12V water maker

[alhambra]

Many thanks to those who replied to my original question - we do not have a generator due to size/cost restraints. The reason we are looking at 12V is to run from battery power, and a fairly simple installation. Cost is also a major factor and the American units appear very expensive compared to European made systems. We have looked at engine driven units but these have clunky industrial pumps with special brackets for mounting etc, and we really do not want to HAVE to run our engine to make water. (Whilst fully appreciating the power has to be put back into the batteries somehow and we were relying on our 420 watt of solar to help with that) The advice to look at litres produced per amp consumed in DC units was particularly helpful .

 

[Neeves]

So in your case you may have been better with an engine driven unit that could make at least double the water quantity without having to resort to the low reliability 12v technology? Just a thought.

Geen, I'm with you on this. Our Spectra unit has been problem free and as a 12v unit is very simple to use. If you are at anchor for a week running the engine is a nuisance, simply to make 60l of water and often the priority is to charge the battery and water is a secondary (but still critical) issue. I'd rather run an engine (petrol) for an hour and make 120l of water.

The Rainman's advantage is - no plumbing.

Something not mentioned - if you have no water maker and you rely on tank water then you really do not have enough. If you have a smaller water maker, say 30l per hour - you apparently have lots of water, except within a few weeks you do not have enough. Move upto 60l - same, same. Its Parkinson's Law all over again. Once you get to 120l/hr maybe the amount of water used for showers, laundry (if you have a water maker then next thing on the list is a washing machine!) starts to get into balance. But Parkinson would suggest not!

 

[geem]

Geen, I'm with you on this. Our Spectra unit has been problem free and as a 12v unit is very simple to use. If you are at anchor for a week running the engine is a nuisance, simply to make 60l of water and often the priority is to charge the battery and water is a secondary (but still critical) issue. I'd rather run an engine (petrol) for an hour and make 120l of water.

The Rainman's advantage is - no plumbing.

Something not mentioned - if you have no water maker and you rely on tank water then you really do not have enough. If you have a smaller water maker, say 30l per hour - you apparently have lots of water, except within a few weeks you do not have enough. Move upto 60l - same, same. Its Parkinson's Law all over again. Once you get to 120l/hr maybe the amount of water used for showers, laundry (if you have a water maker then next thing on the list is a washing machine!) starts to get into balance. But Parkinson would suggest not!

hope you don't mind the slight thread drift but for our liveaboard life the high output watermaker works great.
on wash day we run the watermaker for about an hour and make our 135 litres or so. Wash day uses about 100 litres of water. We got rid of the washing machine before we set off as we didn't want it. We have a spinner instead. We wash in a builders bucket in the cockpit. It is filled with hot water and dirty clothes and left with the occasional prod to agitate for an hour. The soapy clothes are put through the spinner to remove as much soap as possible then dropped into builders bucket number two. More water is added to bucket to rinse soap out then back through spinner. Repeat this and clothes are soap free. Soapy water is used to clean cockpit etc. The spinner is extremely useful to us and we find it more important than a washing machine. The spinner lives under the bunk in the back cabin. Builders buckets live in the front deck locker to store spare lines.
Using the generator to make hot water and fresh water for just an hour without depleting our tanks works well for us. We could just as easily do this with an engine driven watermaker. The key for me is high output. We don't want to run generator or engine for longer than necessary. We don't want to run off batteries to make water as even the highest output 12v systems only seem to make about half the water we make in an hour. I built my watermaker from second hand parts for £1500. It uses reliable parts such as CAT pump and has no electronics at all. I want simplicity in a watermaker not complexity. I am the control system in our watermaker. I flush it. I pickle it. I maintain it.

 

[Neeves]

A few more inputs:

I think these are all correct:

Any desal unit works better in brackish water, so better in a river than an 'ocean' anchorage. Most, all desal units work better in warmer water than cold. DC desal units work better at higher voltages, so lower output if driven from a battery than if driven from a charged battery and the engine running (or being charged at mid-day in full sun from a big solar array).

The differences are small - but worth considering

Then Parkinson:

Water consumption increases to be slightly more than production (more so when guests are on board - who have no idea where water for showers comes from).

Power, electricity, consumption increases to be slightly greater than supply (no matter how big your solar array, wind gen, engine alternator output might be).

edit

We have 360 watts of solar (plenty of room on a cat for solar). We have a LVM aqua4aerogen and 2 x 60amp/hr alternators (one each on a MD2020). Plus a Spectra 60l/hr Desal unit. 400amp/hr house. We sail for a continuous 3 - 5 months a year covering about 2000nm for the 3/5 month cruise. Its a constant battle to keep both water and power supplies up (though we do not like to sail with 400l of water on board). Every time the engine goes on, so does the desal.

close edit

Jonathan

 

[geem]

A few more inputs:

I think these are all correct:

Any desal unit works better in brackish water, so better in a river than an 'ocean' anchorage. Most, all desal units work better in warmer water than cold. DC desal units work better at higher voltages, so lower output if driven from a battery than if driven from a charged battery and the engine running (or being charged at mid-day in full sun from a big solar array).

The differences are small - but worth considering

Then Parkinson:

Water consumption increases to be slightly more than production (more so when guests are on board - who have no idea where water for showers comes from).

Power, electricity, consumption increases to be slightly greater than supply (no matter how big your solar array, wind gen, engine alternator output might be).

edit

We have 360 watts of solar (plenty of room on a cat for solar). We have a LVM aqua4aerogen and 2 x 60amp/hr alternators (one each on a MD2020). Plus a Spectra 60l/hr Desal unit. 400amp/hr house. We sail for a continuous 3 - 5 months a year covering about 2000nm for the 3/5 month cruise. Its a constant battle to keep both water and power supplies up (though we do not like to sail with 400l of water on board). Every time the engine goes on, so does the desal.

close edit

Jonathan

For comparison purposes, We are currently based in the Caribbean. We have 460w of solar, Duogen that we use in wind mode sometimes but always in water mode on route. We have a 60amp @24v alternator and 400 amp hr battery bank @24v (so 800 amp hr in 12v money). We have a 4kw diesel gen set with 2000 hr on it and its past its best. (spare generator sat in garage at home!) We have a 3kw inverter backup that will run the watermaker with the engine on and solar running. We run the watermaker off the genset for an hour every three days or so, making 130 litres/hr. Our tank capacity is 780 litres and we generally have about 500 litres in the tank. In the Caribbean the engine rarely goes on as we have plenty of wind.
No problem making enough water as high output watermaker. No problem making power as solar and Duogen do that without generator. Generator only has a 15 amp charger but we rarely use it or need it.

 

[oldvarnish]

Have a look at Rainman Desalinators, either petrol (Honda 4 stroke) or, 12v, electric powered.. Does not need to be fitted. Works straight out of the box, or 2 boxes. Uses standard components available anywhere, well almost. I have tried one, easy to use, huge output (compared to most others).

Jonathan

nice looking kit. Shame it won't work off 12vdc

 

[Neeves]

They make a 12v model - it was on the website - if not send them an email.

 

[noelex]

I think there are two distinctly separate approaches to choosing the right watermaker.

1. Use a simple non energy recovery water maker and run it only when the main engine or generator are running. It needs to be a high capacity unit that will make lots of water in the short time while the main engine or generator are running. The power consumption in Watts/L is not very important, but the output in L/hr needs to be large.

2. Get an energy recovery watermaker like the Spectra. These can be run from solar/wind (providing you have enough). The output can be low because the unit can operate many hours if needed. The main engine or generator are not needed to power the unit. The Watts/L is very important. The L/hr can be lower than the first option.

Both approaches are valid and work well. The costs for a high capacity non energy recovery watermaker and a low capacity energy recovery watermaker are reasonably close, as are running costs. It is important to get the right option depending on your needs and most importantly how you intend to power it most of the time.

The Rainman high pressure pump is not one of the energy recovery units like Spectra so it falls into the first category.

If the Rainman can be run from 12v the energy needed will be very high. This is no problem if you want the watermaker to run only while the main engine, or generator is operating (or in Rainman's case when its dedicated generator is running). However, if you want to run the unit from solar power the energy recovery watermakers are generally the only practical solution.

 

[geem]

I think there are two distinctly separate approaches to choosing the right watermaker.

1. Use a simple non energy recovery water maker and run it only when the main engine or generator are running. It needs to be a high capacity unit that will make lots of water in the short time while the main engine or generator are running. The power consumption in Watts/L is not very important, but the output in L/hr needs to be large.

2. Get an energy recovery watermaker like the Spectra. These can be run from solar/wind (providing you have enough). The output can be low because the unit can operate many hours if needed. The main engine or generator are not needed to power the unit. The Watts/L is very important. The L/hr can be lower than the first option.

Both approaches are valid and work well. The costs for a high capacity non energy recovery watermaker and a low capacity energy recovery watermaker are reasonably close, as are running costs. It is important to get the right option depending on your needs and most importantly how you intend to power it most of the time.

The Rainman high pressure pump is not one of the energy recovery units like Spectra so it falls into the first category.

If the Rainman can be run from 12v the energy needed will be very high. This is no problem if you want the watermaker to run only while the main engine, or generator is operating (or in Rainman's case when its dedicated generator is running). However, if you want to run the unit from solar power the energy recovery watermakers are generally the only practical solution.

+1. Summarised nicely

 

[Neeves]

The Rainman high pressure pump is not one of the energy recovery units like Spectra so it falls into the first category.

If the Rainman can be run from 12v the energy needed will be very high. This is no problem if you want the watermaker to run only while the main engine, or generator is operating (or in Rainman's case when its dedicated generator is running). However, if you want to run the unit from solar power the energy recovery watermakers are generally the only practical solution.

Not quite true:

If you depend on solar and wind both can be a scarce commodity, most people carry petrol and can commonly replenish same (not so solar in winter and wind tends to be low input at anchor). Solar and wind are also commonly needed for other demands, phone, fridge, autopilot.

Rainman is either 12v or petrol (unless they have added a new option). Their electric power usage will be the same as a Spectra unit, per litre. The pump is an imdustry standard desal pump.

No connection, I just happen to have used one and a Spectra unit and done reviews in Oz and America.

 

[noelex]

Their electric power usage will be the same as a Spectra unit, per litre. The pump is an imdustry standard desal pump.

I know you have used the Rainman watermaker and have written magazine reviews about this product so you have far more experience than me. However, I don't think your understanding that these units will have the same electrical power usage (per litre) as the Spectra units, is correct.

If you are planning on powering the watermaker primarly or even partially via alternative energy (solar or wind), it is important to make a very clear distinction between the watermakers that use energy recovery pumps and those that do not.

Units like the Spectra with a special energy recovery pump (sometimes called a Clarke pump) use 2-3 times less power per litre of water than standard watermakers. The specifications for the Rainman unit are a bit sketchy but my understanding is that the high pressure pump does not use any energy recovery technology. This keeps the high pressure pump simple, which is a good thing. If used as designed, high power consumption is not a problem if a generator is run to supply the power. However, it is important to understand that if you operate this unit from 12v, the power consumption (per litre) of water produced will be much higher than a unit like the Spectra.

It is not practical to operate a unit like the Rainman from alternative energy. A generator, or at least the main engine, will normally be needed during operation.

There are large differences in the amount of power consumed between the energy recovery water makers like Spectra and those that use a conventional high pressure pump. It is vital to understand the distinction to choose the right watermaker for your needs.

On my own boat virtually all our electrical power, including running the watermaker, comes from solar power. A non-energy recovery watermaker, even if it could be run from 12v, would be a very poor choice.

The specifications for the Rainman unit are a bit sketchy so if anyone has any more detailed information, particularly on the output per watt, it would be great to get a definitive answer. I am considering equipment choices for a new yacht. If the Rainman unit does have an efficiency similar to the Spectra units, it would make it far more attractive for my needs.

 

[Neeves]

The original Rainman is a simple desal system powered only by an off the shelf and standard 4 stroke Honda engine. It will produce about 120l of water an hour. Their subsequent development of the electric unit was for those people who, for whatever reason, did not want a petrol power or energy source (they maybe had a genset, possibly the bigger of the 2 Honda gensets ). You can run the electric Rainman from a 12v source but you would need an invertor.

But you are quite correct, and my earlier post was erroneous, its power usage (the electric version) per litre is higher than the Spectra unit, by a factor of, I think, 2 times. In fact it might be worse than 2 times as if you have no power source (other than solar) then as the voltage drops when you use the Rainman, or any desal unit, their efficiency drops (they work better at 13.5v volts than 12.5 volts). You can overcome this by running your engine or a genset (but from your post you do not want to do this - the noise is tedious). But the Spectra unit is hardly quiet, ours is situated under the cabin sole and the 2 electric pumps need to run flat out for 2 hours to make the same as the Rainman and though we have 360 watts of solar - we find we need to run the engine(s) as Australia's much vaunted sunshine is insufficient, certainly in winter.

I only used the petrol unit, the electric unit was not even part of the future when I tried the original product. The electric unit, to me, offers little advantage over many such units - except it does not need plumbed in. The petrol unit offers, if you can stomach a petrol engine running for an hour, copious supply of water from a unit that has no installation cost, open the boxes, connect some pipes (easy connections), start the engine, make water.

I have not kept upto date on pricing but initially the petrol Rainman was good value, compared with many other units. It is, or was made in Australia (whose currency has fallen) but all, or most, of the parts were imported so there will have been changes in prices. Where the electric units fits into pricing, no idea. When we need to replace our Spectra unit the petrol Rainman would be top of the list - because we have better uses (given there is an alternative) for our scarce electricity. If the Rainman were expensive - it would slip down the list.

 

[geem]

The original Rainman is a simple desal system powered only by an off the shelf and standard 4 stroke Honda engine. It will produce about 120l of water an hour. Their subsequent development of the electric unit was for those people who, for whatever reason, did not want a petrol power or energy source (they maybe had a genset, possibly the bigger of the 2 Honda gensets ). You can run the electric Rainman from a 12v source but you would need an invertor.

But you are quite correct, and my earlier post was erroneous, its power usage (the electric version) per litre is higher than the Spectra unit, by a factor of 2 times. In fact it might be worse than 2 times as if you have no power source (other than solar) then as the voltage drops when you use the Rainman, or any desal unit, their efficiency drops (they work better at 13.5v volts than 12.5 volts). You can overcome this by running your engine or a genset (but from your post you do not want to do this - the noise is tedious). But the Spectra unit is hardly quiet, ours is situated under the cabin sole and the 2 electric pumps need to run flat out for 2 hours to make the same as the Rainman and though we have 360 watts of solar - we find we need to run the engine(s) as Australia's much vaunted sunshine is insufficient, certainly in winter.

I only used the petrol unit, the electric unit was not even part of the future when I tried the original product. The electric unit, to me, offers little advantage over many such units - except it does not need plumbed in. The petrol unit offers, if you can stomach a petrol engine running for an hour, copious supply of water from a unit that has no installation cost, open the boxes, connect some pipes (easy connections), start the engine, make water.

I have not kept upto date on pricing but initially the petrol Rainman was good value, compared with many other units. It is, or was made in Australia (whose currency has fallen) but all, or most, of the parts were imported so there will have been changes in prices. Where the electric units fits into pricing, no idea. When we need to replace our Spectra unit the petrol Rainman would be top of the list - because we have better uses (given there is an alternative) for our scarce electricity. If the Rainman were expensive - it would slip down the list.

who's high pressure pump does the Rainman use? Their website avoids mentioning the supplier of the pump or showing a photo

 

[Neeves]

who's high pressure pump does the Rainman use? Their website avoids mentioning the supplier of the pump or showing a photo

General Pumps

There are lots of photos but its just a boring 'black box'

edit Its in the bottom left corner beside the Honda unit in the big blue plastic box. close edit

 

[geem]

General Pumps

There are lots of photos but its just a boring 'black box'

edit Its in the bottom left corner beside the Honda unit in the big blue plastic box. close edit

Just had a look at the General Pumps. They are similar to the Cat pumps being a none energy recovery pump. They should be robust and reliable. The Rainman is very similar to the system I built from parts. Apart from it being boxed it isn't any different from what I can, see to the Echotec watermakers. If I was buying a system off the shelf I would by Echotec unless the Rainmam naked kit is cheaper, then it may be worth considering. I cant understand why anybody would want to have a system in a portable box if it was destined for use on a boat. Using it on route would be a pain without a proper through hull. The naked system would, however , make sense to me.

 

[noelex]

But you are quite correct, and my earlier post was erroneous, its power usage (the electric version) per litre is higher than the Spectra unit, by a factor of, I think, 4 times. In fact it might be worse than 4 times as if you have no power source (other than solar) then as the voltage drops when you use the Rainman, or any desal unit, their efficiency drops (they work better at 13.5v volts than 12.5 volts).

Thanks for clearing that up.

Watermakers use a lot of power. This equipment is primarily of interest to those cruisers who spend time away from easy sources of water like marinas. This unfortunately means watermakers will be mostly also be used away from sources of dockside power.

Understanding the difference between high efficiency (and typically low volume) and low efficiency (and typically high volume) watermakers is fundamental to making the right choice.

 

[Neeves]

Geen,

One of the costs for many people is installation and the Rainman solves that issue, you and I installed our own, ours being the off the shelf Spectra yours being one you assembled from individual components. Many would get it installed 'professionally' at a considerable cost. The other aspect of the Rainman is that it can be used anywhere, if you own both a yacht and caravan/motorhome and travel to places with questionable or no water (Australia is full of them). Its ideal for yacht clubs to hire out.

But the Rainman was developed to be simple and high output and usable with a cheap and readily available energy source - petrol. Most yacht owners complain they have not enough electricity and not enough water. The Rainman solves this issue by not imposing on current electrical availability and offers high output.

I would have to agree that switching our Spectra on and getting instant water is convenient. But I am happy to disassemble our windgen and convert it to watergen mode and to me the inconvenience of using the Rainman would be no different. We tend to run our Spectra when entering or leaving anchorages, as that's when we run our engines and commonly its calm - that's why we chose to anchor in that location, so dropping the pick up in calm water is not difficult. Most people who liveaboard spend 95%, or more, time at anchor - these are no issues in dropping the pickup over the side. if you make water at anchor and fill your tanks - you can sail a few days before you will run out.

Its all about compromise - but one thing we do not compromise on is the idea that its the 21st Century and we should have access to 'enough' fresh water and electricity and critically these 2 fundamentals should not need to be achieved by resorting to a marina. Living on a yacht should not be like camping in the middle of the 20th century - surely we have moved on. How you achieve 'my' ideal - lots of compromises.

edit I think you implied that you would find the Rainman more interesting if you could buy it without the box - I think implying it might suit a fixed installation. There is the issue of where to install - it is a petrol engine. But the pump and Honda are coupled up, obviously - so you need to buy them as one unit (and they are the meat of the system). The membranes are standard Dow units. Much of the rest are simply pipes (the 5 micron filter), though there are a couple of specially made couplings in stainless. But there is no reason why you could not fit it into a lazerette, with a through hull fitting (even take it out of the case). I'd prefer to run the petrol unit 'outdoors'.

close edit

 

[Heckler]

hope you don't mind the slight thread drift but for our liveaboard life the high output watermaker works great.
on wash day we run the watermaker for about an hour and make our 135 litres or so. Wash day uses about 100 litres of water. We got rid of the washing machine before we set off as we didn't want it. We have a spinner instead. We wash in a builders bucket in the cockpit. It is filled with hot water and dirty clothes and left with the occasional prod to agitate for an hour. The soapy clothes are put through the spinner to remove as much soap as possible then dropped into builders bucket number two. More water is added to bucket to rinse soap out then back through spinner. Repeat this and clothes are soap free. Soapy water is used to clean cockpit etc. The spinner is extremely useful to us and we find it more important than a washing machine. The spinner lives under the bunk in the back cabin. Builders buckets live in the front deck locker to store spare lines.
Using the generator to make hot water and fresh water for just an hour without depleting our tanks works well for us. We could just as easily do this with an engine driven watermaker. The key for me is high output. We don't want to run generator or engine for longer than necessary. We don't want to run off batteries to make water as even the highest output 12v systems only seem to make about half the water we make in an hour. I built my watermaker from second hand parts for £1500. It uses reliable parts such as CAT pump and has no electronics at all. I want simplicity in a watermaker not complexity. I am the control system in our watermaker. I flush it. I pickle it. I maintain it.

Laura loves our White Knight Spinner, spins at 2000 revs, it does the biz, Ive posted before now, we tested by spinning in the house one then in the spinner, got another half a liter of water out!
S

 

[oystercatcher100]

I can certainly see the value of a portable watermaking system like the Rainman. I see they are now being sold in the UK by Sailfish Marine who I purchased my energy efficient 12V unit from. www.sailfishmarine.co.uk

 

[Tradewinds]

I can certainly see the value of a portable watermaking system like the Rainman. I see they are now being sold in the UK by Sailfish Marine who I purchased my energy efficient 12V unit from. www.sailfishmarine.co.uk

The Eco-Sistem S25 12v watermaker looks interesting. Small & quiet ('ish).