More water pump issues

[Dr Bob]

If anyone read my other thread on pumps (in the new boating section), you may have noticed our water pump is running for a long time. Not sure how normal this is.

We have a Jabsco Par Max 2.9 (around 2 years old - from a receipt on the boat). It is approx 1 metre from the stainless water tank and installed horizonally at the level of the base of the tank. There is a filter and a stop valve upstream of the pump. About 1/2 metre downstream is an accumulator ( I think? - which looks like about 10 litres in size). The piping then runs to the sink/bathroom halfway down the boat and to the calorifier at the back.

When the pump is pressurised and turned itself off, you can run maybe a litre or two from the tap before the pump cuts in. The issue is that it then takes some time to repressurise the system even after only a few litres are taken out. Maybe 30 secs or a minute. When pressurising with no taps on, it runs very smoothly for most of the time and then at the end as it reaches pressure, it sort of hiccups a bit before switching off - at this stage you are wondering if it is ever going to get to pressure. Once at pressure, it stays off until a tap (or other) is turned on so I guess there are no leaks - ie it wont turn itself on at all during the night.

On our sailing yacht our accumulator was only a 1 lt one and so the pump came on immediately a tap was turned on and cut out 4-5 secs after the tap was turned off.

Is this behaviour normal? Should it be getting to pressure quicker?

A couple of extra points of info that may be relevant.

If there was any air in the system then I can see the pump having a hard time of compressing the air so taking a long time to pressurise. Can't see anyway of bleeding air out if it got in - ie aerated water during filling.

When we got the boat a few months back, it proved impossible to fill the water tank - ie after 20 ltrs or so the inlet was overflowing. I assumed the tank was full. Wrong. It turns out that the breather pipe from the top of the tank goes downwards and then disappear behind the side panelling - so when the tank is overfilled, the breather pipe fills with water,  which then stays put at the lowest part of the tank. This then stops the tank breathing and stops water entering the filling tube and causes a vacuum when the water pump is drawing water. God knows how long it has been operating like this but that must put quite a strain on the pump. I have therefore done a temp repair to get rid of the water and it is breathing again - and I can fill the tank. Could this have knackered the valves?

My first thoughts were to see if there was any air in the system or to drop the pressure the pump is trying to get to as there is lots of pressure and the system works really well. Unfortunately it doesnt look like you can alter the 25psi the pump is going to.

 

[rusty69]

Think the parmax doesn't require an accumulator. 

 

Eta. Have you checked the accumulator pressure? 

Edited July 2, 2017 by rusty69

[Dr Bob]

1 minute ago, rusty69 said:

Think the parmax doesn't require an accumulator. 

Yeah, that's what I read in the blurb, but there is one in the line after the pump - at least it looks like an accumulater (big red sealed container on a T piece with a pressurising valve on the other end). I would think it would be beneficial and this system doesnt pulse at all unlike the one on our old boat - and the shower is brilliant with no cycling of hot/cold at all. Water system works really well apart from the time to pressurise up.

I have bought a spare pump just in case and may swap it in (and service the old one) - but if this is all normal.........?

[rusty69]

It sounds like a large accumulator, so i can well believe it will take a while. Assuming batteries are filly charged and the accumulator pressurised correctly i would think its not unreasonable. 

 

We have a parmax 1.9. I de pressurised the accumulator, and seems ro work a bit better. (not suggesting you do that) 

[Dr Bob]

2 minutes ago, rusty69 said:

It sounds like a large accumulator, so i can well believe it will take a while. Assuming batteries are filly charged and the accumulator pressurised correctly i would think its not unreasonable. 

 

We have a parmax 1.9. I de pressurised the accumulator, and seems ro work a bit better. (not suggesting you do that) 

Batteries are nice and charged (we got another 3 added - so nearly 700aHrs).

Not been able to test the pressure on the accumulator - havent got a tester, but you can run off a litre or two before the pump cuts in so there must be some pressure and capacity in it.

[Ex Brummie]

If the accumulator is red, it should not be on a potable water system. If 10 litres or so, then repressurising time could be as you describe. When you first turn on the tap, it may be putting out water faster than your pump would do on its own, so the pump has to make up for this.

Have you checked that the calorifier does not have an air pocket in it? This could also affect the refilling time.

Edited July 2, 2017 by Ex Brummie

[rusty69]

The jabsco 2.9 should deliver 11l/m which you should be able to measure when the pump is running  , it will give you an indication if the pump is working ok.

My hunch is that it is, but worth checking the accumulator pressure when you can(ours takes a car pressure type gauge) 

 

Eta. You can also get an external square d type pressure switch if you want to set cut in/out pressures

Edited July 2, 2017 by rusty69
Pump has no i in it

[WotEver]

43 minutes ago, Dr Bob said:

The issue is that it then takes some time to repressurise the system even after only a few litres are taken out. Maybe 30 secs or a minute.

That sounds about right to me for a system with a large accumulator  

16 minutes ago, Ex Brummie said:

If the accumulator is red, it should not be on a potable water system

I don't know where you got this from but it's wrong. All Parmax accumulators are red to the best of my knowledge. 

Here's what Parmax have to say about them...

https://www.jabscoshop.com/advice-and-support/jabscoshop-about-pressurised-fresh-water-pumps.htm

[Rickent]

1 hour ago, Ex Brummie said:

If the accumulator is red, it should not be on a potable water system. If 10 litres or so, then repressurising time could be as you describe. When you first turn on the tap, it may be putting out water faster than your pump would do on its own, so the pump has to make up for this.

Have you checked that the calorifier does not have an air pocket in it? This could also affect the refilling time.

My accumulator is red. What is the problem.

[Dr Bob]

1 hour ago, rusty69 said:

The jabsco 2.9 should deliver 11l/m which you should be able to measure when the pump is running  , it will give you an indication if the pump is working ok.

My hunch is that it is, but worth checking the accumulator pressure when you can(ours takes a car pressure type gauge) 

 

 

Now that is a good idea. I hadnt thought of measuring the flow rate. We are back home for a few days so I will check it out on Wednesday when we get back.

[Dr Bob]

1 hour ago, WotEver said:

That sounds about right to me for a system with a large accumulator  

 

Thanks for that, it sounds re-assuring.

[Ex Brummie]

 British standard marking for expansion vessels (accumulators) is red for primary heating circuits, white or blue for potable water. The red ones are not coated to resist tainting the contents. They are also likely to corrode quickly with the continual introduction of fresh water leading to premature failure.

 If there is a label on the vessel, it is worth checking the full specification. Some imported makes may well be exceptions to this rule.

[monkeyhanger]

3 hours ago, rusty69 said:

The jabsco 2.9 should deliver 11l/m which you should be able to measure when the pump is running  , it will give you an indication if the pump is working ok.

My hunch is that it is, but worth checking the accumulator pressure when you can(ours takes a car pressure type gauge) 

 

Eta. You can also get an external square d type pressure switch if you want to set cut in/out pressures

I have a Parmax 2.9 on my boat. What should the accumulator pressure be set at please?

[rusty69]

7 minutes ago, monkeyhanger said:

I have a Parmax 2.9 on my boat. What should the accumulator pressure be set at please?

Set it to pump cut in pressure or just below, so 15psi,although as i mentioned earlier the parmax instructions suggest an accumulator is not required with these pumps, so im not 100% sure

[monkeyhanger]

8 minutes ago, rusty69 said:

Set it to pump cut in pressure or just below, so 15psi,although as i mentioned earlier the parmax instructions suggest an accumulator is not required with these pumps, so im not 100% sure

Thanks for the prompt reply.

[WotEver]

57 minutes ago, rusty69 said:

... as i mentioned earlier the parmax instructions suggest an accumulator is not required with these pumps...

Yes it does but the page I linked to earlier suggests that it's still a good idea to fit one. 

https://www.jabscoshop.com/advice-and-support/jabscoshop-about-pressurised-fresh-water-pumps.htm

[Dinz]

Is the pump inlet from tank smaller bore or restricted in any way?

[Sea Dog]

Dr Bob, I replaced my Parmax 2.9 recently and, because it was cheap enough, replaced my 0.5ltr accumulator at the same time. I went through the same 'it says it doesn't need an accumulator' thoughts but decided: a. that I would keep one in the system and b. that, because these things have a finite life, I'd replace it whilst I had the system apart.  The system now works perfectly.

My advice: your pump is virtually new so 'should' be ok, so replace the next most likely culprit, the accumulator, and keep the costs down by using a small one. The huge one doesn't seem to be bringing you any benefits over my rather more common and perfectly functional set up.

[rusty69]

1 minute ago, Sea Dog said:

. The huge one doesn't seem to be bringing you any benefits over my rather more common and perfectly functional set up.

Although he says the system works really well, so why change it if its doing what it should? 

[Sea Dog]

4 minutes ago, rusty69 said:

Although he says the system works really well, so why change it if its doing what it should? 

Hmmm, you might be right - I got sucked in by the "More water pump issues" title and the fact that his pump runs for a fortnight after he's done the washing up!

Maybe there's an advantage an delivering quite a bit before the pump cuts in, particularly overnight I guess. Personally,  I'd prefer to have my pump cut in shortly after I open a tap and out again shortly after its closed, rather than Dr Bob's sound track. I think that's less intrusive overall and rather easier on my Engineer's Ear (which is always listening for anomalies) than counting  30 elephants every time the tap goes off. That said, if Dr Bob (or anyone else) likes the 'late start - late stop' approach of a big accumulator, I'm not gonna apply any pressure.

[Dr Bob]

12 minutes ago, rusty69 said:

Although he says the system works really well, so why change it if its doing what it should? 

Yes it does work very well apart from the pump running for a while which no one has really said sounds bad. By the way, I got the colour wrong! It's blue. The red one is one I had in the loft for the old boat....Duhhh! Sorry to set that hare running.

One thing I haven't done is clean the filter between tank and pump. 

Thanks Rusty for info on pressure for the accumulator. I will try and check that as it may be over pressure ...but I haven't got a tyre pressure gauge. No one checks their tyre pressures any more do they?

[rusty69]

8 minutes ago, Sea Dog said:

Hmmm, you might be right - I got sucked in by the "More water pump issues" title and the fact that his pump runs for a fortnight after he's done the washing up!

 

The issue as  understand it was whether the pump was running for too long.

By changing the accumulator without understanding the rest of the system it may have detrimental affects on its operation. 

I would think your engineers eye could see that 

[Dr Bob]

19 minutes ago, Sea Dog said:

Hmmm, you might be right - I got sucked in by the "More water pump issues" title and the fact that his pump runs for a fortnight after he's done the washing up!

More like ten days!

I think that's less intrusive overall and rather easier on my Engineer's Ear (which is always listening for anomalies) than counting  30 elephants every time the tap goes off. That said, if Dr Bob (or anyone else) likes the 'late start - late stop' approach of a big accumulator, I'm not gonna apply any pressure.

You obviously didnt read the other post I put in the 'new to boating' forum at

It will give you a bit more background!

On the late start, late stop, its just very different from our previous yacht. I do like the fact that the shower is rock solid one temp whereas with the small accumulator on the previous boat there was a cycling of hot to cold and back to hot every couple of seconds. The pump noise does not bother me other than thinking of piranhas (see linked post above) rather than elephants. I think our boat would sink if we had 30 elephants on it. I think piranhas are safer as it will take them longer to sink the boat.

[mross]

I suggest a test.  

Open a tap until the pump starts and wait until the pump cuts out.

Switch the pump off.

Drain one litre from a tap.

Switch the pump on; it should replace that one litre in five to six seconds per litre.  (Eleven litres per minute).  If pump does not start switch it off and drain another litre and try again.

It it takes significantly longer the pump is defective.

It's important to start with system at pump cut-out pressure.

[Dr Bob]

5 hours ago, mross said:

I suggest a test.  

Open a tap until the pump starts and wait until the pump cuts out.

Switch the pump off.

Drain one litre from a tap.

Switch the pump on; it should replace that one litre in five to six seconds per litre.  (Eleven litres per minute).  If pump does not start switch it off and drain another litre and try again.

It it takes significantly longer the pump is defective.

It's important to start with system at pump cut-out pressure.

Now that is interesting.

Open a tap until the pump starts and wait until the pump cuts out.

Switch the pump off.

The pump is now at cut out pressure (ie 25psi). I then drain off 1 litre. I then put back in one litre but this is against a fair bit of pressure in the system. The pump is rated at 11 lt/m but is this against zero back pressure or is it still good for pumping into  25psi? If there is any air in the system then it could take a lot longer for the pump to pressurise up from 20psi to 25psi than it takes to go from 15psi to 20psi. Is this assumption correct? Listening to the pump it seems like it starts to struggle as the pressure reaches 25psi and has definitely slowed down at this point.

I will be back on the boat on Wednesday and will do some testing. I am pretty sure I only get 1 -2 litres out before the pump cuts in - from full pressure - so that means the accumulator is only pushing 2 litres out so is either too high pressure so only 2 litres of water in it, or too low pressure so that only a bit of air in it. I will also take a tyre pump with gauge along to check the accumulator pressure. I will report back Wednesday.