HX failure question - Isomac Millenium

[gravityboy]

I've had my Millenium on 24/7 for a good 4 years or so with very little problem. Today the machine has a very low water debit and with a blank in the PF the boiler fills to overflow during a backflush. Is there any other possible diagnosis besides a cracked heat exchanger tube (stuck valve perhaps)? I'm the only owner and the system has never left the counter in my kitchen. I descale somewhat regularly and keep a softener on the machine.

thanks,
Keith R.
Warrenton, VA USA

[HB]

A cracked heat exchanger is one diagnosis, though all the cases I've heard were due to storage in freezing temperatures. A stuck boiler refill solenoid is another possibility. From Problems and overhauling on Espresso Restorations' Solenoid valves page:

Water leaking from a normally closed water route - e.g. water leaking from grouphead, or a constant drip from
the relief port on the valve. - This would indicate that the seals of the plunger are worn. It may also mean that the
spring no longer returns the plunger to the desired position. Replace the plunger.

[gravityboy]

A cracked heat exchanger is one diagnosis, though all the cases I've heard were due to storage in freezing temperatures. A stuck boiler refill solenoid is another possibility. From Problems and overhauling on Espresso Restorations' Solenoid valves page:

Ah, ok. I'm really having a hard time believing the HX would crack in normal usage. I'll see about the refill solenoid. I had to rebuild that once on my old Gaggia GX. With the GX though the pressure would also bleed back into the fill line. In the Millenium's case I don't see any return back through the fill line - unless the vibe pump has a blowback stopping capability built in.

thanks,
Keith R.
Warrenton, VA USA

[gravityboy]

You were right. The solenoid was stuck. A good descaling and a slight tap or two on the valve and all is good again.

thanks
Keith R.
Warrenton, VA USA

[HB]

You were right.

Goes to show that even a blind squirrel will occasionally find a nut.