My Isomac Tea 2 has served me well since 2007, but recently started having issues with the brew bressure. I was hoping you might be able to give me some advice.

Here are some observations and facts that might throw light on the problem
  • When drawing an espresso I get brew pressure of about 6 bar. With the blind filter the pressure will climb to about 8 bars. The pressure starts low, and will climb after a few seconds.
  • The boiler pressure is quite high at 1.8 bars, as I’ve raised pressure to see whether this might resolve the problem.
  • After turning off the pump, the pressure reader strangely stays at the highest pressure achieved until the pump is turned on again.
  • Water flow is abnormally low at about 275ml/minute. Lots of water is flowing back to the tank via the return hose both then the boiler is filling and when pulling a shot, but not enough to explain the low flow.

The machine has recently been subject to a fair amount of maintenance, including thorough descaling, group head cleaning with changes of springs and sealings, cleaning of valves, and a change of pressostat. I can’t help wondering whether the descaling (and the scale fragments it may have loosened or corrosion it may have caused) can have triggered the problem

I’ve been considering a range of scenarios, including issues with the pump, the solenoid valve, the bypass valve before it, or any other valve in the circuit – but frankly I feel I’m guessing at possible sources of the problem rather than “debugging” the machine in any systematic manner.

Any advice on appropriate steps and actions would be highly appreciated.