Sundance Senior Member Joined: 26 Jan 2008 Posts: 36 Location: North Dakota Expertise: I love coffee
Espresso: Gaggia Coffee Grinder: La San Marco SM90 Drip: In Closet
Posted Fri Mar 14, 2008, 6:44am Subject: Gaggia Coffee Leak Part II
My Coffee has a leak............
When I first turn on the machine in the AM it drips from the shower screen. This despite the fact that I installed a new valve a couple weeks ago. The leak will stop on its own after a minute or two.
Could the new valve be faulty?? Or is this just the "norm" for Gaggia.
"You've got to kick at the darkness, til' it bleeds daylight" Bruce Cockburn - Stealing Fire
Posted Fri Mar 14, 2008, 8:38am Subject: Re: Gaggia Coffee Leak Part II
Gaggia's without a 3-way will 'leak' from the showerhead from thermal expansion. How much is 'normal'? Your description sounds normal. Here's my take on the subject:
SJM Senior Member Joined: 17 Nov 2004 Posts: 1,508 Location: CA Expertise: I love coffee
Posted Fri Mar 14, 2008, 8:43am Subject: Re: Gaggia Coffee Leak Part II
Frost Said:
Gaggia's without a 3-way will 'leak' from the showerhead from thermal expansion. How much is 'normal'? Your description sounds normal. Here's my take on the subject:
Posted Fri Mar 14, 2008, 11:12am Subject: Re: Gaggia Coffee Leak Part II
Hi Susan, Basically, the Boiler valve becomes the 'expansion relief valve' under situations that create pressures above about 1.5 bar in the boiler. One of those situations is warming a cold boiler that is completely full of water. ....full explanation in the link.
Posted Fri Mar 14, 2008, 12:17pm Subject: Re: Gaggia Coffee Leak Part II
I have the same prob with mine
Sundance Said:
My Coffee has a leak............
When I first turn on the machine in the AM it drips from the shower screen. This despite the fact that I installed a new valve a couple weeks ago. The leak will stop on its own after a minute or two.
Could the new valve be faulty?? Or is this just the "norm" for Gaggia.
SJM Senior Member Joined: 17 Nov 2004 Posts: 1,508 Location: CA Expertise: I love coffee
Posted Fri Mar 14, 2008, 12:20pm Subject: Re: Gaggia Coffee Leak Part II
Frost Said:
Hi Susan, Basically, the Boiler valve becomes the 'expansion relief valve' under situations that create pressures above about 1.5 bar in the boiler. One of those situations is warming a cold boiler that is completely full of water. ....full explanation in the link.
When would you ever have a cold boiler completely full of water? and What is the real pressure relief valve for?
I still think it's not working correctly. Unfortunately my knowledge base isn't as extensive as it should be to refute your contention, but.... I still do not think any water should be coming through the brew head valve except when the brew switch has been thrown.
I'll have to go looking for some other back up, though...
Posted Fri Mar 14, 2008, 12:44pm Subject: Re: Gaggia Coffee Leak Part II
SJM Said:
Two questions:
When would you ever have a cold boiler completely full of water? and What is the real pressure relief valve for?
I still think it's not working correctly. Unfortunately my knowledge base isn't as extensive as it should be to refute your contention, but.... I still do not think any water should be coming through the brew head valve except when the brew switch has been thrown.
I'll have to go looking for some other back up, though...
The boiler is completely filled with water when you turn it on first thing in the morning, or you generally do that after steaming: before shut off. Or first thing in the morning when turning it on. Only time it is not filled with water is when there is a pocket of steam in the top. (or it is drained)
The Boiler valve in the gaggia is a 'passive' design: the water pressure from the pump (or any other condition that creates above about 1.5 bar in the boiler) forces it open. The overpressure valve only opens at much higher pressures as when the coffee puck clogs. (or to whatever brew pressure it's set at: ie: 9.5 bar or so)
There should not be much 'leakage' due to the 'normal' thermal expansion you would see: much less than an ounce for sure. Maybe a tablespoon on a cold machine warming up.
EDIT: On second thought 1 tablespoon is likely too much, closer to a teaspoon. You may also see some if you turn on the steam heat and don't open the steam valve to create that steam pocket in the top of the boiler.
Ok, my full physics explanation is in the link to the other thread. It's easy to see it happen with a pressure gauge on the boiler.
SJM Senior Member Joined: 17 Nov 2004 Posts: 1,508 Location: CA Expertise: I love coffee
Posted Fri Mar 14, 2008, 1:04pm Subject: Re: Gaggia Coffee Leak Part II
Ah, I didn't think you were trying to pull my leg. I just thought you were wrong...
Now I understand your explanation of why it happens, and I'll concede this much: it's not a big problem. If a brand new machine arrived at my door letting water through that valve, I'd return it.
I still contend that it is not how it's 'sposed to be. The valve is supposed to keep water from coming through except when the correct brewing pressure has been reached. If it lets water through when the machine is heating up, the valve isn't functioning properly (or there is scale in the passage).
So....it may be normal, and it may happen with little negative effect in an older machine, but it's not "right".
Posted Fri Mar 14, 2008, 2:14pm Subject: Re: Gaggia Coffee Leak Part II
My Venus has a 3-way and a boiler pressure gauge. On warm up the thermal expansion of the water will cause the pressure to exceed 12 bar and open the OPV without ever turning on the pump. On gaggias with a boiler valve, this pressure is released at the boiler valve. I don't know what the designed pressure release for this valve is, but I'm being generous to say that it should at least hold a pressure of 1.5 bar. My Gaggia is stored dry right now, but try taking yours to steam temps/pressure with the boiler full and the steam valve closed. I would expect the boiler valve to release something, ... or the steam wand to drip the excess pressure. EDIT:.... or the 'self priming valve' to release the pressure if so equiped.
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