# PID Works!



## CoffeeMac (Oct 29, 2010)

Glad to report that the PID control system just set up on my Delonghi Bar 14 works like a dream. The boiler temperature follows the set point exactly so no more second guessing the boiler temperature to get the best moment to pull a shot.

At present the system controls boiler temperature only through the PID set point which is very easy to change. However, the steam thermostat has been left connected so that it will possible with minor modification to use the steam switch later on.

The controller was really easy to set up. Basically there was nothing to do except set the set point and switch on. Heating starts immediately and continuous power is input until near the set point when the power is pulsed on and off until set point is reached. It seemed to work very well with the pre-set PID parameters but I used the autotune function just to try for the best possible control. I think this helped to reduce the temperature overshoot at setpoint.

The majority of the work is in finding suitable mounting arrangements for the SSR and the controller. The SSR fitted nicely inside the case at the bottom while my solution for the controller was to mount it in a plastic box bolted to the side of the case.

Some thoughts on the performance of the system are as follows:

Temperature is controlled to be very close to the displayed setpoint but the actual temperature achieved at the boiler is dependent on the accuracy of the controller/thermocouple combination. Accuracy for my kit was 0.5% of full scale which means a possible differential of 6C for a full range of 1200C. The range can be set lower which I think improves accuracy in proportion. It's important be aware of the system accuracy limitations and not to assume that what you see on the display is accurate at the boiler. I found that boiler temperatures were about 3C higher than displayed so altered the setpoint to achieve the temperature wanted. Money buys more accurate controllers and some with 0.1% accuracy are available at a cost. For the time being, the one I bought, costing about 22 pounds incl postage, is good enough and much better than the old system.

I'll be watching it's performance over time and if it stays as good as now I'll be well pleased.


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## Glenn (Jun 14, 2008)

Thanks for the writeup and decent sized picture too

Do you have any of the inside of the machine where the SSR is mounted?


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## CoffeeMac (Oct 29, 2010)

Thanks Glenn

The SSR is bolted with brackets to the steel baseplate and fits nicely below the pump with just enough room. It is mounted vertically to fit the available space. No photograph, sorry.


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## Greenpotterer (Nov 29, 2009)

Hi coffee mac where did you get it from in the end just wondering if i could fit one to my baby gaggia then if i ever ok when i upgrade transfer it

gaz


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## DonRJ (Apr 3, 2010)

Good stuff there CoffeeMac, let us know where you sourced you parts please, I was off to do the same thing a while back but my parts were much more expensive particularly due to silly postage costs so I didn`t go for it at the time.

I assume your parts list was as follows and how did you fix the thermocouple to the boiler.

PID, SSR, thermocouple, mounting case, cable, spade connectors.


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## liquidmonkey2000 (Oct 4, 2010)

Well done CoffeeMac. I bet you are the first person to PID a Delonghi Bar 14. Let us know whether there is a tangible benefit in the coffee it makes.


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## RoloD (Oct 13, 2010)

Just added a PID from Auber Instruments to my Gaggia classic. Very straightforward to fit and use, works great, thoroughly recommended.


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## ian3193 (Nov 21, 2008)

Nice work, looks the business! good pic as well!


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## PaulN (Mar 10, 2011)

Does the PID on the classic have to be that side or can it be the other?


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## RoloD (Oct 13, 2010)

PaulN said:


> Does the PID on the classic have to be that side or can it be the other?


I can't see any reason why it can't go on the other side.

The relay, which is bolted to the back of the case can go in the middle and, from what I remember, the wires are long enough to reach either side. At the very worst you might have to extend/replace a couple of the wires.


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