Blow off valve?

[zoomin]

6 year old Vivaldi S2 just started behaving badly.

I'm not sure what to call it but on top of the boiler there is a valve type thing that is covered in a white plastic covering (you can see the plastic covering here http://www.home-barista.com/forums/user ... nsides.jpg with the small pie shaped grey bit on it in the top right) - the valve in question is underneith that.

When the boiler kicks in this valve releases a lot of water and steam under pressure.

Any ideas?

[chas]

More info is needed before we can definitively pinpoint the cause.

What is the steam boiler pressure on the pressure gauge when the pressure relief valve opens up?

The normal pressure is ~1.2-1.3bar. If you only see this range of pressure and the valve is popping open it is probably faulty. However, if the valve is working correctly, I would suspect that the pressure gauge would be pegged or close to it.

If you turn the machine on and see the pressure start to go way past 1.3bar, shut 'er down. No need to make another mess of the kitchen. We don't need to know what the pressure is when it opens, just whether it is opening at normal pressure or whether the boiler pressure really is going way high.

[zoomin]

If think it's like you say - when the machine is off, the left gauge is sitting at about 2 (I think before it would sit straight up at zero).

Then when I turn it on the left gauge goes well into the red - almost to 1.3 then I shut it down before the valve released.

[chas]

The left side of the gauge is the group pressure. With a cold machine it will read the line pressure coming into the machine. 2bar means you have 30psi at the machine. The green part of this half of the gauge runs between 8 & 10bar.

The right side of the machine is the steam boiler pressure. 1.3 bar is right on the line that divides green and red. 1.3 is a fine reading on that gauge.

If your problem is the left gauge then your issue is the group boiler and not the steam boiler. If you saw that gauge well up into the red at "1.3" that's not possible. Well up into the red on the left side of the gauge would more likely be 13 bar. Since the expansion valve is supposed to open at 12 bar - at the very least it is not calibrated correctly. There could very well be another problem, but the expansion valve is definitely not set right.

You can find instructions on adjusting it here: s1v2/VII_Expansion.php

[zoomin]

Yes, it was 13 bar on the left scale that I was reading, then lack of caffeine had me mix that up with the "1,3" on the right side between there and the computer :/

Thanks for the link - I will check out that expansion valve function.

[zoomin]

Resolved.

A few things going on here. Resetting the expansion valve as suggested above worked but then it was then blasting water out from I would guess the steam pressure blow off valve. What had happened was the probe/sensor to the left of it had slid up so high I guess it wasn't reading properly any more. I actually had that problem once before - the symptom being too high pressure on the steam side of things and only water coming out of the steam wand, not steam.

Maybe the first problem caused the second?

I dunno, but in any case it's all good now and the family is back to their regular caffeine levels without incident.

Thanks for the help chas!

[chas]

It sounds like you actually had two problems.
1) Expansion valve set wrong: can cause pressure to get too high in coffee boiler.
2) Water level sensor pushed up: causes water level to get too high in the steam boiler. This will definitely cause water rather than steam to come out of the steam arm. Since the steam line coming out of the boiler MUST be above the water level in the boiler to work correctly. This might also cause water to gush out of the vacuum breaker valve even when the boiler isn't yet up to temperature.