especially a PID, will be much better at dealing with the big time lags.

[beermonsta]

The sensor is mounted inside about a foot of copper pipe which helps to average out hot/cold spots in the air.

The smaller bottle idea has some merit but is not as good as just controlling the air temperature imho.

Surely the bottle idea is not that dissimilar to to putting the sensor in a copper pipe, as the air temperature is being buffered as it will take time for the air to heat the liquid inside the bottle and likewise the air will take time to transfer through the copper pipe and heat the air inside the pipe and thus the sensor?
Both are forms of dampening. The volume of liquid will as I said before effect the dampening effect. You say tomato, I say tomahto

Note that here I am talking about the "bang-bang" or "on-off" type of controller like the ATC-800. Any form of proportional controller, and especially a PID, will be much better at dealing with the big time lags.

I fully agree, in fact I am considering if a PID would be better for the heating side of the FV, and leaving the cooling to bang bang control. I'm wondering if the PID I've ordered from Auber will allow heating on PID control but cooling on bang bang control (maybe through the alarm function?)

[leewink]

"if you want near-perfect temperature control then you need to heat and cool the wort directly, monitor its temperature directly and constantly circulate/agitate the wort to eliminate temperature gradients. It is really not necessary to go to these extremes for fermentation though..."

Agreed, on the other extreme of my past, it would be like me trying to heat my fishtank with external means that "conduct" heat through the glass, wouldnt work for that, not without a form of movement inside at worst.

The other way you could do it, using a wort chiller - run the wort from the ferment through it and back in, causing the circulation and flow in the bucket as it were, then connect a fishtank chiller to the water supplies of the wort cooler and run that in a loop seperate to the wort, probably have to run a reservoir type thing though as you'll never fill and seal the loop totally without it.

I dont have problems at all with the risks of contamination as to me personally with no offense, I choose to sanitise and think thats enough, I dont brew in an operating theatre !! LOL

Also I used to work in and run pubs, a good few, and TBH when you look at beerlines / taps, even chillers etc and there lives especially, I mean how long they are in use over there life whatever that is LOL, I never saw any off beers as result, just dont go round your locals asking when the lines were last renewed, nuff said, I personally dont get that anal about it, again no offense its my view only.

At the end of the day, an half decent chiller for small quantities like we use, is merely a TEC chiller linked to a power supply, like you'd get in a water cooler etc, but more powerful, easily made im sure and reletavely cheap compared to a full all whistles computer aided fridge / heat system.

.... on a side note, heres a link to the manufacturers of the AQ tank chillers http://www.aqua-medic.de/index.php?r=ca ... d=34&id=67 although on the pdf's it doesnt state to what the lowest temp settable is.

[leewink]

... or the TEC route as I suggest, theres a probe called an ice probe in the states, exactly the thing if it was more powerfull, their best one goes down to 7 degrees, but shows the principle, a mere probe drilled through the side wall of say the fermenter, the probe inserted through a bulkhead, and the rest sits outside - http://www.vendtrade.co.uk/ice-probe-aquarium.html

... A little searching gave me http://www.cedarcreeknetworks.com/conical_ice_probe.htm LOL

[beermonsta]

... or the TEC route as I suggest, theres a probe called an ice probe in the states, exactly the thing if it was more powerfull, their best one goes down to 7 degrees, but shows the principle, a mere probe drilled through the side wall of say the fermenter, the probe inserted through a bulkhead, and the rest sits outside - http://www.vendtrade.co.uk/ice-probe-aquarium.html

... A little searching gave me http://www.cedarcreeknetworks.com/conical_ice_probe.htm LOL

The ice probe is just a simple Thermoelectric Cooler Peltier Plate. Which are very innefficient and cost a lot of money to run (several times more than a heater!) as they need quite a large power supply (in terms of amperage and wattage). Several people on the forum have experimented with them.
I did once use my maxi 100 with the recirc pumping the ice bath water around a stainless coil submerged in the FV. I'm sure I remember seeing someone on the forum build a similar thing using copper pipe of different diamater fitted inside one another instead of a stainless coil.

[troublebrewing]

It's occurred to me that some guys might be brewing lager, and that this has different requirements for heating and cooling?

Is this the case? Is lagering more complex than ale-ing?

[196osh]

Lagering is just the act of chilling the beer down to a cold temperature between 4C and -2C. So all you need is a cooling source that will do that for you. These days it only really functions to clear the beer and prevent any chill haze.