Hi guys. I just restored a 2000 Rancilio S26...well, not quite finished yet, but now it is up and running. There is one thing that bothers me...it makes a loud noise when water is running through the group. The noise comes from somewhere in the heat exchanger, from what i can tell. Now, when i took it apart i saw something that seemed weird: the water from the pump enters the heat exchanger on top and then continues its journey through the injector to the group.

I said weird because all the other espresso machines i saw had the water entering the heat exchanger through the injector.. I believe that, under these circumstances, a pillow of air is trapped between the injector level and the top of the heat exchanger, causing the noise and, probably, a weird pressure profile.

Any thoughts would be very appreciated...especially if someone can tell me if this is the case with all one group s series rancilio. Thanks.

I just finished an s series rebuild about 8 months ago. There should be no air entrapment in the hx tube. Air allows the water to boil causing over temps to the group. The long dip tube should be the water inlet. As the water heats up in the hx it should rise up and discharge to the group outlet ( through the end casting). If the inlet is reversed then the tube will cause air lock in the hx.

Thanks. I removed the air from the hx tube by releasing the nut of the copper tube above the boiler. Most of the noise is gone...now you can only hear it a little from the one way valve - opv assembly. I'll probably disassemble that too to see if something's wrong there. Any advice on that?

Still the question wether the injector is on the wrong side of the circuit remains...the former owner said that the rancilio was not disassembled. But, if someone tampered with it, why would he/she change the place of the injector? Is there a possibility that this is the way rancilio made them long time ago?

Can someone check his own?