Grainfather clone

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Permalink Reply by Damian McCaul on September 19, 2015 at 11:44am

hey mate really keen to find out how your set up is going. I have same urn but 48L (38). was going to mod that up

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Permalink Reply by andrei cotiga on September 29, 2015 at 12:07pm

Hi, I've been a bit lazy and didn't exactly follow up with the progress on the clone father.

I've done some really good beers (Bitburger clone, classic english bitter, nice pale ale) and also a horrible one (vienna lager). The reason for the nasty one is that the PT100 probe, although it has the actual thermowell mage of stainless, the threaded nipple is not. And it rusted. And stank my beer. A malty metallic taste comes through now which is not pleasant.

I've delayed answering your question as I had planned this past weekend to try and make another one with slight modifications and wanted to see how it performs.

In essence I've taken the probe out of the kettle, I've sealed the hole with a M8 SS bolt and o-rings and moves the probe to the bottom of kettle, in the pocket which harbored the original temp probe (before the kettle was modified). In short: Neah!

The PT100 probe was always a bit off with a non-linear response. Lower temperatures were lower than expected, mid 50-60 temperatures were OK, high temperatures were reported higher than measured.The water was still liquid at -1 and apparently I leave in a bubble which bends the laws of physics and I can boil water at 107C, without increasing the pressure. 

During this weekend's brew, with the PT100 fitted at the bottom, between battling the err readings of the actual RDT, I had to account for the position at the bottom as well. In other words, my grain bed was 63C while the RDT showed on my PID 84. Not good. That's the reason my mashing took about 2.5 hours to finish. At least it was a Pilsner and the expected dryness will be a plus :). All that being said, I managed to hit 78% efficiency relatively easily.

I now modified the way I sparge to an equivalent batch sparge. By that I mean I put the bucket on top of the kettle, fill it with hot water and then give it a mix. Let it drain, repeat. After I got the required amount of water, I increase the T of the wort and start recirculating the whole thing through the bucket which still sits on top of the kettle. All this at about 74C. Was a bit of a gamble but it really worked.

Obviously temperatures read elsewere than in the kettle are not to my satisfaction so I ordered a new PT-100 which is 1/2" and the threaded nipple is SS as well. Also got a SS nut with a groove for an o-ring. 

http://www.ebay.com.au/itm/261931923473?_trksid=p2060353.m2749.l264...

http://www.ebay.com.au/itm/121335042008?_trksid=p2060353.m2749.l264...

The other problem with the whole system is that the wort boils explosively!!! No kidding. It's not a rolling boil, it's an explosive one. The way I wired it, is that when I select the DTDP switch to BOIL it sends 100% power to the electric element. This cannot be sustained.

I'll have to investigate how to put the PID to 80% power or if can't do that I'll need to fit (this is a guess as I haven't yet investigated it properly) a dimmer switch so I can dial in the power of the electric element.

The final issue that will need to be fixed or at least keep an eye on, is that last weekend only, and I assume it was because of the temperature probe under the kettle, the temp of the whole thing got to a point where the actual safety switch at the centre of the element was kicking in and cutting the power. Will have to keep an eye on.

So to recap this long and tortured post:

I will need to change the PT100 probe to something more decent and I need to investigate how I can turn down the power of the electric element in Full BOIL mode only as the boil is too vigorous.

One last thing, if you're from Chch (or passing by) and would want to have a look at my mad contraption, feel free to drop me a line.

I'll try and come back later today with some updated pictures of how it looks now.

Attachments:

• $_12.JPG, 14 KB
• pt2.jpg, 258 KB
• pt.JPG, 22 KB

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Permalink Reply by andrei cotiga on September 30, 2015 at 1:57pm

Explosive boil problem solved by using a cheap Ebay Arduino Nano and two pots that I had lying around. One pot sets the ON duration between 0 and 60 sec, while the second pot sets the Rest interval between 0 and 60 sec. A bit of fiddling will be required the first run but shouldn't be too bad. After the first couple of tries I will probably narrow the range on the two pots, but it should do for now. 

The Arduino HIGH signal will go to the solid state relay used by the PID. I will modify the DTDS switch to control the signal wire that leaves from PID and Arduino.

Makes more sense in my head.

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Permalink Reply by Druid on October 5, 2015 at 8:16am

Re. Controlling your boil with a PID:

I have 2 PIDs, one Auber and one Sestos - the Sestos is used to control the boil kettle and has a non-auto mode that allows you to choose a time period and then specify the percentage of that time that the element is switched on.

I use this quite successfully as a way to control the boil intensity. I usually boil at 75% on over a period of 4 seconds. The period is short enough that the boil does not get too much momentum and so never gets too vigorous. It gives you really good boil control when you need to boil off faster or slower too.

The Auber is only used for the HLT so I never have to use this mode in it but my impression is that the Sestos is functionally equivalent to the Auber and will probably have the same function and work the same way.

Just trying to save you some expense and work if your equipment already does what you need.

PS. You definitely need a solid state relay for this but I suspect you are already using one?

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Permalink Reply by andrei cotiga on October 5, 2015 at 9:21am

I know that the Sestos should be able to do this but I wasn't successful in doing this. I also decided against investigating deeper as it was quite enoying for me to fiddle with the PID during the boil. I set it once to act as a direct thermostat during boil but forgot to move it back to automatic for the next batch. 

In short I thought it was better to separate the two functions completely given that the cost of the Arduino was so low (around 10$ for the whole thing, including pots).

An alternative to this system is to separate the heating element. As it can be seen from the pictures the heater is made of two concentric rings, one of 900W and the other of 1900W. It wouldn't be too difficult to separate them and use both for mashing ans raising temperature, but only the 900W for the boil.

As they say, there any many ways to skin a cat.

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Permalink Reply by andrei cotiga on October 4, 2015 at 4:03pm

The Arduino electronics which will control the rate of boil (to reduce the volcanic boil I now have) has been added. Two linear potentiometres control the time ON and the time to rest between the on intervals of the heating element. The schematic has been slightly modified to allow for the same SSR to control bith the PID Mash and the Arduino Boil.

Also attached is my Instruction document for using the clone father. It's a living document and I modify it depending on the modifications I make to the machine.

I took this chance and finally put together the schematic in Fritzing. The Arduino code is below:

int potRest = 0;    // select the input pin for the potentiometer setting the Rest
int potON = 2;   // select the input pin for the potentiometer setting the ON period
int valRest = 0;       // variable to store the value coming from the pot Rest
int valON = 0;       // variable to store the value coming from the pot ON
int WAIT=60;    //by default the maximum Rest period is 60 sec. Pot will vary from 0 to 60 sec
int ON=60;     //maximum ON period is 60 sec. The pot will vary the ON duration from 0 to 60 sec


void setup() {
  Serial.begin(9600);
  pinMode(4,OUTPUT);    //D4 is set as Output for SSR
  digitalWrite(4, LOW);  //Make sure D4 is LOW
}

void loop() {
  valRest = analogRead(potRest);    // read the value from the sensor
  valON = analogRead(potON);    // read the value from the sensor
 
  int varWAIT=valRest/(1023/WAIT);    //waiting time in seconds is...
 
  int varON=valON/(1023/ON);    //ON time in seconds is...
 
  Serial.print(" Wait ");
  Serial.println(varWAIT);
  Serial.print(" ON ");
  Serial.print(varON);
  Serial.println(" ");
 
  digitalWrite(4,HIGH);    //Start kettle
 
  delay(varON*1000);      //Wait for the set value
 
  digitalWrite(4,LOW);    //Stop kettle
 
  delay(varWAIT*1000);    //Wait for set value

}

Attachments:

• Power scheme_schem.jpg, 734 KB
• Instructions.docx, 37 KB

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Permalink Reply by andrei cotiga on October 4, 2015 at 4:28pm

Also a bunch of photos of how it looks now. The bolt I identified in the picture will have to go and the new PT100 will replace it.

Part 1

Attachments:

• IMG_3706.JPG, 543 KB
• IMG_3707.JPG, 623 KB
• IMG_3708.JPG, 676 KB

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Permalink Reply by andrei cotiga on October 4, 2015 at 4:34pm

Part 2

This is basically the end of my modification. I will maybe come back again after three or four more beers to let you know the efficiency and if the new PT100 is more competent.

Overall my impressions of this system are good and with a bit of handy work a very nice system can be put together wich will rival the commercial one. Of course it will have its little quirks but because you are the one who built it, identifying them would be easy and in my opinion worth the 800$ saving.

I intend to write an Instructable as well but in the meantime, this will probably the only reference. Please don't hesitate to ask any questions.

Attachments:

• IMG_3709.JPG, 695 KB
• IMG_3710.JPG, 769 KB
• IMG_3711.JPG, 682 KB

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