# ECM Anti Vacuum Valve Hissing



## richwade80 (Aug 25, 2017)

I noticed the machine making a slight wet fizzing today. I opened her up before the boiler cooled and saw it was the anti vacuum valve. There was no other visible issue.

I gave it a slight tap with a wooden spoon and it let out some wet steam as expected. I haven't turned it back on yet to see if it repeats the noise.

Is this likely to mean the valve or o-ring needs replacing, or could it just be chance that it didn't activate correctly, or anything worse???

I did give it a usual periodic chemical backflush and cam lube yesterday if that makes any difference.

Machine is three years old and run only on Waitrose essential water.

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## NJD1977 (Dec 16, 2014)

I've just changed mine, the rubber o ring was all hard and brittle and was leaking. It probably just needs a new valve or at the least a good strip down and descale etc.


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## MediumRoastSteam (Jul 7, 2015)

My pavoni does the same every now and then, like, every couple of months. It's as if the anti-vac valve didn't shut properly. A quick tap with the wooden spoon and all is well for months to come.

Mind you, it is a brand new valve. The previous one failed, but failed stuck shut, not open.


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## richwade80 (Aug 25, 2017)

NJD1977 said:


> I've just changed mine, the rubber o ring was all hard and brittle and was leaking. It probably just needs a new valve or at the least a good strip down and descale etc.


I have it all opened up, but the nut is pretty well secured. I was hoping it might come loose a bit easier as it is twisting the whole boiler etc. don't really fancy buggering it all up.

Is there a way to do this?

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## richwade80 (Aug 25, 2017)

MediumRoastSteam said:


> My pavoni does the same every now and then, like, every couple of months. It's as if the anti-vac valve didn't shut properly. A quick tap with the wooden spoon and all is well for months to come.
> 
> Mind you, it is a brand new valve. The previous one failed, but failed stuck shut, not open.


I probably should try this first. But it would be good to check the o ring to know for sure.

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## MediumRoastSteam (Jul 7, 2015)

richwade80 said:


> I have it all opened up, but the nut is pretty well secured. I was hoping it might come loose a bit easier as it is twisting the whole boiler etc. don't really fancy buggering it all up.
> 
> Is there a way to do this?
> 
> Sent from my iPhone using Tapatalk


As far as I valve is screwed into the valve assembly. Do not undo the nut at the bottom!

You should use two spanners: one to secure the nut at the bottom, so it doesn't move, and with the other unscrew the anti-vac valve itself.

Edit:

Watch this. He took out the whole valve and assembly. Personally, I'd have done only the top bit.


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## richwade80 (Aug 25, 2017)

MediumRoastSteam said:


> As far as I valve is screwed into the valve assembly. Do not undo the nut at the bottom!
> You should use two spanners: one to secure the nut at the bottom, so it doesn't move, and with the other unscrew the anti-vac valve itself.
> 
> Edit:
> ...


I've bottled it for now! The machine is back on and so far no noise...

I did assume you'd have to hold the lower nut. There is not much space to do this to be honest. Maybe I need to strip more down to get at it.










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## DavecUK (Aug 6, 2013)

richwade80 said:


> I've bottled it for now! The machine is back on and so far no noise...
> 
> I did assume you'd have to hold the lower nut. There is not much space to do this to be honest. Maybe I need to strip more down to get at it.
> 
> ...


 Get something like this and you can easily remove nuts like that. there are cordless ones as well.

https://www.amazon.co.uk/s?k=Clarke+CIR13C&ref=nb_sb_noss

It's what I always use and saves damaging the boiler. With the right sockets great for heating elements etc.. I got mine decades ago from a car accessories shop cost me less than £15


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## richwade80 (Aug 25, 2017)

DavecUK said:


> Get something like this and you can easily remove nuts like that. there are cordless ones as well.
> https://www.amazon.co.uk/s?k=Clarke+CIR13C&ref=nb_sb_noss
> It's what I always use and saves damaging the boiler. With the right sockets great for heating elements etc.. I got mine decades ago from a car accessories shop cost me less than £15


Cheers Dave,

Would you still have to secure the lower nut when using something like that?

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## DavecUK (Aug 6, 2013)

richwade80 said:


> Cheers Dave,
> 
> Would you still have to secure the lower nut when using something like that?
> 
> Sent from my iPhone using Tapatalk


 No, either the top one would come out or the lower one would, but it doesn't matter. Once it's out you can use as much torque as you want to split it. The great thing it no real chance of boiler damage.


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## richwade80 (Aug 25, 2017)

DavecUK said:


> No, either the top one would come out or the lower one would, but it doesn't matter. Once it's out you can use as much torque as you want to split it. The great thing it no real chance of boiler damage.


 Update - the hissing stopped for a few weeks, and i so i talked to bella barista in the meantime to check which part is right (there a few different looking anti-vacuum valves). BB suggested trying to take the nut off when the machine was hot, but not under pressure, so i gave that a go before borrowing a friends impact driver. That worked fine.

Images below of what i found - general question though - does any of this indicate anything more i should deal with while i have the machine opened up?

Removed Valve - note residue on the thread - i presume this is thread lock or some grease










Split Valve - note bits of sediment and flecks of brass



















Removed Pin and O-Ring - These look okay to me, so i think it was just sediment causing the issue










Boiler Valve Opening & Attempt at the Internal - I can see the main coil inside (Just in shot). It appears a bit milky looking


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## Blue_Cafe (Jun 22, 2020)

Pictures not displaying?

The anti vac valve is a parallel thread. These are either sealed on a face with a Gasket (a-la compression fitting) or, using thread sealing compound. In this case, it appears your is thread sealing compound. There was a thread (!!) on this a few weeks ago with somebodys old boiler.

What i do notice from the picture is that the wet side of the valve is black. This blackening was also prominent in the thread mentioned above and was suspected to be milk residue but, was actually seen to be backflow from the anti vac valve sucking back dirty water from the drip tray. Once complete, you might check that your AV outlet isn't sitting in the drip tray puddle.

I would clean out the boiler thread carefully of any old sealant. I'd also take the opportunity to rinse out and flush the boiler to make sure you don't leave any old sealant in the boiler.

I wouldn't use PTFE to reseal these. It's not what its designed for. a small tube of thread sealant will not go to waste as you will use it again in future repairs, so i would use that.

You don't need to use torque to seal the new valve with sealant. Just a clean prep and threads in good condition.

These are just my thoughts on it anyways.

As always, i am sure the more senior members will be along shortly to tell you differently.

Best of luck.


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## richwade80 (Aug 25, 2017)

Blue_Cafe said:


> Pictures not displaying?


 Cheers - could you seen any pics? tried a different way below;

the anti vac valve is not connected to the drip tray with a tube, and the drip tray is definitely physically separated.

how would you flush the boiler out of interest - i can imagine that would be fun - presumably you'd have to suspend the machine upside down....


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## Blue_Cafe (Jun 22, 2020)

I can see those pictures now.

Interesting black scaling/rouging (?) in that its going up into the vac valve inners (is this causing the valve to stick i wonder?)

Reminds me of the water i get when i flush out my central heating radiators. You are not connected to any steel/Iron water tanks by any chance?

Are you using descale agent for SS boilers?

Interesting.

Can you not get a new seal and bush for those valves? do you need to buy the whole thing? Seems a waste to throw away if so.


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## DavecUK (Aug 6, 2013)

Make sure white teflon bit is clean


buy replacement silicon o ring, you might find FKM will work as well (it's probably hardened by now)


reassemble valve


clean thread


clean boiler thread very carefully, shove a bit of damp kitchen towel in and try and scrape the thread clean in parts, bringing out bits on the kitchen towel, just get off the worst, don't try for totally clean on boiler one


Use PTFE tape to refit valve, not threadlock. When using PTFE tape it's not about how hard it is tightened down but having enough threads engaged and sufficient PTFE (wound the right way) that a good seal forms. Valve should feel tight all the way in (not super tight of course)


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## richwade80 (Aug 25, 2017)

thanks Dave,

to respond to @Blue_Cafe's points - its only been bottle fed - mainly to avoid the need to descale etc.

the black colour was quite alarming - but it does not rub off at all, and looks okay to be honest. i'm guessing that is the natural colour it goes... or there is some other material to prevent bimetallic corrosion. Literally guessing here. Every day's a school day


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## Blue_Cafe (Jun 22, 2020)

richwade80 said:


> thanks Dave,
> 
> to respond to @Blue_Cafe's points - its only been bottle fed - mainly to avoid the need to descale etc.
> 
> the black colour was quite alarming - but it does not rub off at all, and looks okay to be honest. i'm guessing that is the natural colour it goes... or there is some other material to prevent bimetallic corrosion. Literally guessing here. Every day's a school day


 Yea, i just thought it interesting that its clearly migrating up through the valve path which suggests to me its an ongoing process, rather than one from manufacture.

You can see on the valve thread, how far into the boiler void the valve goes as seen from the black line on it!

I am probably wrong, but regardless of the water, i would think decaling periodically is not a bad idea. Perhaps the bottled water has some iron in it or other mineral? There are water buffs ( @Rob1) who might be able to chip in.


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## Rob1 (Apr 9, 2015)

You flush the boiler through the hot water tap a couple of times.

It just looks like an oxide layer on the brass to me.

The water you're using has about 25mg/l Chloride. I wouldn't use it in steel boilers. To be honest I wouldn't let any chloride in a steel boiler, especially for steaming, but I have read up to 10ppm is supposed to be safe. I've also read SCC is evident in steam applications at less than 10ppm so I just err on the side of caution.

How often do you steam and how often do you empty the boiler through the hot water tap and refill with fresh water?


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## richwade80 (Aug 25, 2017)

Rob1 said:


> You flush the boiler through the hot water tap a couple of times.
> 
> It just looks like an oxide layer on the brass to me.
> 
> ...


 cheers Rob,

i steam every day, twice a day. i have never tried to drain an entire boiler tanks worth - the most would be for rounds of tea, so probably only 500mls at a time. Obviously it refills as you do this when its all on etc, but with the boiler opened up as it is - presumably you could siphon it off through the hot water tap - but you still wouldn't get all of it out?


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## Rob1 (Apr 9, 2015)

You'd get almost all of it out. Then just rinse it a couple of times. You'll probably need to descale.

When you steam all minerals are left behind as water is lost as steam. You wouldn't see scale forming with the water you're using but after a couple of weeks of steaming minerals will concentrate and it will scale. Everything else in the water will concentrate too.


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## richwade80 (Aug 25, 2017)

Cheers Rob,

done a bit of reading, and it looks straight forward enough to kill an afternoon.


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## Blue_Cafe (Jun 22, 2020)

as a test, try this with the dirty old valve 1st.....


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## richwade80 (Aug 25, 2017)

enough of the dirty 

are you going to ask me to remove the valve after I've done this?



old valve cleaned and reinstalled with ptfe tape.


machine is on, and valve has just sealed as normal


descaler measured out and raring to go


about to turn off and purge the boiler of water


slightly excited - will report back


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## Blue_Cafe (Jun 22, 2020)

richwade80 said:


> enough of the dirty
> 
> are you going to ask me to remove the valve after I've done this?
> 
> ...


 Nah. I thought you were buying a new one.

It would have been interesting to see how clean it would get.

Glad the machine is now working.


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## richwade80 (Aug 25, 2017)

results of note;



some solid pieces of scale came out when purging the tank, trapped in the hot water wand - i had checked before and it was clean.


while sat descaling, the machine appears far quieter during the boiler and pump cycle


don't turn on the hot water tap/lever fully, it will spray boiling water everywhere....


observed an amount of sediment on the first few purges after descaling (nothing before)


purged tank 6 times after descaling

you get about 900ml of water out each time. the boiler capacity is 2100ml, so you can only dilute the descaler unless you can literally empty the tank


assuming the boiler was full of descaler to start with (which it would not be due to presence of fresh water in the boiler), you lose 57% of the descaler/water mixture each purge, so after 6, you should have only 3.4% of the solution left.


i tasted it after 5 and could just about taste something so did one more to be sure - i couldn't taste any difference then.



it really isn't that hard to do this - just a bit time consuming - about an hour and a half - and not great on a hot day.


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## DavecUK (Aug 6, 2013)

Just remember the boiler isn't full to the brim, it will only contain around 1.4l of water.


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