Posted Tue Jan 22, 2013, 7:43am Subject: Domobar Junior HX - Strange Sounds and Hissing
As per my title, I have a Vibiemme Domobar Junior HX that I really like overall. A couple of weeks ago it started to make a really strange sound on startup. It would began heating normally, but after a few moments of heating the sound of air would begin to become strong, would gradually build more until a large, emphatic puff, and then nothing. When sitting idle now, there is a constant hissing of air, a "pssssss" kind of sound.
As this is my first HX, I am not yet as familiar with all the inner workings of the machine as I would like to be. Anyone else experience something similar with their machine/any suggestions as to how I can begin to address the issue?
Here's a video of the 'opening crescendo' of air. The noise is question begins around 40 seconds until the video ends, so just skip until there:
stefano65 Senior Member Joined: 30 Oct 2004 Posts: 1,337 Location: Eugene OR Expertise: Professional
Espresso: Vibiemme,Elektra, Grinder: Vario,Macap, Vac Pot: not Drip: not Roaster: not
Posted Tue Jan 22, 2013, 7:47am Subject: Re: Domobar Junior HX - Strange Sounds and Hissing
If the hissing starts as pressure build up and eventually although it still leaks the boiler pressure builds Open the machine and check the anti-vacum valve
Posted Tue Jan 22, 2013, 8:30am Subject: Re: Domobar Junior HX - Strange Sounds and Hissing
Do you know where I could find a diagram to show me where the anti-vaccuum valve is/what to check for? I can't seem to find one online and I did not receive the manual with the machine (I bought it second hand and it was not included).
calblacksmith Moderator Joined: 25 Nov 2007 Posts: 5,683 Location: Riverside, Ca, U.S.A. Expertise: I live coffee
Espresso: ECM Veneziano A1 Grinder: Many different commercial Vac Pot: 40s era Silex Drip: Milita, Bunn&Curtis... Roaster: Cast iron pan, gas burner
Posted Tue Jan 22, 2013, 12:55pm Subject: Re: Domobar Junior HX - Strange Sounds and Hissing
Just take the top of the machine off, as it warms and the steam starts to leak, ...... you will find it.
Give it a twist or two with pliers, if it is only dirt stuck in it, that more than likely will clean it out. Even just tap the stem a few times with pressure in the system and that may be enough to do the job.
In real life, my name is Wayne P.
Feed the newbs, starve the trolls and above all enjoy what you drink!
Posted Wed Jan 23, 2013, 11:20am Subject: Re: Domobar Junior HX - Strange Sounds and Hissing
I've easily located the stem, as you said I would, and it is in perhaps the most annoying difficult spot to reach with pliers or a wrench. I fiddled with the stem to release some steam, but that didn't seem to change the constant hissing sound. So, now to take more apart. Thanks for the help so far!
Posted Wed Jan 23, 2013, 11:50am Subject: Re: Domobar Junior HX - Strange Sounds and Hissing
You might they the "Moron's Valve Job" *1 method. Allow the machine to heat up completely, then smack the valve's little steam a few times causing the valve to seat more dynamically. That might clear the scale that is likely causing it to stay open a bit.
A socket and extension should be able to access it easily (although that is a guess as I do not have personal experience with the Jr.). A larger problem may be that the machine could use a thorough descaling as sale in the valve could be an indication that scale exists in other areas of the machine. When you have the anti-vacuum valve out, use a strong light and look into the boiler. Also, pull the mushroom out of the group, allow it to dry, and check it for scale.
*1 - This is an old mechanics' trick that was used on overhead valve engines. Pull the rocker then smack the valve stem with a hammer. It caused the valve to slam shut against its seat by the force of the valve spring. The goal was to clear any stuck carbon or other debris on the valve or its seat.
calblacksmith Moderator Joined: 25 Nov 2007 Posts: 5,683 Location: Riverside, Ca, U.S.A. Expertise: I live coffee
Espresso: ECM Veneziano A1 Grinder: Many different commercial Vac Pot: 40s era Silex Drip: Milita, Bunn&Curtis... Roaster: Cast iron pan, gas burner
Posted Wed Jan 23, 2013, 11:51am Subject: Re: Domobar Junior HX - Strange Sounds and Hissing
If you could not get it to slow down or stop by fiddling with it, it is likely that the seat in the valve has gone bad. They are very inexpensive, under five dollars if I remember right. It is just the work of changing it out that can be the hard part if located in a bad spot.
In real life, my name is Wayne P.
Feed the newbs, starve the trolls and above all enjoy what you drink!
Posted Wed Jan 23, 2013, 3:07pm Subject: Re: Domobar Junior HX - Strange Sounds and Hissing
I used the trick you both suggested (shooting out steam by playing with the valve). And, to my dismay, now when I turn the machine on water is running out consistently, suggesting that the valve is probably gone, I suppose. Now to find a new valve and replace it.
Posted Wed Jan 23, 2013, 4:13pm Subject: Re: Domobar Junior HX - Strange Sounds and Hissing
TheProfessor Said:
I used the trick you both suggested (shooting out steam by playing with the valve). And, to my dismay, now when I turn the machine on water is running out consistently....
SStones Senior Member Joined: 24 Nov 2012 Posts: 209 Location: Canada Expertise: Professional
Espresso: Giga 5, ECM Giotto, Rocket... Grinder: Anfim Milano-Best Vac Pot: No :( Drip: Some $30 thing from Walmart Roaster: I buy pre-roasted.
Posted Wed Jan 23, 2013, 6:35pm Subject: Re: Domobar Junior HX - Strange Sounds and Hissing
If the boiler is overfilling, you'll want to take the boiler probe out and clean it. It will be located on top of the boiler, it will be a hexagonal fitting screwed into the boiler with an electrical connection and one wire plugged on to it. Don't just yank the probe out of the fitting. Take the wire off trying to make sure you don't move the probe mounted through the fitting. Then unscrew the fitting out of the boiler to see the bottom "Inside" end of it. It will probably be covered with calcium if the boiler was overfilling. You can simply clean it off with a wire brush, sandpaper or steel-wool. Screw it back into place with a bit of teflon tape or one of the loctite thread sealants, reattach the wire and turn the machine back on. Once it is hot enough to pressurize the boiler, open your hot-water valve to lower the water level in the boiler. When the pump comes on, the water is below the probe. Close the water-valve and when the pump shuts off the boiler is filled to the bottom of the probe, the correct level. Now... If the boiler has been over filling, I'm suspecting that your leak is actually comong out through the safety relief. The bigger thing that looks like your anti-vacuum valve.
To locate a tiny, hissing leak on a boiler. Put a butter knife in your freezer for a half hour. Take the top off of the machine and turn your machine on. Once the machine is hot put the cold knife tip near the boiler connections and near the valves on top. The steam will condense visably on the cold knife, you will see it. If it is the safety valve it might be best to replace it or have a technician replace it. We're not supposed to suggest you try to clean and set it yourself. That said, you can set your pressostat yourself and so long as the safety isn't leaking at all at 1.2 Bar, and your boiler pressure never exceeds 1.2 Bar, then Bob's your aunt's fiance.
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