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Thread: Does this model require a PID - YES

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    Default Does this model require a PID - YES

    Classic 2015 RI9403/18 - Manufactured in Italy week 36/2018

    1050W element, 200ml Stainless steel boiler, brew thermostat = 95C, steam thermostat = 127C, no solenoid valve, plastic steam control valve, auto shutoff.

    Temp readings taken from a sensor fitted on boiler case with heat paste between both thermostats, using an RS Pro meter.

    Switch on, brew temp stabilised at 99.4C.

    Switch on steam, temp stabilised at 127.7C.

    Switch on steam control, purge and use steam wand, thermostat kicked in again at 105.2C and quickly maintained a temp of 108C whilst continuing to use wand.

    Switched off steam control, purged group, brew thermostat kicked in again at 78.4C .

    20 second extraction using 18g in a VST basket, starting temp = 96C, finished temp = 81C. Coffee tasted OK, at a hot drinkable temp.

    The brew temp variation is too great from min to max, definitely needs a PID control for the SS boiler even though it's 200ml.
    Classic 2015 Ri9403/18 + Sage Grinder Pro + VST-18 and a prayer

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    Every single boiler will be improved by adding PID.
    ☕Gaggia☕Enthusiast☕

    Buying expensive equipment won't make you barista!

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    I have just tried another experiment.
    With the temp probe still fitted to the stainless steel boiler, let it heat up along with the portafilter.
    I then purged the group until the temp hit 78C so that the element started to reheat.
    Refitted the full portafilter and waited till the temp hit 96C.
    Pressed the brew button and counted down 25 seconds for an 18g dose to deliver into 2 cups.
    The element stayed constantly heating at full power but could not hold a temp higher than 85C until I pressed the brew button again, so no cold water entered the boiler.


    My conclusion is:
    The 2015 RI9403/18 classic needs a more powerful element than the 1050W it has.
    So in theory, if at full power the 1050W could not keep the water at a temp anywhere near 92C, what use is fitting a PID if the element can't work any harder.
    Classic 2015 Ri9403/18 + Sage Grinder Pro + VST-18 and a prayer

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    Quote Originally Posted by mr-bean View Post
    I have just tried another experiment.
    With the temp probe still fitted to the stainless steel boiler, let it heat up along with the portafilter.
    I then purged the group until the temp hit 78C so that the element started to reheat.
    Refitted the full portafilter and waited till the temp hit 96C.
    Pressed the brew button and counted down 25 seconds for an 18g dose to deliver into 2 cups.
    The element stayed constantly heating at full power but could not hold a temp higher than 85C until I pressed the brew button again, so no cold water entered the boiler.


    My conclusion is:
    The 2015 RI9403/18 classic needs a more powerful element than the 1050W it has.
    So in theory, if at full power the 1050W could not keep the water at a temp anywhere near 92C, what use is fitting a PID if the element can't work any harder.
    Fit a preheat coil so the water entering the boiler is already at a higher temp.

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    Problem with a preheat coil is that the new SS boiler does not have enough room around its outside to use the boiler to radiate heat into a coil.

    I think the reason for Gaggia going back to the smaller aluminium boiler and solenoid valve in the latest model is because users have been complaining.

    One complaint has to be the bigger boiler with a smaller wattage element. I know the water displacement while brewing is the same for both boilers, but 1050w can't heat it fast enough.
    Last edited by mr-bean; 4 Days Ago at 04:03.
    Classic 2015 Ri9403/18 + Sage Grinder Pro + VST-18 and a prayer

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    Quote Originally Posted by mr-bean View Post
    I have just tried another experiment.

    The element stayed constantly heating at full power but could not hold a temp higher than 85C until I pressed the brew button again, so no cold water entered the boiler.
    My conclusion is:
    The 2015 RI9403/18 classic needs a more powerful element than the 1050W it has.
    So in theory, if at full power the 1050W could not keep the water at a temp anywhere near 92C, what use is fitting a PID if the element can't work any harder.
    Brew water is drawn from a pipe near the top of the boiler, so there is a temperature gradient across the water, while the pump is running, with colder water low down in the boiler and hotter water being drawn off up top. You are only drawing 30-50g of water, so your brew water is probably holding somewhat higher temp that the "average" that you are measuring. The correct place to measure brew water temp is at the shower screen or top of the puck. This is what the Scace device and many other home engineer designs do.

    A PID does not affect maximum power, as you point out. What it does is use 3 equations (Proportional, Integral, Derivative) to bring the boiler to set temperature as fast as possible (but not faster than full power) and then hold that set temperature much more closely than a thermostat can. PID's pulse the power on and off very fast and adjust the power level, using the equation values, to hold usually within a degree or two of set point. All the equation levels and the set point are adjustable.

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