Fresh water pressure sensing pump nightmare!

[adrian's boat]

Hi, I'm after a bit of help.

Our old water pump wore out so I've just fitted a new one. It's a Shurflo AquaKing 4.0 (model number 4901 4215) which cuts in at 10psi and out at 25psi and has a 15 litre per minute flow rate.

It is, quite frankly, a nightmare. The pressure cut in is so low that my Morco boiler refuses to co-operate with it. It's also so noisy that it seems to shake the boat to pieces.

 

Does anyone have any experience of more expensive or quieter pumps? I don't mind spending a few quid if I can get something that actually works. Does anyone have any experience of the Jabsco VFlo Constant Pressure System? Is it worth nearly £300?

 

Your advice is appreciated as always.

[by'eck]

Do you have a pressure accumulator fitted? They smooth out the flow and limit how often the pumps cuts in.

 

Pump vibration can be reduced by mounting on rubber grommets and not screwing down too hard.

[Phil Ambrose]

I've had Surflo pumps in my boats for the last 14 years and have not had any problems as you describe. Thw noise and vibration could be down to air in the system also I would second the comments about fixing and rubber mounts, also an accumalator, I have one on the hot water circuit and one on the cold.

Phil

[Hawkmoth]

We have a a Flojet VSD (similar to the Jabsco) pump fitted and it's fabulous. Fairly quiet (not silent) gives wonderful, constant pressure. BUT, they aren't cheap.

Bob

[adrian's boat]

Thanks, By 'eck and Phil,

 

I have an accumulator which I've set to 7 psi as specified by the manufacturers. The problem with the accumulator is that it lets the pressure reduced very slowly to 10psi (when the pump cuts in again), during which time the flow to the Morco is constantly being reduced causing it to switch off. It drops to 10psi, the pump cuts in, then the Morco is being asked to deal with a pressure which is constantly varying anywhere between 10psi and 25psi.

 

As far as the noise goes the thing still makes a racket if I un-mount it and just hold it in my hand! I wonder if it's a 'Friday Afternoon Pump'?

 

Thanks for the advice on the dual accumulator thing. I don't think that's going to work for me since the pump is one end of the boat and the Morco is in the middle.

 

I'm thinking about a 2 pump system though, maybe one for the cold and one for the hot, with an accumulator each. That still won't deal with the pressure varying between 10psi and 25 psi though, which is why the expensive 'constant flo' things looks attractive (even if shedding expensive).

 

Your thoughts?

 

 

[adrian's boat]

We have a a Flojet VSD (similar to the Jabsco) pump fitted and it's fabulous. Fairly quiet (not silent) gives wonderful, constant pressure. BUT, they aren't cheap.

Bob

Bob,

 

Thanks very much indeed, that's just the endorsement I was after.

Did you name your boat after the Philip Pullman trilogy, by the way?

[Machpoint005]

>>As far as the noise goes the thing still makes a racket if I un-mount it and just hold it in my hand! I wonder if it's a 'Friday Afternoon Pump'?<<

 

 

 

Could well be faulty - when disconnected from the mountings there's no 'sounding board' to resonate and emit the noise, so it should be a gentle hum, no more. Not silent, though.

[ditchcrawler]

I couldn't find the 4901 4215 but the 4901-4212 pressure range is adjustable with a cut in of 25 psi

"Adjustable Switch. Shut-Off 45 PSI [3.1 Bar] ± 5 PSI [0.4 Bar]

Restart 25 PSI [1.8 Bar] ± 5 PSI [0.4 Bar]"

Even for 10 psi the pressure in the accumulator should be higher than 7 psi.

[Hawkmoth]

Bob,

 

Thanks very much indeed, that's just the endorsement I was after.

Did you name your boat after the Philip Pullman trilogy, by the way?

Yes, my wife's idea and it's a great one.

[by'eck]

The accumulator contains a small balloon shaped bladder within, with water surrounding it. Air should be pumped into this (bicycle pump) to take it to the same pressure as that of the pump cut-in switch, but with it switched off and a tap open. The pump then pressurises against the bladder reducing its volume such that it continues to pressurise the water supply after the pump cuts off.

 

Setting it in this manner theoretically allows the accumulator to work in the most efficient manner, although some experimentation with its pressure may allow it to better suit your needs.

 

BTW recommend Flojet pumps - no issues after 21 years of regular use.

Edited August 3, 2014 by by'eck

[RLWP]

The accumulator contains a small balloon shaped bladder within, with water surrounding it. Air should be pumped into this (bicycle pump) to take it to the same pressure as that of the pump cut-in switch, but with it switched off and a tap open. The pump then pressurises against the bladder reducing its volume such that it continues to pressurise the water supply after the pump cuts off.

 

Setting it in this manner theoretically allows the accumulator to work in the most efficient manner, although some experimentation with its pressure may allow it to better suit your needs.

 

 

It also means 7 psi is the wrong pressure

 

Richard

[by'eck]

 

It also means 7 psi is the wrong pressure

 

Richard

 

Absolutely and furthermore I don't see how an accumulator manufacturer can suggest a specific pre-charge pressure since its pump dependant.

[Alan Saunders]

 

Absolutely and furthermore I don't see how an accumulator manufacturer can suggest a specific pre-charge pressure since its pump dependant.

Maybe means that the accumulator is supplied pressurised to 7psi?

[adrian's boat]

Gents,

 

The accumulator is a Cleghorn Waring CW385. The installation instructions can be downloaded here: http://www.jabscoshop.com/files/Accumulator%20and%20Expansion%20Tank%20Instructions%20ZPWL4%20doc595.pdf

 

It seems to be pretty specific about setting the pressure to 7psi (for a 10 psi cut in). I'm happy to try alternatives though, if you recommend a pressure?

 

Also, the spec sheet for the Shurflo AquaKing 4.0 (as can be seen here: http://www.shurflo.com/files/Education-Center/Product%20Data%20Sheets/Fresh%20Water%20Pumps/pds-Aqua%20King%20Premium%2012v%204901-4202%2012.pdf ) and as ditchcrawler notes, it claims to have some adjustment for the pressure. The specs on the sheet are all over the place though, the sheet says 25psi cut in 45psi cut out, the website says 55psi cut out under the Features and Benefits tab and 45psi under the specifications tab, and the box has '30psi' written on it.

 

I'll see if I can find some kind of adjustment screw on it, in the mean time any recommendations for accumulator pressure?

[Machpoint005]

I was caught out by the Aqua King design and it caused me problems too. The pressure adjustment screw is the middle one of the five in 'domino' formation, if you see what I mean. No, it doesn't look like an adjuster screw, but it is!

[adrian's boat]

I see the screw you mean, Machpoint. How does it work?

Does clockwise increase both cut-out and cut-in?

[Machpoint005]

IIRC it's a matter of adjusting the maximum pressure the pump can supply. My problem was that the pressure was higher than the pump it replaced, so the accumulator was overpressurised and the PRV on the calorifier didn't like it. I got my stumpy screwdriver out and twiddled, and I think screwing it in (clockwise) restricted the cut-out pressure, but I can't honestly remember which way it went!

[smileypete]

Might be good to know a little about the rest of the system, is there a calorifier with 3 bar PRV?

 

As far as I know, most with Morco D61s are likely to have a 10lpm pump, so 15lpm is a bit overspecced. But it should be OK IF the cut in pressure can be set to be just above the min operating pressure of the Morco.

 

With the adjusting screw clockwise should increase pressure, but don't overdo it or the pump may stall and possibly overheat when the batts are low.

 

cheers, Pete.

~smpt~

Edited August 5, 2014 by smileypete

[ditchcrawler]

Gents,

 

The accumulator is a Cleghorn Waring CW385. The installation instructions can be downloaded here: http://www.jabscoshop.com/files/Accumulator%20and%20Expansion%20Tank%20Instructions%20ZPWL4%20doc595.pdf

 

It seems to be pretty specific about setting the pressure to 7psi (for a 10 psi cut in). I'm happy to try alternatives though, if you recommend a pressure?

 

Also, the spec sheet for the Shurflo AquaKing 4.0 (as can be seen here: http://www.shurflo.com/files/Education-Center/Product%20Data%20Sheets/Fresh%20Water%20Pumps/pds-Aqua%20King%20Premium%2012v%204901-4202%2012.pdf ) and as ditchcrawler notes, it claims to have some adjustment for the pressure. The specs on the sheet are all over the place though, the sheet says 25psi cut in 45psi cut out, the website says 55psi cut out under the Features and Benefits tab and 45psi under the specifications tab, and the box has '30psi' written on it.

 

I'll see if I can find some kind of adjustment screw on it, in the mean time any recommendations for accumulator pressure?

 

Gents,

 

I'll see if I can find some kind of adjustment screw on it, in the mean time any recommendations for accumulator pressure?

This can only be answered once you decide what the pump cut in pressure is