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Flojet pump sounding different


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I have a flojet pump and accumulator set up on my narrowboat. I put the pump in 2 years ago (with v helpful advice from people on this forum!!) and has worked perfectly since.

 

It's still working fine, but the noises it makes have changed slightly. I'm wondering if it's symptomatic of anything, or maybe implies it is about to fail.

 

It cuts in as usual when a tap is open and the accumulator pressure drops low enough. It then continues for 10s or so after a tap is closed as it should, still sounding normal. For a few seconds before it cuts out again it suddenly starts sounding a little bit sluggish (like its working less hard if anything), sometimes flicking between this sluggish sound and normal before then cutting out. It does always cut out in a reasonable (and it's usual) time frame so don't think it's overworking or at any risk of burning out....it just sounds weird for those final few seconds.

 

There's plenty of water in the tank, and no leaks. Have checked all the pipework forensically, and it never cuts in without a tap open so am confident about this.

 

It's only in the few seconds before it cuts out that it sounds weird, so assume it must be something to do with the pressure cut off mechanisms.

 

Ultimately it still works fine so am inclined to keep using it. It's always isolated when I'm not on the boat so would know straight away if it got worse or was cutting in/out when it shouldn't be.

 

I wondered if anyone had had similar experiences, or would suggest doing anything beyond waiting for it to fail and then installing a new one.

 

Thanks in advance!!

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4 hours ago, Sam T said:

I wondered if anyone had had similar experiences, or would suggest doing anything beyond waiting for it to fail and then installing a new one.

 

 

 

I'd suggest the electrical switch in the pressure switch is wearing out and getting high resistance just as the motor works the hardest as it approaches cut-off pressure. 

 

Time to buy a whole new water pump I suggest, ready to swap out when yours properly fails. 

 

Yes water pumps can be repaired but my own experience is repairing them is a fool's errand. Once one thing goes wrong they are approaching end of life and if youy fix that one thing, another fault promptly appears. so nowadays I just fit a whole new pump at the slightest hint of trouble.

 

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Pump noises do change over time. If you live on board, you get hyper attuned to the changes. I use the decreasing time between closing a tap and shut off to decide when the accumulator and/or expansion tank need reinflating. Other than that, I only check for leaks regularly. Unlike @MtB, I leave a dying pump in till it can no longer raise enough pressure to trigger the shut off switch, or is leaking, before replacing it. I've always meant to have a new one ready to go, but never been organised enough to actually arrange it. Some people even have a new pump already wired and plumbed in on a parallel route that can be swapped in seconds by flicking a switch and opening and closing a couple of valves.

The water pump is one of the things that is important for life on board being closer to a house than to camping, so having a replacement on hand is a good idea, as they have a finite life*.

 

*Except @blackrose, who has an immortal water pump, that originally belonged to Noah, who gave up living on board after only 40 days and 40 nights. 😀

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The pressure switch in most pumps is the weakest point, IME   followed by the shaft seal.  It is worth fitting a separate pressure switch.  Square D have a good rep and are adjustable.  It will need a suitable tee fitting in the pressure pipe from the pump to taps.

 

N

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22 minutes ago, Ex Brummie said:

Just a thought, how are your batteries? A reduction in voltage can give this symptom, and we're getting to the time of year when battery charge may lower than in the summer.

Good thought on the batteries, but I don't think so this time. They were still showing 12.8 long after dark last night having noticed the issue in the afternoon so I think I'm in the clear there

27 minutes ago, BEngo said:

The pressure switch in most pumps is the weakest point, IME   followed by the shaft seal.  It is worth fitting a separate pressure switch.  Square D have a good rep and are adjustable.  It will need a suitable tee fitting in the pressure pipe from the pump to taps.

 

N

Thanks, will look into this in more detail

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1 hour ago, Sam T said:

Good thought on the batteries, but I don't think so this time. They were still showing 12.8 long after dark last night having noticed the issue in the afternoon so I think I'm in the clear there

Thanks, will look into this in more detail

Might be worth putting your voltmeter on the motor connection while its running just to check what is getting there under load

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51 minutes ago, ditchcrawler said:

Might be worth putting your voltmeter on the motor connection while its running just to check what is getting there under load

Good idea, will have a play this evening

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13 hours ago, BEngo said:

The pressure switch in most pumps is the weakest point, IME   followed by the shaft seal.  It is worth fitting a separate pressure switch.  Square D have a good rep and are adjustable.  It will need a suitable tee fitting in the pressure pipe from the pump to taps.

 

N

An alternative is to put an automotive type relay next to the pump, with the pump's microswitch switching the relay and the relay contacts handling the pump load.

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10 hours ago, Sam T said:

Good idea, will have a play this evening

I've been messing around with a volt meter this evening. There's definitely a reading of 12.8v at the point the pump connects, so there's not a voltage drop between there and the batteries.

 

But it's not very accessible, so very tricky to get a reading at the motor with it connected and running.

 

The voltage across the batteries drops to 12.5 with it running, but never below this, even when it's making the sluggish sound.

 

With some rearranging and moving of wires I could get a reading at the motor with it running, but realise I'm not sure what this would tell me. If it was drawing more amps than it should be, or the voltage reading was unexpected, this would just confirm that I need to replace the pump, or am I looking for anything else?

 

I'm leaning towards replacing it anyway, which will probably solve any issue, but if not, I will continue diagnosing and at least I'll have a spare for next time. 

 

I would like to get away from relying on the inbuilt switch if it is prone to fail, but think I need to improve my understanding/get someone to come over and guide me through this as a longer term aim. My knowledge/ability is pretty shaky at the moment!!

 

Thans for all the useful comments.

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9 hours ago, Sam T said:

With some rearranging and moving of wires I could get a reading at the motor with it running, but realise I'm not sure what this would tell me.

It will tell you if there is volt drop between battery and motor. Your 12.8V off load is just the battery voltage and in this case has very little diagnostic value. It certainly in no way supports your view that there is no volt drop. Volt drop will not occur if no, or very few amps are flowing.

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4 minutes ago, Tony Brooks said:

It will tell you if there is volt drop between battery and motor. Your 12.8V off load is just the battery voltage and in this case has very little diagnostic value. It certainly in no way supports your view that there is no volt drop. Volt drop will not occur if no, or very few amps are flowing.

Right I see. Thank you for clarifying

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10 hours ago, Sam T said:

I've been messing around with a volt meter this evening. There's definitely a reading of 12.8v at the point the pump connects, so there's not a voltage drop between there and the batteries.

 

But it's not very accessible, so very tricky to get a reading at the motor with it connected and running.

 

The voltage across the batteries drops to 12.5 with it running, but never below this, even when it's making the sluggish sound.

 

 

If it drops to 12.5 volts at the battery it WILL be lower at the pump

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30 minutes ago, ditchcrawler said:

If it drops to 12.5 volts at the battery it WILL be lower at the pump

I see. I had misunderstood the purpose of the test you were suggesting and (evidently) how voltage drops work.

 

The 12.5 down from 12.8 at the battery is in line with how it's always been when the pumps been working properly. But I understand I haven't come close to ruling out volt drop as an issue, so will investigate further.

 

Thanks.

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11 hours ago, Sam T said:

 

I would like to get away from relying on the inbuilt switch if it is prone to fail, but think I need to improve my understanding/get someone to come over and guide me through this as a longer term aim. My knowledge/ability is pretty shaky at the moment!!

 

Some years ago I introduced a 'square D' type pressure switch into the plumbing on our boat. Should the pump internal pressure switch fail, which it has done in the past, I just connect the external switch and use that until the pump fails. Having a spare pump on the shelf to swap when the old one leaks (which it will), is then a five minute job to swap.

 

I have the external switch settings such that they are just outside that of the internal one. Not ideal, granted, but prolongs the life of a pump should the cheap micro switch fail.

 

You can, of course, change the internal micro switch for not much money, but that does mean dismantling the end of the pump.

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1 minute ago, Sam T said:

I see. I had misunderstood the purpose of the test you were suggesting and (evidently) how voltage drops work.

 

The 12.5 down from 12.8 at the battery is in line with how it's always been when the pumps been working properly. But I understand I haven't come close to ruling out volt drop as an issue, so will investigate further.

 

Thanks.

 

Don't take this as in any way authoritative but a battery voltage dropping by 0.3 volt under just the pump load looks a bit high to me. Depending upon where the meter is connected that may indicate an electrical system that is not quite correct.

 

What sort of fuses/circuit breakers does the boat use? If they are plastic/ceramic torpedo fuses make sure their tips are clean and FIRMLY held by the springy end bits. However, unless the voltage at the motor under load shows a significant drop (say 0.5V maximum) deal with the pump before even thinking about anything else.

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49 minutes ago, rusty69 said:

 

Some years ago I introduced a 'square D' type pressure switch into the plumbing on our boat. Should the pump internal pressure switch fail, which it has done in the past, I just connect the external switch and use that until the pump fails. Having a spare pump on the shelf to swap when the old one leaks (which it will), is then a five minute job to swap.

 

I have the external switch settings such that they are just outside that of the internal one. Not ideal, granted, but prolongs the life of a pump should the cheap micro switch fail.

 

You can, of course, change the internal micro switch for not much money, but that does mean dismantling the end of the pump.

I have done similar but in my case the pump is designed for a higher pressure than my system so hopefully the pump will last a bit longer. I think the lowest my pump would switch was 4 barr but I run between about 1.5 and 2 Barr

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