Stuart Turner Pump turning on and off

zzyxxx

I have a M330N Stuart Turner pump and it will come on at random times.

Sometimes it stays on indefinitely. Sometimes it comes on for a minute and turns off.

I have searched high and low for leaks but cannot find any - pulled out the washing machine, behind toilets, put paper in the toilets to see if it gets wet, took out baseboards etc etc but there's nothing evident.

Also what's interesting is that if it comes on, if I open a tap just for a couple of seconds, then close it, the pump will stop running about 5 seconds later.

I used to have a different problem where when I turned on any tap, the pump wouldn't kick in, it would make a noise like it wanted to start (humming) but didn't properly start. Temporarily I put a magnet to the switch and it kicked in, but after a while I discovered that it was happening because a flextail coming out of the pump was bent on it's route downstairs, so I wedged the pipe straight and that one has been fine since.

I have also replaced the PCB and the capacitor recently so they should be fine.

Is there anything else I should check?

Thanks!

10-10-20

I was goint to suggest PCB and cap, but that's done. I wonder if a leaky accumulator vessel could do the same…?

zzyxxx

https://www.boards.ie/discussion/comment/122095348#Comment_122095348

Is that the pressure vessel on top, that I can pump? Would that be an easy replacement?

10-10-20

https://www.boards.ie/discussion/comment/122095877#Comment_122095877

That, I'm not sure about. I'm hoping somebody else on here might know. You could try phoning Domestic and see what they say:

https://www.domesticpumps.ie/

Actually the parts are all listed there, but I'm only guessing on the cause. I wouldn't like to cause you to waste 69 EUR on a rough guess.

GreeBo

https://www.boards.ie/discussion/comment/122095877#Comment_122095877

Check the pressure of the pressure vessel, if its low then it can confuse the pump, the last one I had was just a standard tyre valve.

zzyxxx

There was no pressure in the vessel so I pumped it a bit, checked it again a few hours later and there was no pressure in it again.

Does that mean it needs to be replaced?

10-10-20

https://www.boards.ie/discussion/comment/122111719#Comment_122111719

I'd say it does.

GreeBo

Try closing the valves on the pump and see if it still turns on by itself.

That would confirm that its not a leak anywhere.

But if your pressure vessel is on 0 bar then that will cause the pump to do weird things as the water heating and cooling will change the pressure and confuse the flow switches/pump.

The guys in Modern Plant look after these pumps in Ireland, so should be able to sort you out with a replacement vessel.

zzyxxx

Anyone know the procedure for replacing the pressure vessel?

I'd imagine step 1 is to disconnect power to the pump?

Does the pump need to be drained / how would that be done?

GreeBo

https://www.boards.ie/discussion/comment/122139377#Comment_122139377

I Would also disconnect the power :)

But from what I remember there is a couple of screws over a face plate and then the vessel itself screws off, then you "just" need to repressurize the new one.