Expansion valve leak effects on espresso

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
adi84g

#1: Post by adi84g »

So frustrated with this Sanremo Treviso LX (HX; rotary pump) machine...I've been struggling for months now, only getting vapid drinks, not acrid nore bitter.I first suspected a faulty flush routine; going from flush&go to flush&wait (even 4+ minutes) did not realy help - rarely nailing good shots, only when the stars align the right way.Then I suspected my grinder (SJ), so I reinstalled my Ascaso - this also lead to a dead-end.I also expected bad coffee, so I changed roasters; origins; I've prepared my own blend...no good.The same was with changing Pstat settings...

Today I've noticed that I have significant leaking from the expansion valve located under the boiler on a T fitting (water line - lower termosyphon tube - expansion valve).I'm not plumbbed in, using water out of a PET.I noticed that after actioning the pump with no PF installed, water trickles from the expansion valve.This takes place after stopping the pump.I inserted a blind basked into the PF and started the pump - water was coming out in a stream.I reduced pump output to 8 bar., results being the same.

Naked PF showings are good, nice flow; crema usually good but rather on the lighter colour side.I play with extraction rates between 40 and 50%, usually the drinks are batter with 40% extraction rate - 50 and above are virtually tastless in my flat-white-ish drinks.

Could this leak be the cause of my HUGE frustration - bad espresso? I feel like a total jackass...
The problem will be taken care of PRONTO , but could someone explain the effects of a leaking expansion valve on brewing?

I don't want to get all excited and then hit rock bottom again.
My guessing is that I'm way bellow normal brew pressure and temperature - pressure escaping through the expansion valve, giving also a lower brew temp.

Thanks!
Adi

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erics
Supporter ★

#2: Post by erics »

Could this leak be the cause of my HUGE frustration - bad espresso?
Yes, to the extent that the expansion valve is sensing the pressure in the heat exchanger circuit and is normally set to drip . . . drip . . . drip at a pressure of ~12.0 bar in a rotary pump machine.

While you say that you see the leak even when doing a simple flush, even a slight leak will render the thermosyphon system useless and take brew temperatures very low. So, rebuild the valve, set it as per the above with a blind filter and post about the resulting shots.
Skål,

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

adi84g (original poster)

#3: Post by adi84g (original poster) »

Thanks Eric!

I guess I'll need a vice to disassemble the valve...



A drop can be seen in the pic :)

Adi

adi84g (original poster)

#4: Post by adi84g (original poster) »

I'm back with bad news :(

Well, I've disassembled the valve and found that I had serious scale inside.



After perfoming a descale, I set things back together.Everything seemed fine.
I inserted the blind basket and performed a test...no leaks at ~8.8 bar so I increased my pump pressure to approx.9.5, maybe to a max.of 10 bars to see what happens.Couldn't actualy see this pressure because the lever got stuck, couldn't activate pump. While I was taking out the lever to see what's the problem a blow occured.The silicone tube entering the Tee blew and water under pressure ran out like a geyser.

I know that the former owner of the machine performed an unorthodox operation on the solenoid valve - CEME.According to him, it was producing a high pitch noise while autofill so he cut in half the spring from the coil (?) to reduce the strain on it.This made the sound go away...

I'm wondering why did the tube blow out? Is this related to the mod the solenoid valve suffered?
Could I have modified the opening pressure of the expansion valve to a higher pressure by tightening things back together too tight? Was it working fine in the first place, although full of scale, showing there's a problem somewhere else?

Starting to get worried here...help will be really appreciated.

Thanks!
Adi

adi84g (original poster)

#5: Post by adi84g (original poster) »

I'm adding some pics.with the case:









Any ideas would be great.
I'm suspecting either the two-way solenoid valve (not sure on how it could produce such a failure) or maybe the rotary pump (?).

Thanks!
Adi

User avatar
erics
Supporter ★

#6: Post by erics »

At least this manufacturer has some good support pages: http://www.sanremouk.com/portfolio/treviso-lx/

The flexible tubing used in this machine is 4 mm x 2.5 mm Teflon with quick disconnects. Be sure to use this same tubing when replacing. I would also replace the solenoid valve (boiler fill solenoid valve) as there should have been no reason to modify the spring for same.

The tubing that failed is subjected to the temperature and pressure in the heat exchanger and, if the expansion valve were improperly adjusted, then certainly that can lead to failure. Another possibility is that improper tubing was installed as it also looks as though the water circuit has been disassembled at some point.
Skål,

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

adi84g (original poster)

#7: Post by adi84g (original poster) »

Thanks a lot Eric!!!

What I cannot understand is why was my lever stuck, almost full down? Might the brew valve have been under serious pressure? This is a mistery for me...

Could this be a pump related problem? Maybe relief valve failure?

Adi