Water pump sporadic cycling - accumulator?

[sailorbenji]

Hi,

I've tried to google this, but get false results as I get a load of pages explaining water pumps pulsing etc without an accumulator, but whilst water is being demanded.

Our issue is that the water pump occasionally runs (like every 5 minutes or so). I'm aware, of course, that this is down to the system pressure dropping below the "switch on" pressure of the pump...

I've explored every inch of piping I can get to, and certainly all of the joints and junctions that the pipework makes...and can find absolutely no sign of a leak in the pressured water system anywhere. For good measure, I tightened up every hose-clamp, but still have this frustrating 5 minute cycling.

We have an accumulator in the system (just a very small shurflo one), and I wondered if this could be the cause of the issue?

So, that's my question, could a failed diaphragm in an accumulator cause a pressure water pump to cycle occasionally, with no demand for any water supply occurring? Or do I need to go further exploring....

 

[thinwater]

If the diaphragm failed you have no accumulator.

The leak down can be a tiny leak backwards through the check valves in the pump. It may be the pump valves, not the accumulator. If it is quiet enough, you might be able to here the leak.

Most likely, some of both.

 

[PaulRainbow]

Also, check the pressure relief valve isn't releasing pressure.

 

[HunterWanderer]

Its probably some debris in the pump itself under the poppet valves allowing the pressure to release back to the inlet.
Usually quite easy to clean and put back.
If it is, then add a jabsco pumpguard water filter to the inlet hose to prevent it happening again.

 

[VicS]

Agreed It is almost certainly water leaking back though the pump due to debris in the valves but if you have a hot water system check the relief valve as P Rainbow suggests.

 

[vyv_cox]

Others beat me to it. Debris in the inlet valve is most likely. Is there a suction strainer? This helps considerably in keeping debris out.

 

[sailorbenji]

Thanks all. I had indeed thought of the hot water relief valve, I've given it a few twist/clicks which as I understand it should help re-seal that if it was leaking.

Having not found evidence of a leak on the pressured side anywhere, the advice to check valves preventing water returning back to the inlet is great, and I'm fairly confident it will turn out to be correct.

The pump is an ancient (original to build in 2002) Shurflo. Has no name on it, just a long reference, so I'll try and dig out any online documentation I can.

Thanks all!

 

[Jodel]

The most frequent source of this problem is the cockpit shower leaking.

 

[sailorbenji]

The most frequent source of this problem is the cockpit shower leaking.

Indeed(!!), ours split a few seasons ago, replaced it fully and double and triple checked it this time, no sign of a leak at all.

 

[Irish Rover]

@sailorbenji Did you find the source of your problem and how did you fix it? I have the same issue now.

 

[Irish Rover]

@sailorbenji Did you find the source of your problem and how did you fix it? I have the same issue now.

I checked everywhere I could and found no trace of a leak. I disconnect the feed from the pump to the accumulator tank - these quick connect fittings are a God send. I ran the pump a let a couple of litres flow into a bucket. I reconnected, and hey presto, problem solved. Not for the first time, thank you to @vyv_cox + @VicS and @HunterWanderer .