Water pump problem

[Happydays66]

Hi

I have replaced a leaky shurflo 30psi pump with a new shurflo 30psi pump. Whilst I don't expect the same performance as mains flow the pulsing of the water is that prominent my water heater pulses along with it. I have tried adjusting the pump but it makes no difference. I fitted a water expansion tank and set the pressure in relation to the pump and it makes no difference. The water out of the hot tap heats enough through the taps but had shower hot tap is always cold. This wasn't a problem with the old pump. Any ideas as to what it could be please?

[Geo]

Hi

I have replaced a leaky shurflo 30psi pump with a new shurflo 30psi pump. Whilst I don't expect the same performance as mains flow the pulsing of the water is that prominent my water heater pulses along with it. I have tried adjusting the pump but it makes no difference. I fitted a water expansion tank and set the pressure in relation to the pump and it makes no difference. The water out of the hot tap heats enough through the taps but had shower hot tap is always cold. This wasn't a problem with the old pump. Any ideas as to what it could be please?

 

Where is the accumulator fitted in the system?

 

What pressure is the accumulator set to?

[blackrose]

Switch the pump off, open a couple of taps to let the pressure out, set the accumulator tank to about 4psi below the pumps cut in pressure. (You should have a cut in and a cut out pressure on the pump or in the specs).

 

See if that works.

[Sea Dog]

Hi

... I fitted a water expansion tank and set the pressure in relation to the pump and it makes no difference.

As above, what pressure have you set? The accumulator should be about 3psi lower than the pump pressure, so 27psi in your case. If it's set too hard, it might as well not be there which would give the symptoms you describe.

[mross]

Is there air in the accumulator - there should be!

 

Does pump stop and start when one tap is open?

Edited November 4, 2016 by mross

[IDS]

Simple accumulator functional test. Turn off all tabs. Turn on pump, wait until pump stops, turn off pump. Turn on a tap and collect the water in a measuring jug and measure how much water you get. If you get about half the volume of the accumulator then everything is set up fine. If you get nothing then either the accumulator is isolated from the system or there is too much pressure in it. Release some pressure and repeat the test see if that improves things. Adjust the pressure in the accumulator until you get about 1 litre from a 2 litre accumulator.

[ditchcrawler]

Simple accumulator functional test. Turn off all tabs. Turn on pump, wait until pump stops, turn off pump. Turn on a tap and collect the water in a measuring jug and measure how much water you get. If you get about half the volume of the accumulator then everything is set up fine. If you get nothing then either the accumulator is isolated from the system or there is too much pressure in it. Release some pressure and repeat the test see if that improves things. Adjust the pressure in the accumulator until you get about 1 litre from a 2 litre accumulator.

An easy way of setting it up as most people don't know if their pump is supplying 25 or 30 psi or somewhere in between. Best have a greenie (or is that greeny)

[Happydays66]

Thanks for your feedback. I was looking for the starting pressure or cut in pressure in the pump instructions but couldn't find any info so set the accumulator to 30psi. I will try out all your suggestions when I'm back on the boat on Sunday and let you know what happens.

[DHutch]

Moved to 'Building and Maintenance' section.

 

 

Daniel

[ditchcrawler]

Thanks for your feedback. I was looking for the starting pressure or cut in pressure in the pump instructions but couldn't find any info so set the accumulator to 30psi. I will try out all your suggestions when I'm back on the boat on Sunday and let you know what happens.

It didnt make noises as you pumped it up did it.

[Tony Brooks]

Good rule of thumb is to pressurise the accumulator to about half the pump cut out pressure.

[Sea Dog]

Good rule of thumb is to pressurise the accumulator to about half the pump cut out pressure.

An even better rule of thumb, since he says he fitted an accumulator when he replaced the pump, would be to follow the instructions that came with it (or are printed on the side of it if it's a Jabsco)!

[ditchcrawler]

An even better rule of thumb, since he says he fitted an accumulator when he replaced the pump, would be to follow the instructions that came with it (or are printed on the side of it if it's a Jabsco)!

Assuming he can measure the pump output pressure.

[Sea Dog]

Assuming he can measure the pump output pressure.

Well it's a new pump too so he always could RTFM with that as well! Actually I think he did, cos he said it was 30psi. OK there's probably a bit of a tolerance on the pump output so it might not be exactly the 30psi to within 0.001psi, but it'll be close enough to set his accumulator by.

 

Both my (Jabsco) accumulator and pump are very clearly marked as to how they should be set and what their output pressure is respectively. If Shurflo don't do that, it will be in the paperwork or on the box. Failing that, I'll bet the instructions for the ones he bought are on the Web.

[mross]

Can OP confirm if expansion tank was fitted when the previous pump was working? I think he fitted the expansion tank after the new pump but that means the boat had no expansion tank originally which seems odd.

[Sea Dog]

Can OP confirm if expansion tank was fitted when the previous pump was working? I think he fitted the expansion tank after the new pump but that means the boat had no expansion tank originally which seems odd.

That's how I read it too (or at the same time as the new pump).

[blackrose]

Can OP confirm if expansion tank was fitted when the previous pump was working? I think he fitted the expansion tank after the new pump but that means the boat had no expansion tank originally which seems odd.

 

It's not that odd is it? My first boat didn't have one - quite a few don't. Also just to clarify, we are talking about accumulator tanks here aren't we - not expansion tanks?

[PeterDHS]

Any tips for actually inflating/ measuring the accumulator pressure ?

I find it very hit and miss. Awkward location etc and the very process of unscrewing the airline loses 10 psi so you never know the actual pressure.

[Sea Dog]

Any tips for actually inflating/ measuring the accumulator pressure ?

I find it very hit and miss. Awkward location etc and the very process of unscrewing the airline loses 10 psi so you never know the actual pressure.

The airbag is quite small, so you don't need anything which delivers a high volume of air or hisses like crazy whilst you unscrew it. I use my car foot pump with a built-in gauge and a push-on cam lock end which pulls off quickly without losing significant pressure. A (schrader fitting) bicycle pump together with a press-on pencil style pressure gauge would be even easier really.

[blackrose]

Any tips for actually inflating/ measuring the accumulator pressure ?

I find it very hit and miss. Awkward location etc and the very process of unscrewing the airline loses 10 psi so you never know the actual pressure.

I just use a tyre pressure gauge (pump must be off and taps open). Unscrewing the airline? The only thing I unscrew is the dust cap on the end of the valve. You shouldn't lose any pressure doing that. Use a bicycle pump to inflate.

Edited November 4, 2016 by blackrose

[Iain_S]

Thanks for your feedback. I was looking for the starting pressure or cut in pressure in the pump instructions but couldn't find any info so set the accumulator to 30psi. I will try out all your suggestions when I'm back on the boat on Sunday and let you know what happens.

 

That will be too high, as that is the pump cut out pressure.

 

Ideal is JUST below pump cut IN pressure, but it's not that critical, and half cut out pressure should be fine.

 

The pressure can be measured with a tyre pressure gauge on the accumulator valve, which will show EITHER the pressure in the water system, or the pressure the accumulator is charged to, whichever is the higher.

[blackrose]

 

That will be too high, as that is the pump cut out pressure.

 

Ideal is JUST below pump cut IN pressure, but it's not that critical, and half cut out pressure should be fine.

 

The pressure can be measured with a tyre pressure gauge on the accumulator valve, which will show EITHER the pressure in the water system, or the pressure the accumulator is charged to, whichever is the higher.

Isn't that why the pressure should be set with the pump off and taps open? Then you know you're checking the accumulator pressure.

[Tony Brooks]

To clarify what Blackrose said.

 

Pump off, taps open = measure pressure. If at or higher than the pumps cut out pressure let air out until about 10 psi.

 

Tap closed, pump on with pressure gauge on accumulator. This will now read the pump cut in pressure.

 

Open tap and watch gauge. When the pump cuts in it will read the cut in pressure - note this.

 

Turn pump off and leave tap open. Set accumulator pressure to the cut in pressure.

 

If the accumulator air pressure is higher than the pump cut out pressure the accumulator will have no effect and the air pressure will never show the water pressure.

[IDS]

You don't need a pressure gauge if you use the volume method as described earlier. You check your accumulator setting without even going anywhere near it just using a tap and the pump switch.(remember Boyles law !) Set the accumulator inflation using a bike pump until test volume is about half the accumulator volume. This method as well as being simpler than using a pressure gauge is probably more precise than most commonly abailable cheap pressure gauges. However use a pressure gauge when setting the pump cut out pressure (measure pressure at accumulator with the pump turned on)

[blackrose]

You don't need a pressure gauge if you use the volume method as described earlier. You check your accumulator setting without even going anywhere near it just using a tap and the pump switch.(remember Boyles law !) Set the accumulator inflation using a bike pump until test volume is about half the accumulator volume. This method as well as being simpler than using a pressure gauge is probably more precise than most commonly abailable cheap pressure gauges. However use a pressure gauge when setting the pump cut out pressure (measure pressure at accumulator with the pump turned on)

 

Of course there's more than one way to skin a cat, but most tyre pressure gauges I've used seem fairly accurate when checked against calibrated gauges at work and I can't help thinking that your volume method isn't that accurate because depending on the plumbing you may be getting some unpressurised water in your jug that was left sitting in the pipes after the tap stopped running. The use of a tyre pressure gauge is about as simple as it gets. If someone can fit a new pump then surely it's not going to be too taxing to take an accumulator pressure reading.

Edited November 5, 2016 by blackrose