[Matt Stanley]

Hi all
I’ve got a 4 stage pumped RO unit, which I’ve had for 4 years+ and it’s been working perfectly until this evening.  When I turned the unit on, the pump started and the system performed its usual 5 second back flush cycle. However, when the system switched from back flush to normal production the pump cut out. I’ve checked the water supply to the system and there are no blockages after the RO unit, so I’m a bit puzzled.
Has anyone any ideas?
Many thanks
Matt

[Don Kee]

Is the pump hot to touch before it cuts out?

It might be that the water running through the pump has left deposits on the bushes over the years and that now the pump is having to work a lot harder.
The extra friction might be causing a shed load of heat causing the thermal cut off to kick in?

[Matt Stanley]

Hi Don
Thanks for getting back to me.
No, the pump isn’t hot at all. I’ve just tried it again after the system being off all day and the pump starts up briefly and then just cuts out. I’m happy to buy another pump, but I just didn’t know whether there are other components that might be at fault.
Thanks again.

[H2GoKent]

Don't be insulted if you have, but have you changed the pre-filters?

With RO equipment it can be frustrating so what I always did was construct a kind of flow chart in my mind or on paper.
Start off with the obvious and work through.
Is the pressure switch on the pump faulty, is all wiring connected, is the inlet water flow same as usual. Do the pre-filters need changing?
Asking these basic questions and slowly going through them helps.

I'm sorry if this sounds a bit patronising it's not meant to.
I know when mine went wrong I would get annoyed and stop thinking logically.

[dd]

If the system automatically switches from back flush to water production cycle, it seems likely that whatever electrical component regulates this is at fault.

[Matt Stanley]

Don't be insulted if you have, but have you changed the pre-filters?

With RO equipment it can be frustrating so what I always did was construct a kind of flow chart in my mind or on paper.
Start off with the obvious and work through.
Is the pressure switch on the pump faulty, is all wiring connected, is the inlet water flow same as usual. Do the pre-filters need changing?
Asking these basic questions and slowly going through them helps.

I'm sorry if this sounds a bit patronising it's not meant to.
I know when mine went wrong I would get annoyed and stop thinking logically.

I’m not insulted at all. Yes, I’ve changed the prefilters. I’m in touch with the supplier now so hopefully will be able to fault find everything on Monday. I’ll report back when I get a solution.
Thanks for your suggestions.

[Matt Stanley]

If the system automatically switches from back flush to water production cycle, it seems likely that whatever electrical component regulates this is at fault.

That was my thought - not sure what does what though 
I’m in touch with the supplier now so will hopefully get to the bottom of things on Monday.
Thanks for your response.