jduvivier Senior Member Joined: 14 Mar 2009 Posts: 6 Location: California Expertise: I love coffee
Espresso: Isomac rituale
Posted Fri Jan 11, 2013, 10:21pm Subject: Pump runs constantly on Isomac Millennium
The pump on my Isomac Millennium started running continuously. I timed the duration and it runs for 60 seconds and stops. If you turn the power switch off and leave it off for a few seconds it will start again for 60 seconds. It will continue in this fashion for as long as one is willing to repeat the sequence. When the pressure sensor finally achieves full pressure the red light indicator turns of and the green light turns on, however the pump will continue to cycle in the same way. It is clear that there is a sensor which is not working or the controller unit has failed in some way or ??????? Does anyone have an idea what this might be. Thanks for your help.
DavecUK Senior Member Joined: 21 Sep 2005 Posts: 923 Location: UK Expertise: I love coffee
Posted Fri Jan 11, 2013, 11:34pm Subject: Re: Pump runs constantly on Isomac Millennium
Unfortunately it sounds like the Proelind control unit (depending on how early the model is) may have failed. I would think these might work out a bit expensive in the US, replacing it with a Gicar RL30 or similar (which might be cheaper) for your voltage is possible, but would require some knowledge to do successfully. All these units have a timer sequence which slightly overfills the water in the steam boiler (this prevents constant" burping" of the pump to keep it topped up while steaming, as would happen if the pump when on and off whenever the autofill probe was uncovered/covered. I guess if this bit of the circuitry has gone wrong, it could give this unusual problem.
I can't really think of anything else in the Millenium that could go faulty and cause a timed 60 second fill each time it's switched on. The sensor that switches the pump on/off is a simple resistance probe in the steam boiler.
P.S. I am making the assumption that if the lever is lifted, then water is actually flowing from the group...or the steam boiler is overfilling, or significant water is flowing from the expansion valve, because if these things are not happening, then you could have a different problem?
jduvivier Senior Member Joined: 14 Mar 2009 Posts: 6 Location: California Expertise: I love coffee
Espresso: Isomac rituale
Posted Sat Jan 12, 2013, 11:04am Subject: Re: Pump runs constantly on Isomac Millennium
Thank you for your response. Yes when it is pumping the relief valve is working. When I lift the lever switch water comes from the group head so I believe that all the other functions work correctly. I forgot to mention that after cycling the pump through 8 or 10 of these cycles the pressure/temp rises and the red light indicator turns off and the green light indicating that pressure in the tank is correct turns on. If the cycle terminates at this point the green light will turn off in the normal amount of time but the red light indicator will not turn back on and the machine does nothing other than loose temperature and pressure. In addition if you leave it on indefinitely it will never turn on again although the main power switch is still on. I have looked at wiring diagrams for the US unit and I don't see anything that indicates there is a timed circuit in either the unit or the controller. The controller is a Giemme and as you guest is about $160.00 US which is why I was reaching out to see if there was hope for a less expensive solution. Also I don't want to spend the $160 unless it actually will solve the problem. Thanks again.
DavecUK Senior Member Joined: 21 Sep 2005 Posts: 923 Location: UK Expertise: I love coffee
Posted Sat Jan 12, 2013, 5:06pm Subject: Re: Pump runs constantly on Isomac Millennium
I am afraid US pricing for those units really sucks, we used to be able to get them for $60 a few years ago, but they are now about $125 in the UK. Unfortunately it's a safe bet that the Giemmie box has gone. They are sometimes repairable and this might be your next move. They are quite simple inside. Again with a little knowledge and skill a repair may well be affected for a few $
Inside they have a logic circuit/IC this is not repairable, but it's not usually the problem, it's generally one of the more mundane components such as a relay. Often it will be obvious, so definitely worth a try.
jduvivier Senior Member Joined: 14 Mar 2009 Posts: 6 Location: California Expertise: I love coffee
Espresso: Isomac rituale
Posted Mon Feb 18, 2013, 8:13pm Subject: Re: Pump runs constantly on Isomac Millennium
Just wanted to thanks you for your comments and describe what I eventually determined the problem to be in case someone else encountered the same. After staring at the wiring diagram I decided to test two things, the sensor for the boiler water and the solenoid valve that controls water going into the boiler. I pulled the lead from the water level sensor and touched it to the boiler while the pump was running. The pump immediately stopped running which told me that either the boiler didn't have enough water in it to ground the water level sensor or there was a problem with the grounding circuit which based on the diagram could only be broken by the solenoid switch, or at least it looked like that. I removed the solenoid and tested it for continuity and it seemed to be all right. Then a disassembled the solenoid and found that the plunger was somewhat stuck once I got it out of the valve I cleaned it and examined the body of the solenoid and discovered that the opening in the body was plugged with a small chunk of debris. I clean it out made sure it worked properly, reassembled the parts and turned on the unit. It all worked perfectly, who knew. Thanks for your attention.
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