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Hi, 
Please could someone advise me on an occasional leak from the safety valve in my expobar dual boiler? 

 

It’s about 5 years old and I bought it second hand about a year ago. It’s worked well but recently it has occasionally leaked a big pool of water while warming up. 

 

I finally managed to see it leaking earlier today. After changing the vacuum breaker and water level probe (which seemed like potential candidates) it occurred to me that using the hot water tap might give it a good test as the steam boiler pressure would drop and force it to refill and heat up again. So I emptied ~200ml of hot water and watched while the lid was still off. The pump kicked in to refill it but didn’t switch off- water then started squirting in all directions out of the safety valve. I switched it off again at the point. After drying things off I switched it on and it worked fine with no leak.

 

It seems like it wasn’t registering the water level. Perhaps due to a dodgy wire/connection rather than the probe itself. I’m no expert though and there may be other more likely causes I haven’t thought of.

 

Does anyone have any suggestions for things I should look at or troubleshooting I can try?

 

 

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Could be the control unit which is hooked up to the water level sensors.

Theres not too much can go wrong with the sensors but the control unit can fail or have a loose wire.

Quickmill Andreja Premium---Eric's E61 Thermometer---Eureka Mignon---MBK 58.35mm---Grindenstein

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Is the water level probe you replaced the original with of the same length? 

Check the connection is good with the control box and find the ground wires and make sure it/they hasn't come loose or is covered in scale from the leak.

Could also be the gicar box itself.

I'm assuming since you haven't mentioned a time scale that this is immediately after replacing the probe and could not be caused by scale. 

 

ACS Minima (Beta) with Bianca Paddle -- Reskinned Ceado E8, Niche Zero --- Gene Cafe CBR101 with Dimmer Mod and Bean Mass Probe

WATER CALCULATOR

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5 minutes ago, Rob1 said:

Is the water level probe you replaced the original with of the same length? 

Check the connection is good with the control box and find the ground wires and make sure it/they hasn't come loose or is covered in scale from the leak.

Could also be the gicar box itself.

I'm assuming since you haven't mentioned a time scale that this is immediately after replacing the probe and could not be caused by scale. 

 

Thanks Rob,

The new probe wasn’t the cause of the leak, I was just trying to rule it out as a potential cause as it’s a cheap part. It only sometimes leaks on startup though. A dodgy connection could explain it I guess. 

I’ll check the wiring again and see if I can measure the resistance across the connections.
Yes the probe is the same length- I had to cut/file it so I made double sure! 

Cheers,

Pete

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21 minutes ago, NJD1977 said:

Could be the control unit which is hooked up to the water level sensors.

Theres not too much can go wrong with the sensors but the control unit can fail or have a loose wire.

Thanks NJD - I’ll recheck the wiring and hope it’s something simple. I’m guessing the control unit isn’t the cheapest to replace!

Pete

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Check any earth connections.   Also check the fill solenoid / possible scale or sticking

I think there is an O P V after the pump I would have thought this would return the water to the tank before opening the  safety valve ?

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Thanks El Carajillo - I appreciate the help.

The earth connections measured ok. I just retested the water level probe connection and it had a slight resistance (~1 Ohm) when cold which didn’t seem quite right. I’ll switch it on and test it when warm today - the resistance may be high when hot and causing it to overfill. It seems like the machine has an electrical/electronic fault as it worked immediately after switching it off and on. The one time I saw water spraying out of the safety valve I could hear that the pump was still running. So it didn’t seem mechanical. I’m aware I may be missing something though. 

The OPV seems fine as I can see it working while pulling a shot but you make an interesting point about it coming out of the safety valve rather than OPV. Perhaps it came out of both and I was too busy looking at the water spillage and switching the machine off to notice :) 

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Fairly cetain the 'opv' is just part of the brew circuit and the water to the service boiler doesn't pass through it. If the service boiler is overfilling when pulling shots it could be the solenoid failing to close properly. A simple test is to draw water off the service boiler by the hot water tap, measure the volume, then after the autofill is triggered measure again. Then pull a few shots against a blind basket and draw water off from the service boiler untill the refill is triggered and measure the volume. It should be comparable to the previous amount (the first draw off was to 'reset' the boiler fill level).

If it's just filling from the autofill and not stopping it's the gicar box or wiring, or a scaled probe. It's possible a wire itself is broken especially if it has been kinked, trapped, or tugged.

ACS Minima (Beta) with Bianca Paddle -- Reskinned Ceado E8, Niche Zero --- Gene Cafe CBR101 with Dimmer Mod and Bean Mass Probe

WATER CALCULATOR

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19 minutes ago, Rob1 said:

Fairly cetain the 'opv' is just part of the brew circuit and the water to the service boiler doesn't pass through it. If the service boiler is overfilling when pulling shots it could be the solenoid failing to close properly. A simple test is to draw water off the service boiler by the hot water tap, measure the volume, then after the autofill is triggered measure again. Then pull a few shots against a blind basket and draw water off from the service boiler untill the refill is triggered and measure the volume. It should be comparable to the previous amount (the first draw off was to 'reset' the boiler fill level).

If it's just filling from the autofill and not stopping it's the gicar box or wiring, or a scaled probe. It's possible a wire itself is broken especially if it has been kinked, trapped, or tugged.

I did wonder after I typed it, is it just solely the brew circuit 

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Would a stuck solenoid cause the pump to continue to run though? I wouldn't think it would but I am not all that familiar with this machine.

My first thought was faulty probe but if that is all ok then I would be looking at the PCB as the culprit.

 

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Firstly I would check ALL connections very carefully. As the Gicar sends and receives signals from the various components, poor / damaged / corroded contacts could affect signals to open / close solenoid / signal to pump / signal from fill probe to turn off pump / close S/valve.

Remove fill probe again and clean thoroughly (pot scourer) Don't get grease or oil on the probe.

Remove and check solenoid fill valve / as well as operation of solenoid.

As far as I know the only way co check Gicar is by substitution

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It may be worthwhile to run an extra earth cable directly from the boiler to the reference earth pin on the gicar. Don't just rely on the boiler to frame bolts to provide continuity.

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Londinium L1, Compak E8, Gaggia OWC, Kitchenaid Artisan, ECM Giotto, Gene Cafe 101.

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Good point about the opv being part of the brew circuit - I think I understand that now. (It’s on page 3 of the Bella Barista pdf but I missed that when I was looking at it.)
I’ve replaced the water level probe and will give the cables a more thorough test. The cable connecting the probe is kinked (under a cable tie which I’ve now removed) so I’ll replace it once I get some suitable cable and terminals. 

While I’m in there I’ll take a good look at the solenoid too.
Thanks for all the help everyone!

 

D858A85B-2C5E-4744-8435-5ED3A2E49A4C.jpeg

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14 minutes ago, VonPete said:

Good point about the opv being part of the brew circuit - I think I understand that now. (It’s on page 3 of the Bella Barista pdf but I missed that when I was looking at it.)
I’ve replaced the water level probe and will give the cables a more thorough test. The cable connecting the probe is kinked (under a cable tie which I’ve now removed) so I’ll replace it once I get some suitable cable and terminals. 

While I’m in there I’ll take a good look at the solenoid too.
Thanks for all the help everyone!

 

D858A85B-2C5E-4744-8435-5ED3A2E49A4C.jpeg

Looks like you might have found the cause.  

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ACS Minima (Beta) with Bianca Paddle -- Reskinned Ceado E8, Niche Zero --- Gene Cafe CBR101 with Dimmer Mod and Bean Mass Probe

WATER CALCULATOR

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4 minutes ago, El carajillo said:

Where does the white single cable coming from bottom right go ??  That looks almost like a cut in it, has it fractured any strands ?

That’s connecting the water level probe so could well explain the over filling if it doesn’t always conduct properly. The photo makes it look worse than it is but the sleeve is clearly damaged so the strands may well have suffered. I’ll replace it and see how it goes. 

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I thought I’d post back now that I’ve fixed the problem. At least I think I have - it was always intermittent so it could still come back to haunt me!

In the end I believe it was down to a bad capacitor in the control box. It hadn’t yet burst but was clearly swollen and read 18uF on my multimeter and not 470uF. (The replacement read 473uF which is well within tolerance and it also has a higher max operating temp.) 

I also replaced a few things that may have brought it back to working order.

  • I initially replaced the water level probe as its a cheap part to rule out. 
  • I replaced the cable attaching the water level probe as it had a couple kinks caused by tight cable ties.
  • I also replaced the service boiler earth cable as it was thin with scorched/brittle plastic and had a tarnished connector.

Thanks for the pointers and helpful input. And if anyone wants a replacement capacitor for the same control unit I now have 9 spares in my box of random components.
 

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