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Old 24-08-2019, 10:37   #1
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Dessalator Water Maker Problem?

When I turn the lever on the side of the filter mount to flush no flushing water goes through the systems. When I start the water maker immediately a fitting in the low pressure circuit blows of..... for example the soft plastic screw in fitting that holds the electrodes for the produced water quality sensor.


Before I start pulling things apart does anyone know what might be wrong?
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Old 24-08-2019, 12:10   #2
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Re: Dessalator Water Maker Problem?

It sounds to me like you have filed to open a valve on the waste water dump. I assume (maybe a bad idea) that you have a valve on the output that directs water in the product water line to either the tank or waste. If you are looking to dump the flush water overboard and there's a valve that's not open pressure will build to equal the pressure in the pressure vessel. If you turn on the high pressure pump with the valve closed then you'll blow the weakest point in the low pressure side of the product water line. Don't ask me how I know. If the flush water is coming from a bucket and not a pressurized water system it will not flow until the pump is turned on. If It's coming from a pressurized it is possible that the pressure is insufficient to open the small check valves inside the the high pressure pump. Has this unit been working or has it been shut down a while?
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Old 24-08-2019, 13:14   #3
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Re: Dessalator Water Maker Problem?

Is the fresh water pump on on board and the lever vent oŘen, so that fresh water from the tank arrives at the vent you are switching?
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Old 24-08-2019, 13:16   #4
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Re: Dessalator Water Maker Problem?

Cpt. Bill, you sound like the man to talk to.


There is a valve on the outlet, but that's open. I think both the flush water and waste saline come out of it.


The flush comes from the low pressurized house system. There's plenty of pressure there.


You mention the check valve in the high pressure pump could this be seized? It was run 2 months ago, but not since then. So yes it has been shut down a while.
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Old 24-08-2019, 14:09   #5
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Re: Dessalator Water Maker Problem?

Quote:
Originally Posted by Andy Todd View Post
Cpt. Bill, you sound like the man to talk to.


There is a valve on the outlet, but that's open. I think both the flush water and waste saline come out of it.


The flush comes from the low pressurized house system. There's plenty of pressure there.


You mention the check valve in the high pressure pump could this be seized? It was run 2 months ago, but not since then. So yes it has been shut down a while.

Your pressure vessel will have two outlets and one inlet. Raw water and flush water both should be coming in the inlet. The output side is the one with two outlets. and is on the opposite side of the pressure vessel from the inlet. One of the outputs (the larger one) is the discharge for both waste brine and waste flush water which goes directly through from the inlet. The outlet will go to a pressure control valve of some sort depending on the brand of water maker. This valve could be a a manual valve that you have to close to adjust the pressure or an automatic pressure regulating valve. If it's an automatic valve it is usually set to around 800 PSI. When you are using flush water and are running the pump this is way too much pressure and the membrane starts producing way more water than the product water outlet is designed to handle. If you have the pressure control valve wide open you are probably still going to have 100 psi or so on the system just due to resistance in the plumbing caused by the various valves and restrictions. Because fresh water has no osmotic pressure to overcome it flows easily through the membrane. The product water outlet is the small one and is supposed to run with little or no back pressure. My membrane specifies less than 3 PSI which is probably pretty typical. If your pressure regulating valve is set to anything but wide open you are going to be increasing the pressure in the product water line simply because that small outlet cannot move huge volumes of water at once. Most of those small fittings, especially the push-in types are designed to hold at household water pressure and sometimes regulated pressure at that which is about 25 psi. Once the back pressure exceeds the limits something has to give. If your regulator valve is wide open you are not likely to exceed the flow and pressure on the product water side as long as the product water has an escape route. One normally has a diversion valve on the product outlet to steer the product water to the storage tank or to waste. When flushing or cleaning one normally sets the diversion valve to waste and dumps the product water overboard or to a hose to a bucket or waste water container. Sometimes the product water waste line will have a valve on it somewhere and it must be opened when diverting the output to the waste line or the pressure in the product line will climb almost instantly and pop off the weakest point in the product water line. Most diversion valves can divert the product water to either the tank or waste lines, but if the handle is placed in the intermediate position it shuts off the outlet to either one. In this position there is no place for the product water to go at all and pressure will build almost instantly and pop the weakest link in your product water line. While it is possible that your product water waste outlet is plumbed to your brine outlet this is unlikely as most systems allow one to collect product water not going into the tank for pickling and membrane cleaning (using acid or alkaline cleaner not just fresh water flushing). I think I've pretty much covered what can cause your product water line to be over pressurized.
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Old 25-08-2019, 10:29   #6
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Re: Dessalator Water Maker Problem?

Hello,
This happened to me with a Dessalator AC100.
The system is working fine with no feading pump.
The soft plastic you mentioned is the salinity tester. It pops out when waste line is closed. If valve is opened, I suggest you have some growth blocking it.
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Old 26-08-2019, 09:24   #7
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Re: Dessalator Water Maker Problem?

Thanks... It turns out there is a value on the waste/flush outlet buried under the hot water tank. The flush circuit is working. Now the HP pump runs and I get a set of red and amber flashing warning lights that suggests the pressure is too low (Dessalator d60). And when I turn the manual pressure control valve the needle on the gauge does not increase.


There is a little grey button. I think it is on the side of a solenoid on the outlet of the flow gauge in the low pressure circuit. I presume the solenoid opens when the quality detected is good. The button looks to be out. I won't stay in. Does this indicate anything?
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Old 28-08-2019, 10:43   #8
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Re: Dessalator Water Maker SOLUTION!!

After many hours and help from Martin at Dessalator here's the solution.


The pressure vessels are at the top of the system. There was a air lock in the top vessel that would not clear by normal flushing. Cured by removing the low pressure pipe at the pressure vessel and running to produce desalinated water to clear the airlock.
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Old 28-08-2019, 10:52   #9
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Re: Dessalator Water Maker SOLUTION!!

Quote:
Originally Posted by Andy Todd View Post
After many hours and help from Martin at Dessalator here's the solution.


The pressure vessels are at the top of the system. There was a air lock in the top vessel that would not clear by normal flushing. Cured by removing the low pressure pipe at the pressure vessel and running to produce desalinated water to clear the airlock.

That's good news. I guess I forgot that I always make sure that the waste brine outlet is at the top and not at the bottom. It helps clear any trapped air.
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