The USA distributor of AKO controllers can help with any questions http://schindlertechnologies.com/
On Thursday, May 5, 2005 at 10:46:25 AM UTC-5, Doug Shannon wrote: > > AKO's New Temperature Controller > > First, I have to thank Sean for the hours he has spent on the phone > with me discussing and guiding me through this process. If it wasn't > for him, none of this would have been possible. > > Description: > > AKO's newest controller (model 14725) is capable of displaying 3 digits > in degrees F up to 999F. Temperatures below 100F can be displayed in > tenths of a degree resolution. This enables the user to set the all > important offset parameter in tenths of a degree. The new controller > accepts a J or K type thermocouple allowing for faster response times > as compared to the stock controller RTD type sensor. > > The size of the controller (due to having 3 digits) is slightly larger > than the stock controller which will require a somewhat bigger panel > cut out. Although tedious, the current cut out can be made the correct > size with the use of a dremel tool. The width of the current cut out > needs to be 1/2 in. wider and the height needs to be increased by 1/8 > in. There are no depth issues. > > You can see a picture of the 14725 on the brewtus group under user > folders/Doug. > > Programming and Connections: > > I connected a common household extension cord to the power terminal of > the controller. This allowed me to take my time programming the > controller without fear of it affecting the operation of the brewtus. > Once the controller was programmed which was a simple process by the > way, I connected it to the brewtus using the same wires used to connect > the stock controller. There are a total of 4 wires (power, sensor, > relay, and common). As recommended by Sean, I used a 30 ga. K type > sensor installed in the brew boiler's thermo well along side the stock > sensor in order to hold it in place. As compared to the RTD stock > sensor, the K type has greater accuracy and much faster response. > Finally, I temporarily installed another sensor in the thermo well so > that, using my Fluke 54, I could test the accuracy and response of the > new controller. > > Initial Testing Results: > > After all connections were made and verified I plugged the brewtus' > power cable into the wall, took a deep breath, and flipped the power > switch with my barely controllable trembling hand. At this point, I had > Sean on the phone who was intently listening for explosions and looking > south outside his office window for mushroom clouds. Thankfully, there > were none. The controller powered up and called for heat. Once the > steam boiler reached 1.2 bar the temperature display began it's rise. > Once it reached my set point of 203F, the heat light went out. But, oh > no, the temperature display kept rising! The fluke display kept rising > matching the readings from the controller. What could be wrong? The > stock controller never rises above the set point! There must be > something wrong with the controller, I thought. I certainly didn't > program it incorrectly and if I did it would have been Sean's fault, > not mine (hehe). After verifying the programming was correct and > apologizing to Sean we decided to re-connect the stock controller and > compare it's readings to that of the fluke. Our eyes were opened! The > stock controller display would dip to 94 causing a call for heat. At > this time, the fluke read 94C and then started to climb back to 95C as > it should but alas, it kept rising all the way to 99C. That's an 8F > temperature swing within the boiler but the stock controller's > display never rose above 95C! Based on this information, we suspect > that AKO specially programmed the stock controller for Expobar so that > it would never show readings above the set point which gives the > impression that the controller is doing a much better job at > controlling boiler temperature than it really is. The new controller > doesn't do this. It truly shows the actual temperature, whatever it > may be. > > After watching many heating/cooling cycles on the stock controller and > determining there is on average an 8F swing in boiler temperature, I > re-connected the new controller and continued testing. Upon watching > numerous heating/cooling cycles, I determined that, on average it was > able to control boiler temperature to within a 4.5F range - ½ that > of the stock controller. I believe this is due to the difference in > resolution between degrees F and degrees C as well as better > electronics, faster probes, and the ability to set offset in tenths of > a degree. > > How did all of this affect brew temperature variance and average? > Here's a comparison between the two controllers. First, let me > outline the testing parameters: > > Warm Up Time: 2 hours > Tested only 1st shot of the day (this is because I only brew one shot > in the morning then one at night) > Coffee used: vivace vita > Shot volume: 1.5 oz. > Shot time: 25-30 sec. > Tamp pressure: 40lbs. > Flush routine: 1.5 oz. flush, 1 minute to dose/tamp, 1.5 oz. flush, > immediately pull shot. > Target Brew Temp: 203F > > Stock Controller: > > Brew Temperature Variance: 1.2F (readings taken from the 10 sec. on as > per Schomer) > Average Brew Temp off target: +- .8F > > New Controller: > > Brew Temperature Variance: .7F (readings taken from the 10 sec. on as > per Schomer) > Average Brew Temp off target: +- .2F > > picture of a brew temp graph for the new controller is available on the > brewtus group under user folders/Doug > > It should be noted that the time in which you start the shot within the > heating/cooling cycle will greatly affect average brew temperature. If > you start the shot just as the controller heats up to the set point you > will get the results seen above. However, if you start the shot during > the cooling phase or just before the controller calls for heat, your > average brew temperatures will be off as much as minus 2F. > Unfortunately, this is the Achilles heel of these controllers. It would > take installing a PID controller to eliminate this problem. The AKO > controllers are really just glorified thermostats. Their operation is > analogous to a car approaching a stop sign at 60 MPH. It waits until it > reaches the stop sign before applying the brakes causing sever > overshoot whereas a PID controller is analogous to that same car gently > applying the brakes as it approaches and actually stops at the stop > sign. Sigh. > > In conclusion, I feel the new controller although falling way short of > a PID controller, offers the following improvements over the stock > controller: > > 1. Displays 3 digit degrees F > 2. Faster more accurate readings and response time > 3. Ability to program offset in tenths of a degree > 4. Offers improved temperature stability > > Questions and comments are welcome. If enough people are interested we > can put together a group buy. I will glady put together an installation > manual for the group if there is enough interest. > > -- You received this message because you are subscribed to the Google Groups "Brewtus" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/brewtus. For more options, visit https://groups.google.com/d/optout.
