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Londinium App Pressure Readings

What sort of readings should I be seeing on the app when the machine is idle or when pulling a shot?
The numbers drift quite a bit.
Please help me interpret what is normal.


  • hi michelle

    the pressure reading is the pressure reading at the transducer, net of the offset value

    this value fluctuates for two reasons

    (1) when cold water is driven into the manifold, past the non return valve in the bottom of the manifold, it is then heated by the system and this causes thermal expansion of the relatively cold water by a tiny amount, yet because liquids are non compressible it causes the pressure in that section of the system to keep increasing until the expansion valve opens at 12-13 bar, which is what you will observe

    (2) once the expansion valve has opened on the first heating cycle of the newly introduced cold water the pressure in that part of the system will cycle in response to the cycle of the heating element in the boiler

    the system has been designed so you dont have to worry about the measured pressure at the transducer, but rather just set the pressure you want and the system gives you a repeatable result in the cup

    where the measured pressure at the transducer is extremely useful is for fault diagnosis, so for this reason we have chosen to keep it visible to the operator

    kind regards

  • Thank you for the explanation, Reiss.
    Less to worry about!
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