koffeekev Senior Member Joined: 21 Jul 2002 Posts: 693 Location: Connecticut Expertise: Professional
Posted Fri Aug 6, 2004, 12:53pm Subject: Need help brainstorming problem PLEASE?
Here are the details. Rebuilt Rancilio S-29 automatic, commercial, water line fed, rotary pump, HX espresso machine.
All was well after replacing heating element and cleaning entire boiler and componants. I returned the machine to it's owner and didn't hear a word for at least 3 months. The complaint was too much steam volume and milk not frothing correctly. Being a little puzzled I checked the system and found water coming from the steam valve in strange little bursts. Adding boiling water to milk is a sure way to flatten the foam.
Sometimes the steam is dry and quiet, other times it's almost straight water. Most times it steams then lets out a burst at any given moment. The burst of water will startle you and soak your hand in a couple seconds flat. It will do it if the pressure stat is open or closed. I checked the water level and changed it from very high in the boiler too very low and everywhere in between. No difference. The boiler is not overfilling. The exchanger is not cracked. Steam build up is fine with no hisses or leaks. The only thing that is certain is the problem seems to be more pronounced after pulling a couple of shots but that may be a coincidence. I am at a wall. Any ideas? Questions? Kevin
malachi Senior Member Joined: 5 May 2002 Posts: 1,758 Location: SFCA Expertise: I love coffee
Espresso: Monster Mia (for now)_ Grinder: Monster Cimballi Junior Vac Pot: Not any more Drip: never Roaster: Ecco, Stumptown, Intelli,...
Posted Fri Aug 6, 2004, 1:40pm Subject: Re: Need help brainstorming problem PLEASE?
is it possible that the water level is fluctuating severely over time?
i'm just trying to think of why it would become more noticable after pulling shots and the only things i can think of are water fill, water temp and pressure. hmmm... just typing out loud so to speak...
koffeekev Senior Member Joined: 21 Jul 2002 Posts: 693 Location: Connecticut Expertise: Professional
Posted Sat Aug 7, 2004, 9:42am Subject: Re: Need help brainstorming problem PLEASE?
All of my and my co-workers deductive reasoning skills have been exhausted with this one. I definately need help from someone outside my circle.
Here is my time line. Original repair. Inlet solenoid failed, boiler ran dry, blew heating element and solenoid coil. Opened boiler, removed all the sludge left from machine that hadn't been filtered in 10 years. Terrible water quality. Heat exchanger and all tubes almost closed shut from build up. Could not find correct heating element from my suppliers but found a Bunn heater of the same wattage and size that fit perfectly. Put everything back together, tested on my bench for a week and returned to customer. All is great.
Three months later I get a call that something is wrong with the steam wand, volume too high, will not froth correctly. I figured it was time for remedial training, tip cleaning or pressure adjustment. What I found baffled me on-site so I brought in a loaner machine and brought this back to the shop.
I first thought that the level probe was too high so I pushed it in as far as practical. No change.
Then I thought maybe the level probe was too low causing the water to really boil as soon as the heater kicked in creating mass turbulance. I pulled the probe up as high as practical. No change.
In the mean time I disconnected the supply line to the (new) inlet solenoid to see if it was malfunctioning by allowing water to pass by and over fill boiler. No such luck.
Final thought was a rotted heat exchanger allowing water in to boiler causing over fill. Split the boiler and removed base through the bottom of the frame keeping the top with heater, exchanger, probe, anti-siphon etc. intact. Disconnected auto fill and heating element and turned brew switch to bring exchanger pressure to 9 bars thereby forcing water out of any hole in the exchanger. Dry as a bone.
The level is fine as is the heating cycle, pressure shut down and all obvious functions. For no reason and with no warning water will blow out of steam wand. It could be 5 seconds or 40 seconds from opening valve. Sometimes it's heating or not heating. At one point I opened the steam valve and pointed it off of my bench towards the floor. It made a puddle 20 inches in diameter. Sometimes it will run itself out of dry steam and never squirt water.
Posted Sat Aug 7, 2004, 11:18am Subject: Re: Need help brainstorming problem PLEASE?
Weird. Chris' theory was the first thing that occurred to me. More information is needed... how about temporarily installing a sight glass to observe the water level directly? You probably have enough parts in your bin to rig something up. Oh, if you tap the vacuum breaker during one of these spurts, does wet steam come out there too?
Posted Sat Aug 7, 2004, 11:59am Subject: Re: Need help brainstorming problem PLEASE?
My first thought was a leaking inlet solenoid, but you've eliminated that.
I'm clutching at straws, but is it possible that water is somehow collecting in the steam valve or steam wand intermittently? As you know, most steam arms spit water on first use after sitting idle for a while. Obviously, water gets into or condenses in these valve/arm assemblies. But usually, once the arm is cleared, nothing but dry steam. Could something be increasing the rate at which water condenses in the arm/valve? Maybe water backs up in the valve and gets released when steaming??? I know this sounds pretty far-fetched, but this one is weird. Try repacking the steam valve???
koffeekev Senior Member Joined: 21 Jul 2002 Posts: 693 Location: Connecticut Expertise: Professional
Posted Sat Aug 7, 2004, 12:32pm Subject: Re: Need help brainstorming problem PLEASE?
The two things that I will try next will be replace the heating element with a factory replacement. What if the Rancilio one was insulated to only provide heat at the bottom 1/3? Perhaps even though they are both rated 1300 watts there is some difference I don't know about between Italian vs. American products.
My next thought would be the anti-siphon. It does seem to bubble slightly when this is happening. The valve is much larger than any I stock. I would have replaced it as a matter of course if I had one. Once right after it acted up I shut the machine down, let off the pressure and removed the anti-siphon and shined a flash light in. The boiler was not over filled.
On other machines I have witnessed serious turbulance in the site glass when water was removed via the tap though I can't seem to remember the cause. Thanks
koffeekev Senior Member Joined: 21 Jul 2002 Posts: 693 Location: Connecticut Expertise: Professional
Posted Sat Aug 7, 2004, 12:37pm Subject: Re: Need help brainstorming problem PLEASE?
Going back to the non stock element replacement. What if the pressure was greater coming from the steam wand. So much so that is was empying the boiler faster than it could be replaced? Do you think it could somehow create enough turbulance to to actually imitate boiling water jumping (for lack of a better word) up and out? What if I tried a two hole tip to test the theory? I really like brainstorming. Thanks
malachi Senior Member Joined: 5 May 2002 Posts: 1,758 Location: SFCA Expertise: I love coffee
Espresso: Monster Mia (for now)_ Grinder: Monster Cimballi Junior Vac Pot: Not any more Drip: never Roaster: Ecco, Stumptown, Intelli,...
Posted Sat Aug 7, 2004, 12:49pm Subject: Re: Need help brainstorming problem PLEASE?
i like Dan's idea. can you install a sight glass?
my only other guess would be that the element you're using is creating the problem - either through something odd like your speculative "asymetric" heating idea or simply as a result of too rapid or too slow a cycle.
something about the "boiling water" theory strikes me as important. i think it's the whole turbulance thing - it would explain the pulsing, etc. hmmm...
malachi Senior Member Joined: 5 May 2002 Posts: 1,758 Location: SFCA Expertise: I love coffee
Espresso: Monster Mia (for now)_ Grinder: Monster Cimballi Junior Vac Pot: Not any more Drip: never Roaster: Ecco, Stumptown, Intelli,...
Posted Sat Aug 7, 2004, 12:54pm Subject: Re: Need help brainstorming problem PLEASE?
wait... two quick questions...
1) are the same symptoms occurring at two locations? or were they isolated to that shop? 2) is the brew pressure at the group consistent or does is see fluctuation (less severe but more than you would expect)?
koffeekev Senior Member Joined: 21 Jul 2002 Posts: 693 Location: Connecticut Expertise: Professional
Posted Sat Aug 7, 2004, 2:23pm Subject: Re: Need help brainstorming problem PLEASE?
It is weird isn't it?
I don't think a site glass is possible because this is a top load boiler. It has a plated solid drum that attaches to a brass plate that itself is attached to the frame and group assembly. The exchanger is a vertical tube that hangs low in the boiler. There are no holes on the drum so how would I create a gravity level system?
The symptoms are occurring at both locations and with differing incoming water pressures
The brew is fine, no spiking at all.
I'm happy to bring this head scratching dilemma to the forums. It's nice to not be the only one with a motivated, if not confused, noggin.
To Rick. I forgot to address the steam valve idea. If you saw how it was acting you probably wouldn't consider it a valve problem. It seems to just happen at any time. Sometimes it is dry as dust with the pressure down to 0.3 bars running out fast and all of a sudden...................water in your hand.
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