have a ECM Giotto and regularly have an issue where during brewing the boiler pressure gauge starts dropping and the boiler is being overfilled as the pump runs.
when this happens the shot is black coffee with no crema and then the boiler is too full and I get all kinds of issues like spitting water from steam wand and other stuff.
now that I know the behavior I can stop brewing if I see the pressure dropping and if I stop and start the lever a few times then pull some water from the hot water wand and give it a minute to reheat....it clears up and works normally. unfortunately if any one else uses the machine its a train wreck.
seems like a sticking valve or something but any suggestions would be great.
SStones Senior Member Joined: 24 Nov 2012 Posts: 477 Location: Canada Expertise: Professional
Espresso: Giga 5, ECM Giotto, Rocket... Grinder: Anfim Milano-Best Vac Pot: No :( Drip: Some $30 thing from Walmart Roaster: I buy pre-roasted.
Posted Sun Apr 20, 2014, 4:56am Subject: Re: Giotto Boiler overfill during brew
The most likely cause would be that the boiler-fill solenoid-valve is stuck open with a bit of calcium or other crud. Running descaler through the valve could clear it out and get it working again. This would be the easiest fix, if it works. Let machine heat as normal. Shut machine off and let a couple cups of water out through the water wand. Replace reservoir water with your descaling solution. The machine will pump this through the boiler-fill valve when you turn it back on and it tries to refill the boiler. Obviously, once this is in your boiler, you will have to empty and refill your boiler a couple times to flush it all out. You could do so just by heating it, shutting it off (So it won't be trying to refill while emptying), and letting the water out through the water-wand.
Though. Since you might have to dismantle the boiler-fill solenoid's circuit to clean/replace it, you could also drain it through that hole in the belly of the boiler. If the quick and easy descaling doesn't work, take the solenoid valve apart toi determine if a cleaning could work or if it will need replacing.
I used to do this once every few years. If it wasn't stuck open, it was clogged closed. :) Now I have a much larger solenoid valve in my older Giotto (ECM), it's been there for less than a year. I'm curious to know in the next half decade if the larger solenoid will have fewer issues.
Although I do not regret descaling and it needed doing anyway...... the root cause was corroded spade connector blades on the fill solenoid valve. (high resistance) causing intermittent bad connection.
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