# Mara vacuum valve leaking



## Mocochoco (Dec 26, 2016)

Hi guys,

I had my mara open to replace a hose that was leaking and noticed that when the boiler is getting up to temperature the vacuum valve seems to be spluttering out water. Have no idea how long this has been an issue but the top of the tank is looking a little green.

Here is a link to a video showing the issue.






Anyone have any idea how I should sort this? Many thanks


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## woodbar (Aug 28, 2020)

That's a bit annoying - the top of my Mara X is a little contaminated as well but that was from a leaking temp sensor fitting.

I assume this has been occurring from new as this type of valve is designed to work like that. If you actually had excessive amounts of overflow then it could mean that the boiler is overfilling but your video tallies almost exactly with what happens on my Mara X.

On the Mara x the top of the anti-vacuum valve has a hose connector and this is plumbed into the waste line to the drip tray - when it warms up you get a little steam/water dumped before the valve closes with steam pressure.

Might be possible to replace your AV valve with the Mara X variety - presuming the fitting into the boiler is the same size and thread and you are able to add some suitable tubing and break into one of the existing waste hoses with a new T piece for your new hose?

Alternatively I have seen a couple of machines (can't remember where) that actually have a silicon cup fitted around the AV valve which collects the small amount of overflow which then just evaporates when the machine gets hot enough.

Just some thoughts!


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