Variable Speed Fresh Water Pump

[Dockhead]

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?

[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.

[Dockhead]

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.

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.

[Simi 60]

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.

[Dsanduril]

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:

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.

The new language:

The digital controller adjusts water flow as the demand is increased and decreased while maintaining a very smooth flow.

Which is followed by a little note (elsewhere in the documents):

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.

[redneckrob]

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.

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.

[rslifkin]

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.

[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 ! Varying speed has no sense apart from complicating matters.

[RaymondR]

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.

[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.

[Simi 60]

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

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.

[Emmalina]

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.

If you add a relay to the system the pressure switch will last forever !

[sailormed]

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.

[Sailorman40]

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

[jharding]

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.