# How long can descaler stay in copper boiler?



## NJD1977 (Dec 16, 2014)

I'm still getting brown water coming out of my Andreja Premium. If I leave it a few days it literally comes out of the hot water arm the colour of coke. (The brew path water is very clear, its just the steam boiler that produces the brown water).

I did a full descale about 4 weeks ago (I live in a soft water area). I left the descaler in for 1hr and it doesn't seem to have helped much. I'm considering leaving it in overnight in the tank, or maybe even 24hrs. Is this likely to cause any problems with the copper? Also considered warming the boiler up to temperature with the descaler in and then switching off.

If that doesn't work I guess I'll have to take the whole tank out again, remove the element and scrub away by hand.

The photo is 48hrs left in the tank!


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## ronan08 (Dec 21, 2019)

Dont think there is a limit on copper although the bigger question is why is it brown? A copper descale will usually come out green blue, might be worth pulling the boiler


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## DavecUK (Aug 6, 2013)

If there's limescale in there it can come out looking like that, once the limescale is gone it starts going green/blue as @ronan08 pointed out. What he didn't mention is the Green/Blue is the copper being dissolved. Not such a problem on a thick boiler wall perhaps but as the machines age the copper gets think in places and you can get pinhole leaks, especially around the brazed areas. in addition the copper on the heating element is MUCH thinner and again you can get a pinhole in any areas that have become weak over time...then it's failed heating element.

You say you're in a soft water area...*so why does it need descaling*, or is there secret information you're holding onto in case it has value?


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## NJD1977 (Dec 16, 2014)

No nothing secret. I bought it from UrbanBumpkin 2nd hand around 5yrs ago and tbh have never really used the hot water and steam function much. I did a full strip of the machine a few weeks ago and gave the boiler a soak in the sink with descaler for around 1hr. On re assembly it still produces water like this so I can only assume the boiler has something in it that is causing the brown. Could even be something that's been in there from before I had it. Or maybe it's just a very long period of water sat in there without use turning crappy and deposting grime on the boiler walls?

So do you think an overnight soak would be detrimental to the element?

UrbanBumpkin lived down Birmingham way which is much harder water than me. Maybe it just had some scale in it from then. I didn't descale it for 5yrs because I knew I was in a soft area. Maybe old scale has just sat in there for years and needs more of a longer exposure to a descale?

Btw, the element was brand new 2 months ago so shouldn't be aged.


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## DavecUK (Aug 6, 2013)

NJD1977 said:


> Btw, the element was brand new 2 months ago so shouldn't be aged.


 Who changed the element?


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## NJD1977 (Dec 16, 2014)

DavecUK said:


> Who changed the element?


Me. It burned out a few weeks ago. That's why I did the strip down.


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## DavecUK (Aug 6, 2013)

Was their scale on the element...did you notice scale in the boiler. I would have assumed you shone a torch in there simply to see what much was in it in case you needed to wash it out. That's normal procedure when you change a heating element....just natural human curiosity


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## NJD1977 (Dec 16, 2014)

Yeah the element was a horrible colour but maybe that was just it turning black through burning out. I did have a peek inside the boiler. It didn't look shiny like the outside after the descale bath, from memory it looked a fairly dark colour, not white and scaly. I just assumed that's how boilers looked on the inside. Maybe I just didn't descale it long enough or with a bit of heat?

Outside photo of boiler in next post.


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## NJD1977 (Dec 16, 2014)

Outside of tank, the inside definitely didn't look like this.


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## Blue_Cafe (Jun 22, 2020)

Forgive my ignorance, but would a soft metal boiler like brass/copper not need some form of passivating after a chemical cleaning?

Especially if they are submerged in water and thus not open to the air/elements for natural oxidation?

I seem to remember reading something about this on the back of a bottle of furnox one time...

Could it also be that by removing the scale, you have exposed the boiler void to internal corrosion (like on top of the boiler in the picture you show) and this is getting into the water?


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## NJD1977 (Dec 16, 2014)

Bottom of boiler before I fitted new element. Wish I'd taken a photo inside now.


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## DavecUK (Aug 6, 2013)

I bet you wished you had shone a torch inside as well


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## NJD1977 (Dec 16, 2014)

DavecUK said:


> I bet you wished you had shone a torch inside as well


Hmm, I know, I really don't fancy pulling it all to bits again.

Think I'm going to dose it up with citric acid tonight, give it a boil for 15mins and then leave in until midnight or so.


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## NJD1977 (Dec 16, 2014)

Been in for 3hrs now, boiled for 15mins then left to sit.

Fair amount of brown/yellow water coming out now and weird dark bits in the bottom of the jug. I guess this is what's causing the problem.


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## NJD1977 (Dec 16, 2014)

Well, boiler is all stripped out, disassembled, and element out. When looking inside the walls were coated with black and no matter how strong a citric acid solution I put on it, it just wouldn't shift. So I bought some mini wire brushes, got most of it off through scrubbing in an acid bath. Then finally turned to the karcher to jet wash it all out.

It's now having a final bath and final scrub before being put back together. No idea what it was but it's looking very clean now.


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## Blue_Cafe (Jun 22, 2020)

Are you sure the black is not a boiler treatment (magnetite)??

Would you not message the OEM for advice?

Seems odd to me that you need to do this to this degree.


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## NJD1977 (Dec 16, 2014)

Blue_Cafe said:


> Are you sure the black is not a boiler treatment (magnetite)??
> Would you not message the OEM for advice?
> Seems odd to me that you need to do this to this degree.


Its an old machine. Probably 10yrs old or more. It's just some kind of grime. Turns the water black.


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## DavecUK (Aug 6, 2013)

NJD1977 said:


> Blue_Cafe said:
> 
> 
> > Are you sure the black is not a boiler treatment (magnetite)??
> ...


 Possibly some milk in the boiler.


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## NJD1977 (Dec 16, 2014)

DavecUK said:


> Possibly some milk in the boiler.


Yeah I thought that but I hardly ever steam milk, and when I do I always flush. If it is milk, it's been in there for years!

Would descaler not remove milk?


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## Blue_Cafe (Jun 22, 2020)

NJD1977 said:


> Yeah I thought that but I hardly ever steam milk, and when I do I always flush. If it is milk, it's been in there for years!
> 
> Would descaler not remove milk?


 I would think protein residue would be much harder to remove than scale? Scale doesn't require anything other than soaking in my experience.

Perhaps the milk crud has been there for years since before you bought it and your recent deep clean has disturbed it......

Yuk.


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## DavecUK (Aug 6, 2013)

NJD1977 said:


> Yeah I thought that but I hardly ever steam milk, and when I do I always flush. If it is milk, it's been in there for years!
> 
> Would descaler not remove milk?


 It can stay there for years and no descaler won't move it, of course it may not have been milk, just a combination of scale & copper oxide from the old heating element as it degenerated...loads of stuff.


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## DavecUK (Aug 6, 2013)

At least you've done the job properly now and all should be good from now on


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## NJD1977 (Dec 16, 2014)

Lovely and clean in there now.


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## NJD1977 (Dec 16, 2014)

@DavecUK I've hit a problem. The head of the heat exchanger is leaking. When I put it back together it wasn't even hand tight but it aligned with the connection to the group. If I tighten it up, it won't align with the feed to the group.

How do you solve a problem like this? Can you add a copper washer or shim of some kind beneath to nip it up to?

I'd really appreciate your help. Almost back to a working machine!

I also suspect this has been the cause of my thermosyphon stalls.

Photo below.


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## DavecUK (Aug 6, 2013)

Usually they use thread sealant and position it. I would recommend you put a LOT of turns of PTFE tape on it (in the correct direction, that's critical), it might be 7-12 turns or more if the thread is very coarse. You want it to that it's very tight to screw on from the start, then get it most of the way down until it tightens up (don't turn it any other way than to tighten.).


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## NJD1977 (Dec 16, 2014)

DavecUK said:


> Usually they use thread sealant and position it. I would recommend you put a LOT of turns of PTFE tape on it (in the correct direction, that's critical), it might be 7-12 turns or more if the thread is very coarse. You want it to that it's very tight to screw on from the start, then get it most of the way down until it tightens up (don't turn it any other way than to tighten.).


Brilliant, thanks for the advice. I owe this forum (and you) a lot over the last few months. I must donate.

Are there any particular lock sealers that are safe to use or should I just hammer it with PTFE?


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## El carajillo (Mar 16, 2013)

NJD1977 said:


> Brilliant, thanks for the advice. I owe this forum (and you) a lot over the last few months. I must donate.
> 
> Are there any particular lock sealers that are safe to use or should I just hammer it with PTFE?


 I think you would find Loctite 557 suitable. Personally I would go with what Dave said.

Try 4/ 5 turns initially as a dummy run, this way you will be able to judge how many turns you need to get it nice and tight ((increase No of turns until you get it right) then clean off and apply what you need to achieve good torque. As Dave also said DO NOT go past tight point and back off.


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## NJD1977 (Dec 16, 2014)

El carajillo said:


> I think you would find Loctite 557 suitable. Personally I would go with what Dave said.
> Try 4/ 5 turns initially as a dummy run, this way you will be able to judge how many turns you need to get it nice and tight ((increase No of turns until you get it right) then clean off and apply what you need to achieve good torque. As Dave also said DO NOT go past tight point and back off.


Cheers mate.

It's very loose at the moment. Basically finger tight, not even hand tight.

Will PTFE really tighten it up that much?

Daft question then, if the fitting screws in clockwise, looking down on the top of the fitting, I should wind anti-clockwise round the thread?


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## El carajillo (Mar 16, 2013)

NJD1977 said:


> Cheers mate.
> 
> It's very loose at the moment. Basically finger tight, not even hand tight.
> 
> ...


 YES. hold the start firmly as you start to wind and keep it firm ( NO SLACK)


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## NJD1977 (Dec 16, 2014)

What a mission. Finally got it all back together. Had one final leak at the pressure stat outlet. Fixed that and was just screwing the anti vav valve in with plenty of PTFE on and pop it went, sheared at the base leaving the rest inside the machine.

Fortunately I used a screw extractor to drill it out so now I just need a new anti vac valve and it should all be finished.
@DavecUK and @El carajillo I'm so grateful for your help over the last few weeks. I'd like to say thank you by shipping you a bag of my favourite beans. If you could PM me your address they'll be in the post from Mancoco in Manchester.


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## DavecUK (Aug 6, 2013)

NJD1977 said:


> What a mission. Finally got it all back together. Had one final leak at the pressure stat outlet. Fixed that and was just screwing the anti vav valve in with plenty of PTFE on and pop it went, sheared at the base leaving the rest inside the machine.
> 
> Fortunately I used a screw extractor to drill it out so now I just need a new anti vac valve and it should all be finished.
> @DavecUK and @El carajillo I'm so grateful for your help over the last few weeks. I'd like to say thank you by shipping you a bag of my favourite beans. If you could PM me your address they'll be in the post from Mancoco in Manchester.


 I'm good for coffee thanks, have it coming out of my ears, put the money toward a new antivac valve and use a tad less PTFE next time 

Thanks for the thought though, appreciated.


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## El carajillo (Mar 16, 2013)

Glad you managed to get it all sorted, I think you need to get more of a feel for how tight fittings are👌🦾.

Thank's for the thought, glad I could be of help.


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## DavecUK (Aug 6, 2013)




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## NJD1977 (Dec 16, 2014)

El carajillo said:


> Glad you managed to get it all sorted, I think you need to get more of a feel for how tight fittings are🦾.
> Thank's for the thought, glad I could be of help.


Yeah I have a deep socket for the anti vac valve and was using a ratchet on it. Pretty difficult to feel how much pressure was on it.

It's got me worried that I could have overstressed some of the other fittings by putting too much PTFE tape on but at least they haven't sheared.

Is it common for fittings to shear as you're tightening them up? I presumed they would comfortably take the sort of torque a human could put on them with a spanner.....but obviously not!

The outlet from the HX was mega tight by the time I got it aligned with the outlet to the group. Could barely shift it another mm. It didn't leak and didn't shear though! Parts like that are much more rare to find so I'm very glad I didn't shear it.


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## Northern_Monkey (Sep 11, 2018)

@DavecUK - In a similar vein to the hulk gif, Eddie Hall of 500kg deadlift and WSM fame used to be a car/truck mechanic.

I pity the the next person who had to undo his "hand tight" fittings! His colleagues must have peer pressured him into using a torque wrench for just looking at stuff...

Carbon bicycle bits and bearing preloads was a steep learning curve on my side a few years back, plus slightly embarrassing!


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## DavecUK (Aug 6, 2013)

Yeah but you know what they say, "weighed 45 stone but were light on is feet....could dance like Michael Jackson". So size isn't everything, hence the term "Gentle Giant" I bet people used to think "gentle giant" when getting beaten up by Tyson.....


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## Blue_Cafe (Jun 22, 2020)

NJD1977 said:


> Brilliant, thanks for the advice. I owe this forum (and you) a lot over the last few months. I must donate.
> 
> Are there any particular lock sealers that are safe to use or should I just hammer it with PTFE?


 For future info, PTFE tape is more for thread lubrication than sealing. A few turns is all you should do as it can gather in the thread voids and lock the joint.

Use it for ensuring a seal rather than making one.

Whilst the max service temp of PTFE is above steam temps found in boilers, in industrial settings where forming a seal, it is avoided as the mechanical properties begin to change once you get above boiling water temps. This can degrade a seal over time.

If you need to seal a thread, use thread sealant rated for steam temps as these get better, not worse, with heat (upto a limit)

This way, you'll be able to undo the joint in the future.

I'm sure taping joints works for most anyways....


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## El carajillo (Mar 16, 2013)

NJD1977 said:


> Yeah I have a deep socket for the anti vac valve and was using a ratchet on it. Pretty difficult to feel how much pressure was on it.
> 
> It's got me worried that I could have overstressed some of the other fittings by putting too much PTFE tape on but at least they haven't sheared.
> 
> ...


 t


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## NJD1977 (Dec 16, 2014)

El carajillo said:


> t


t?


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## DavecUK (Aug 6, 2013)

The reason it sheared was probably a little too much tape, but also a deep socket. Using off center pressure it's easy to apply a force that shears. e.g. a T bar vs a rachet handle type thing. e.g. a spanner near the base probably would have not sheared it.

PTFE tape is fine for sealing (except for heating elements and thread sealer shouldn't be used on those either) and I much prefer it over thread sealant/locker. The manufacturers use sealant for speed and assembly reliability without testing. Sometimes you get blobs of sealant in the boiler and it can lodge in components and sometimes cause a problem, it can also be very hard to undo years later.


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## Blue_Cafe (Jun 22, 2020)

DavecUK said:


> The reason it sheared was probably a little too much tape, but also a deep socket. Using off center pressure it's easy to apply a force that shears. e.g. a T bar vs a rachet handle type thing. e.g. a spanner near the base probably would have not sheared it.


 I use a pair of opposing ring spanners on my bikes bottom bracket to avoid this issue of torque moments. Works a treat.


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## NJD1977 (Dec 16, 2014)

Blue_Cafe said:


> I use a pair of opposing ring spanners on my bikes bottom bracket to avoid this issue of torque moments. Works a treat.


How does that relate to screwing an anti vac valve in? A torque applied on a fitting cannot be unapplied by an opposing spanner, all it does is stabilise the base that you're screwing into. On a boiler there is no nut to stabilise against so you have to just use a bar wedged into the fittings on the top of the boiler to stop the boiler twising.......but this doesn't remove the torque applied to the fitting.


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## Blue_Cafe (Jun 22, 2020)

NJD1977 said:


> Blue_Cafe said:
> 
> 
> > I use a pair of opposing ring spanners on my bikes bottom bracket to avoid this issue of torque moments. Works a treat.
> ...


 I think in the instance of a soft body copper boiler, you need to apply any threading torque in one plane only and as Dave says, remove any off plane shear or bending moments as much as possible. You can't do this with a single arm wrench. You need to have a double arm wrench or torque drive which just applies torque only.

I wouldn't be jamming anything anywhere if I could help it. A high friction rubber strap lock around the base or head seam if the boiler (the stiffest part of the cylinder) would be a much better way of stopping the boiler from spinning. Certainly, if it's not enough, you have either a locked thread/joint or are going at it too hard.

Good seals on threads shouldn't need high torque.

Be careful to note the thread types (parallel or tapered) note the recommended jointing (dry, lube, tape, goop, etc) and note the sealing mechanism itself. By example, many people think goop, tape, etc is needed on compression fittings but don't realise the threads are just for there to apply the sealing force.

It's a nuanced field with many variables.


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## El carajillo (Mar 16, 2013)

NJD1977 said:


> El carajillo said:
> 
> 
> > t
> ...


 I wrote a short post regarding torque / tightening but it vanished into the ether and left t ???

Basically you need to develop a feel for pressure/ torque on spanner and bolt / fitting. == Muscle memory like tamping. Most people tend to way over tighten. If you tighten a bolt to its recommended torque with a torque wrench then ask someone to try the bolt with a spanner they will say it is too lose.


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## NJD1977 (Dec 16, 2014)

El carajillo said:


> I wrote a short post regarding torque / tightening but it vanished into the ether and left t ???
> Basically you need to develop a feel for pressure/ torque on spanner and bolt / fitting. == Muscle memory like tamping. Most people tend to way over tighten. If you tighten a bolt to its recommended torque with a torque wrench then ask someone to try the bolt with a spanner they will say it is too lose.


New valve arrived today and I'm scared to death of screwing it in!!!


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## Blue_Cafe (Jun 22, 2020)

NJD1977 said:


> El carajillo said:
> 
> 
> > I wrote a short post regarding torque / tightening but it vanished into the ether and left t ???
> ...


 Best of luck. I am sure you will be ok.

Looking at your picture, perhaps corrosion was the cause of the failure, not over torquing.

If you don't mind me saying, and i would think Dave may know better* it seems odd, the way the valve is sat in the boiler head (on your last photo).

For a parallel thread fitting , its weird that there is no sealing ring or bushing, etc.

I suspect that the manufacturer used thread seal for this (you can see it on your photo).

This means then that in manufacture, this was simply a dip an nip affair to get the boiler sealed. Importantly, you trying the same with tape (especially on a parallel thread) is going to cause you problems.

May i suggest you see how this is supposed to be done (ask the manufacturer) before doing it again?

Either way, you are going to struggle to get good tight seals with parallel threads.

Hope it works out!

Edit: https://www.home-barista.com/espresso-machines/fittings-in-top-of-boiler-teflon-tape-or-thread-lock-t25009.html#p292734

* I am being genuine here btw


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## NJD1977 (Dec 16, 2014)

Blue_Cafe said:


> Best of luck. I am sure you will be ok.
> Looking at your picture, perhaps corrosion was the cause of the failure, not over torquing.
> If you don't mind me saying, and i would think Dave may know better* it seems odd, the way the valve is sat in the boiler head (on your last photo).
> For a parallel thread fitting , its weird that there is no sealing ring or bushing, etc.
> ...


Yeah, there's no bushing, the anti vac valve just screws straight in. In the factory it probably was threadsealed. In the past I have replaced it with PTFE tape and it was fine.

I've just tried it without PTFE and got it tightish, but it still leaked so I'll have to pull it out and try 3 wraps of tape.


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## NJD1977 (Dec 16, 2014)

All fixed. No more leaks. OPV reset to 10bar. Crystal clear water out of the hot tap now. I'm a very happy boy. She's just warming up now for an espresso.

Thanks all for your help.


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## El carajillo (Mar 16, 2013)

Gold star for that man, now get to the coffee   :good:


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## NJD1977 (Dec 16, 2014)

Just a quick update on this for future learning.

I had crystal clear water out of the boiler for a week, then suddenly, overnight, it turned all brown again. I was stumped. I flushed the boiler through so it was crystal clear again and then started trying to work out what the hell was going on.

I think I've come to a conclusion. The anti-vac valve tube discharges to the drip tray with quite a long tube. Once the drip tray starts to become more full, the tube becomes submerged in brown drip tray water. When the boiler cools, the anti-vac valve does it's job and tries to suck in air from the outside, unfortunately it can't do this because the tube is submerged in the drip tray. It was literally sucking drip tray water back up into the boiler through the anti-vac valve. I'm guessing this is what caused the whole dirty-boiler problem in the first place......just years of drip tray water being sucked back into the boiler and then baking onto the inside of the boiler. Anyway, it's all clear now and I think I know how to stop it happening in the future.

This seems a clear flaw in the design of boilers with anti-vac valve tubes running to the drip tray. The solution is to make the tube very short and ensure it doesn't drop into the drip tray.......and keep your drip tray emptied regularly.


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## Blue_Cafe (Jun 22, 2020)

Great post and a particular success that you've discovered the true nature of the issue rather than just treat the symptoms.

Perhaps something is a miss from earlier on in the machines life and a hose or clip has been re installed badly. Perhaps it's bad design. If I had a machine with this AVV, I'd be checking for syphoning as you have.

Your coffee should taste much better now


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## DavecUK (Aug 6, 2013)

NJD1977 said:


> This seems a clear flaw in the design of boilers with anti-vac valve tubes running to the drip tray. The solution is to make the tube very short and ensure it doesn't drop into the drip tray.......and keep your drip tray emptied regularly.


 All current manufactures no this with todays machines, fortunately it was yesterdays problem. Well done for finding it, it had to be something simple...Occam's Razor and all that. e.g brown water doesn't come from clean boilers, so what are the other 2 places brown water comes from...group and drip tray.


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## NJD1977 (Dec 16, 2014)

Blue_Cafe said:


> Great post and a particular success that you've discovered the true nature of the issue rather than just treat the symptoms.
> Perhaps something is a miss from earlier on in the machines life and a hose or clip has been re installed badly. Perhaps it's bad design. If I had a machine with this AVV, I'd be checking for syphoning as you have.
> Your coffee should taste much better now


I think it's just bad design. I found a thread on another coffee forum with this exact same problem. They should have made some sort of clip to keep a short piece of the tube above the water line in the drip tray. Mine was about 3-4" long and just sat in the drip tray, a few flushes and it would've been underwater.

3 months ago I didn't even know what an AVV did, so I had no chance of working out what the issue was. The good thing about all these problems is that they force you to learn all about your machine and the issues. I now feel like I have a machine that I can take care of for years to come.


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## DavecUK (Aug 6, 2013)

NJD1977 said:


> 3 months ago I didn't even know what an AVV did, so I had no chance of working out what the issue was. The good thing about all these problems is that they force you to learn all about your machine and the issues. I now feel like I have a machine that I can take care of for years to come.


 Think of all the help you can now give to others...


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