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Pump intermittently turns on (at pressure and no activity)
Hi Reiss,
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.
Thanks in advance for your help,
Mark
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.
Thanks in advance for your help,
Mark
Comments
have you got all the panels on the machine?
kind regards
reiss
Yes, all of the panels are on the machine.
If you tell me not to worry, I won't or if there is some change to a setting I should make, I'll do that. I love my machine and want to make sure I've not set something up incorrectly.
Regards,
Mark
a short (20s) clip of the numbers on the pre-infusion screen would be the best way to convey this information as it would also capure the pump activity
kind regards
reiss.
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.
Regards,
Mark
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)
kind regards
reiss.
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).
Regards,
Mark
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
the instructions on how to do that can be found here; https://londiniumespresso.com/permanent-file/1336-does-the-pump-stutter-on-and-off-repeatedly-when-the-lr-is-idle
i dont understand your last paragraph
kind regards
reiss.
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.
Regards,
Mark
in that case check that the pump pressure adjustment screw is not more than two turns out from fully turned in; https://londiniumespresso.com/permanent-file/1141-lr-secondary-pressure-switch-not-turning-rotary-pump-off
kind regards
reiss.
I was having trouble getting this done and after three tries, I think it is finally the way we want. I don't need anything from you but want to document what I saw for myself and anyone else with this situation:
1. The adjustment screw on the pump was definitely too far out. I tried hand tightening it but that wasn't working. Using a 10mm wrench allows much more understanding about how many turns I had made. I didn't overly tighten when moving it in - I just put the wrench on the bolt and gently pivoted - and was able to take advantage of the wrench giving me an indication of how many turns. Each time, I was moving 1/4 turn. Because the bolt is "blind" (being under the machine), I found using the wrench helped a lot.
2. It took me three tries to get the expansion valve adjustment correct. I thought I was experiencing "opposite day" since I tried what you said and the first couple of times it wasn't working. Your directions are correct, and maybe the loosening and then tightening freed something up. Perhaps the item above (pump pressure adjusted too low) was complicating things. I did find that after removing the top to the expansion adjustment, it was "weeping" water and having a rag handy to dab it so it didn't overflow was helpful.
Anyway, I'm all good for now. I appreciate your clear directions.
Thanks for all your help,
Mark
good stuff. yes the expansion valve weeping indicates that it is working (relieving hydraulic pressure as the cold water introduced to the system is heated by the system)
happy new year
reiss.
Thanks and happy new year to you!
Best wishes for 2020,
Mark
thank you for your post
yes, that is correct; the digital pressure transducer will detect any leak in that section of the system from the non-return valve in the bottom of the manifold all the out to the piston seals, and call the pump to restore pressure
kind regards
reiss
I am running PI between 2.5 and 3.5 most of the time. My expansion valve kicks in at 12.3 bar - easy to tell this now with the app, although it confused me at first until I realised that the display goes around again once it hits 10, so 12.3 displays as 2.3.
any chance of a video clip that captures the behaviour you are experiencing?
kind regards
reiss.
The pump starts just after the pstat kicks in.
Anyhow, from looking at the pressure readings in the app I figured out what is going on. The pump is just doing its job and kicking in when the pressure drops below the set point. With my usual PI range of 2-3.5 bar it doesn't happen that often, but the pressure does fall that low from time to time. Moving the PI pressure to 6 bar causes the behaviour more frequently. Normally the pressure is around 8-12 bar.
The original question from me was whether the low pressure in the system might mean I have a piston seal leaking slightly. Is that possible, or is the occasional drop to below 3 bar normal? In my case with the expansion valve isn't an issue as I am getting the occasional check valve warning.
if it is more than 12 months, certainly if it is more than 15 months, since you changed the piston seals that is where i would start because it is the easiest and will need to be done soon anyway
because your 'pressure leak' is so slow i doubt that it is the inlet solenoid failing to fully close as a result of a piece of grit in it as it would leak much faster
reiss.
However right now from every 20 seconds or few minutes (not really related to heating cycle) my pump turn on for half a second.
Is it a sign that seals need to be changed or lubricated? Or some other problems (water level in tank)? I do not see any leaks at the moment...
Not a dramatic situation.
The Non Return Valve that's at the low end of the manifold could have a tiny bit of scale and seeping a tiny tiny bit of water back over time causing the pressure drop and causing the pump to come on. You could replace that NRV and then clean the 'old' one for later re-use.
The piston seals could be a little worn. When were they last replaced? You could order 6, replace the 3 and keep the other 3 for a later replacement.
The solenoid could be closing fairly well but not perfectly dus to a tiny bit of grit or scale. You could get a new one, and then after replacing it taking the 'old' one apart and see if you can clean it and re-assemble for later re-use. Reiss has posted a how-to do that in the permanent file area.
Solenoid was cleaned recently, don't think it is a problem. Pump for tank is usually on much longer.
Seals were replaced over a year ago. Month ago I re-lubed them, as I think there were letting some water to shower screen.
Currently, I see no leak, just the pump turn on, hence not sure if it seals or this non-return valve. Is there some good diagnostic method for this? I would like to avoid removing valves from machine, unless I know they are faulty...
I would bet on the seals then. Re-lubing may have been reasonably effective but not 100%
There's no way to "look into" the NRV unless you take it out.
If you replace the seals and the issue is gone, that was it.
If you replace the NRV and it makes no difference, that was not it.
These are relatively simple things to do with basic tools.
If you recentlly turned / dragged the machine on its feet without fully lifting it up, and it moved with a brbrpbrpb tremor, this may have slightly dislocated the simple tiny piston with its rubber ring inside the NRV and then it may allow a little leak backwards out of the manifold.
If so, a measured whack with a small hammer could shake the NRV back into the right inner attidude. If the NRV was not the issue, this whack may cause the issue to get (temporarily) worse and some tactful tapping with the hammer would help the little piston to jump into its perfrectly centered position.
I recently dragged the machine for some distance, so there is chance NRV was dislocated. Maybe I will try the hammer method, where exactly is this NRV located and where should I try to hit (middle of it or from top)?
https://kostverlorenvaart.blogspot.com/2020/09/nrv-pix-helping-out-fellow-londinium.html
So I guess I need replace it for modest sum, or splurge and go for digital kit.
Aby recommendations?