Little Wonder water maker

[joe_bower]

I have a Little Wonder water maker on my Hunter sailboat. I believe it's the LW200 model. It does not seem the prime easily or get adequate water flow to the unit. It has a March booster pump. Has anyone replaced their booster pump on this type of unit? Thank you for any help or recommendations.

[syohana]

I got a cheap Chinese 12v pump off aliexpress for about $8, does the job just as well as the crazy priced original, quieter and uses less power. There are a huge range of pumps on ali express, it should be a centrifugal type rather than diaphragm. They are sold mainly to drive garden fountains. If in doubt as to the longevity just buy two! Mine has been fine though.

I also replaced the main drive motor with a BLDC motor so I can set the rpm exactly and uses less power.

Edit: PS check the booster pump is mounted below the waterline and with a straight pipe to prevent airlock or preferably directly to the seacock, it is not self priming and will be damaged if run dry.

[joe_bower]

Thank your response. I am just curious why the pump cannot be a self priming diaphragm type?

[joe_bower]

Also, what GPM and pressure should the new one produce? Thanks so much.

[SV_Harbinger]

I would assume it would have to do with the pulsating flow that comes out of a diaphragm type pump not being entirely familiar with the unit you have, I can't say with certainty but if I were to come up with a reason I would say that would be it. I'm sure someone here could give you a better answer than I can.

[44'cruisingcat]

Originally Posted by joe_bower

Thank your response. I am just curious why the pump cannot be a self priming diaphragm type?

You could use one of those, but unless you spend a lot,not many are suited to continuous running for hours at a time.

The pressure needed depends on how high your high pressure pump is mounted.

The Parker Racor pump only requires pressure greater than zero on its suction side.

Required flow rate is pretty small really. Something like 400 litres per hour.

[GRIT]

Just a slight correction to 44's post.

As I recall. The Little wonder 200, hp pump only pumps 0.3 gallons per minute, which is just a little more than a litre a minute. So any march pump that pumps even 100l an hour would do the trick.

I don't mean to step on anyone's toes, but you'll have more choice in pumps if you know what the true minimum is.

The 200 has the 708-1 pump, at 0.37GPM (1.4lpm) max flow. That's about 85 lph.

A US gallon (Gallonette) is 3.78 litres in volume.

http://www.aquacontrolmarine.com/wp-...rol-Marine.pdf

Cheers.
Paul.

[chris14679]

Originally Posted by joe_bower

Thank your response. I am just curious why the pump cannot be a self priming diaphragm type?

I did repurpose a shurflo diaphragm pump from the deckwash as a temporary fix until the one from aliexpress arrived, it did work but it was 20 times the price, very noisy, cycled on and off every 3 seconds on the pressure switch, used way more power and has lots of moving parts and seals to wear out or fail, which it eventually did, so I then had to rebuild it too.

A sealed magnetic drive centrifugal type like the original one is ideal, cheap, reliable and will last an extremely long time if you don't let it run dry. It will KISS principle. Not sure what effect the constant fluctuations of input pressure from a diaphragm pump would have but it can't be good.

Check what pipe fittings it comes with, all options are available and it's a lot less hassle if you can put your original hoses straight on it, most of them have smaller diameter or threaded fittings.

[a64pilot]

Any kind of positive displacement pump will need some kind of relief valve etc. to prevent pressure from going too high when the high pressure pump is off.
Then most likely it’s not a continuous duty pump, and if not then you will likely need some supplemental cooling as many are temp protected and will shut down when they overheat.

Centrifugal pumps like ones meant for air conditioning would seem to be ideal as they run for thousands of hours, continuously.
However they may not develop enough pressure to have a significant pressure left after going through two partially clogged filters

[44'cruisingcat]

Originally Posted by GRIT

Just a slight correction to 44's post.

As I recall. The Little wonder 200, hp pump only pumps 0.3 gallons per minute, which is just a little more than a litre a minute. So any march pump that pumps even 100l an hour would do the trick.

I don't mean to step on anyone's toes, but you'll have more choice in pumps if you know what the true minimum is.

The 200 has the 708-1 pump, at 0.37GPM (1.4lpm) max flow. That's about 85 lph.

A US gallon (Gallonette) is 3.78 litres in volume.

http://www.aquacontrolmarine.com/wp-...rol-Marine.pdf

Cheers.
Paul.

I was basing it on the output. Ours, with a different membrane, makes 40 - 48 lph fresh water. I was assuming that would be about 10% of saltwater flow.

Looks like our yield is actually much higher than 10%.

[stormalong]

To get it to prime you need to back off the pressure regulator valve until water is flowing through the pump then adjust the regulator to your high pressure setting. At least that is the way I did it on my Little Wonder 150.

[joe_bower]

Thanks everyone for help and support. I ordered a cheap pump from Amazon. I'll let everyone know how it works out.