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Boiler pressure spikes while pulling shot with HX [Pasquini Livia 90]
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bwashburn
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Joined: 29 Aug 2013
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Location: Peoria
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Posted Mon Jan 20, 2014, 12:34pm
Subject: Boiler pressure spikes while pulling shot with HX [Pasquini Livia 90]
 

Recently acquired a used Livia 90 for a price too good to pass up. Only problem is that when I pull a shot the boiler overpressurizes and blows the safety relief valve. A little more detail:

-Dialed back to a very course grind and of course the shot pulled much too fast.

-Ground a little finer, pulled around 2oz in 25 sec but thin and watery and no crema.

-Ground even finer - seemed to be coming out at a decent rate, although still hardly any crema, then the boiler pressure gauge went way past red and the safety valve blew water everywhere and I stopped it short, around 1oz which was a little thicker but still watery and no crema.

-The problem also happens when I try back flushing. Builds pressure for a few seconds, then the boiler pressure gauge spikes and the safety valve blows.


Perhaps it's because I'm a noob, but I don't understand why/how the boiler pressure would be spiking on a HX machine while pulling a shot. I would really appreciate any help. Thanks in advance.
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SStones
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SStones
Joined: 24 Nov 2012
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Posted Mon Jan 20, 2014, 7:43pm
Subject: Re: Boiler pressure spikes while pulling shot with HX [Pasquini Livia 90]
 

The water inside the exchanger is/should be contained and not have any affect at all on the boiler pressure (Save for cooling it very slightly, potentially a slight drop in boiler pressure). So, if your boiler pressure is going up when brewing either the exchanger is leaking out to the boiler which is not likely, or, your boiler fill solenoid valve leaks. The pump pressure/brew pressure is forcing its way through the boiler fill valve (Which should be closed when the boiler is at the right level). A descaling of the boiler-fill valve, followed by a complete flushing and rinsing of the boiler might fix it. If not, removing/examining/cleaning the solenoid valve is in order, with the final answer being to replace the boiler fill solenoid. Do check that the solenoid isn't live (Energised and opening with voltage from some other reason when brewing). If it's live when brewing, after the boiler is properly filled, then the electrical problem isn't a leakage ofer a valve.   Make sense?
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bwashburn
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Posted Mon Jan 20, 2014, 8:32pm
Subject: Re: Boiler pressure spikes while pulling shot with HX [Pasquini Livia 90]
 

Thanks for your reply. What you said does make sense. I have a detail I didn't mention previously, not sure if it helps narrow anything down:

When I first got the machine, I checked that the backflush worked, and it did, without causing the boiler to overpressure. Then, before I tried brewing anything, I did a full descale using the technique of removing the fill level probe so that the boiler would fill completely with solution (I used Urnex Dezcal). Now, after descaling, the boiler overpressures when I try backflushing.

Should I check that the solenoid isn't live as my first step, before I disassemble anything? I have access to a multimeter but I'm not sure where to put the two contacts to test the solenoid. Is it possible that during the descale something got lodged in the solenoid valve?
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SStones
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SStones
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Posted Mon Jan 20, 2014, 9:53pm
Subject: Re: Boiler pressure spikes while pulling shot with HX [Pasquini Livia 90]
 

bwashburn Said:

When I first got the machine, I checked that the backflush worked, and it did, without causing the boiler to overpressure. Then, before I tried brewing anything, I did a full descale using the technique of removing the fill level probe so that the boiler would fill completely with solution (I used Urnex Dezcal). Now, after descaling, the boiler overpressures when I try backflushing.

Posted January 20, 2014 link

Ahh.
Try backflushing, again, just to be sure that it now overpressurized the boiler now...
If it overpressurize the boiler now, like brewing does, then you can be pretty sure that something is preventing your boiler-fill solenoid-valve from closing properly. Whenever the pump is on, the water has an easy escape through the solenoid to a 1.5 Bar boiler safety-relief rather than having to build to 10 Bar to escape the OPV relief.  Perhaps just a bit of crud stuck in it.  Almost certainly NOT an electrical problem.
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bwashburn
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Expertise: I love coffee

Posted Thu Jan 30, 2014, 2:39pm
Subject: Re: Boiler pressure spikes while pulling shot with HX [Pasquini Livia 90]
 

Wanted to post an update to my problem. Wasn't sure if I should start a new thread so I'll do it here:

I disassembled the auto fill solenoid and it looked a tad grimy, but nothing terrible. I cleaned it and reassembled and was able to pull 6-8 shots without the boiler fill problem…and then it started happening again; overfilling the boiler any time the pump is pushing water to the group head against back pressure.

I'm wondering if I just need to replace the solenoid. The one in my machine is a Sirai marked:

Type   Z610A
V110   Hz 50/60
V120   Hz 60
VA      10 Hold 16 Inrush
ED:     100%

I found a similar solenoid (Parker brand) on OE for sale for only $25 (normally they're between $70-90). I would pull the trigger, but even $25 is too much to waste if the new one won't work. Here is a link to the one on OE:

Parker 2 Way Solenoid

The fitting size matches, as does the voltage, but the Parker is rated at 9 watts and I don't know the wattage on the current Sirai. Is this an important consideration or should I just buy the Parker since it's fairly cheap?

bwashburn: eighthsolenoid.jpg
(Click for larger image)
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SStones
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SStones
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Drip: Some $30 thing from Walmart
Roaster: I buy pre-roasted.
Posted Thu Jan 30, 2014, 6:53pm
Subject: Re: Boiler pressure spikes while pulling shot with HX [Pasquini Livia 90]
 

So long as it's not an electrical issue (ie. the boiler fill circuit is not trying to fill the boiler while you're pulling the shot, because then the solenoid valve would be open despite working perfectly) then "Yes", that solenoid is a perfect replacement for your potentially leaking one.

You could confirm that it's not an electrical problem by disconnecting the wires to the solenoid and seeing if you can still overpressurize the boiler.
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calblacksmith
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calblacksmith
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Location: Riverside, Ca, U.S.A.
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Roaster: gave it a try, decided no
Posted Fri Jan 31, 2014, 7:05am
Subject: Re: Boiler pressure spikes while pulling shot with HX [Pasquini Livia 90]
 

The wattage of the unit is how much power IT uses, not what it can handle, wattage does not have anything to do with power handling or pressure values, simply the power used by the unit. In other words, how many MPG the unit gets, not how big of a load it can tow. So if the fittings fit, it will work.

That is not to say that it is the problem. You are getting pressure from some place in the brew system getting into the boiler, two different places in the machine and they should never cross into each other. You need to find where the connection is between the two water circuits, it MAY be a leaking valve or a cracked HX, or something else.

 
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Anything I post is personal opinion and is only worth as much as anyone else's personal opinion. YMMV!

Feed the newbs, starve the trolls and above all enjoy what you drink!
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bwashburn
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Joined: 29 Aug 2013
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Location: Peoria
Expertise: I love coffee

Posted Fri Jan 31, 2014, 10:05am
Subject: Re: Boiler pressure spikes while pulling shot with HX [Pasquini Livia 90]
 

Thanks for the suggestions. I'm obviously not super confident with electrical concepts, so I really appreciate the help.

Am I correct that the auto fill valve should be receiving no current unless the boiler is filling? (normally closed solenoid).

I could check it with a multimeter if that would be better, or just disconnect it from power at SStones suggests.

What other things should I be ruling out besides cracked HX and autofill solenoid? How else could water be getting into the boiler along the route from pump -> HX -> group head?
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bwashburn
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Joined: 29 Aug 2013
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Location: Peoria
Expertise: I love coffee

Posted Fri Jan 31, 2014, 1:48pm
Subject: Re: Boiler pressure spikes while pulling shot with HX [Pasquini Livia 90]
 

So I just fired the machine up, disconnected the autofill solenoid from power, and ran the pump against the blind basket -- same problem as before, the boiler immediately overpressurized. I'm assuming this means I can rule out an electrical problem?
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SStones
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SStones
Joined: 24 Nov 2012
Posts: 452
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 Fri Jan 31, 2014, 10:34pm
Subject: Re: Boiler pressure spikes while pulling shot with HX [Pasquini Livia 90]
 

Am I correct that the auto fill valve should be receiving no current unless the boiler is filling? (normally closed solenoid).

Yes, that is correct.

bwashburn Said:

So I just fired the machine up, disconnected the autofill solenoid from power, and ran the pump against the blind basket -- same problem as before, the boiler immediately overpressurized. I'm assuming this means I can rule out an electrical problem?

Posted January 31, 2014 link

That is correct.

If you're still leery about replacing the solenoid valve without testing it further, you could remove the solenoid valve completely again, as you did to clean it and try blowing through it (Though you can't possibly blow at 10 bar pressure). If it leaks at low pressure it's certainly bad.  If it doesn't leak at low pressure you haven't proven anything, but you can clean it again. and plan to replace it, sorry.
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