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Has anyone needed to adjust the pump pressure on their Silvia, and if so, why? Just wondering under what circumstances it needs to be adjusted or how you would know if it was necessary.
Originally posted by SamR link=1205469057/0#0 date=1205469056
Has anyone needed to adjust the pump pressure on their Silvia, and if so, why? Just wondering under what circumstances it needs to be adjusted or how you would know if it was necessary.
General consensus is that 10 bar (measured with a portafilter gauge) is about right for a Silvia. This is under "no flow" conditions, i.e., when 100% of the pump discharge is flowing back into the reservoir through the overpressure valve (OPV).
When water is flowing through both the group and the OPV, the pressure will drop by around 1 bar below the no flow condition. This will give you the desired 9 bar in the coffee puck.
If you measure the pressure at 11 bar or higher at the grouphead, then you might want to adjust the OPV downward. On newer Silvias, this is a relatively simple adjustment. Older OPVs are not adjustable, so some trickery (along with a collection of copper washers of varying thickness) is required.
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