House Pump Won't Turn Off (sometimes)

[carlyai]

I have a small Mitzubishi 155 W pump from a 3000 L water tank, through a 3 stage passive filter system, supplying the house and yard.

 

The feed to the kitchen goes through an RO filter system for our drinking water.

 

The power feed is one phase, through an Over and Under voltage protector. 

 

There is also a bore pump on the same phase, with an Over and Under voltage protector.

 

Sometimes, often after a power phase failure (but not always), the house water pump turns on and keeps running.

 

I have checked the RO unit and it is not backwashing or filling the tank, I have checked that all taps are off and the toilets aren't leaking, and I have checked the OverUnder voltage relay and it is on, and working OK. This doesn't seem to happen with the bore pump.

 

If I turn a tap on there is instant water.

 

So I try and turn taps on and off, also turn the power on and off and the pump keeps going, then , for some reason stops, and everything is back to normal.  Turn a tap on and off and the pump goes on and off.

 

Trouble is the problem is intermittant. Once a week, once a fortnight, once a day, and nothing I do seems to fix it, it just comes good.

 

If it was a faulty pressure switch, wouldn't the fault be there most of the time?

Any ideas?

 

 

[sidgy]

I have had similar problems with my Hitachi water pump, usually occurred after power outage, and the wife turning on taps whilst no electric.
This has led to excess air getting in the system and solved by bleeding air out top of pump and filling with cup of water,
On my pump this is located at the very top of pump,


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[Artisi]

As above, I would check pump prime, if "air-locked / unprimed" the pump can not achieve pressure to activate the high pressure switch. 

 

" ..... nothing I do seems to fix it."  ----  that do you do? 

 

[colinneil]

We used to have a problem with our house pump not turning off.

Got man out to fix, thinking we will need new parts.

Problem fixed in 3 minutes   ANTS they were stopping the terminals meeting.

Quick clean job done. Now my wife uses ant chalk around the pump every few weeks.

[carlyai]

Sorry i did not answer, I did not get the replies, just checked tv.

 

I think i may have found the problem.

 

I think the pump turns off when it becomes overheated; thermal cutoff, that's why it seems random.

 

I'll change the pressure switch tomorrow morn.

 

The pump is so silent, and out the back, that it is hard to hear.

 

Specially if you've 'pulled the pud' too long and gone deaf...(blindness happened years ago).

 

And watching the ooo.i

[Artisi]

what model Mitsubishi is it, would help with analysis of the problem. 

 

It might not be a pressure switch problem.

[carlyai]

On Monday, August 08, 2016 at 8:59 PM, Artisi said:

what model Mitsubishi is it, would help with analysis of the problem. 

 

It might not be a pressure switch problem.

Hi

 

Yeah, seems to be a switch problem.

 

The pump is a wp155 hitachi.

 

I caught it when it wouldn't turn off and took the cover off the switch and gave it a bump and it 'clicked' and the pump shut down.

 

Turned a tap on and switch operated but would not turn pump off when tap turned off, so I put a phillips screwdriver in the pump adjust screw and turned it clockwise and anticlockwise a few times, and that seemed to fix the problem.

 

The pump can run for ages and get very hot before it trips out on heat. I never thought the overheat trip worked.

 

NOTE IF ANYONE WHO IS READING THIS, AND NOT FAMILIAR WITH THE SWITCH IT IS LIVE, SO YOU NEED AN INSULATED SCREWDRIVER TO ADJUST THE SWITCH.

 

I'll get a new switch next time in Mukdahan.

Thanks for the replies.

 

 

 

 

 

[carlyai]

Went to Muk and bought a switch for B500 but haven't got round to installing it yet as I have had no more trouble with the pump.

 

Just must have been that intermittant sticking pressure switch. ?