I recently did a complete teardown and acid soak on my late 80's HX pavoni pub. More on that later.

As always the machine needed to be burped with the steam wand during warmup / startup to achieve the correct operating temperature. I would like to put a timer on it so it would be ready in the morning when I get up and not have to burp the steam wand.

Does anyone know a solution to not have to burp the boiler?

OPV.

/Uldall

I was under the impression that a vacuum breaker is needed to ensure the boiler contains only steam after warming up.

That's correct; see Can someone please explain false pressure?

Billc wrote:One simple way I used to explain this to customers is:
Everything expands when heated. Gases expand faster than solids. In the case of a steam boiler with air and water; when heated the gas (the air) expands much faster than the solid (the water). The pressure in the boiler increases quickly due to the expanding air. The expanding air causes the pressure switch to activate, turning off the heating element. Once the air is released and is replaced by water vapor then everything returns to normal.

If the vacuum breaker is sticking, the boiler will be a mixture of water vapor and air. Opening the steam wand releases the air, doing what the vacuum breaker should have done on startup.

Pavonipub wrote:I recently did a complete teardown and acid soak on my late 80's HX pavoni pub. More on that later.

As always the machine needed to be burped with the steam wand during warmup / startup to achieve the correct operating temperature. I would like to put a timer on it so it would be ready in the morning when I get up and not have to burp the steam wand.

Does anyone know a solution to not have to burp the boiler?

You have to add a vacuum breaker to the boiler somehow.

It is a simple device, basically just a ball in a valve. When the pressure drops in the boiler as it cools off, the ball falls down and vents it to the atmosphere. As the boiler heats up, steam begins to build and the steam pushes the ball up into a seat and closes it off allowing it to come up to pressure.

The question is whether your Pavoni has a suitable fitting on the boiler to which you can add such a breaker valve.

Otherwise, when you shut it down, you open the steam wand and let the pressure bleed off. Then in the morning, you turn it on, wait until it starts hissing, and close the steam valve.

Understandably inconvenient if you want a timer.

Thank you all for the insight.

I will research vacuum breakers and see if I can add one in to the top of the machine.
The OPV valve is exit only on my machine and i do not believe there is any vacuum breaker.
Previously the machine didn't do this as badly because the steam wand used to leak a little prior to refurbing. Now that the steam wand doesn't leak (on shut down) the vacuum is so powerful it is pulling water into the boiler.

I would be quite surprised if your boiler doesn't have a vacuum breaker valve, it's certainly not recent technology and every older commercial semi-auto machine I've ever seen has one. Photos of your boiler would help.

However, if it doesn't the easiest way to add one is to plumb it in on the pipe leading to the steam wand, which saves trying to drill new holes in the boiler.

Alan

I would be quite surprised if your boiler doesn't have a vacuum breaker valve, it's certainly not recent technology and every older commercial semi-auto machine I've ever seen has one.

I could not agree more.

The vacuum relief valve appears to be mounted on the top of the sightglass as per this: Help Needed - Newly rebuilt LaPavoni "Pub" Startup Problems .

Maybe that was one of the items you neglected to "tear down" ?

Strange plumbing, that. The 3-way "T" (pressurestat, manometer, steam valve) seems like a more obvious place for it. A twisty mind seems to be an Italian Espresso Machine Designer feature, given some of the machines I've seen.

Alan