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Thread: PID set too cold?

  1. #1
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    PID set too cold?

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hiya,

    so i just purchased a pid with steam control and preinfusion and have successfully set it up. *Only problem is that I fear the PID is set too cold - I preheat machine for 1 hour and get 60ml double shots in 25seconds (which suggests flow rate is fine) but I am getting blonding and a sour tasting shot. *I noticed that this particular commercial PID for Silvia kit sets the temperature at 105 degrees. *Is this too cold and does this explain why my shots are not so good? *ALso, should I be flushing through some water (say 60ml), allowing boiler to reheat and then pulling shot?

  2. #2
    Senior Member greenman's Avatar
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    Re: PID set too cold?

    Hi Hugh, when I installed a PID on my ex Silvia it was recommended to set it on 109C, Jim had it set at that temp and I got good shots from the start, I took it up and down a couple of degress but 109C seemed to be the best temp.

  3. #3
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    Re: PID set too cold?

    thanks greenman Ill give 109 a go and see what happens. Somewhat cryptically the instructions say "It should be noted that the setting temperature we recommended is lower than
    some people suggested on the internet forums." But they dont explain why...

  4. #4
    Mal Dimal's Avatar
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    Re: PID set too cold?

    Quote Originally Posted by 5B46545B44565151330 link=1234436330/2#2 date=1234437549
    thanks greenman Ill give 109 a go and see what happens. *Somewhat cryptically the instructions say "It should be noted that the setting temperature we recommended is lower than
    some people suggested on the internet forums." *But they dont explain why...
    Is this one of Jims Kits Hugh?

    Might be related to where Jim, or someone else, has positioned the feedback probe on the Boiler. Nothing wrong with experimenting though mate; if 109C doesnt do it for you, move it up or down a couple degrees until the brew starts to taste the way it should. At least then, you will know youre in the ballpark and can fine tune from there.... :)

    Mal.
    P.S.
    For what its worth, resist the urge to play around with the P, I and D parameters unless you know what you are doing. You may just end up with a system in total disarray for all your trouble. Nothing wrong playing around with the Setpoint(s) though.

  5. #5
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    Re: PID set too cold?

    No, its the PID kit from the other major PID kit retailer. :) I havent been tempted to muck around with the P, I or D variables.

    Ill update shortly on how I go with 109 degree setting....

  6. #6
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    Re: PID set too cold?

    Gday hughwebb,

    I installed a home jobby PID on my Silvia (see http://coffeesnobs.com.au/YaBB.pl?num=1227428190/50 for some pics)
    I found 109C far too hot. For my setup 100C was about right.
    109C is a good place to start though.

    One thing that alerted my to the high temp was the water leaving the spout was bubbling. This meant it was above 100C.

    Also flushing will defeat the point of the PID. The PID should keep the boiler to the right temp. If it is out the set point should be moved, not flushing the machine.
    I do some times give mine a very short flush but only when I want the temp to go down a little quicker (after steaming).

    Hope this helps. ;D

  7. #7
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    Re: PID set too cold?

    Hmm, I have done more testing over past couple of days and found that 109 seems to be about right for my Auber set up. Finally getting nice tasting shots - quite a relief after dropping all the $.

    Obviously 109 is measuring the boiler temp - not the temp at the group head (i.e. the brew temperature - Tb). Differences between your set up bassway may also relate to positioning/type of thermocouple you are using (as mentioned by Jim in the post that you linked to above).

    In terms of flushing, my thinking was based on the temperature study that was included on the cd with the pid I bought where I noticed that they said:

    "Test 15 in Figure 3 indicated that even after machine was powered up for 45 minutes, the first pull was still two degrees below the stabilized Tb. This indicates that a few blank pulls to flush the cold water in grouphead are important."

    At the moment I am flushing, waiting for pid temperature to restabilise and then pulling shot. Just wondering if others bothered with this or not?

  8. #8
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    Re: PID set too cold?

    Hmm, I have done more testing over past couple of days and found that 109 seems to be about right for my Auber set up. Finally getting nice tasting shots - quite a relief after dropping all the $.

    Bassway, my guess is that differences between your set up may relate to positioning/type of thermocouple you are using (as mentioned by Jim in the post that you linked to above).

    In terms of flushing, my thinking was based on the temperature study that was included on the cd with the pid I bought where I noticed that they said:

    "Test 15 in Figure 3 indicated that even after machine was powered up for 45 minutes, the first pull was still two degrees below the stabilized Tb. This indicates that a few blank pulls to flush the cold water in grouphead are important."

    At the moment I am flushing, waiting for pid temperature to restabilise and then pulling shot. Just wondering if others bothered with this or not?

  9. #9
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    Re: PID set too cold?

    Yes I usually do a small flush just before I pull the shot, to clear out the water that has been sitting in the group head while its been warming up and stabilising.
    In that case you are quite right to do a small flush.

    Stress it is not a cooling flush as is commonly used on HX machines, they need it for different reasons, and some of them need significant amount of flushing if the machine has been idle for some time.

    The only exception with Silvia would be if you need to pull more shots after steaming, then you might do some flushing to cool the system back to brew temp, and then allow time to stabilise.

    Bullitt

  10. #10
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    Re: PID set too cold?

    Opps! My mistake in terminology.

    Flushing to me was running water through the group head on a TX machine to flush out the super heated water.
    A blank shot was to heat/cool/clean out by pumping water through the group head and the group handle.

    In the end I guess thay are the same.

    I do do blank shots.

    When measuring the water temp out of the group head I found that after a few blank shots the temp went from 94 to 97. this was after the Silvia had been on for 30 mins.

    On Gregs site (PIDkits) he show that the theory of a 30 min warm up is just crap. I also found the same. Although any warm up is better than none.
    My measurements showed that my Silvia requires 60 mins to warm up.

    This is unless I pull blank shots.

    If I forget to switch on my Silvia as soon as I get up in the morning I run a few blank shots to warm everything up.
    I can also see on the PID when the Silvia isnt really warmed up. On the first blank shot (about 60-80ml of water) the boiler dips to 88. Second to 90. When completely warmed up the boiler dips to about 92-94.

    Another trick I do is turn on the steam switch, wait to the PID shows 80C and switch off. The overshoot from 80 on my Silvia stops at 100C.



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