lttlscamp Senior Member Joined: 25 Dec 2009 Posts: 40 Location: Toronto Expertise: I like coffee
Espresso: Rocket Giotto Evoluzione Grinder: Baratza Vario
Posted Sat Aug 4, 2012, 4:31pm Subject: Giotto Evoluzione boiler pressure gauge weirdness.
Hey everyone,
Have a little mystery that I'm hoping someone can help me solve
I plumbed in my Evoluzione recently and am experiencing some weid behavior with the boiler pressure gauge. I let it come up to pressure and into the green zone between 1.1 and 1.5 bar. As soon as I flip the brew lever the pump kicks in and the pressure gauge starts climbing rapidly for some reason. It'll actually peg itself if I let it.
This doesn't happen every time I brew. It stopped doing it for a while but started again today.
Not sure if I've done something wrong (how can you get flipping a switch wrong?) but any hints would be appreciated.
Your issue sounds a lot like another machine we had recently, except for the intermittent part. There are one or two gauges on a machine depending on how the manufacturer made it.
The first one is the static boiler pressure, what it really is measuring is the temp of the boiler, this is the gauge that typically reads from 1 to 1.5 bar, this reading of pressure is a reflection of the temp in the boiler, the hotter the boiler, the higher this gauge will read.
There is sometimes a second gauge, this gauge reads the brew pressure and it normally reads line pressure at idle then when brewing it shows the pressure of the water in the brew system. This gauge reads about 8 bar or so when brewing but at idle it will show line pressure, if the machine is plumbed in, it will read what the water pressure in the home is, about 2 bar give or take, in a water tank operated machine, this will be zero.
Your temp gauge is rapidly climbing only when you start the brew cycle, this indicates that there may be a leak between the HX tube and the boiler, it may be a cracked HX tube or some other leak between the HX tube and the boiler. The brew pressure may be pressurizing the boiler thus causing the temp gauge to climb.
The only other thing that can cause the temp gauge to climb is that the heater is not turning off or it is turning on somehow when you start brewing, this would also cause the temp gauge to climb and either case, if the pressure rises high enough, they will trigger the safety valve and the boiler will bleed pressure and a large cloud of steam.
In real life, my name is Wayne P.
Feed the newbs, starve the trolls and above all enjoy what you drink!
I'd recommend switching to the Evo's internal tank to see if everything runs normally in that mode. If it does, then you'll know the problem is related to your plumbing installation.
Not to hijack, but I also have a recent anomoly in my Giotto (two gauges). I noticed it after a period of several months of inactivity (the Giotto is in a seasonal home.) When the machine is rock cold the right guage (line/brew pressure) is normal, at or near zero (I do not have it plumbed in but run it from a water jug.) The left guage (boiler pressure/temp) is at .5 bar, never going below that, even with the machine not plugged into the power mains. When I turn it on to warm up for use, the needle goes to about 2.5 bar. The fact that it does not drop below .5 bar when cold wouild lead me to the conclusion that it is probably a bad gauge, but my experience level with thee machines is very low, so I hesitate to jump to even an obvious conclusion without some experienced validation.
In spite of the gauge anomoly the machine still makes good espresso, no pressure release valve goes off, etc.
the gauges are fairly easily damaged, sometimes just due to age. If it does not zero, when it should then it is off by at least as much as the zero error and it can be more when in use.
Ya, your instinct was right, it sounds like a bad gauge.
In real life, my name is Wayne P.
Feed the newbs, starve the trolls and above all enjoy what you drink!
..... The left guage (boiler pressure/temp) is at .5 bar, never going below that, even with the machine not plugged into the power mains. When I turn it on to warm up for use, the needle goes to about 2.5 bar. The fact that it does not drop below .5 bar when cold wouild lead me to the conclusion that it is probably a bad gauge, but my experience level with thee machines is very low, so I hesitate to jump to even an obvious conclusion without some experienced validation.
In spite of the gauge anomoly the machine still makes good espresso, no pressure release valve goes off, etc.
The gauge issue could also be caused by a stuck vacuum pressure valve. When the machine is off and cold, try opening the steam wand. Does the boiler pressure fall to zero? If so, then the vacuum pressure valve is stuck closed.
The gauge issue could also be caused by a stuck vacuum pressure valve. When the machine is off and cold, try opening the steam wand. Does the boiler pressure fall to zero? If so, then the vacuum pressure valve is stuck closed.
Well, I got the regulator all hooked up but new problem! For some reason the vacuum breaker on the boiler is spitting out water now as it comes up to pressure! And it's not around the threads but right out the top.
Seems that it's not closing like it should be?
Ok, after a bit more reading it sounds like this can be caused if the boiler is overfilling. That can happen because the water pressure is too high (if your machine is plumbed in like mine). That seems strange considering the pressure regulator is set to around 30 PSI (2 Bar) which is well within the recommendation for the intake pressure of the machine when plumbed in.
And this wasn't happening before the regulator was in place and you'd think the pressure was probably higher then.
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