Fresh Water Pump replacement

[Richardcn]

Hi All

 

Our very old fresh water pump is, after several pressure switch repairs, grumbling it's way to retirement (Johnson WPS 3.4, 13 l/min, cut in 15psi cut out 20psi). I have fettled the pressure switch adjuster to try different pressures (as I've made changes to various parts of the system) but we've ended up happiest back at 20psi max. We've got a cold accumulator, hot expansion tank, 2 bar prv and a system pressure gauge, cauliflower is 35psi max. Problem is I'm struggling to find a suitable pump. I've considered:

https://www.foxschandlery.com/jabsco-12v-25-psi-par-max-3-pressure-water-pump-31395-2512-3a

 

...but I'm loathe to push the system pressure up at all. Does anybody have experience of this pump and is it tweekable? (Yeah I understand about the warranty). Or does anybody know of a suitable pump. I have considered fitting a Square D and I will if its the only real option but I'd rather not have the extra work right now (slow cruising Roydon to Wigan) and finding the right one looks like a task in itself, let alone the extra work. I do like the adjustability factor though

 

Thanks

Richard

Edited August 1, 2022 by Richardcn
Spelling

[Jen-in-Wellies]

The 2bar prv on the cauliflower is 29psi, still comfortably above the 25psi pressure of the par-max-3.

Jen

[Tony Brooks]

Or simply fit an external pressure switch like a square D and then use any pump of similar volume output.

[ditchcrawler]

10 minutes ago, Tony Brooks said:

Or simply fit an external pressure switch like a square D and then use any pump of similar volume output.

Thats what I did

[Richardcn]

10 hours ago, Jen-in-Wellies said:

The 2bar prv on the cauliflower is 29psi, still comfortably above the 25psi pressure of the par-max-3.

Jen

That's getting a bit tight though and the tank (and most of the plumbing) is 30+ years old. Also the expansion tank is set at 25psi for water heating so I have a nicely balanced system (for once) ;).

[Tracy D'arth]

I found that the Square D was right at its lower limit of adjustment at 25psi and the cover would not fit back on.

I think you are being over concerned about the pressure, the calorifier is made to stand 29-30psi and there will be a margin. A 25psi pump should be fine.

I have seen  low pressure calorifiers set up with 3 bar PRVs and 35psi pumps and they have survived.

[Richardcn]

10 hours ago, Tony Brooks said:

Or simply fit an external pressure switch like a square D and then use any pump of similar volume output.

Yeah I did mention that I might. Has anybody got any photos and experience of their 'Square D' set up?

2 minutes ago, Tracy D'arth said:

I found that the Square D was right at its lower limit of adjustment at 25psi and the cover would not fit back on.

I think you are being over concerned about the pressure, the calorifier is made to stand 29-30psi and there will be a margin. A 25psi pump should be fine.

I have seen  low pressure calorifiers set up with 3 bar PRVs and 35psi pumps and they have survived.

Will the rest of the plumbing though! I understood there was plenty of choice with regards to pressures and ranges with the external pressure switches, are there none below 25psi?

[Tracy D'arth]

8 minutes ago, Richardcn said:

Yeah I did mention that I might. Has anybody got any photos and experience of their 'Square D' set up?

Will the rest of the plumbing though! I understood there was plenty of choice with regards to pressures and ranges with the external pressure switches, are there none below 25psi?

If your plumbing won't stand 2 bar it needs redoing. Domestic water pressure is around 8 bar, all plumbing systems are made to stand more than this.

Low pressure switches are rarely used, everyone wants needle showers these days.

[Thames Bhaji]

8 minutes ago, Richardcn said:

Yeah I did mention that I might. Has anybody got any photos and experience of their 'Square D' set up?

i just fitted one - it’s working fine, although my pressure is closer to 3 bar. 
 

I’d had one on board for about 3 years meaning to fit it. Last week I was up to my arm pits in dismantled mascerator in the shower tray removing a blockage and was just about to hose everything down…. which of course was the exact moment the pump’s pressure switch finally died…. 

[BEngo]

 

1 minute ago, Tracy D'arth said:

If your plumbing won't stand 2 bar it needs redoing. Domestic water pressure is around 8 bar, all plumbing systems are made to stand more than this.

Low pressure switches are rarely used, everyone wants needle showers these days.

Domestic water pressure is never  8 bar.  That is well over 110 psig and   would result in failing combi boilers, cylinder and pipework.  3.5 bar is about the maximum, and the legal minimum at the kitchen tap is 1 bar.

 

Square D pressure switches are available in a range of maximum pressures: something llike 10 to 30 psi 30 to 50 and so on up.  The problem with picking one on line is that the literature is confusing to say the least.  Best to go to a decent plumbers merchant and ask for one that covers the pressure you want.  Mine is a 30 to 50 psi which is set to cut in at  about 20 and out at 30., switching a Johnson WPS 5.1.  Setting up was a fiddle because the adjustments affect each other and one is a set pressure and the other is hysteresis (IIRC) .   The lid fits fine. The 30 year old copper  pipework seems OK.

 

N

 

 

[Richardcn]

20 minutes ago, BEngo said:

Square D pressure switches are available in a range of maximum pressures: something llike 10 to 30 psi 30 to 50 and so on up.  The problem with picking one on line is that the literature is confusing to say the least.  Best to go to a decent plumbers merchant and ask for one that covers the pressure you want.  Mine is a 30 to 50 psi which is set to cut in at  about 20 and out at 30., switching a Johnson WPS 5.1.  Setting up was a fiddle because the adjustments affect each other and one is a set pressure and the other is hysteresis (IIRC) .   The lid fits fine. The 30 year old copper  pipework seems OK.

 

N

 

 

I did think there was a full range but, like you, I found choosing the right one a real challenge, hence my desire for a simpler route if at all possible. Good to hear that you got there in the end though.

Edited August 2, 2022 by Richardcn

[blackrose]

Sorry for hijacking the thread. Has anyone used higher water pressure to get a Morco D61B to work properly rather than switching on and off with accumulator pressure?

 

My 12 year old pump cuts in/out at 10/25psi. It's still working fine but I bought a 40psi cut out pump as a replacement for when it finally expires along with a Square D pressure switch. Will that help run the Morco consistently or would the higher water pressure just reduce the life of my 17 year old calorifier? 

Edited August 2, 2022 by blackrose

[Richardcn]

32 minutes ago, Thames Bhaji said:

i just fitted one - it’s working fine, although my pressure is closer to 3 bar. 
 

I’d had one on board for about 3 years meaning to fit it. Last week I was up to my arm pits in dismantled mascerator in the shower tray removing a blockage and was just about to hose everything down…. which of course was the exact moment the pump’s pressure switch finally died…. 

Perfect timing then, it gave you the incentive to fit it

 

I've got enough bits waiting to be fitted, I don't want another one

[Tracy D'arth]

21 minutes ago, BEngo said:

 

Domestic water pressure is never  8 bar.  That is well over 110 psig and   would result in failing combi boilers, cylinder and pipework.  3.5 bar is about the maximum, and the legal minimum at the kitchen tap is 1 bar.

 

 

 

N

 

 

Sorry, wrong. Been involved with plumbing for 50 years. Steel sealed system hot water systems are designed to run to 8 bar, incoming mains pressure is allowed to be 8 bar by the water supply companies. Night time creep can often get to this.

Hydrant pressure is higher than 10 bar 

[Richardcn]

36 minutes ago, Tracy D'arth said:

If your plumbing won't stand 2 bar it needs redoing.

No doubt, I'll add that to 'the list'! However, if I can replicate my current system pressures (somehow) then it won't need to go on in the first place, which would make me happier.

[Tony Brooks]

I used Square D switches on all the hire fleet, in fact they were a part of the Godwin and a weird US water pump. My ex hire boat had one already fitted and I operated it at around 1 bar perfectly happily for years.

 

Put a T into the pressure side of the pump somewhere convenient to accept the switch. They are two pole switches normally so you have the choice of using just one of the contact pairs or both in parallel. I cut the positive cable between the pump's own switch and motor and connect the pressure switch to that so the pum'ps own contacts are no longer in use.

[Richardcn]

54 minutes ago, Tony Brooks said:

I used Square D switches on all the hire fleet, in fact they were a part of the Godwin and a weird US water pump. My ex hire boat had one already fitted and I operated it at around 1 bar perfectly happily for years.

 

Put a T into the pressure side of the pump somewhere convenient to accept the switch. They are two pole switches normally so you have the choice of using just one of the contact pairs or both in parallel. I cut the positive cable between the pump's own switch and motor and connect the pressure switch to that so the pum'ps own contacts are no longer in use.

Thanks, I'm leaning toward this now. I'll  need to do it all via t'interweb so I'll post my Square D finds here for perusal.

[Thames Bhaji]

1 hour ago, Richardcn said:

Perfect timing then, it gave you the incentive to fit it

It did rather bring things to a head, as it were. 

[ditchcrawler]

3 hours ago, Tracy D'arth said:

I found that the Square D was right at its lower limit of adjustment at 25psi and the cover would not fit back on.

 

Mine is cranked right down as well

[Richardcn]

Ah here's a slight annoyance that threw a spanner into my pump search. The specs (and indeed model no's) for new pumps are in US Galls NOT UK Galls! I should have realised earlier duh! Hence all these '3' models are 11 l/min and not the 13 l/min that I was looking for. So either I need a 3.5 or to convince myself that we won't miss that 2 l/min of flow. Maybe a new pump will be as good as (or better than) our very old one anyway. Anybody running a 3 g/min pump with a thermostatic shower and 4 taps happily? Probably the majority I'd hazard a guess.

[Tracy D'arth]

You never use all the taps and shower at the same time, so its plenty.

[Richardcn]

7 minutes ago, Tracy D'arth said:

You never use all the taps and shower at the same time, so its plenty.

Indeed, much as I suspected.

 

Thanks

[Jen-in-Wellies]

The 11l/min flow rate is what it can deliver with the pump not actually connected to any plumbing on the outlet, so the absolute maximum it can do. In practice, the upstream and downstream pipework in the boat restricts flow a lot. Especially 15mm pipework. With all taps on the boat open, I've measured the actual flow rate of my supposedly 11l/min pump at 6l/min.

Edited August 2, 2022 by Jen-in-Wellies

[Richardcn]

18 minutes ago, Jen-in-Wellies said:

The 11l/min flow rate is what it can deliver with the pump not actually connected to any plumbing on the outlet, so the absolute maximum it can do. In practice, the upstream and downstream pipework in the boat restricts flow a lot. Especially 15mm pipework. With all taps on the boat open, I've measured the actual flow rate of my supposedly 11l/min pump at 6l/min.

We just checked ours on one tap (cold nearest to pump) and got a similar 6 l/min!

 

Just ordered a Jabsco 25psi 11 l/min from eBay £75. Currently looking for an external pressure switch for later fitment (hopefully not 3 years later though!).

Will post the pressure switch for future reference.

[Richardcn]

How about this one?

 

https://uk.rs-online.com/web/p/pressure-sensors/1242164