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Thread: PID Thermocouple Location Quaha/Lelit/Mokita/Nemox

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    PID Thermocouple Location Quaha/Lelit/Mokita/Nemox

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    I am hoping for some clues to where other users have mounted (and how) their thermocouple on a Quaha boiler.
    It is a bit different to a Silvia boiler.
    The Quaha uses thermostats with integrated screws that mount into a threaded hole in the boiler providing really good thermal coupling.
    My first attempt was to remove the brew thermostat and place the thermocouple in the hole left by this.
    However this hole is directly in-line and close to the water inlet.
    While there is water flowing into the boiler (during a shot), the thermocouple always measures a low temperature, and keeps the heating element on continuously, as would be expected.

    Mounting near the water outlet from the boiler is the obvious choice for better control but there are no screw holes or other mounting points that seem useful. I am not ready to start drilling holes into the boiler and was just wondering if other people had done this differently.

    Apologies in advance if this has been asked previously - although I can find images/description of Pidded Quahas etc, I can't find details.

    thanks
    Taan

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    Subbed possibly same project in time

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    Mal Dimal's Avatar
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    Mounting in the original t/stat position is actually ideal, as it provides pseudo 'feed-forward' to integrate with the PID Controller's own PID algorithms. Gives you a control system that is very responsive to a wide range of operating conditions. It is what I did with mine years ago, and I loved it...

    Mal.

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    Quote Originally Posted by JWILL View Post
    Subbed possibly same project in time
    ??? I'm not quite following.

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    Quote Originally Posted by Dimal View Post
    Mounting in the original t/stat position is actually ideal, as it provides pseudo 'feed-forward' to integrate with the PID Controller's own PID algorithms. Gives you a control system that is very responsive to a wide range of operating conditions. It is what I did with mine years ago, and I loved it...
    Mal.
    Thanks Mal. I'll try again - maybe it's an issue with my coupling. I'll try mounting the sensor with better thermal contact in the hole. My first attempt had it sitting in the hole rather loosely, just to try things out.

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    Quote Originally Posted by saeco_user View Post
    ??? I'm not quite following.

    I have a combi as well and a diy pid is on the cards once running
    By commenting I get full notifications from the thread it is a done thing of forums across the net

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    Mal Dimal's Avatar
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    Quote Originally Posted by saeco_user View Post
    Thanks Mal. I'll try again - maybe it's an issue with my coupling. I'll try mounting the sensor with better thermal contact in the hole. My first attempt had it sitting in the hole rather loosely, just to try things out.
    Does the PID Controller you have, incorporate an "Auto-Tune" option?
    If so, I'd use that in the first instance as this will get you pretty close to where your PID parameters need to be.
    After that, you can tweak these settings a little to fine tune the responsiveness and control you seek, to best suit what you prefer....

    Mal.

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    Quote Originally Posted by Dimal View Post
    Does the PID Controller you have, incorporate an "Auto-Tune" option?
    If so, I'd use that in the first instance as this will get you pretty close to where your PID parameters need to be.
    After that, you can tweak these settings a little to fine tune the responsiveness and control you seek, to best suit what you prefer....

    Mal.
    Yes, has auto-tune, which I've run and holds the boiler temp nice and constant between shots. It was only my impatience/lack of research that led to my question. I had assumed that due to mass of the boiler and small volume of water flowing in during the shot that the boiler temp would only fluctuate by a few degrees during a shot. But, as many other users have already explained, there can be a 10-20 degree fluctuation, on the boiler surface, during a shot. Shot temp is much more stable than this but I haven't measured it accurately (don't want to drill a hole in my filter basket).

    In summary, the PID was very easy to implement (probably hardest part will be mounting it neatly and safely). It takes any guess work out of temp surfing while reducing the time it takes to get the temp right before a shot.

    Taan

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    Mal Dimal's Avatar
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    Quote Originally Posted by saeco_user View Post
    Shot temp is much more stable than this but I haven't measured it accurately (don't want to drill a hole in my filter basket).
    Hi again Taan...

    No need for that mate...
    If you have a spare Bead type t/couple handy, or can get one, you just need to feed this over the edge of the filter basket such that the bead sits about midway between the centre of the puck and the rim of the basket, then lock the Group Handle in tightly such that there are no leaks around the t/couple cable.

    Just prepare a shot as you would normally do, follow the above routine and give it a go. No need to keep reloading with fresh coffee since the main aim is to provide a simulation of normal brew water flow characteristics in order to gain a realistic impression of the performance of the PID Controller's settings... Just need to make sure that you only pull a normal Single or Double Shot Volume each time.

    You can even hook the t/couple up to a CS DMM and use the CS Roast Monitor software to record and chart each shot...

    Have fun,
    Mal.



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