VBM Junior 2b steam erratic behaviour
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- Posts: 5
- Joined: 2 years ago
Hi,
I bought a second hand VBM Junior dual boiler. The machine was heavily neglected, so I revised the E61 group and took the thing apart to clean and descale.
I renewed the teflon tubing and the pressostat.
Now, the brewing part is working ok, building 8 bar with a blind filter.
The problem is the steam part. When switched on, pressure is rising on the manometer. When using the steam/hot water tap, all works ok, the pump kicks in after a few seconds. But very soon (after 10 - 15 seconds) the pressure drops to zero, no water no steam. The pin of the anti vacuum valve goes down. After a couple of minutes for no apparent reason the steam boiler builds pressure again and water and steam can be delivered for a few seconds. What could be the cause of this?
TIA!
I bought a second hand VBM Junior dual boiler. The machine was heavily neglected, so I revised the E61 group and took the thing apart to clean and descale.
I renewed the teflon tubing and the pressostat.
Now, the brewing part is working ok, building 8 bar with a blind filter.
The problem is the steam part. When switched on, pressure is rising on the manometer. When using the steam/hot water tap, all works ok, the pump kicks in after a few seconds. But very soon (after 10 - 15 seconds) the pressure drops to zero, no water no steam. The pin of the anti vacuum valve goes down. After a couple of minutes for no apparent reason the steam boiler builds pressure again and water and steam can be delivered for a few seconds. What could be the cause of this?
TIA!
- HB
- Admin
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- Joined: 19 years ago
Sounds like the vacuum breaker isn't opening during the steam boiler's initial heating phase, leading to so-called false pressure (TL;DR - it's due to a mixture of air and steam in the boiler instead of pure saturated steam). Vacuum breakers usually stick due to scale buildup or wear.Albert wrote:But very soon (after 10 - 15 seconds) the pressure drops to zero, no water no steam.
Dan Kehn
- cafeIKE
- Posts: 4715
- Joined: 18 years ago
Sounds more like a sticky pressure stat and the steam heating element is not turning on after the first cycle.
Does the steam heat lamp light when steam boiler first heats?
Does it NOT light when the steam pressure drops after first use?
Does it light when the steam pressure again builds?
If so, it's the P-Stat
Does the steam heat lamp light when steam boiler first heats?
Does it NOT light when the steam pressure drops after first use?
Does it light when the steam pressure again builds?
If so, it's the P-Stat
Ian's Coffee Stuff
http://www.ieLogical.com/coffee
http://www.ieLogical.com/coffee
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- Posts: 5
- Joined: 2 years ago
Thanks. When I bought the machine the vacuum breaker was leaking a lot. I took it apart and descaled it and cleaned it. Now it is doing its job, you can see that: popping up when the pressure is building and sinking after that. No leaking at all (at least not noticeable).
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- Posts: 5
- Joined: 2 years ago
YescafeIKE wrote:Sounds more like a sticky pressure stat and the steam heating element is not turning on after the first cycle.
Does the steam heat lamp light when steam boiler first heats?
Indeed.cafeIKE wrote: Does it NOT light when the steam pressure drops after first use?
I don't think so.cafeIKE wrote:Does it light when the steam pressure again builds?
That was also my conclusion. I put in a brand new one today. But no change...cafeIKE wrote:If so, it's the P-Stat
- cafeIKE
- Posts: 4715
- Joined: 18 years ago
What year is your machine? The pump date is a close indicator if you can see it. The build label, if still attached, should also indicate build date. DB Jr Instructions if you don't have them.
I assume you can hear the P-Stat click when the steam valve is opened?
If the steam boiler is left, does it maintain temperature?
Is there any voltage across the overheat when the boiler is not heating?
Can you measure the resistance of the steam boiler heater when the machine is cold and when the boiler is hot after the drop in steam pressure? Be sure to unplug the machine!
It could be a bad connection somewhere in the steam circuit. Look for badly discolored wire or connector. Unplug the machine after the steam boiler reached pressure and see if any electrical component [switch, connector, wire] feels overly hot.
Be careful. There are plenty of HOT areas.
I assume you can hear the P-Stat click when the steam valve is opened?
If the steam boiler is left, does it maintain temperature?
Is there any voltage across the overheat when the boiler is not heating?
Can you measure the resistance of the steam boiler heater when the machine is cold and when the boiler is hot after the drop in steam pressure? Be sure to unplug the machine!
It could be a bad connection somewhere in the steam circuit. Look for badly discolored wire or connector. Unplug the machine after the steam boiler reached pressure and see if any electrical component [switch, connector, wire] feels overly hot.
Be careful. There are plenty of HOT areas.
Ian's Coffee Stuff
http://www.ieLogical.com/coffee
http://www.ieLogical.com/coffee
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- Posts: 5
- Joined: 2 years ago
I think I found something. The thermal safety at the steam boiler (Eletgldomm165) makes a very bad electrical contact. It breaks the contact almost when you point at it. That might be the cause of the trouble. I am trying to order a new one, and will post here if that is the solution.
Thanks for the help (the machine is from the beginning of the year 2011, already the 'new-after-2011' design).
Thanks for the help (the machine is from the beginning of the year 2011, already the 'new-after-2011' design).
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- Posts: 5
- Joined: 2 years ago
Thank you all for your help! My problem is solved, the problem was a faulty thermal safety of the steamboiler. It made contact at random, I didn't understand what was going on.
So the machine is working perfectly now.
Maybe some of you would like to hear what I did to the machine:
I bought a second hand Vibiemme Junior Dual Boiler for about $ 300.
The machine is made in 2011.
When I tried it, a lot of steam was escaping and the coffee lever was difficult to move.
The machine was heavily neglected and scaled. I took most of the machine apart and descaled it with a solution of citric acid. The steam leakage was caused by a leaking anti vacuum valve, wich was easy to repair after descaling.
I replaced the Pressostat, the thermal safety, the teflon tubing and a signal lamp.
Then I renewed the parts of the grouphead, a new lever group cam with rings, bush and spring solved the problem with the lever.
When I thought that al was ready, I still saw water leaking after testing with a blind filter.
This was caused by a leaking auto prime valve at the exit of the pump, which is very cheap to replace.
Thank you all for your help!
So the machine is working perfectly now.
Maybe some of you would like to hear what I did to the machine:
I bought a second hand Vibiemme Junior Dual Boiler for about $ 300.
The machine is made in 2011.
When I tried it, a lot of steam was escaping and the coffee lever was difficult to move.
The machine was heavily neglected and scaled. I took most of the machine apart and descaled it with a solution of citric acid. The steam leakage was caused by a leaking anti vacuum valve, wich was easy to repair after descaling.
I replaced the Pressostat, the thermal safety, the teflon tubing and a signal lamp.
Then I renewed the parts of the grouphead, a new lever group cam with rings, bush and spring solved the problem with the lever.
When I thought that al was ready, I still saw water leaking after testing with a blind filter.
This was caused by a leaking auto prime valve at the exit of the pump, which is very cheap to replace.
Thank you all for your help!