# Is there a problem?



## emradguy (May 24, 2014)

Hi,

I'm trying to figure out if my Duetto II has a problem or not. I just entertained today, and made about 10 drinks back-back. All went really well, but about an hour or two later, I walked by the machine and notice the steam pressure gauge read 2.5 bar. I flushed some steam and there was a lot of water in the pitcher, which of course is really weird. So, I turned off the machine (in part because I knew I was done using it for the night). A couple more hours later, there are nice puddles on the counter under the machine and on the floor. Steam boiler temp is set to 259F and read normal throughout. On opening the case, there were water droplets in the holes of the vacuum breaker, but nowhere else. I used a flashlight and a mechanic's retractable mirror to look around pretty thoroughly.

In thinking about this, I'm wondering if my fill sensor failed and the steam boiler overfilled. So, I just removed it and gave it a good cleaning with high grit sandpaper and then re-installed it...but haven't put the cover back on or anything else, and haven't tested it...yet.

My machine is plumbed in, line pressure about 3 - 3.5 bar (and read normal all through the above scenario). Last descale was about 6 months ago. Water is treated with a Mavea C300 filter.

Thanks in advance,

Ron


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## DavecUK (Aug 6, 2013)

Well the "holes" you talk about are not in the Vacuum breaker, are you sure you don't mean the safety valve?

The fill sensor could have allowed it to over fill, a friend of mine actually had a sticky auto-fill solenoid valve which caused a similar problem, we opened it up, cleaned and lubricated and it's been fine since.

If your temperature definitely did not go above 259F, then the pressure should only be around 1.35 to 1.4 bar, but as the pressure was 2.5 bar, the implication is the pump was adding further pressure. It can't go any higher than 25 bar, because the safety valve will always let by at or before that, depending on the model of valve. Usually before that.

If you cleaned the auto-fill sensor and it does it again (even though I doubt it's the problem as you would have heard the pump running and running without the lever lifted), then dirty auto-fill solenoid valve is my bet. You can also do some tests, run the machine against a blind filter and watch the Safety valve (lid off), if it's filling the steam boiler, then eventually you will see water start to trickle out of the safety valve. Try the test with the machine hot...but only run the pump for 60s at a time, pausing for 15 seconds, do this around 4 or 5 times. During the 15s pause look for elevated steam boiler pressures


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## emradguy (May 24, 2014)

Thanks Dave. I guess I misread the diagram in the bellabarista closer look. I though the safety valve sat on top of the vacuum breaker, but yeah, the only water was definitely in the holes there...and the pump was not running when I noticed the high pressure at normal temp. I was thinking maybe it had overfilled at the end on the session, without me noticing until later.

I closed her back up and ran her for about 30 minutes only and all was normal, but it sounds like I need to check my auto-fill solenoid. Last problem I had with that turned out to be crud in the mesh screen just before it, but I had taken it all apart, cleaned it up and lubed it....maybe last Spring the day I did my last descale.


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## emradguy (May 24, 2014)

Well, so, I got up a little later than anticipated. The steam boiler pressure gauge read about 2.75 bar, but the PID display showed normal bumping around between 257 and 260. At least there wasn't a big puddle again! I bled water off through the hot wand until the pump came on and auto-filled. Temp didn't really drop, but almost as soon as I opened the valve, the pressure dropped to about 1/5 bar, and it stayed there throughout. After the boiler refilled, everything looked normal. I decided to bleed off steam too, and after clearing water from the wand the steam was dry and normal, and the pressure gauge dropped appropriately down to about 1 bar during the process, temp dropped too, as expected. After closing the valve, the temp and pressure both rose appropriately back to normal, and all seems well again. I'm a bit confused by al this. Perhaps it means it's time for another descale...or maybe my gauge is going bad?


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## DavecUK (Aug 6, 2013)

I'm going to assume you have checked the Vacuum breaker isn't sticking closed, which can cause the exact situation you describe!!


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## emradguy (May 24, 2014)

In case anyone doesn't know it yet...*Dave is the man! *I cross posted this on Coffeegeek, and he's not only replied on both sites, but hasn't complained once about having to type his responses twice. I think it's good to have the info out there for both forums though. Dave has helped me a lot with my Duetto II over the past couple of years, and I feel I owe him a really big public thanks!

Anyhow, back to the topic...I feel a little pride in coming up with the possibility of my vacuum breaker sticking this am, and also in actually knowing which part that is (lol)...but to answer the question, No, I haven't opened the machine again yet to check it. In truth, I don't know what steps to take to check it, so help there is also going to be very much appreciated.

Oh, and totally off topic...Dave I just noticed you're in Surrey. One of my close friends used to live in Windlesham, and when visiting him, we used to go over to Hogsback Brewery in Tongham. In fact, I love that place so much that I have one of their tea towels in use at my coffee bar all the time. My friend has since moved to Somerset, and is owner/operator of Moor Beer.


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## DavecUK (Aug 6, 2013)

emradguy said:


> Anyhow, back to the topic...I feel a little pride in coming up with the possibility of my vacuum breaker sticking this am, and also in actually knowing which part that is (lol)...but to answer the question, No, I haven't opened the machine again yet to check it. In truth, I don't know what steps to take to check it, so help there is also going to be very much appreciated.
> 
> Oh, and totally off topic...Dave I just noticed you're in Surrey. One of my close friends used to live in Windlesham, and when visiting him, we used to go over to Hogsback Brewery in Tongham. In fact, I love that place so much that I have one of their tea towels in use at my coffee bar all the time. My friend has since moved to Somerset, and is owner/operator of Moor Beer.


I have been to the brewery on a Visit, very enjoyable as long as you are not driving.

With the Vacuum breaker, there is a tube to allow it to vent to the drip tray, remove this and then with the machine fully up to temp (steam boiler), use *a long handled* wooden spoon to fully depress the metal rod on the top, do this for 10 seconds, wait for pressure to come up and repeat a few times...this might well steam clean the valve without it needing to be disassembled.

*if you have to take apart and clean the vacuum breaker is has to be completely removed from the boiler, if take it apart without doing so, part of the mechanism will drip inside the boiler and be very difficult to remove!!!!*


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## espressotechno (Apr 11, 2011)

A closed anti-vacuum valve will give a false steam pressure reading & low water temperature, but the boiler won't overfill.

Overfilling in this case is probably due to the cold water inlet solenoid valve not closing 100% - ? hard water scale ?


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## DavecUK (Aug 6, 2013)

espressotechno said:


> A closed anti-vacuum valve will give a false steam pressure reading & low water temperature, but the boiler won't overfill.
> 
> Overfilling in this case is probably due to the cold water inlet solenoid valve not closing 100% - ? hard water scale ?


You are correct, but could be a combination of both, each one intermittent, as the second post described the problem, but it was slightly different.



> Well, so, I got up a little later than anticipated. The steam boiler pressure gauge read about 2.75 bar, but the PID display showed normal bumping around between 257 and 260. At least there wasn't a big puddle again! I bled water off through the.......


This is the subtle difference...


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## emradguy (May 24, 2014)

Didn't get a chance to open her up last night, but today everything was normal. It's unlikely I'll get a chance to open her up before next week, given we're traveling for Thanksgiving (yeah, I'm a yank), but I'll report back once I can.


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## emradguy (May 24, 2014)

So everything remained normal after the last fiasco self-corrected...until today. The problem has recurred, but of course, it's not exactly the same...or so it seems.

I woke up today to a fair amount of water on the counter, etc, and a tripped GFCI. (My machine is on a dedicated GFCI 20 Amp 110V circuit with a Panamax surge protector and then an Intermatic Timer - also 20Amp rated - so it comes on at about 5:30am, and I got downstairs today around 7a). After cleaning up the water mess, I opened up the machine, removed the solenoid between the pump and steam boiler, cleaned it thoroughly and put it back together. Intermittent blasts from my wife's hair dryer and a couple of hours later, I was able to plug the machine back in without tripping the circuit again, and then fire her up. All seemed to be going well, until the steam boiler temp got high enough to increase it's pressure, and then water started coming out of the safety valve, steaming off the top of the boiler and then the GFCI tripped again. Obviously, I unplugged her and flipped the on/off switch, but now I'm kind of baffled. Oh, I also opened the steam valve and drew a little over a pint of water off the steam boiler via the hot water pipe. During the warm up, the pump never came on. My machine is plumbed, and so now I'm wondering if the solenoid is bad and so the line pressure overfilled the boiler, with the solenoid stuck open, or what. During warm up, water was sort of bubbling through the vacuum breaker silicon tubing (which I'm guessing is normal during warm up), and water does drip into the drip tray via the 3-way valve tubing.

It's now about 10 minutes later. I plugged the machine back in, and it didn't trip the GFCI again. I turned it on and the pump did it's normal topping off of the boiler and shut off. I have to run out on an errand, but intend to first check for a reply here, and second, turn the machine back on and see if it happens again.

ok, so I'm back and have the machine on. Everything seems to be ok now. I'm thinking I'd better replace my solenoid?

Any other helpful thoughts would be greatly appreciated!


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## DavecUK (Aug 6, 2013)

emradguy said:


> ok, so I'm back and have the machine on. Everything seems to be ok now. I'm thinking I'd better replace my solenoid?
> 
> Any other helpful thoughts would be greatly appreciated!


OK you have a steam boiler pressure gauge and a temperature indication on the PID.

1. If the machine was getting too hot and the pressure increasing, it would hiss steam loudly the temperature would also be high

2. If the machine isnt hissing really loud, but the water is coming out of the safety valve...a lot, then the boiler is probably overfilling (especially if it isn't getting overly how on the PID). If your line pressure is higher than 2 bar, it will easily fill the steam boiler against a leaky solenoid

3. As the pump isn't necessarily running when it does it, then the autofill probe is certainly doing it's job

4. If it was a faulty safety valve it would hiss all the time, but you wouldn't get lots of water

5. if you run it from the tank...I'll bet you won't get a problem for a much longer time, although the steam boiler will gradually fill each time you make a coffee.

*I would replace the auto-fill solenoid valve and see if that solves the problem...it's an inexpensive part and at worst you will have a spare.*

*
*


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## emradguy (May 24, 2014)

Thanks Dave...yet again!

To respond to your comments:

Yes, steam boiler pressure reads just under 1.5 bar and PID fluctuates in the 258-260 range (where it's set)

1. hissing softly, while at temp. I made a couple of lattes and the hissing disappeared until the temp and pressure returned to rest.

2. water is no longer coming out of the safety valve. Line pressure is in the 3.0-3.5 bar range.

3. I agree, the auto-fill probe does seem to be doing it's job.

4. It is hissing softly all the time. However, I have the housing off now. I understand putting the housing on won't stop the hissing, but it may be soft enough that I wouldn't hear it (which would otherwise make me say, no it's not hissing). I guess what I'm trying to say is...should it not hiss at all, or is only loud hissing worrisome?

5. I'd really hate to run from the tank. Been there, done that, so to speak and it's not a m.o. I'd want to return to.

yeah, thanks for the affirm on the replacement solenoid. I'll definitely order one.

So, please tell me if this makes sense...

My solenoid failed (stuck open), causing my boiler to overflow. The safety valve did it's job, allowing both steam and water to run out of the too full boiler. the water spillage tripped the GFCI. I woke up and found the mess. Despite the water leak, it wasn't enough to reduce the steam boiler to the correct volume, and in fact, the solenoid probable never closed allowing line pressure to keep the boiler too full, so that after I cleaned the solenoid, the boiler still needed to be bled some. The repeat problem I actually witnessed was from the already too full boiler (hence, the pump not coming on during warmup). Once I bled the boiler, having already cleaned the solenoid, the machine was back to operational.

I'm now in the market for a replacement solenoid and possibly a new safety valve (depending on if the my low volume hissing is worrisome). I guess if that's a cheap part too, I'll replace it as well.


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## emradguy (May 24, 2014)

So, I spoke to a tech at Chris' Coffee Service. He said he thinks my solenoid is fine and I only need to replace the boiler relief (safety) valve.


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## emradguy (May 24, 2014)

Yesterday, I had an online text chat with a tech at espressoparts who helped me diagnose my issue. As it turns out my autofill probe needed cleaning, and yeah, my boiler safety relief valve (OPV) needs replacing. In our discussion, we reasoned the solenoid is fine. If it weren't, the line pressure would be driving water out the faulty OPV at a steady rate...and it's not. Having cleaned the autofill probe and tested it for continuity with a multimeter, my machine is again working normally (except for the soft hiss from the faulty OPV. A replacement valve is on order.


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