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Water pump always running (pressure switch or leak?!) Pressure switch replacement.


James H

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The accumulator and the schraeder valve on it is a red herring as far as the root cause of @LadyG's problem is concerned. The core bit is that something is depressurising the water system when it shouldn't be, or the pump is thinking the system is depressurised.

So before, the pump would run occasionally when the pressure dropped below its cut in pressure, then stop when it reached its cut out pressure. This would happen intermittently, which @LadyG has assumed is down to a dripping tap. Now, with the bladder in the accumulator being depresurised by the valve having been accidentally pressed, anything which either causes the system pressure to drop, or makes the pressure switch think it has dropped, will make the pump come on, but the effective lack of an accumulator will mean that it comes up to cut out pressure very quickly and going through this cycle every minute. Water is basically incompressible, so without the air in the accumulator acting as a spring, the pressure in the pipework will rise and fall very quickly, with only tiny leaks, or more water added. There is either a leak in the water system somewhere, or the pump internal one way valve is leaking back to the water tank and letting the pressure out that way.

Pressurising the accumulator again needs to be done, but won't solve the fundermental problem of the pump coming on every so often, just make it less frequent. The source of the pressure loss needs to be found. Either a leak in the plumbing, or the pump back flowing.

If there is an on/off valve between the water tank and the pump, then this can be used to test the pump internal non return properties. Closing the valve after the pump comes up to pressure and stops will prevent that pressure being lost back to the water tank. If this stops the pump cycling every few minutes, then the pump is the problem. If the pump starts up and won't stop, because it can't now draw water from the tank, then there is a water leak downstream from the pump.

There could still be a dripping tap, which needs fixing, or there could be a leak elsewhere, filling the bilge, or going overboard, if it is a dripping PRV that is plumbed that way.

Jen

47 minutes ago, LadyG said:

I read a few Threads and they all talk about cycling. I don't know what this is.

Not a push bike. Cycling is a way of describing any repeating pattern. Stop start, up down, etc. So in this case, the pump starting, stopping, then some time later starting, stopping and so on.

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  • 1 month later...

OK so I ran out of water, the pump has stopped working. I wanted to check that the trip switch had not reset to off, now this is a kind with orange switches and black push buttons.

I have set all the switches up in the same way, other things are working,, but the pump is still not working, and the trip switch seems to be OK.

I have added five litres only to the tank, do I need to add a lot more, obviously im not at a waterpoint, and its -5C outside, snow and ice.

Edited by LadyG
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1 hour ago, LadyG said:

OK so I ran out of water, the pump has stopped working. I wanted to check that the trip switch had not reset to off, now this is a kind with orange switches and black push buttons.

I have set all the switches up in the same way, other things are working,, but the pump is still not working, and the trip switch seems to be OK.

I have added five litres only to the tank, do I need to add a lot more, obviously im not at a waterpoint, and its -5C outside, snow and ice.

If you have a voltmeter, measure the voltage at the pump. 

 

A pump running dry for short periods of time should not damage it. 

 

How do you know you have run out of water? 

As well as ensuring any fuse/circuit breaker is intact, make sure all in line switches are turned on. 

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3 minutes ago, LadyG said:

Yes, tx, I left the thing to settle don't, and it did.

Ok, then if it isn't simply a blown fuse or switch that is off then if its the same 20 year old pump as before, it may be on borrowed time. 

Edited by rusty69
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1 hour ago, rusty69 said:

If you have a voltmeter, measure the voltage at the pump. 

 

A pump running dry for short periods of time should not damage it. 

 

How do you know you have run out of water? 

As well as ensuring any fuse/circuit breaker is intact, make sure all in line switches are turned on. 

09.00 Hmm, yes, all inline switches are on.

10,30 UPDATE, i remember finding another switch which is not far from the water pump last night, it was running so I turned it off, I tried turning it on again and it does seem to be sound as though it might be pumping water, no water is coming out of taps, but they seem to have a tiny bit of air /water coming out of the tap when I turn it on. I think the best thing is to try to get more water in to the tank.

 

The water stopped coming out of taps, both are mixers.

The water tank has been dipped, empty, apart from the 5l from the nearest tap, I think I'll have to get some some more.

The pump is not making any attempt as far as I can tell, it is not easy to hear it at the moment due to general road noise.

No sign of a  thaw, there is a water tap fairly close.

What voltage is needed to make pump work, it's close to my bow batteries, are you suggesting no power is getting to the pump, or not sufficient power?

Edited by LadyG
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5 minutes ago, LadyG said:

Hmm, yes, all inline switches are on.

The water stopped coming out of taps, both are mixers.

The water tank has been dipped, empty, apart from the 5l from the nearest tap, I think I'll have to get some some more.

The pump is not making any attempt as far as I can tell, it is not easy to hear it at the moment due to general road noise.

No sign of a  thaw, there is a water tap fairly close.

What voltage is needed to make pump work, it's close to my bow batteries, are you suggesting no power is getting to the pump, or not sufficient power?

Try giving the pump a tap or two with a bit of wood or heel of a shoe, on the metal motor part not on any plastic part with it switched on. You need a lot more water.

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7 minutes ago, LadyG said:

Hmm, yes, all inline switches are on.

The water stopped coming out of taps, both are mixers.

The water tank has been dipped, empty, apart from the 5l from the nearest tap, I think I'll have to get some some more.

The pump is not making any attempt as far as I can tell, it is not easy to hear it at the moment due to general road noise.

No sign of a  thaw, there is a water tap fairly close.

What voltage is needed to make pump work, it's close to my bow batteries, are you suggesting no power is getting to the pump, or not sufficient power?

I'm not suggesting anything, just that if you can, measure the voltage at the pump to eliminate a faulty fuse or switch further back up the line. You ideally want more than 12V on it. It will obviously be lower when its running.

 

If you can't hear the pump, you should at least be able to feel it, if you put your hand on it. 

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8 minutes ago, LadyG said:

What voltage is needed to make pump work, it's close to my bow batteries, are you suggesting no power is getting to the pump, or not sufficient power?

 

Actually you don't need voltage to make the pump work, you need sufficient amps BUT as it is voltage that pushes the amps (electrons) around the circuit insufficient volts can't push sufficient amps so with THE CIRCUIT IN GOOD CONDITION and WITH THE PUMP SWITCH TURNED ON you need to see at least 12V at the pump connections. It is no good doing it with the pump turned off.

 

The point is no one knows if power is getting to the pump or not because we are not on the boat with a meter.  The foirst step in the diagnosis now is to see if there is 12V at the pump with the circuit turned on.

 

If there is but the pump wont run then there is every chance the pump is faulty, be it the internal  pressure switch or, if it is 20 years old, worn out motor brushes. In either case experience shows a new pump is the easiest solution but if you know how to bypass the pressure switch and the pump runs fitting an external (Square D type) pressure switch is an effective repair.

 

To bypass the pressure switch locate the single wire running form the box like end structure on the pump and into the cylindrical motor body. Push a pin through the center of the cable. Then use a bit of cable or metal to join the positive in the connector where the pump wiring joins the boat's wiring to the pin. If the pump runs (with sparks at the pin probably) then you can be fairly sure the pressure switch is at fault.

 

 

9 minutes ago, rusty69 said:

It will obviously be lower when its running.

 

 

True but if it is more than (say) 0.5V lower(I would prefer 0.2 to 0.3) then it indicates excess  volt drop on the circuit.

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3 minutes ago, Tony Brooks said:

 

True but if it is more than (say) 0.5V lower(I would prefer 0.2 to 0.3) then it indicates excess  volt drop on the circuit.

It should still run though, albeit with low voltage. I was just trying to find an easy way to determine there is actually power at the pump without investigating fuses and switches nearer to the battery.

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1 minute ago, rusty69 said:

It should still run though, albeit with low voltage. I was just trying to find an easy way to determine there is actually power at the pump without investigating fuses and switches nearer to the battery.

 

Agreed, she needs to do that ASAP to confirm thee is at least some power at the pump.

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45 minutes ago, LadyG said:

10,30 UPDATE, i remember finding another switch which is not far from the water pump last night, it was running so I turned it off, I tried turning it on again and it does seem to be sound as though it might be pumping water, no water is coming out of taps, but they seem to have a tiny bit of air /water coming out of the tap when I turn it on. I think the best thing is to try to get more water in to the tank.

Ah, update indicates if the pump is now running, you need to fill your tank. Turn the pump off until you do.

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1 hour ago, LadyG said:

10,30 UPDATE, i remember finding another switch which is not far from the water pump last night, it was running so I turned it off, I tried turning it on again and it does seem to be sound as though it might be pumping water, no water is coming out of taps, but they seem to have a tiny bit of air /water coming out of the tap when I turn it on. I think the best thing is to try to get more water in to the tank.

 

 

As Rusty said, sounds like you have got the pump running.

 

That second  switch is an object lesson on really getting to know your boat.

 

Personally I would ignore any circuit breaker as far as switching is concerned and use a pair of two way house light switches, one by the sink and one by the basin in the toilet compartment, to drive a simple relay that turns the pump on and off. That way the pump can be controlled right by where you need water and either switch will turn the pump on or off as desired.

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Incedentally Lady G always switch the water pump off if you go out and leave the boat unattended, or you might return to find some fitting on the water pressure side has come adrift and your tank full of water pumped into the boat.

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15 minutes ago, Tony Brooks said:

 

As Rusty said, sounds like you have got the pump running.

 

That second  switch is an object lesson on really getting to know your boat.

 

Personally I would ignore any circuit breaker as far as switching is concerned and use a pair of two way house light switches, one by the sink and one by the basin in the toilet compartment, to drive a simple relay that turns the pump on and off. That way the pump can be controlled right by where you need water and either switch will turn the pump on or off as desired.

Thanks Tony, but there are more than enough switches on the boat without any attempt to change anything.

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46 minutes ago, LadyG said:

Thanks Tony, but there are more than enough switches on the boat without any attempt to change anything.

 

I was not suggesting that you should, but pointing out that switches at the point of use are far less likely to get forgotten than one that is not obvious and probably not labeled.

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43 minutes ago, Tony Brooks said:

 

I was not suggesting that you should, but pointing out that switches at the point of use are far less likely to get forgotten than one that is not obvious and probably not labeled.

We have a switch in the kitchen and one by the pump itself in addition to a circuit breaker. 

 

They are extremely useful when the tank runs empty or when pump work is required,or even draining down the pipework or relieving pressure on the pump when we are away. 

Edited by rusty69
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3 hours ago, Tony Brooks said:

 

Agreed, she needs to do that ASAP to confirm thee is at least some power at the pump.

Tx all, yes it's too icy outside to try to fill tank at this moment, I have searched boat twice and have not yet found the multimeter, or my crampons.

Now waiting for thaw. Moored at the pub, I might have to make full use of their facilities very soon!

Met office did not predict this scenario.

No boats moving today, ice on canal is pretty much established.

It's not the end of the world, plenty of coal, logs, diesel, christmas pies,  not far from shops.

Edited by LadyG
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27 minutes ago, LadyG said:

Met office did not predict this scenario.

I'm not sure the Met office have yet been able to produce an accurate weather forecast, so I don't suppose they would be much use predicting when your water tank will be empty.

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I have found a label maker to be an excellent tool to have on a boat.

When one has discovered the use for a switch/circuit breaker/fuse then It enables one to label all the said objects so that in the event of failing memory one knows what they are next time. 🤭

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14 minutes ago, Loddon said:

I have found a label maker to be an excellent tool to have on a boat.

When one has discovered the use for a switch/circuit breaker/fuse then It enables one to label all the said objects so that in the event of failing memory one knows what they are next time. 🤭

 

Or you add it and a phoot showing its location to the boat manual one is constantly updating.

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17 hours ago, Loddon said:

I have found a label maker to be an excellent tool to have on a boat.

When one has discovered the use for a switch/circuit breaker/fuse then It enables one to label all the said objects so that in the event of failing memory one knows what they are next time. 🤭

 

Indeed, the company that built my boat labelled every electrical cable at both ends as well as pipes,  valves etc.

 

It made fault finding so much easier.

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