DIY Watermaker

[SV THIRD DAY]

Originally Posted by dkenny64

I know this thread is old..

but..
I've learned alot from it...series is the way to go

how much to filter..5 micron before the high pressure pump.. 2micron or less require carbon filters.. 5 is easy with a spun whole house type filter.

in rush surge...are you starting those pumps with the needle valve( high pressure regulation).. closed? if these are open the inrush current surge should be low..low 1.5x running..not 6x..

12v motors..yes they work..there is a guy in my marina that made his watermaker using a 2hp 12v DC motor...no he doesn't run it off batteries(but could) nor solar..he has small 3 cylinder diesel that power two 180amp alternators and a fridge compressor..yep..while making water he freezes his ice box to -10F...fyi he has 10 batteries in main bank.. no solar..no wind..

I just hope to put together a system that runs on 120V( have generator) and make 30-50gal per hour.. if I have to run the generator for an hour each day(1 gallon). while making breakfast, charging the batteries.. OK..for crossings..conserve water..solar to keep everything running..rough guess 10days without making water..we carry 180g of water..

-dkenny

Don't need to filter less than 5micron, doing so is a waste of energy and increased pressure drop. Just to a 20 followed by a 5 micron and you will be good.

Stay away from the single use string wound prefilters and the solid blown filters. They are cheaper, but can't be cleaned like the pleated. So with space being a premeium on a boat...go with pleated 20 and 5 micron. NO AC is needed on the inlets sea water, you only need an AC filter for fresh water flushing from your water tanks.


In Rush at start-up.
Plan on double the running load amps and that's typically good.
Our 1.0Hp motor uses 9.3A at full load 800psi and has an inrush for example of 21A

If you want over 35GPH then you will need a 2.3GPM Hp pump and a 1.5Hp motor, so that's 13.3A at 800psi. You can't run that on a 2000W inverter if your genny dies...which is why our most popular selling water maker is the SM30 that sticks to the 1.0Hp motor.

Cheers

[dkenny64]

is your inrush current loaded or unload.. makes a hugh difference. as does
a soft start vs. hard start..
why clean the pre filter setup..unless you have no choice.
sorry the spin filter work longer under dirt load than the pleated type..
I have the spun on the house system..they last years..plated..months... yes the spun will last until the filter is half full of junk..pleated,.not that long.
I can see that if one needs to clean the pre filters. spun forget it. pleated..maybe. if it came to that use a tee shirt..remove the spin fiber and replace with a tee shirt or jeans.

I've not sized my inverter, but I know I can run that on a 3000w inverter..
I've run lots of power equipment including 1hp air compressor and a 15amp saw from it..2000w. i agree..maybe..startup is ify..3000w..not a problem
I do this just about every day to using construction power tools..

-dkenny

[a64pilot]

A pleated filter has much more surface area, and for that reason ought to trap more contaminants. It’s for this reason that automotive air filters, and better HVAC filters are pleated, your oil filter, your Racors etc are all pleated. If spun was better, I bet Racors would be spun.
If you have a spun filter that is lasting longer than a pleated filter, my bet is because it’s not stopping the contaminates.

[SV THIRD DAY]

Originally Posted by dkenny64

is your inrush current loaded or unload.. makes a hugh difference. as does
a soft start vs. hard start..
why clean the pre filter setup..unless you have no choice.
sorry the spin filter work longer under dirt load than the pleated type..
I have the spun on the house system..they last years..plated..months... yes the spun will last until the filter is half full of junk..pleated,.not that long.
I can see that if one needs to clean the pre filters. spun forget it. pleated..maybe. if it came to that use a tee shirt..remove the spin fiber and replace with a tee shirt or jeans.

I've not sized my inverter, but I know I can run that on a 3000w inverter..
I've run lots of power equipment including 1hp air compressor and a 15amp saw from it..2000w. i agree..maybe..startup is ify..3000w..not a problem
I do this just about every day to using construction power tools..

-dkenny

All water makers have an unloaded inrush current draw because you NEVER start a water maker under load...it hurts the membranes. Some motors (like the ones we use) have a soft start capacitor build in...some don't and use 1/3 more power.

I just service water makers for a living...so what do I know....if you want to use cheap non-washable filters that have less loading capacity and higher Delta P (the killer of Hp Pumps) and carry 4 times more of them so that the price savings is Zero....hey Amigo...your call. There is a REASON ALL of the water maker companies use pleated filters (surface area and pressure drop is KEY). But hey...Tee shirt or jeans...ya you do that and let me know how long your $220 RO Membranes last and how soon you need a Hp pump rebuild from flow starving. There is a difference between being cheap (like me) and foolish like your Tshirt idea.

Inverter to run a AC Water Maker...ONLY while under way with your alternators running of if you have LiFePO4 batteries because the 100A (1.0Hp motor) of the 140A (1.5Hp motor) will kill your lead acid without some type of charging source at the same time. Our approach is Honda 2000 at anchor to make water and power at the same time and then 2000W inverter while motoring with your alternator helping to keep your batteries from being KILLED.

[dkenny64]

spun vs pleated.. I've had plaeted fall apart..never had a spun fall apart.. ever..
your welcome to stay with pleated..but air is not water.. pleated oil have bypass means...spun don't..as spun fill up they filter more not less. pleated break down...

ok.. when you change your pleated filter is the housing 1/2 full of crud? I'm guess not..but that's when I change my spun filters..at my house..and they are still working not bypassing..

-dkenny

[SV THIRD DAY]

Originally Posted by dkenny64

spun vs pleated.. I've had plaeted fall apart..never had a spun fall apart.. ever..
your welcome to stay with pleated..but air is not water.. pleated oil have bypass means...spun don't..as spun fill up they filter more not less. pleated break down...

ok.. when you change your pleated filter is the housing 1/2 full of crud? I'm guess not..but that's when I change my spun filters..at my house..and they are still working not bypassing..

-dkenny

Amigo....if you think a water maker prefilters has the same operating parameters as one in your house....ah....well....no. Again...it's what I do for a living...but what do I know.

My apologies I thought you were coming here for advice on a DIY system, my mistake, you already know it all.

[dkenny64]

SV Third Day - please forgive my attitude.. I know I have lots to learn. I also have lots more
questions. what about back flushing the RO with fresh water? I don't recall this being talked about in this thread. good idea/bad idea..


using a Tshirt or blue jeans as a filter medium would a last resort..

as far as filters..I know I have lots to learn.. a reusable pleated might hold up.

as for running a water maker on an inverter possible but I agree with you.. not a good idea..unless that was the only way. as in generator died..and out of water..

and yes I know that the HP pump must have a positive inlet pressure. so do you think a 24GPM gear pump would be enough..set for a 60psi bypass..
I only ask because I have one...

-dkenny64

[a64pilot]

There are times when running a high output AC Watermaker off of an inverter makes sense.
One example, you have a high output alternator, bank is charged and your motoring. Why crank the generator, the alternator will keep up with the majority of the power required.

[john61ct]

The question isn't really the inverter, as much as whether off the battery bank or not.

It would require a very efficient watermaker and a nice big bank to do that for long, even then only if plenty of recharging power was coming soon.

Using the inverter does make things less efficient though, if you're regularly making water from battery power better to get a 12V unit in the first place.

[a64pilot]

Got it, however of course either an AC or a DC Watermaker can now be run from either AC or DC, and a good battery charger or a good inverter is better than 90% efficient I think.
The dividing line between AC and DC isn’t as clear cut now as it used to be as now either is easily converted to the other.
However just as always AC is easier and cheaper to wire for.
I ran 12ga wire for my 1 HP AC motor, if it were DC, it likely would have had to be 3/0 wire.
Of course that is for a 1HP motor and I’m sure an efficient DC Watermaker isn’t pulling 100 amps, but it does illustrate the point.

I can run my 30 gl an hour AC Watermaker when motoring and only pull on average 10 amps from the bank, my 125 amp alternator seems capable of 90 amps continuously.
In my installation, I can think of no other time other than motoring that it makes sense to run the Watermaker off of the inverter, however if you are motoring, why crank the generator?

[newhaul]

Originally Posted by a64pilot

Got it, however of course either an AC or a DC Watermaker can now be run from either AC or DC, and a good battery charger or a good inverter is better than 90% efficient I think.
The dividing line between AC and DC isn’t as clear cut now as it used to be as now either is easily converted to the other.
However just as always AC is easier and cheaper to wire for.
I ran 12ga wire for my 1 HP AC motor, if it were DC, it likely would have had to be 3/0 wire.
Of course that is for a 1HP motor and I’m sure an efficient DC Watermaker isn’t pulling 100 amps, but it does illustrate the point.

my 12v watermaker draws 4.5 amps. But also only produces 35 gpd.

[john61ct]

The marketeering specs as to high efficiency are not what you get IRL, the less conversion going on the better.

Of course if you're burning dino juice regularly anyway, motoring means pumping out 450A, then who cares?

but people living on the hook making their water from solar, or trying to minimize genny runtimes, it's best for any long-running consumer to use the native current.

[a64pilot]

An inverter gives us the freedom when we are motoring to make water, make ice, wash clothes, do lots of things without having to run the generator.
When at anchor it allows us to make frozen Daiquiris, watch TV, run the vacuum cleaner and any number of 110 V appliances that are way cheaper and usually more available and cheaper than their 12V counterparts.
It’s the 21st Century, solid state battery chargers and inverters are very efficient and way better than they used to be.

However my point was that if you have a high output AC Watermaker, which is likely if it’s a DIY as that is the simplest, then a big inverter gives you a way to make water when or if your generator is on the fritz.
Without one, you couldn’t make water, and a big inverter is way more useful than a backup generator is.

[john61ct]

Yes everything you say, for that scenario, is in alignment with the qualifications of my more general statements.

Any disagreements lie in our "energy use philosophy" and different individual use cases, rather than in any of those implementation details.