I don't remember this happening before but since I replaced the heating element and installed the digital pre-infusion module, I hear the machine cycling the motor. At first I didn't understand the correlation but now I think I do. The boiler pressure gauge shows the pressure varying between a max of just over 1 bar to just below 0.85 bar. It appears that every time the pressure drops, which it does just because things are cooling off between heating cycles, when it gets to just below the 0.85 bar level, the pump (motor) turns on briefly and just after the pump turns on, the heater turns on. Pressure goes up, pump turns off and the cycle repeats. The pump is on for only 2-3 seconds (so not long).
The "oscillation period" is about 3 minutes - meaning that it repeats this heating and pump cycling every 3 minutes. I've just logged three cycles of this.
For my part of the world, we are experiencing cold weather and the inside temperature of the walls is about 60 degrees. I suspect this is making the phenomenon more obvious.
Is there some setting on the digital pre-infusion that I should be using to lessen this? In the past, I remember the heater repeatedly cycling but not the pump. I have the timer on the digital pre-infusion set to below 1 second.
I had turned off the machine for the day before getting the video. It is warmer today, and it is behaving as usual. Answers to your questions:
PI is set to 2.9 bar
Not sure on your second part of the question as the pump isn't running. The pressure was showing 5.9 bar when the heater turned on and then it goes up to about 8.3 when the heater turns off.
I guess I'll wait and see if it does this again and then get the video to help understand this.
If a video is still useful, I'm happy to get that.
so if you set the PI to 6.0 bar and then pull the lever to release a small amount of water, say 50mL, please tell me the highest pressure value displayed on the pressure transducer before it drops down by perhaps 0.1 bar (this is the pressure at which the expansion valve is opening)
Prior to pulling the lever, the pressure was reading 7.1 bar.
Then, over the course of about 20 seconds, it went through the following pressure readings:
0.5, 0.3, 4.4, 5.3, 5.9, 6.4, 7.0, 7.7, 8.3, 9.0, 9.5, 9.6
I have another video where because the pressure is set to 6.0, the temp (I'm guessing) causes it to drop below 6.0, which turns on the motor, then, it runs and runs as the pressure drops down to about 4.6 before it starts climbing again and switches off when it goes back to 6.0. The pump was on for a long time (about 1 minute).
im assuming you have the PI set to 6.0 bar - and from the number sequence you provide when you pull the lever and introduce cold water into the circuit it expands as it is heated, which causes the pressure to rise. this continues until the expansion valve opens, which in your case appears to be 9.6 bar
this is why your pump is blipping on
adjust the expansion valve so it does not open until say 10.5 bar
Thanks for the details. I'll try this tomorrow, following the direction that says do it when I'm not rushed!
My last paragraph was simply saying that with the Pre-infusion pressure set to 6, I had a case where the pump turned on for a minute. The start of this minute time was the pre-infusion pressure falling to 5.9, which turned the motor on, and the reported pressure continued to fall even with the motor on until it was at 4.6 bar and then the pressure rose as the pump was able to get it back up to 6.0 bar at which point the pump turned off. This seemed quite odd - having the pressure drop even though the motor was on.