L'anna water height sensor and possible vacuum valve issues

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L'anna water height sensor and possible vacuum valve issues

Postby dr.chris » Sun Aug 25, 2013 1:37 pm

The time has come for the Lovely Anna to develop a couple of problems. I have changed the pump which has helped a lot of problems but there are two more I just wanted to get some advice on.

The simplest is the vacuum valve on the boiler. It hasnt always been closing properly following a recent boiler descale. I have removed and soaked it in citric acid (assuming the problem might be a small piece of scale) which I hope will resolve the issue but was wondering about the tiny rubber seal at the bottom of the valve and if it occasionally needs replacing.

The second but much more annoying problem is the water level sensor in the reservoir. There are two sensors (i.e. bits of wire sticking into the water). The top one indicating a full tank works fine. The second one that indicates if the tank is empty is not. It seems to work fine if you test in when you first turn the machine on, but can stop working after everything heats up. On L'anna this stops everything else from working. I have gone through the connections to the controller (not sure of the name of the part) and pulled apart and pushed everything back together. I am now wondering about the controller itself. Is there anything that I can do to that if the problem continues? Or am I looking at getting a new controller.

In the short term I think I can swap around the sensors - as the 'too full' sensor seems to overide the 'empty' sensor - and then just be careful about overfilling, but its not a long term solution.

Putting in a little more water seems to also sort it out for short time also, but its no fun when it cuts out mid extraction
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Re: L'anna water height sensor and possible vacuum valve iss

Postby GreenBean » Mon Aug 26, 2013 8:09 am

dr.chris wrote:...The simplest is the vacuum valve on the boiler. It hasnt always been closing properly following a recent boiler descale. I have removed and soaked it in citric acid (assuming the problem might be a small piece of scale) which I hope will resolve the issue but was wondering about the tiny rubber seal at the bottom of the valve and if it occasionally needs replacing.

If the gasket and the mating surfaces are in good condition I doubt that the joint would leak. You could try holding a spoon close to the valve when you suspect it is leaking. Any steam leaking will condense on the spoon making the leak visible. By moving the spoon to any suspect locations you should be able to identify what is leaking. If you attempt this then obviously you must keep the spoon away from any mains connections inside the machine :? The vacuum valves are quite cheap so it may be easiest to just replace it.

dr.chris wrote:...The second but much more annoying problem is the water level sensor in the reservoir. There are two sensors (i.e. bits of wire sticking into the water). The top one indicating a full tank works fine. The second one that indicates if the tank is empty is not. It seems to work fine if you test in when you first turn the machine on, but can stop working after everything heats up. On L'anna this stops everything else from working. I have gone through the connections to the controller (not sure of the name of the part) and pulled apart and pushed everything back together. I am now wondering about the controller itself. Is there anything that I can do to that if the problem continues? Or am I looking at getting a new controller.
...

The usual suspect is scale on the level sensor probe insulating it so the water level is not detected. Have you removed and descaled the probe? If the boiler is also heavily scaled it will also reduce the conductivity of the circuit. If you are using RO water and have scale on the probe or boiler then that could compound the problem. I would think that these issues are more likely suspects than the controller.
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RE: Re: L

Postby dr.chris » Mon Aug 26, 2013 11:07 am

Thanks for the reply GB.

Scale isnt an issue - we are in a soft water area and shes just been descaled. There is no scale evident on the sensors at all :(
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Postby GreenBean » Mon Aug 26, 2013 4:52 pm

I apologise Chris. I was in a hurry this morning and did not read your post properly :oops: I was assuming the problem was the boiler water level sensor not the water reservoir sensor. I have no information on the sensor you are having problems with. I suggest you talk to Scott at Happy Donkey who should be able to advise you.
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Postby dr.chris » Mon Aug 26, 2013 10:55 pm

That was the next step - I'll report back when I find a solution
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Postby dr.chris » Fri Aug 30, 2013 11:13 pm

Hmmm - talked (as in emailed) Scott - he basically suggested getting an engineer involved as it may get complicated with the wiring and it can be hard to trace the error back to a single cause. Its a good suggestion- be a chance to get her checked over and any niggles to be sorted out by someone who knows what they are doing as opposed to me making guesses, (however well informed those guesses may or may not be). Next step is finding someone within range.

We have a couple of ideas as to where to start looking but it may not be easy....
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Postby GreenBean » Sat Aug 31, 2013 11:07 am

I hope you can get it sorted soon, Chris. :( I have no information at all on these sensors on your machine. I assume they are just sensing the resistance of the circuit and, when the resistance is high enough, it assumes that the water level is below the sensor. If this is the case it will be sensitive to any extra resistance caused by oxidation/dirt on any contacts in the circuit. It may be worthwhile ensuring all contacts are very clean and trying again.

When you do get it sorted, it would be helpful if you could advise what the problem was with photos if possible.
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Postby dr.chris » Sat Aug 31, 2013 1:38 pm

That thing you say about the circuit is what makes it frustrating - its not exactly the most complicated piece of kit but electrics plus intermitant fault is just a pain
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Postby dr.chris » Thu Oct 31, 2013 2:03 pm

Just a quick update. I got a new controller from Happy Donkey (and yes it was a very competitive price - but they are not cheap). Fitted last night and so far working very well.

I am not sure if that is all the problems sorted - there seems to be some issues with keeping a constant pressure in the boiler (it cycles over about 0.2bar rather than staying constant) and the steam wand (so I am told) isnt working as well as it should. Thinking about it I should have got a new vacuum valve at the same time :roll: . Also not completely convinced the pump is working as well as it should be - which may be due to the motor as the pump itself is new.
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Postby GreenBean » Thu Oct 31, 2013 5:59 pm

Great to hear that the new controller is working well.:D I hope that is the original problem sorted. I do not think the boiler pressure cycling about 0.2 bar is a problem. All pressurestats have a dead band and I believe that 0.2 bar is normal. The steam wand is a fairly simple bit of kit. If the boiler pressure is normal you can only check the steam valve is working and the wand is not blocked. Why do you think the pump is not working as normal? Perhaps you just need to learn to love Anna again after a period of forced separation. :wink:
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Postby dr.chris » Mon Nov 04, 2013 2:12 pm

We kept on running Anna- its just we always had to almost overfill the reservoir. I did try switching over the reservoir height sensors to try to persuade Anna that she was always over full but for whatever reason it didnt work.

The issue of the pump is that we are still maybe not getting as much pressure through the head as we'd like, but I dont really have a way of measuring it other than playing with a clear pipe and a lot of water. Sometimes I do wonder that that is as much about spending too much time without playing with the 'variables' so that you loose touch. Still - there is a new (old) grinder on the horizon which may help as we will be forced to go through all the basics of adjusting grind etc all over again.

Steam - wand isnt blocked that I know of. I do appreciate that the valve doesnt last forever but I would guess there would be some physical evidence if it wasnt working (a hiss or even some moisture where it shouldnt be). I am just going by what the better half says as she makes caps and I do not. The boiler pressure does seem to drop down fast when she uses the steamer.
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Postby GreenBean » Mon Nov 04, 2013 2:34 pm

dr.chris wrote:... I am just going by what the better half says as she makes caps and I do not. The boiler pressure does seem to drop down fast when she uses the steamer.

That sounds like a good description of a vacuum valve that is stuck in the closed position. With the valve closed air can not escape from the boiler when the machine heats up. The air escapes when you open the steam wand and the boiler pressure drops rapidly. You can test if this is the issue by letting the machine warm up then opening the steam wand valve until the pressure drops to almost nothing then close the steam wand valve and let the machine warm up again. This will remove any air from the system. When you now try steaming it should be back to normal allowing significant steaming without loss of pressure.

If this is the problem you can try opening and cleaning the valve or just replace it they are quite cheap. Another option, at least in the short term, is to go through the above routine of opening the steam valve to remove the air and then let it warm up again before steaming milk.
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Postby dr.chris » Fri Nov 08, 2013 1:03 am

OK - Dug a bit further into poor Anna's problems and it seems that somehow there is also a heap of scale sitting in the wrong bits of the group head. It is probably possible to apply descaler to some useful locations but I cant help feeling it would be easier to start with to take the group head off to get access to all of it.

Given the tightness of some of the nuts holding it in place I was wondering if there was any advice around before the big spanners come out
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Postby GreenBean » Fri Nov 08, 2013 9:28 am

If there is serious scale build up in the group head then there will also be serious scale build up in the heat exchanger and pipework. I would suggest descaling the entire circuit a few times first and then remove the top nut from the group head and inspect the mushroom to see what scale remains. At that time you should inspect the gicleur and the associated filter to ensure they are not blocked with scale. This thread may be helpful.
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Postby dr.chris » Fri Nov 08, 2013 4:04 pm

Thankyou for that link - that is very much where I ended up last night and very useful to read of different takes on a similar situation. Double shot of this parish has also sent me some useful stuff that will end up on here at some point.

The 'mushroom' on Anna wasn't as bad (I still think it looked bad, until I saw Simon's pic - now not feeling so bad at all). We have been in relatively soft water areas for the last few years and have done full scale descales, including one not so long ago. Like in Simon's description there just seemed to be a pile of loose scale underneath the mushroom. I have cleared as much as I can but it looks like some has gone further down and Anna currently isn't pumping at all.

I think where the scale is is usually an indication that there is high temperature and not enough water flow, and certainly there looks to be a pocket around the mushroom where water wont move so much. I do wonder if part of the problem right now is that some of the scale on the outside of the mushroom slipped down inside when I pulled it out.

The easiest thing to to is probably to get some more citric acid and actuall put it directly down into the chamber under the mushroom. I do feel however that I would be happier if I actually got the group head off and stripped it down and cleaned it properly, its just that thing about tackling stiff bolts on soft copper pipes and being concerned about wrecking new things in the course of trying to fix old ones. I'll do more research and try to remember to take some pics.
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