Nosleep Senior Member Joined: 17 Dec 2003 Posts: 82 Location: California Expertise: I love coffee
Espresso: Isomac Tea Grinder: Rocky Doser, Solis Maestro Drip: French Press, Bialetti Roaster: Hearthware I-roast,...
Posted Sat Nov 24, 2007, 7:46am Subject: Isomac Tea Pressure Issue - I am stumped
I have searched the forum and attempted to locate advice, so my apologies if I am redundant.
My Tea is 4 years old. For the first three years, I would get shots with about 1 3/4 ounces, thick/oozing with the pressure hitting around 9 3/4, with the max set at 10.2. The max number is what I saw with the blind filter in.
For the last few months, the pressure was going lower, I could not get a shot (except sporadically) with more pressure than 6 or 7. I also needed to grind successively finer.
I had a new pump put in as well as a group head reassembly/descaling/flushing.
Now:
My pressure is at 10.5 with the blind portafilter. I still need to grind fairly finely (one or two clicks left on a Rocky) The pressure only goes to the 7 to 8 range when pulling a shot. I get exactly two ounces in 25 seconds (from pulling the lever, the pressure moves up at 8 seconds).
If I grind more finely/tamp hard/add more coffee, I can get pressure in the 9 + range but the machine basically chokes and issues only an ounce of liquid.
Is this normal? Should I be getting more pressure at the time I brew a shot.
Qualitatively, the coffee is good but it still does not "ooze" as much as it did when the machine was new and, perhaps, it is a bit more sour than I am used to.
jbraman Senior Member Joined: 1 Dec 2002 Posts: 124 Location: Fort Wayne, IN Expertise: I love coffee
Espresso: La Spaziale Vivaldi S1 Grinder: la Cimbali Jr.; Solis... Drip: Technivorm Roaster: Hottop;Behmor 1600
Posted Sat Nov 24, 2007, 8:52am Subject: Re: Isomac Tea Pressure Issue - I am stumped
I had a "Tea" for several years and upon reading this, felt that your boiler might need de-scaled,however,that has apparently been done.
Several thoughts;
Check all tubing and connections for a small leak. ( I had tubing that due to positioning, melted through).
Sour shots, indicate possible temperature issues IMO and I recall replacing thermostats at least twice in two years.
Because of similar issues that you have described and a perceived lack of repeatability, upgraded to a La Spaziale Vivaldi and have been very satisfied.
The "Tea" was a good machine and a very good learning experience, but I had a good share of component issues and lost patience and tired of not knowing what I was going to get from shot to shot.
Also found this post that discusses Isomac pressure click here Good Luck with your troubleshooting.
JGG Senior Member Joined: 31 Mar 2006 Posts: 947 Location: Kentucky, US Expertise: I like coffee
Espresso: PID Silvia; PID Alexia Grinder: Mazzer Mini E (A), SJ; Rocky... Roaster: Hottop D w/PID; Thermometric...
Posted Sat Nov 24, 2007, 10:26am Subject: Re: Isomac Tea Pressure Issue - I am stumped
The symptoms (high static pressure, low dynamic pressure) suggest that an unintended constriction (scale?) is causing losses when there is water flowing. I'd look for the constriction between the pump and wherever the tap is for the pressure gauge. If the losses were occurring downstream of the gauge, it would read nearer the static value.
Nosleep Senior Member Joined: 17 Dec 2003 Posts: 82 Location: California Expertise: I love coffee
Espresso: Isomac Tea Grinder: Rocky Doser, Solis Maestro Drip: French Press, Bialetti Roaster: Hearthware I-roast,...
Posted Sat Nov 24, 2007, 12:45pm Subject: Re: Isomac Tea Pressure Issue - I am stumped
I removed the smaller top nut (there were two, the top one about 1 inch in diameter, the second more than 2 inches). Inside was the screen. Completely clean. At the bottom of the well was the pinhole. Completely clear.
I am starting to think it is the gauge or the tubing to the gauge. I just ran the blind filter and it only went to 8.0. Two weeks ago it was at 10.5 (when I brought it home after the new pump was installed and the machine descaled).
Not only that, but 10 minutes later I checked again. This time the blind filter reading was 9.0............
chriscoffee Senior Member Joined: 5 Mar 2002 Posts: 197 Location: Albany Expertise: Professional
Posted Sat Nov 24, 2007, 1:03pm Subject: Re: Isomac Tea Pressure Issue - I am stumped
It could be your expansion valve. That is what controls your pumps maximum out put pressure. the ones used in Isomac machines were not that good a quality. If you plan to keep the machine I would upgrade your expansion valve.
Chris Nachtrieb, Pres. Chris' Coffee Service, Inc.
Posted Sat Nov 24, 2007, 2:05pm Subject: Re: Isomac Tea Pressure Issue - I am stumped
Nosleep Said:
I removed the smaller top nut (there were two, the top one about 1 inch in diameter, the second more than 2 inches). Inside was the screen. Completely clean. At the bottom of the well was the pinhole. Completely clear.
I am starting to think it is the gauge or the tubing to the gauge. I just ran the blind filter and it only went to 8.0. Two weeks ago it was at 10.5 (when I brought it home after the new pump was installed and the machine descaled).
Not only that, but 10 minutes later I checked again. This time the blind filter reading was 9.0............
I assume that when you had the mushroom out you glanced at the upper pipe opening and didn't see any crustiness... If so you can be sure your decal methods are working great. Amazed the screen was clean if this was the first time you've been in there - great job!
Check the tubing from the reservoir that goes into the pump - make sure it's not pinching during operation, and cut the reservoir end on a slant to prevent bottom sucking.
Also make sure water is not seeping out the E61 bottom or lever seals during a pull.
I suppose there might be sporadic gunk in the capillary tube to the gauge, but I don't recall seeing that as a prob on these forums.....
Preparatory to trying Chris' idea you could disassemble the OPV and check that it's clean and shiney.
Nosleep Senior Member Joined: 17 Dec 2003 Posts: 82 Location: California Expertise: I love coffee
Espresso: Isomac Tea Grinder: Rocky Doser, Solis Maestro Drip: French Press, Bialetti Roaster: Hearthware I-roast,...
Posted Sat Nov 24, 2007, 4:19pm Subject: Re: Isomac Tea Pressure Issue - I am stumped
Sorry, I was not clear before. I just had the machine descaled, flushed group assembly rebuilt.
I did not send it back to Chris only because I was not excited about the costs and timing of shipping.
I am concluding it is the pressure gauge or the connections (capillary tubes?). Earlier today, the machine maxed out at 8.0 with the blind filter. An hour later is was at 9.0. Three hours later it was at 10.5 (the pressure I was getting immediately after the rebuild).
I read somewhere here that the gauge can be erratic if there is moisture in the capillary tubes. Does this sound like the issue?
Is this the type of symptom that would relate to Chris' reccomendation about the expansion valve?
Posted Sat Nov 24, 2007, 5:32pm Subject: Re: Isomac Tea Pressure Issue - I am stumped
no, you said it, I just didn't read it. sorry.
Okay, so machine trucked to Chris who did work and trucked it back and then prob started immediately? Or did prob start a while after? or was that the reason it was shipped to be fixed? or? (timing?)(and what time of year was it shipped?)
What I'm wondering is if the gauge went screwey. I had one machine arrive where both gauges were uniformly and consistantly 1/8 of a turn (45 degrees) high. I removed the gauges, removed the needles, replaced the needles at zero and never had any more problems or inconsistancies. This would NOT explain a variable gauge unless someone here has had that experience. I've had other machines arrive with no gauge problems.
Do unscrew the OPV valve and check the spring and seal, just to have that out of the way.
Also check the number on the pump.
Also hold the reservoiv return tube in the air and check it for an undue amount of water flow during a pull. Also no kinks in that line.
I find it tougn to believe that there is no one on the west coast that can bench an Isomac and figure out what is wrong.
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