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08-06-2021, 14:46
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#1
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Moderator

Join Date: Mar 2009
Location: Denmark (Winter), Cruising North Sea and Baltic (Summer)
Boat: Cutter-Rigged Moody 54
Posts: 35,303
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Variable Speed Fresh Water Pump
What are the odds?
A week ago my 20 year old accumulator tank exploded. I was pleased that I had miscellaneous plumbing bits on hand sufficient to blank it off (I carry a lot of spares, but not a spare accumulator tank).
Then today, as I was leaving the boat to go on a business trip, literally the last second I needed to use water before running for the airport -- the fresh water pump just stopped.
It's a Johnson washdown pump which I pressed in to service a few years ago to replace the original Shure-Flo pump which had a failed bearing for the wobble shaft. I corrected the pressure of the washdown pump by cutting loops out of the spring in the pressure switch.
I bought a new bearing for the Shure-Flo and put it into spares.
I have no idea what's wrong with the Johnson pump -- I was already late for my flight and no time to do any diagnosis. But I won't have time to mess around much with it before leaving for my race and then summer cruise. So there's a new Johnson fresh water pump in my SVB24.de shopping cart, but I stopped --
Maybe this is the time to ditch the whole pump-accumulator tank system -- all the more since I have this double failure. And go for a variable speed pump which doesn't need an accumulator tank at all?
Anyone have any experience with one of these?
__________________
"You sea! I resign myself to you also . . . . I guess what you mean,
I behold from the beach your crooked inviting fingers,
I believe you refuse to go back without feeling of me;
We must have a turn together . . . . I undress . . . . hurry me out of sight of the land,
Cushion me soft . . . . rock me in billowy drowse,
Dash me with amorous wet . . . . I can repay you."
Walt Whitman
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08-06-2021, 15:47
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#2
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Registered User
Join Date: Apr 2007
Location: Australia
Boat: Island Packet 40
Posts: 6,501
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Re: Variable Speed Fresh Water Pump
Not keen on the concept, it's going to drain electrical power all the time whilst actively maintaining pressure in the system whereas the accumulator did it with only intermittent power use.
__________________
Satiriker ist verboten, la conformité est obligatoire
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08-06-2021, 15:57
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#3
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Moderator

Join Date: Mar 2009
Location: Denmark (Winter), Cruising North Sea and Baltic (Summer)
Boat: Cutter-Rigged Moody 54
Posts: 35,303
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Re: Variable Speed Fresh Water Pump
Quote:
Originally Posted by RaymondR
Not keen on the concept, it's going to drain electrical power all the time whilst actively maintaining pressure in the system whereas the accumulator did it with only intermittent power use.
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I don't think that's how it works. It doesn't run all the time, any more than my normal pump with no accumulator in the system runs all the time.
__________________
"You sea! I resign myself to you also . . . . I guess what you mean,
I behold from the beach your crooked inviting fingers,
I believe you refuse to go back without feeling of me;
We must have a turn together . . . . I undress . . . . hurry me out of sight of the land,
Cushion me soft . . . . rock me in billowy drowse,
Dash me with amorous wet . . . . I can repay you."
Walt Whitman
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08-06-2021, 15:57
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#4
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Registered User
Join Date: Jun 2016
Location: Australia
Boat: Milkraft 60 ex trawler
Posts: 4,651
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Re: Variable Speed Fresh Water Pump
How do you get that sort of life from an accumulator?
We got about 3 years from a small jabso one
Replaced it with an 8 litre one from an irrigation shop and the bladder failed after 18mths.
Before that we had a variable speed pump but It didn't last any longer than the standard types.
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08-06-2021, 16:05
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#5
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Registered User
Join Date: Aug 2011
Location: Petersburg, AK
Boat: Outremer 50S
Posts: 4,229
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Re: Variable Speed Fresh Water Pump
I can only speak to a Johnson variable speed, with no accumulator it will let you know about every single drip pretty quickly. Not necessarily a bad thing.
The old advertising language for the Johnson 10-13329-103:
Quote:
The unique variable flow feature of the Flow Master pump allows the pump to be mounted without an accumulator tank and still maintain an even flow even when multiple taps are being used.
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The new language:
Quote:
The digital controller adjusts water flow as the demand is increased and decreased while maintaining a very smooth flow.
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Which is followed by a little note (elsewhere in the documents):
Quote:
For minimizing the number of starts and stops - and thereby reducing wear and tear on the pump when only small amounts of water are drawn off - it is recommended to install the WPS pumps together with and [sic - I type this way a lot too] accumulator tank.
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08-06-2021, 17:14
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#6
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Registered User
Join Date: Mar 2019
Posts: 1,636
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Re: Variable Speed Fresh Water Pump
Quote:
Originally Posted by RaymondR
Not keen on the concept, it's going to drain electrical power all the time whilst actively maintaining pressure in the system whereas the accumulator did it with only intermittent power use.
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I have one and it doesn't work that way. It just comes on when you turn a faucet on, and even then not right away. Pressure is entirely constant, which wasn't the case with my accumulator system that bled off then bumped up when the pump came on. I would guess total electricity use is very comparable, but then I'm not a milliwatt hour counter either and in the grand scheme no water pump makes up much of my energy budget except the water maker.
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08-06-2021, 17:32
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#7
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Registered User
Join Date: Jun 2019
Location: Rochester, NY
Boat: Chris Craft 381 Catalina
Posts: 6,991
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Re: Variable Speed Fresh Water Pump
My only experience with a variable pump was a couple of Shurflos in the mid/late 2000s. Unreliable is too kind a word for those... The longest lived one made it 3 or 4 months. So we went back to the standard pressure switch pumps with no issues.
My system was built with no accumulator, even with the standard pumps. Yeah, it cycles and pulses at low flows, but with only a 3 gpm pump, it's not excessive and it doesn't take a lot of flow to prevent cycling. And reliability doesn't seem to be an issue, as the current pump was installed in 2007-ish (and was a spare with a 1989 build date) and is still doing just fine.
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08-06-2021, 18:03
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#8
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Marine Service Provider
Join Date: Jan 2012
Location: Thailand
Boat: Herreshoff Caribbean 50
Posts: 1,127
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Re: Variable Speed Fresh Water Pump
I would guess a lot of boats don't have accumulator tanks mine included and the pump is 20 years old. If you have enough plumbing on your boat it acts like an acc tank ! Varying speed has no sense apart from complicating matters.
__________________
Steve .. It was the last one that did this !
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08-06-2021, 18:37
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#9
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Registered User
Join Date: Apr 2007
Location: Australia
Boat: Island Packet 40
Posts: 6,501
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Re: Variable Speed Fresh Water Pump
Accumulators are very easy to build, 1 ply rubber hose inside black poly pipe will do the job very reliably. With a largish one you can take mist of the pressure surges out of a pressurized boat water system.
I am permanently installing a demand type gas hot water heater which is very sensitive to flow variations and will be fabricating an accumulator to fix the problem. I am thinking 3" pipe with 2" hose about 3-4' long in the bilge somewhere.
__________________
Satiriker ist verboten, la conformité est obligatoire
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08-06-2021, 19:37
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#10
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Registered User
Join Date: Jan 2013
Location: Boat in the Med. home base Vancouver.
Boat: 52' Cheoy Lee Motorsailer
Posts: 116
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Re: Variable Speed Fresh Water Pump
We had a Jabsco Flo 5.0 variable. Really liked it when it worked. As others noted the pressure switch broke after a few months. (the pump itself was fine). A google search showed it was a common fault. I found that Jabsco sells the pressure switch separately - no doubt due to all the failures. I bought 2 so I have a spare and will try it again. The jury is still out. Like I said when it worked it was great.
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08-06-2021, 22:36
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#11
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Registered User
Join Date: Jun 2016
Location: Australia
Boat: Milkraft 60 ex trawler
Posts: 4,651
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Re: Variable Speed Fresh Water Pump
Quote:
Originally Posted by Emmalina
I would guess a lot of boats don't have accumulator tanks mine included and the pump is 20 years old. If you have enough plumbing on your boat it acts like an acc tank
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I would think a twin level 60fter should have enough PEX plumbing on board yet we have hammering pipes at the moment now that the accumulation tank is gone.
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09-06-2021, 05:53
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#12
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Marine Service Provider
Join Date: Jan 2012
Location: Thailand
Boat: Herreshoff Caribbean 50
Posts: 1,127
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Re: Variable Speed Fresh Water Pump
Quote:
Originally Posted by nmuir
We had a Jabsco Flo 5.0 variable. Really liked it when it worked. As others noted the pressure switch broke after a few months. (the pump itself was fine). A google search showed it was a common fault. I found that Jabsco sells the pressure switch separately - no doubt due to all the failures. I bought 2 so I have a spare and will try it again. The jury is still out. Like I said when it worked it was great.
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If you add a relay to the system the pressure switch will last forever !
__________________
Steve .. It was the last one that did this !
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09-06-2021, 06:18
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#13
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Registered User
Join Date: Nov 2013
Location: Nice, France
Boat: Hunter Marine 38
Posts: 1,345
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Re: Variable Speed Fresh Water Pump
I have this pump originally installed by Hunter Marine since 2005. No accumulator. No problems. It is variable speed, when 2 faucets are open it increases speed.
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09-06-2021, 12:47
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#14
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Registered User
Join Date: Jan 2013
Posts: 5
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Re: Variable Speed Fresh Water Pump
FYI , I bought a Jabsco 5.0 variable speed ( no accumulator tank needed )fresh water pump for our system 7/20 Pump never shut off properly & continued to pulse Have been waiting for replacement however, they are in California and not yet back to work/production They have been very responsive and assured me that the will be shipping a new standard 5.0 gph pump with accumulator tank approx 7/20/21 as they will not be producing the variable speed unit & are discontinuing it
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09-06-2021, 14:03
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#15
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Senior Cruiser

Join Date: Jan 2012
Location: where my boat is anchored
Boat: Irwin 52
Posts: 133
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Re: Variable Speed Fresh Water Pump
when I bought my boat 11 years ago the pump speed raised and lowered, I thought it was getting ready to die, I bought a spare and then realized it was a variable speed pump and was working normal. I have not had to install the spare yet, original is at least 11 years old. I live on my boat and it gets used a lot, love it.
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