What functionality are you seeking from a micro-controller?

[troublebrewing]

Such as the STC-1000 or the ATC-800?

Are you ONLY interested in controlling the heating and cooling in terms of being just able to set the temperature you want to achieve, or is there a call for more functionality from the units, such as being able to program in a period of time that you would like the heater to come on for, at a certain temperature, for example?

Is a basic, on/off control the sole thing you are looking for? And you decide if the brew has had enough time under the conditions you have set?

Cheers for the input on this.

TB

[Scotty]

I use my ATC-800 to regulate the temperature of my fridge when fermenting beers. I use it from the start of fermentation to the end and it allows me to regulate the ambient temperature within +/- 2c of my desired wort temperature.

[GrowlingDogBeer]

My biggest problem with it is the flip flop effect, if thats what you call it.

I have mine set at +/- 1 centigrade from a ferment temp of 18.5C. If the fridge cuts in to cool, the ATC switches it off when it reaches 18.5, but often the coolant left in the pipes is enough to reduce the temp of the fridge to 17.5, at which point the ATC turns on the heater. The heater comes on, warms the fridge to 18.5 and then the ATC turns it off, the problem is, the heater is now hot, and has enough heat left in it to raise the temp to 19.5, guess what, the fridge now cuts in, and so we continue, burning up the electric.

If there was a way around this that would be great, I don't know quite how it would work but there must be a way.

i.e. If I could have a target temp of 18.5C, but set the system so it would only power the cooler or heater while the temp was outside a x.x C window.

For example, when the temp drops down to 17.5C, then turn on the heater, but turn it off once we reach 18C, and at the other end, if the temp hits 19.5C turn on the chiller, but turn it off once we hit 19C.

That would sort out my problems and give me better control I think. At the moment I just either unplug the heater or chiller to prevent the flip flopping.

[leewink]

I think your "flip flop" effect is called hysterisis or the effects of, or something like that, dont quote me on it

I used to keep marine fish in a small tank, and had the same problem sort of, I controlled mine with an IKS as they are known, very similar to the systems used here. http://www.iks-aqua.com/html/engl/aquastar.php If say you were going to use such system here, then id say the "midi" version of it would be better, although im not 100% sure on the hysterisis settings, im pretty sure it was 0. odds of a degree tho, obviously youd have to check up on the "amperages" etc on the sockets themselves to see if it could handle fridges etc !!

you can see here as example, at the top, a chart of how sensitive the hysteresis switching is on these computers - http://www.iks-aqua.com/download/GB_Tips.pdf 0.15 degree is shown, but it could be made to be less im not sure.

although the IKS aquastar is far more advanced, I used to run dimmable T5 lighting with a full sun up and down simulation, various filters with probes, plug socket bars that were programmable from the IKS ie for pumps / feed pumps etc to be programmed throughout the day, and it was linked to my pc, where i could see everything on screen, I think you can also get a plugin that texts your phone in emergency.

The only way I could manage to keep a degree or under hysterisis, i think i used to be able to get either 0.1 or 0.2 increments, was when the lights were on, they were the heat, and the chiller just compensated that down, when they were off there was enough pumps and filters etc that gave heat too.

So it could be possible to leave a small heat generating light bulb etc / heating element of some kind permanently on, and then just run the cooler to drop it down, although with this way, you'll need a very small heat emmiting light or heat, otherwise you'll end up with what you have now, it would be cheaper i'd though in this case to use the "heat" side as the permanently on bit, that over a fridge cooler etc.

its just an idea, lee

[leewink]

.... in my case, it was better to have one permanently on (a heat source), and maybe here it would be the same, running a dead non fluctuating temperature item (beer) with both heat and cool on a micro controller will lead to what you suggest, i'd set a bulb in the fridge or whatever, and have the controller set at the ideal ferment temp of what your brewing, and the chiller comes on when it goes above this, still set the hysterisis at a degree if thats the lowest you can set, although this will give you a deffinite 1 degree swing if that is all you can set at, really if you ask me what functionality i'd need, it'd be -

1) cooling and chilling and the capability of running them properly (electrical rating)
2) ease of use.
3) a hysterisis less than 1 degree, ie 0.1 or 0.2 increments, 1 degree to me is a lot.

.... although if your running a ferment cooler than the room, then the reverse would be needed, the fridge permanently on, but then a heat element to on and off, then youd have to play with the temp setting on the fridge to just cool beyond the needed temp, otherwise the arguement between heat and cool will be far to strong. (the same pretty much with the heat to, just over the amount of heat you'd need)

.... lastly, if the original thread starter is asking what functionality etc, with a view of making them up, then the primary here would be a hysterisis less than one degree, way less, IMHO one degree swing is to much, if you used a well insulated fridge carcase then a "micro" hysterisis is the way to go, a one or two degree swing in marine fishkeeping is to much, especially when its swinging loads of times per day, the stresses on the inhabitants is to much, comparing - we still have live yeasts here, that need a constant quality temperature.

[troublebrewing]

Phew! Cheers for that.

Yes, Lee, I'm trying to understand a bit better about precisely what the requirements are. Up to now I have only dealt with the ATC, the STC and one other controller that I am considering putting in an enclosure. As for the the STC, at least, it looks to me like a very simple instrument, nothing wrong with that, it's just that compared to the 'other' controller I mention (not the ATC), it looks like it might be limiting. But then if a simple device is all that is needed, then there's no problem. Simple is good!

As far as the hysteresis is concerned, even on my super-dooper all bells and whistles controller (the number of parameters is 50 fold those on the STC/ATC!), the range of the hysteresis is 1-9999, ie, it is not possible to set it lower than 1*C. I'm guessing about this, but I think if this model won't allow it, none of them will, but I might be wrong.

It's coincidental, but only yesterday I was talking with another forum user, and as part of that conversation I remarked that I had the feeling that 1*C was actually a big number relative to what you are trying to achieve. That guy said that brewing lager was even more demanding in terms of being able to control the heating and cooling, or crash cooling as he called it. I'm not sure that's the same thing as having a very closely controlled hysteresis, however.

Anyway, thanks for the feedback.

TB (Tim)

[AnthonyUK]

To those guys experiencing the constant temperature swing -
Where is your temperature sensor situated and are you measuring air or liquid.
Is 1' significant to worry about?

[beermonsta]

Steve and anyone else with this problem, you need to place your thermocouple/thermometer for the controller inside a vessel that has liquid inside it. This will dampen (not the wetting sort!) of the swinging of the heating and cooling.
In other words when cooling, it will take longer for the liquid than the surrounding air to reach the target temperature. When it does the cooler is then switched off. At this point the air is probably still going to be cooling or colder than required, but it will take a long time before the liquid "catches-up". In reality the fridge will be slowly warming up to the outside air temperature so it will take even longer for the liquid to cool.
If the liquid does actually cool to below the set point then the heater will kick in and the process is reversed.
So in reality the air inside the fridge will go above and below the set point but the liquid will stay a lot closer to the set point.
Now think about the FV, as this has an even greater volume of liquid it will dampen the temperature of the wort/beer inside to a greater affect, so the temperature will be even more stable. (don't forget to think about the heat that the yeast will generate and compensate for this by reducing the set point of the controller to 2-3'C cooler during the main ferment - ideally measure the temp inside the FV to calculate this offset more accurately).

Try to experiment with the liquid volume (500ml, 1l, 2l etc) as this will vary the hysteresis and the dampening effect.

[Rparkera]

Beermonsta - is the same damping effect possible by taping the sensor to the outside of the FV with a thick cover of polystyrene insulant? That would link the sensor temp to the FV liquid temp?

[leewink]

And yes, 1 degree is a large amount if your trying to achieve a taste of beer based on temperature of ferment, remember this 1 degree is swinging what could be hundreds of times per day, I only say this because alot of brewers deem it paramount to have a solid "quality" if you like temperature, and with this, to them comes great beer.

Myself, I brew with room temp whitelabs vials, 029, 001, 008 etc, and they literally ferment in room temp whatever that is at this time of year.

But, If i was brewing a lager etc that needed a very low ferment temp, and I had it setup for such, then 1 degree is to much, its just my opinion, I personally would email various breweries to see if i was being fussy aswell, to be sure.

Its all good fun though, lee

[leewink]

and yes, i agree that it would be worse to heat/cool the surrounding area rather than the liquid itself, with the liquid taking alot of time to absorb the surrounding effects.

the only true way to do it is to cool and heat the actual beer and just use the fridge carcase as insulation or cushioning, with say a tank chiller heater like this http://www.aquacadabra.co.uk/Aqua-Medic-Titan-250.html Im not sure if that is just a chiller though, Teco do a mixed version cos thats what I had, it is a very simple solution though.

although saying that, pumping fermenting beer has its own probs with all the "gunk" envolved.

even with the said setups, these can only work when the beer is moving and fermenting, otherwise the heat or cool is only effecting the outside of the vessel, and really, this system can only work if the probe is dangled into the centre of the actual beer whilst it ferments.

[AnthonyUK]

My thoughts on this would be that measuring the liquid temp. would increase the hysterysis effect due to lag.
If there is a difference in temp between the air in your fridge and wort then measuring the air should result in a stepping pattern of measured temp over time as you heat or cool the air. It takes an amount of time for the liquid to follow due to poor conduction rather than the constant see-sawing which is a result of over cooling\heating.

[leewink]

agreed ant, yes it would possibly increase lag times, really though, this is the overall prob with heating/cooling the outside of the fermenter as it were all round, we need an "actual" beer cooler that chills the beer directly, to me then you'll win

ant would you agree on this though ? if you only brewed beer cooler than the room itself, you'd do better with a quality chiller that would circulate the beer itself and be of a hysteresis lower than 1 degree, i mean an overpowered chiller as such, then you wouldnt need the fridge or insulation surely ? just use an overpowered chiller ? like the ones ive linked ?

[AnthonyUK]

I must first say I can not back up any of my assumptions with any evidence as yet

Leewink - I think circulating the beer would reduce the lag time as you wouldn't be waiting for the temperature change to conduct its way through the liquid.

[beermonsta]

Beermonsta - is the same damping effect possible by taping the sensor to the outside of the FV with a thick cover of polystyrene insulant? That would link the sensor temp to the FV liquid temp?

Yes the sensor temp will closely measure the same temp as the (fv liquid) wort/beer temperature, although I believe it will be even warmer in the centre due to heat being lost to the outside (presuming that outside is cooler). By placing an insulation material over the probe you are in effect isolating it from the outside air temperature and only measuring the heat (or coolness) that has conducted from the FV liquid through the FV wall to the probe.
To answer you question though the same damping effect will take place but the downside is that you will have the air temperature sit at the heater maximum output when heating or the fridge/freezer at it's lowest when cooling. So if you for instance have a 60watt heater then it will be pumping out 60watts of heat continuously until the FV liquid reaches the set point. This, in a well insulated container such as a fridge, could cause the air temperature to go very high.
Same goes for when it's cooling. Until the controller detects the FV liquid temperature go cool enough to its set point the fridge or freezer will be running continuously and so you will get the air to a very low temperature (-18 or lower depending upon the refrigerant).
By placing the probe in a small vessel of liquid the heater and cooler will not be on for as long and should limit the extremes of air temperatures but without causing rapid switching between heating and cooling.

I have a greenhouse heater which is 300Watts which would normally be overkill and could cause the air temperature to become far too hot, but it has a built in thermostat. So if I switch this to 25'C then the air temperature will not go much above this, but will be sufficient to raise the temperature of the liquid to the desired FV temperature.
It is also for this reason that I have chosen to use a fridge with a smaller cooling coil (evaporator) and small condenser as opposed to a freezer with more powerful pump and larger evaporator coil as I don't need to freeze anything just lower the ambient air temperature. The lowest I need to go is for lagering at around 0'C or so.

For home brewing it's just not practical to cool the wort directly. well OK, I could run the wort through my maxi product chiller but as already mentioned this means pumping the wort around and from a sanitary point of view I'm not happy about doing this. Same goes for heating, I don't want to dangle any form of heater such as a fish tank heater into my wort (been there, done that) as it increases the infection risk and also means more cleaning to do!

Hence why a modified fridge with heating source inside, controlled by a ATC-800+ with the probe inside a smaller vessel of liquid is the way most home brewers go. If I was a professional with large scale FV's then I would choose to use dimple jackets that are heated by steam and cooled by chilled water to control the FV temperature.