Author: P.B
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The Andreja has a reputation as being one of the noisier prosumer HX espresso machines with a vibe pump, certainly when compared to an Izzo Vivi. The principal reason usually stated is that the Andreja has a ventilated case, whereas the Vivi does not, allowing the noise a path out. However, this particular Andreja was very noisy.
Using experienced gained in the automotive development industry the noise was subjectively judged to be more structure borne than air borne. Additionally, there were two different noises: when the pump is filling the boiler; and when the pump is feeding the HX brew path. The two noises were of similar volume but slightly different in tone, but both appeared to be structure borne.
The Andreja without its casing or its water tank, and viewed from the rear.
The installation of the vibe pump is difficult to see from a photograph, even after removing the Gicar auto-fill controller.
The schematic below shows how the pump is located and moves.
The pump is suspended between two rubber "L" shaped brackets. In operation the pump vibrates in the direction of the blue arrow. When moved by hand, the pump moves easily in the direction of the green arrow. When moved in the direction of the red arrow the bottom left corner of the pump touches the rubber mount, restricting its movement. Whether the pump touches the mount in operation is unknown, although from a visual inspection during the operation of the pump it does not. However, the mounts are stiffer in one direction than the other.
Further investigation revealed a touch condition between the end of the pump and the panel on which the water tank is located, the "L" shaped panel to the right in the picture below. The touch condition is highlighted at the end of the screw driver in the second and third pictures below:
To eliminate the touch condition wooden dowelling was cut to the correct height and glued next to the part of the pump where the touch condition had existed. This stops the weight of the water tank pushing the metal panel against the end of the vibe pump.
Result.
When the pump is now activated for the HX brew path the amplitude of the noise is massively reduced and the tone "quality" subjectively improved. The noise of the pump filling the boiler is similar to before the modification.