How Long Should the WaterMaker Run Before it Cuts Out - Dessalator D60

[monte]

Anyone else with a dessalator D series WM or any brand, do you have problems keeping it running? Ours has a pressure gauge, you adjust it to keep in the green. If it goes to down to the Orange or up to the red it cuts out. I usually set it and check every 5 mins to make sure its stable, or do a slight adjustment if its out of the green. Sometimes it will run for hours without adjustment, but mostly it seems to alter pressure and cut out every 20-30 mins if I dont check it.
Is this normal? are there any tricks to keep it set correctly? the filter is new and we are anchored in calm clear water.
One thing with the installation, it is supposed to be below the waterline, but its about midway on the waterline, would this have an effect on it?
Possibly it has a dodgy pressure gauge...or maybe this is the norm...
interested to hear others observations with dessalator or any other brand.
Thanks
Monte

[colemj]

What pressure gauge are you talking about? The one on the pressure vessel (should read ~800psi) or do you have one on the prefilter stage(s)?

It sounds like you are talking about the pressure gauge on the pressure vessel, since that would be the only part where you could adjust pressure. If so, then it is not normal and something is wrong. The pressure there should only vary slightly with water salinity and temperature - and not vary at all in a period of weeks/months. Ours was set 5 years ago and hasn't budged.

You certainly are not adjusting the gauge itself, so what are you adjusting to make the pressure change? I am assuming it is the pressure regulator.

If the pressure gauge was bad, it would have no effect on the watermaker operation unless you have a highly controlled unit that measures and acts on gauge readings.

It is possible that the pressure regulator valve is bad. It is also possible that you do not have enough pumping ability to lift the water sufficiently. A feed pump is always a good idea regardless of the mounting position. If you have a spare galley or washdown pump, you could plumb this between the water inlet and the watermaker inlet and see if that solves the problem. Only test it this way, as the feedpump pressure is likely to be set higher than the watermaker spec. If it works, you can adjust the feedpump pressure regulator screw to lower the pressure.

Mark

[monte]

well the control panel looks like this.

you turn on the switch, adjust the pressure knob and viola, water !

[colemj]

Ah yes, you are adjusting the pressure regulator valve, which is controlling the high pressure in the pressure vessel.

Why does the watermaker cut out if the pressure is not in the green? It must have controlling electronics for this? In that case, a bad gauge may be the problem if the electronics are actually reading the gauge and do not have a separate pressure sensor.

If it isn't the gauge, then you have a pressure regulation problem that could be caused by some of the things I listed above.

Mark

[monte]

thanks Mark, yes its supposed to cut out when ts not in the green, and it does. Yes it has electronic circuits, Im just wondering if its normal to have to adjust very reguarly or if it may be a problem with a sensor or something.

[colemj]

Well, it definitely is not normal - not by a long shot. So you will need to figure out if the electronics are sensing a bad signal or if the pressure is really varying so much.

Does the back of the pressure gauge only have a single hose going into it with no electrical wires or second hose? If so, then it sounds like you do have a pressure problem. Either a leak somewhere, a bad O-ring on the pressure vessel (you would have high TDS output with that), or the intake suction side is not sufficient. If the latter, you can try adding a temporary feed pump like I described above to see if the problem goes away.

If the gauge has wires to it or a second hose, then it is possible just the gauge is bad and tripping up the electronics.

Mark

[Paul L]

My HP seems to go up after the WM has run for about 45 mins. If I set it back to 800psi it stays there for the rest of the run. Maybe due to the heat that builds up near the system.

[colemj]

Originally Posted by Paul L

My HP seems to go up after the WM has run for about 45 mins. If I set it back to 800psi it stays there for the rest of the run. Maybe due to the heat that builds up near the system.

Does this correlate to a charging source coming on line? The pressure will go up with voltage. Ours varies between 800-825 from 12.5-14.5V Heat could also be a factor.

Mark

[Paul L]

Originally Posted by colemj

Does this correlate to a charging source coming on line? The pressure will go up with voltage. Ours varies between 800-825 from 12.5-14.5V Heat could also be a factor.

Mark

Don't think it is voltage going up/down, but it could be. It goes from 800psi to 900-950. So I think something mechanical is changing in the pressure regulator. Heat is all I can think of. Its one of those 'problems' that is on the 'not enough of an annoyance list to actually do something about'.

[colemj]

Yes, that is too big a jump for voltage fluctuations unless you have too small of wiring and a large voltage drop. Also seems too much for heat. Is it possible you have a small leak on a valve or fitting that eventually firms up and seals under pressure?

Mark

[Paul L]

Maybe that's it. It could seal up with pressure or heat. I'll have to get in there and see if I can see anything. One other thing I see is that the regulator valve adjustment is pretty touchy and not that smooth.

[goboatingnow]

From memory The dessalators have a electronic pressure transducer that expects to see 800psi nominal otherwise its cuts the power to the motor

My experience found that (a) The needed valve isnt particulary stable and is affected by heat and secondly from my own experience fouling and water flow can lead to pressure problems.

dave

[caradow]

Monte,
I also have a Desalator 60 and have used it extensively for around 3 years.
It has worked flawlessly however it can be a little painful if I bring the pressure up too fast and if left alone it will cut off.
However by slowly turning up the pressure and checking it once or twice at 2-4 minutes and adjusting accordingly it will run perfectly until I cut it off.
Now mind you, the dial is extremely sensitive and it takes a little learning curve with just how much you turn the dial but once "locked in" I have no more trouble.
It does make more water (60 L/min) on AC than only (50 L/min) while using DC current.
I am interested to hear if in fact yours is actually making 60 L/min when the meter is in the green?
Also how big is your genset and what size prefilter are you using?
ciao

[dan360]

We have a Dessalator 100, and we do sometimes see it cut out. As caradow says, the trick with ours is to get used to the sensitivity of the pressure adjustment. I've found that if I get it stable at the beginning of the green after about 3 or 4 minutes of use it will then run and run.

I have also found that if we are in rough seas, then it will cut out occasionally. We've taken to just checking it every so often. It is not ideal, but it is a simple thing. I was assuming that the rough sea thing was some sort of pressure change in the intake water as a result of surfing a big wave or decelerating into a trough or something like that.

[monte]

well it's been working better since I put Jenijane in charge of making water, it doesn't bother me nearly as much
Actually the first time she touched it it ran flawlessly for a few hours so I guess she has the magic touch. It does still need checking and adjusting occasionally.
Caradow, ours it 12V so DC only. Generally the gauge shows its making around 40 l/h. I did a rough test a while ago and it was pretty accurate. We are using one 5 micron filter, no additional filter. I will also check the amps used depending on the output. i.e. if we set it on the lower edge of the green, it produces 40l/h and the pump seems to run easier and more stable. If we put it to the upper edge of the green it makes about 50l/h, it is still stable, but there is less time till it cuts out if the pressure begins to rise, and the pump sounds more laboured. I assume it will be using more amps also.
I will check it tomorrow and confirm. I'm happy enough with 40 l/h if it works out the same l/ampere, it just means running it a bit longer to fill the tanks.
Thanks for the other replies and input as well


PS. the seawater temperature is about 21 degrees here now, I wouldn't expect peak volume produced unless the water was a lot warmer, maybe 30 degrees?