# Recognise this? On La Marzocco boiler



## FullBloomCoffee (Mar 19, 2015)

Hi all,

quick issue I'm having today, just started hearing a hissing sound from my machine (La Marzocco FB80) had a quick look and there is a small amount of water on this top connector which is evaporating and causing thenhissjng sound.

cant get hold of my engineer at the moment, but wondered if anyone knows what this connector or valve is for, as it doesn't appear to be connected to anything...

safety pressure valve seems to be fine.


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## customcoffee (Jan 9, 2013)

looks like anti vacuum valve, helps release air from boiler when heating, little pin in the middle will pop up and seal when boiler becomes pressurised

quite likely a little bit of scale/debris is stopping it from sealing properly, easy enough to dismantle and clean, and also cheap enough to replace. eBay - (anti vacuum valve 1/4") should see you right

no real initial danger at the moment, more of an annoyance but look to get it sorted as it will only get worst over time


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## customcoffee (Jan 9, 2013)

actually sorry may of jumped the gun here, which part exactly is the steam/water coming from??


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## espressotechno (Apr 11, 2011)

If the hissing is coming from the brass thingy in the middle of your pic, then that's the anti-vac valve. (you can poke it, carefully, just when the hissing starts, with a thin screwdriver to check)

The steam leak is probably due the the rubber o-ring inside becoming hard & not closing fully.

Easier to fit a new valve, as overhauling the old one is rarely successful.


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## FullBloomCoffee (Mar 19, 2015)

Thanks guys, to confirm it is the top piece you can see in the centre of the pic (it has a couple of drops of water on)

it is continually dripping which is causing some annoyance as it is hissing when it comes into contact with the hot metal and dropping onto the counter.

any idea on where to get this part? As this doesn't seem to appear on any la Marzocco pets diagram for spares, and I'm having trouble getting hold of any engineers! :/

appreciate your help!


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## customcoffee (Jan 9, 2013)

Ebay mate, it's a fairly generic part. Search for anti vacuum valve 1/4"


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## espressotechno (Apr 11, 2011)

As CC said above - easy to buy off EBay.

Your leaky a/v valve looks like a replacement, as the teflon tape indicates. Use this tape (B&Q etc) when fitting the new valve.

*PS* Looks like a scorched spade connector in the bottom LH corner of the photo. You should check the cable for overheating / hardening while the lid is off.


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## El carajillo (Mar 16, 2013)

espressotechno said:


> As CC said above - easy to buy off EBay.
> 
> Your leaky a/v valve looks like a replacement, as the teflon tape indicates. Use this tape (B&Q etc) when fitting the new valve.
> 
> *PS* Looks like a scorched spade connector in the bottom LH corner of the photo. You should check the cable for overheating / hardening while the lid is off.


Well spotted:good:


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## FullBloomCoffee (Mar 19, 2015)

Thanks guys,

it was the anti vac valve. just needed tightening.

booked in for a full service on tuesday anyway, but wanted to double check.

and the spade connector is slightly scorched, but isn't posing a problem


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## El carajillo (Mar 16, 2013)

BeanAbout said:


> Thanks guys,
> 
> it was the anti vac valve. just needed tightening.
> 
> ...


As yet,these faults tend to progress:whistle:


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