La Marzocco Linea with random steam boiler over-pressure problem

Need help with equipment usage or want to share your latest discovery?
duke-one
Posts: 463
Joined: Sat Apr 14, 2007 2:44 am

Postby duke-one » Tue Oct 09, 2012 7:40 pm

Hi All: My one year old Linea is going over pressure in the steam boiler but only once and a while. I have it set at 1.5bar and most days all goes well. It has over pressurized 2-3 times since new (I use it every day). I think they should have put a more serious pressurestat in such an expensive machine but it is what it is. The tube that feeds it is U shaped; is that to keep condensate from building up? Could "water-lock" cause intermittent problems? Have other Linea owners replaced the pressure control with a more robust unit?
Thanks, Duke Masters

User avatar
erics
Posts: 4867
Joined: Tue Aug 09, 2005 6:32 am

Postby erics » Wed Oct 10, 2012 12:04 pm

That pressurestat (likely a MA-TER) controls a secondary relay if I remember correctly.

The U shaped tube intentionally keeps condensate in contact with the pstat diaphragm.
Skål,

Eric S.
http://users.rcn.com/erics/
E-mail: erics at erols dot com

USBC champion, voted 2009 'best micro-roaster'
User avatar
stefano65
Sponsor
Posts: 945
Joined: Sat May 19, 2007 1:27 pm

Postby stefano65 » Wed Oct 10, 2012 1:59 pm

yes some years back they went from full size psat
to small (CEME for a while now MATER)
and a big contactor (in Italian called teleruttore)) that takes the load off of the pstat
Stefano Cremonesi
Stefano's Espresso Care
Repair & sales from Oregon.

duke-one
Posts: 463
Joined: Sat Apr 14, 2007 2:44 am

Postby duke-one » Wed Oct 10, 2012 4:08 pm

My single group has the smallish p-stat feed the heater directly. I turned it down a bit and exercised the adjustment a bit. I hate these problems that happen 2-3 times a year then go away. I should get a replacement p-stat to have it on hand.
Duke

User avatar
stefano65
Sponsor
Posts: 945
Joined: Sat May 19, 2007 1:27 pm

Postby stefano65 » Wed Oct 10, 2012 8:05 pm

I didn't notice you where talking about a 1gr
the contactor will be on 2 groups and up
Stefano Cremonesi
Stefano's Espresso Care
Repair & sales from Oregon.

User avatar
erics
Posts: 4867
Joined: Tue Aug 09, 2005 6:32 am

Postby erics » Thu Oct 11, 2012 2:07 am

Thanks for correcting me on the pstat operation, KDM. When I was initially responding I wanted to say CEME but somehow that came out as MA-TER. The new MA-TER I have in front of me (XP110) is stamped with a 15A rating at 125/250 VAC so it should be able to handle that steam boiler electrical load fairly easily.

But . . . a pstat failing so infrequently as yours seems a little strange to me so I would simply replace it and keep the original as an emergency spare.
Skål,

Eric S.
http://users.rcn.com/erics/
E-mail: erics at erols dot com

duke-one
Posts: 463
Joined: Sat Apr 14, 2007 2:44 am

Postby duke-one » Thu Oct 11, 2012 3:44 am

Eric: Yes, that it goes wild once in two or three months and then back to normal is a bit odd. I will get a replacement and either install it on arrival or wait till the next incident. Probably will tear up the original looking for the fault, to no avail.
Duke

expert repairs with an italian touch
User avatar
Paul_Pratt
Posts: 613
Joined: Wed Aug 10, 2005 3:59 am

Postby Paul_Pratt » Thu Oct 11, 2012 10:44 am

I've seen this before, like Eric says p-stats don't usually fail like this. Either all or nothing.

You may want to check that your pressure gauge is accurate. It could be off by a few 0.1 bars. Having it at 1.5 it may be closer to 1.8 open value than is indicated on the gauge which is why it opens the valve.

I have also seen faulty safety valves that open below 1.8.

Just a thought.

duke-one
Posts: 463
Joined: Sat Apr 14, 2007 2:44 am

Postby duke-one » Thu Oct 11, 2012 5:37 pm

Paul: I think the gauge is OK, it showed the overpressure when the p-stat was sticking and the safety was blowing off, showed the 1.5 I had it at and now shows the about 1.3 I reset it at. Thanks for the idea.
Duke