Water pump cycling

[TimCr]

Hi. I ran completely out of water. When I refilled the tank, my pump now runs for 3 seconds with an interval of 5 seconds. There’s no leak anywhere in the system so I suspect it’s a pressure valve, the pressure on the accumulator or, most likely, the pump itself. Has anyone had the same problem and what was the solution?

[Midnight]

4 minutes ago, TimCr said:

Hi. I ran completely out of water. When I refilled the tank, my pump now runs for 3 seconds with an interval of 5 seconds. There’s no leak anywhere in the system so I suspect it’s a pressure valve, the pressure on the accumulator or, most likely, the pump itself. Has anyone had the same problem and what was the solution?

I had similar trouble with a new ShurFlo I found an American boat forum which suggested I tweak the two grub screw adjusters and that fixed it. Sorry it was ages ago so can't remember which forum. Just make sure you note the starting position of the screws before proceeding.

Alternatively check your accumulator it may have punctured the diaphragm when you run dry.

[David Mack]

In running the tank dry you may have sucked crud up from the tank bottom into the pump valves, allowing water to leak back through the pump.

[bizzard]

I'd rather go cycling on my bike than on a water pump.

[TimCr]

Thanks. For more background I have a jabsco par max 2.9 with a Shurflo 182-200 accumulator 

4 minutes ago, David Mack said:

In running the tank dry you may have sucked crud up from the tank bottom into the pump valves, allowing water to leak back through the pump.

New pump then? 

[David Mack]

8 minutes ago, TimCr said:

 

New pump then? 

 

Almost certainly not. I would dismantle the pump and clean it. If you have a strainer between the tank and the pump check that too. If not, now would be a good time to fit one.

[Tony Brooks]

10 minutes ago, TimCr said:

Thanks. For more background I have a jabsco par max 2.9 with a Shurflo 182-200 accumulator 

New pump then? 

 

No, fit a flap type plumbers non-return valve in the supply pipe to the pump, just make sure you get it the right way round.

[ditchcrawler]

2 hours ago, TimCr said:

Thanks. For more background I have a jabsco par max 2.9 with a Shurflo 182-200 accumulator 

New pump then? 

Where is the strainer that should be between the pump and the tank to catch the crap

 

[Tony Brooks]

Just noticed the thing marked accumulator looks very small for  a typical canal boat so that won't help the cycling much.

[ditchcrawler]

If you give the pump a good run with as many taps open as possible, say for 10 minutes or so you may be lucky and flush it out, but please get a strainer also look at having short lengths of hose before and after the pump, it takes the strain off the connections. I would not consider taking the pump apart as they can be buggers to stop leaking afterwards

 

edit

Just noticed it is hose on the suction side where the strainer should be

 

Edited May 24, 2021 by ditchcrawler

[TimCr]

46 minutes ago, ditchcrawler said:

If you give the pump a good run with as many taps open as possible, say for 10 minutes or so you may be lucky and flush it out, 

yep. Tried that. Spent a very long wet morning at Ellesmere services filling up and flushing. 
 

so I need a non-return valve and a strainer in there between the pump and the tank in the section at the top of the photo. Also  I have read that the accumulator pressure might not match the pump pressure which is between 1 bat and 1.7 bar on this model of pump

56 minutes ago, Tony Brooks said:

Just noticed the thing marked accumulator looks very small for  a typical canal boat so that won't help the cycling much.

There’s also an accumulator on the calorifier

[ditchcrawler]

20 minutes ago, TimCr said:

 

There’s also an accumulator on the calorifier

That is an expansion vessel similar but different 

[Tony Brooks]

35 minutes ago, TimCr said:

There’s also an accumulator on the calorifier

 

As Brian says, similar but different. I would say may well be identical to the eye.  An accumulator is pressurised to about the pump cut IN pressure or about half the cut out pressure. The expansion vessel is pressurised to the pump cut OUT pressure or a tad less so the pump will never produce enough pressure to compress the air in the accumulator.

 

If by some chance there is not a non-return valve in the cold feed to the calorifier then provided the expansion vessel is depressurised to the accumulator pressure it will work as both but with far less expansion capacity.

[TimCr]

Update. I was unable to resolve the issue for 3 weeks so I bit the bullet and bought a new pump (with strainer). Just prior to installing the pump I washed my hands. The hot tap spluttered and the problem resolved itself. Must’ve been a bubble of air in the system somewhere!!!  Now I have a spare pump ?

[Opener]

12 minutes ago, TimCr said:

Update. I was unable to resolve the issue for 3 weeks so I bit the bullet and bought a new pump (with strainer). Just prior to installing the pump I washed my hands. The hot tap spluttered and the problem resolved itself. Must’ve been a bubble of air in the system somewhere!!!  Now I have a spare pump ?

Hey-ho!! That's boating for you!!?