Small watermaker 3 gph

[Captain Bill]

Originally Posted by Mr B

Hi Pizzaz,

I used this pressure pump on my water maker, 40 inch x 2.5 inch,
Its a 240 volt motor I run off my 3000 watt invertor,
It puts out 3200 PSI but is regulated to run a constant 900 PSI thru my pressure gauge and valve before it goes into the Pressure vessel and Membrane,

Perhaps I am not understanding your description of your setup, but reducing the pressure before you get to your membrane and pressure vessel will not work unless you are also restricting the flow and regulating the pressure within the pressure vessel. The 8-900 psi pressure at the membrane must be maintained within the pressure vessel. If you are reducing the pressure to 900 PSI before it reaches the pressure vessel and having no regulator on the output will only raise the pressure in the vessel slightly because of the restriction of the plumbing fittings on the outlet but nowhere near the required 800 psi. Oddly enough because feeding fresh water to the membrane as you described requires very little pressure in the vessel to push water through the membrane it will result in water coming out of the product line, giving the illusion that it is working. However it will not work with seawater. Again perhaps I misunderstood your description. If I haven't then you need to move your pressure regulator to the brine outlet of your pressure vessel.

[Pizzazz]

Regarding the 3 gph watermaker, the dimensions are determined by the pressure vessel, approx. 19” by 3”, the pump motor combo is attached to one end, adding around 10”. In addition, you need a 10” filter. The Pumptec is a positive displacement pump, so it does not need a feed pump, even if you mount it above the waterline. Just make sure that the connections are tight so that air does not get in the way. In general, most high pressure pumps do not need a feed pump.

The needle valve is after the membrane, as to maintain the desired pressure in the membrane. As mentioned before you do not need a regulator, just a simple needle valve.

I have been running the design on and off, it starts immediately, even after weeks of non use and the water quality has improved over time, now averaging 90-95 ppm which means that I could have easily used the longer membrane, increasing the output by 50%. One day will get to it.

[Lost Horizons]

What is the consensus on using an air conditioner water intake and strainer to feed a water maker? Do not want to add another opening in the hull if it all possible. I do not envision ever using the A/C and WM simultaneously.

[Mr B]

Originally Posted by Captain Bill

Perhaps I am not understanding your description of your setup, but reducing the pressure before you get to your membrane and pressure vessel will not work unless you are also restricting the flow and regulating the pressure within the pressure vessel. The 8-900 psi pressure at the membrane must be maintained within the pressure vessel. If you are reducing the pressure to 900 PSI before it reaches the pressure vessel and having no regulator on the output will only raise the pressure in the vessel slightly because of the restriction of the plumbing fittings on the outlet but nowhere near the required 800 psi. Oddly enough because feeding fresh water to the membrane as you described requires very little pressure in the vessel to push water through the membrane it will result in water coming out of the product line, giving the illusion that it is working. However it will not work with seawater. Again perhaps I misunderstood your description. If I haven't then you need to move your pressure regulator to the brine outlet of your pressure vessel.

Sorry, I explained it wrong, The fresh water trial was because the boat was on the hard,
It is on the Brine outlet where the pressure gauge is and I use the valve on the outlet to bring the pressure slowly up to 900 PSI,
Im not sure how it works, But I have Zero pressure before I open the valve,
It was the same configuration before i changed to the pressure washer motor,

The little wonder pressure pump was all turned on, Then I opened the valve to get the pressure right, It worked and gave me fresh water, after I cleared the brine running thru it, Couple of minutes thru a dedicated Brine tap,
Then I turn another valve to put the water into the tanks, and turn off the brine tap,

It still sucks seawater thru the same filters as before I changed the pressure pump,

[jimbojonesbos]

Just an update for anyone considering building this. I am putting together both a 12gph 12v watermaker that should pull about 90 amps @12v, and the 3gph system in this thread. I have been unable to find the pumptec 116c with the .105 cam as anything other than a special order and consequently I'm getting quotes in the $650-$675 range.



The key elements of the 3gph design, as of Feb 2020, have the following prices:


-116c-105 pumptec HP pump , $675 from pumptec direct or through a dealer

-14" membrane housing $320 from freshwatersystems.com
-membrane, $221 from freshwater systems
-stainless needle valve, ~$100 from mcmaster carr
-flow meter, also about $100 from mcmaster carr
-prefilter housing, ~$20 from any plumbing supplier
-prefilters, ~$5 a piece from any plumbing supplier
-NC 1000psi switch , ?? I have been unable to source one.

-assorted plumbing fixtures not included



I'm looking at about $1,500 for the 3gph design. Still comparatively low cost and will be great to be able to run it off of solar alone, but I have not been able to get to Pizzaz's sub $1k figure at current costs. costs are comparable to the 12gph one I am building using a cheap(treated as a consumable) brass HP pump driving a 40" membrane partly due to the fact that most components are the same and the 14" membranes and housings are more expensive than the 21" and 40" ones by a fair margin.


As an aside I am building both as a technology demonstration / testbed for use in disaster relief situations, not strictly for use on a boat.

[Pizzazz]

Originally Posted by jimbojonesbos

Just an update for anyone considering building this. I am putting together both a 12gph 12v watermaker that should pull about 90 amps @12v, and the 3gph system in this thread. I have been unable to find the pumptec 116c with the .105 cam as anything other than a special order and consequently I'm getting quotes in the $650-$675 range.

The key elements of the 3gph design, as of Feb 2020, have the following prices:

-116c-105 pumptec HP pump , $675 from pumptec direct or through a dealer
You can get a 50% discount = $340 if you register as a dealer (or through me)

-14" membrane housing $320 from freshwatersystems.com
-membrane, $221 from freshwater systems

Fiberglass housing+membrane from HCTI, ~$400 combined

-stainless needle valve, ~$100 from mcmaster carr
Any on Amazon will do, as long as it is SS316, $30

-flow meter, also about $100 from mcmaster carr
You do not need one after the initial testing, you can just measure the output by timing how long it will take to fill in a container of known volume

-prefilter housing, ~$20 from any plumbing supplier
OK
-prefilters, ~$5 a piece from any plumbing supplier
OK

-assorted plumbing fixtures not included
Total so far $795+assorted fixtures and the high pressure hose and dial.

As I have mentioned before, I build these for friends and I believe the market is too small to make a profit while providing support and warranties and all sorts of support. If anyone has the time to partner and make a business out of this, let me know. But for me this is strictly DIY at this point.

Another interesting modification to this project is to use two pumps from Pumptec (for redundancy and for added volume). My estimation is that with two pumps and the 21" membrane the fresh water production would be around 8-9 gph with both pumps operating and 4-5 gph with only one of the pumps operating. The total cost will be still around $1,200. I am building one of these for a cruising friend right now. He wants max reliability.

SV Pizzazz

[jimbojonesbos]

Originally Posted by Pizzazz

-116c-105 pumptec HP pump , $675 from pumptec direct or through a dealer
You can get a 50% discount = $340 if you register as a dealer (or through me)

SV Pizzazz

PM sent,
thanks

[lizardofoz]

How much did it cost overall? Do you have a breakdown of that?

Originally Posted by Pizzazz

I am sharing my 3 gph watermaker design for those who want to DIY. After many months of experimentation I settled on the following design:

Parts
- Pumptec 116C stainless steel pump/motor combo. Make sure you order the .105 CAM which gives you around 15 gph total flow. The cost is substantially less than $500, feel free to negotiate with distributors but I can't disclose the actual discount I am getting.

http://www.pumptec.com/media/downloa...8215_80940.pdf

- Fiberglass pressure vessel and membrane from HCTI. The company is very easy to work with and they have great prices, expect to pay less than $400 for the pressure vessel and the membrane. I am using the 2514 size but I believe the 2521 could work as well.

HCTI - Vessels

The rest is fittings, pressure hose, a simple needle valve and a pressure gauge. You should aim to obtain all parts for less than $1,000.

Design
Salt water goes from intake to a strainer, 20-micron filter and then to the pump. The pump has three inlets and three outlets. Plug the four that you do not need. The pump output is attached directly to the pressure vessel (to minimize the number of connections). The high pressure output from the vessel goes (via a suitable length hose) to a t-connector that has a 1,500 psi gauge on one end and a needle valve on the other end. After the needle valve you can use common low pressure hose and fittings.

For extra safety, you can get a 1,000 psi pressure switch that can be inserted in one of the free pump outlets. It will cut current to the pump motor if the pressure is exceeded. You do not need a regulator, although Pumptec sells some if you want to experiment with one.

Performance
This design makes between 2.8 and 3.2 gph (Socal waters) at approx. 14A or about 4.5A/gallon. Water quality is 105-110 ppm. You do not need a feed pump (adds complexity). Best performance is around 850-900 psi. The pressure can vary somewhat with voltage (i.e. if you set the unit in operation at 12.2V and then the solar panels kick in raising the voltage to 14.4V, then the pressure will increase by about 100 psi. So, either you need to be careful when setting the max operating pressure, you need a safety switch or you need to tend to the watermaker. I typically run it when the engine is running to minimize the relative noise.

Improvements
I believe the water maker can be improved in a couple of ways. If we connect a longer membrane, say 2521, I believe the water output will increase to around 4 - 4.5 gph without losing much water quality (i.e. the ppm can jump to 200-250 ppm but that is still reasonable). One can add a soft start circuit to the motor, so that the needle valve can be left in its position and you only use an on/off switch to operate.

I believe this is the lowest cost watermaker on the market today, using standard parts (stainless steel pump, good pressure vessels, etc.). For the record, I experimented with cheaper stainless steel vessels rated for 300 psi and they work fine at 1,000 psi after strengthening the bolts, etc. but it is too much effort to save a few bucks. The pump motor combo is incredible, the pump is supposedly 96% efficient, the motor has average efficiency. It may be worth experimenting with a more efficient, higher output motor (the pump will just turn faster, allowing higher water output) but I never bothered.

Comparison to PS35 / PS40.
This unit makes double the water for one quarter of the price of the PS40. It is noisier but the noise is a regular pump noise vs. the thumping sound of the PS40 which some find objectionable. I have both on the boat and I use 3 gph watarmaker much more often.

Reliability
I have had the pump in various configurations for over a year. Max continuous run times has been about 18 hours. Never had any issues. I have had the watermaker sit unused for over two months, then it starts with no problems and the water quality is as described above. I see no need for regular cleanings, just run it every now and then to replenish the water.

Good luck and let me know if you have questions.

SV Pizzazz

How much did it cost overall? Do you have a breakdown of that?

[Pizzazz]

The breakdown is shown above. The key components are pump motor combo for $320, housing for $240 and an RO membrane for $180. The rest is small parts including the needle valve. One improvement I have considered since is to add two pumps for redundancy and to increase the output. This is an additional cost of $320 for the second pump and a few more connections. With both pumps on and the longer membrane, the output is around 7-8 gph, at around 3.5A per gallon. I stopped experimenting with this because the current setup meets my needs perfectly. All of the electronic stuff I was considering, auto shutoff, clean, etc. is not that valuable in practice. Sometimes I even leave the needle valve dialed in and just operate it with the on off button. May be it shocks the membrane but I have not observed any deterioration. Sometimes I run it once every couple of days, sometimes once a month. No cleaning so far.

Clearly, if I go extended cruising I would be much more careful but for now I just want to test the limits of the membrane. One worthwhile option I have considering is soft start where the pumps ramp up over a period of 15 seconds.

I do not plan to make this commercially (although these days there may be more demand than expected) but the pumps need to be ordered in sets of 9 pieces to get the discount, otherwise the shipping cost is not trivial.

Send me a pm if you need additional info.

SV Pizzazz

[Tsuru]

PM sent regarding a PumpTec pump.

[Fore and Aft]

Pizzazz any chance of a photo of a completed unit? This really sounds like a project I could do.
Cheers

[jimbojonesbos]

Here is a pic of one using the pump discussed in this thread, membrance is not installed as my boat is not in the water and may not go in this year at all. And of course this will require a prefilter and discharge lines but this is the heart of the system. I will be installing below waterline without a feedpump and rely on the head of the inlet to provide positive feed.


edit: not sure why this pic won't embed here is a link
https://imgur.com/a/DS7OlTn

[NorthernMac]

Originally Posted by jimbojonesbos

Here is a pic of one using the pump discussed in this thread, membrance is not installed as my boat is not in the water and may not go in this year at all. And of course this will require a prefilter and discharge lines but this is the heart of the system. I will be installing below waterline without a feedpump and rely on the head of the inlet to provide positive feed.


edit: not sure why this pic won't embed here is a link
https://imgur.com/a/DS7OlTn

Very impressive!!!




So what was the out the door price tag you ended up at?

Could this have the switch and gauges remotely mounted and use a auto shutoff for a full tank or max pressure????

[jimbojonesbos]

Originally Posted by NorthernMac

Very impressive!!!




So what was the out the door price tag you ended up at?

Could this have the switch and gauges remotely mounted and use a auto shutoff for a full tank or max pressure????

My costs are in an earlier post in this thread. I paid full retail for the pump. But total cost including miscellaneous small stuff that I always forget to account for was a bit less than 1500. Pizzaz has shown it can be done much cheaper than I did it. My needle valve and gauge are us made and very high end, in addition to the fact that I bought my pump from pumptec at full list price . I also have a cat overpressure valve on the way since I could not find a suitable pressure switch. That's another hundred bucks.

You certainly could make a remote panel. That is something I may do down the line just using some tubing to put the pressure gauge and needle valve in an easy to reach spot along with the tds meter . You certainly could also do all types of automation with solenoids and an Arduino board. I am building a 12v 16gph watermaker and for that I intend to go all out , but this one is simple and elegant in it's minimal part count and low current draw. Assembly time was less than an hour once all the parts came together, it's dead simple.

I agree with Pizzaz that the beauty of using this pump is in the simplicity. Before finding this thread I had come across this pump but Pizzaz's post demonstrated it's viability and convinced me to go ahead with it.

[BjarneK]

Originally Posted by Pizzazz

I am sharing my 3 gph watermaker design for those who want to DIY. After many months of experimentation I settled on the following design:
...
I am using the 2514 size but I believe the 2521 could work as well.
...
Performance
This design makes between 2.8 and 3.2 gph (Socal waters) at approx. 14A or about 4.5A/gallon.

Thanks for sharing your design. Amazing how nice and simple a watermaker can be. I am no expert on watermaker design at all and I have a question: If I am reading the DOW FILMTEC datasheet right for size 2514, the fresh water rate is 150 gpd at 800 psi which is 6.25 gallons per hour. How do you end up with 3 gph?

The datasheet is here:

http://www.hcti.com/pdf/mem/DOW/DOW-SW30.pdf

Are you using a different brand? Other brands seem to have similar specifications for product flow.