Hi

my liftstation control makes a chattering thunk-thunk-thunk sound for a few seconds sometimes after water has been run in the house. doesn't happen immediately after starting water flow but happens during showers and usually after other shorter uses.

I'm assuming this is the relay turning off/on quickly.

Doesn't this have to be a problem with one of the float switches?

I can't imagine a defect in the controller logic board could be causing this.

Thanks,
Tom

You need to troubleshoot the problem. Start with the float switch. Is the voltage to the controller fluttering? Is the voltage to the relay correct? Is the relay coil partially shorted? Are the relay contacts burned? All problems are "IN", until you rule them "OUT".

thanks for replying,

when I run the pump manually the relay seems to work fine - but I will make the checks you suggest

I can't really test the voltage to controller when the problem occurs because its too infrequent and random to witness it and be able to check before it stops the chattering - that's what you're talking about right, the voltage on the line to the float switch?

The voltage from the float switch, would be what I'd look at, to tell if that is the source of the problem.I don't have it in front of me, so I can only give generic advice.Troubleshooting is ABC logic. Once you've determined where the problem is, you backtrack to find it's source. Intermittent problems are a PITA. They require time and patience.

The lower float turns it off and the upper run turns it on. If the lower one is stuck so the controller always thinks the water is gone, the pump will turn on and off as the upper one floats up and down with the water level as the pump operates. This would create a rapid on/off sequence depending on how sensitive that float is the changes in water elevation and how fast the pump changes the water level.

ok - I narrowed it down quite a bit - I think its the logic board or possibly the relay (but doubt its the relay because it works fine when I operate it with the "run pump manually" switch).

as water rises in tank, first float switch closes then eventually 2nd. when 2nd closes, a fairly quiet buzzing starts (maybe more like a hum). this goes on for a while, 30 seconds to a minute I think, then the relay finally closes. This is when the loud chatter starts, sometimes it lasts for only a second then the relay closes, but sometimes it goes on longer and there's a lot of sparking between the relay contacts before it finally closes. When I run the pump with the manual switch it just closes right away, there's a quick "clack" as it closes but no chatter or extra sparking.

pump controller is CentriPro s10020 (simplex single phase 20 amps indoor)
[documentlibrary.xylemappliedwater.com]

Why I don't think the float switches are having any problems:

there are 3 pairs of terminal screws on logic board for the wire pairs to each of the 3 float switches. There's one for pump off, pump on, and alarm.
When water is lowest and all 3 switches are open, the voltage on 1 of each of the pairs is something like 90 or 100 volts (or maybe 115 I wasn't paying attention to exact value).
When float switches close these terminals are pulled down to 0 volts.

When either the on or stop switches start closing the voltmeter needle isn't erratic or jumpy (no fluttering), the needle just smoothly moves to 0 volts.

oh, and the alarm float switch never closes.



Edited 3 times.

quote; oh, and the alarm float switch never closes.

It is only supposed to "close" when the pump fails to do its job.

When you run the pump manually, what are you bypassing?

>> When you run the pump manually, what are you bypassing?

not sure. schematic in my literature shows the manual switch setting just connects something called "L1" on the logic board to neutral. when switch is set to "auto" setting, which is the normal operation setting, it connects something on logic board called "R1" to neutral.

And now things seem to have degraded on the logic board even further - relay now won't automatically trip AT ALL, when both the "start" & "stop" float switches close, where I would see the "start" and "stop" LEDs light up followed by relay tripping, now relay doesn't trip at all and both these LEDs start flashing about twice a second. I can still run the relay manually without issues, which at this point I do and at some point the "start" LED goes off and "stop" LED stops flashing and stays on, then eventually it goes off as expected when the water level goes down enough.

so I really think I've got a logic board issue and will be calling the local place I bought all the lift station parts from to see what we can do about it.


thanks to everyone for your help



Edited 1 times.

new logic board fixed it