My 2000 ECM Giotto Classic is plumbed to the water mains. A month ago something happened...

The boiler kept filling until water came spurting out of the vacuum breaker valve, and pressure dropped to zero. I removed and cleaned the boiler level probe, replaced some worn plastic protectors on electrical connections and I emptied the boiler. After that, the machine seemed to be working again but water autofill started more often than before.

The last couple of days I have been adjusting the boiler pressure on the pressurestat and this morning the same problem happened again. First very wet steam and then spurting water from the top. I emptied water from the hot water wand but when I started the machine again the autofill started again and again and filled up the boiler.

I know that there is something called autofill valve (or similar) in the machine but I don't know what it looks like or where it is located. Should I try and replace that? Could the pstat adjustments have something to do with the problem?

I must also admit that I'm not using a water pressure regulator and I think pressure on the mains is higher than recommended. Has this busted parts on my machine?

If the pump is not running when it overfills then it is likely that either the autofill valve is failing or dirty, the line pressure is too great, or both. Do you have a filter on the supply line just before the machine? There should at least be a particle filter or a carbon filter used. These prevent foreign matter from causing just this sort of problem as well as damaging the pump.

The pump is running while filling. It usually runs for a couple of seconds but now it just went on and on so I had to turn off the machine.

Could a bad electrical connection somewhere be the cause of the problem? It's frustrating not having neither electrical nor mechanical skills.

There's no filter before the machine.

7Urban wrote:I know that there is something called autofill valve (or similar) in the machine but I don't know what it looks like or where it is located. Should I try and replace that?

It's an electromechanical valve - in the pic below is the circled black box connected to a brass fitting. (And I don't think it's causing your malfunction.)


Since the pump is running when you have your overflow autofills, I bet the autofill sensing system is probably failing. Some possible causes I can think of:
- bad connection to ground from the controller
- bad connection between the controller and the autofill probe
- scaled autofill probe (but you cleaned that already)
- no electrolytes in the boiler water (not applicable in your case - you use tap)
- malfunctioning controller

Thank you. I'll try and sandpaper the connections (spades?) and see if that helps. It might be worth giving the probe another treatment too.

Problem fixed, hopefully. It seemed to have been a bad electrical connection that caused the overfill problem. I cleaned some connections and replaced some worn plastic insulators. One of the connections on the autofill valve didn't have an insulator at all. I also cleaned the water level probe again just in case.

Thanks for helping out. I'm one step closer to actually understanding my machine.