Water Maker low pressure supply pump

[a64pilot]

Well some of it is true. The part of these motors are not meant for 100% duty cycle is I’d say true, and I’d go out on a limb Rich and guess that is why you have fitted that fan and bracket? Cause they are not really meant to run continuously, and will overheat if they do, so to live a long life, they need additional cooling, cause heat is the enemy of most things electric.

If I had rolled my own Watermaker, this is one of what I’m going to assume many little tricks I would have learned the hard way, usually finding out about an issue after I bought the second replacement part, cause first failure you put down to a bad part, after two you realize there is a problem with your design.
If I had, had time to mess with it, it would have been fun if somewhat frustrating to work through all the little issues that come up.

The March air conditioner pump would likely work, but then how do you use it to fresh water flush and pickle the membrane? Besides you now need to run your generator just to do a fresh water flush, no big deal, but if it were a DC pump, then you don’t need to run the generator.
Worse is you will likely lose your membranes if the generator stays broken for very long, or you will need a large enough inverter to run the AC powered pump

It gets complicated when you figure out that you ideally need to accomplish multiple tasks with an item.

[CdS2 Roland]

Hello,
My Dessalator 100 l/h is installed under waterline with just part of the filter above. No need of feed pump and/or fan. It works perfectly since 10 years, no damages on HP pump.

[SV THIRD DAY]

Originally Posted by CdS2 Roland

Hello,
My Dessalator 100 l/h is installed under waterline with just part of the filter above. No need of feed pump and/or fan. It works perfectly since 10 years, no damages on HP pump.

If only all water makers could be mounted below the water line....but alas....most can't and need a boost pump. Because Piston Pumps don't like to suck...CAT, General or Brand X. It damages the packing and in extreme cases causes pressure pulsations that can rupture the membrane.

[desdestiny]

[Not true.
The Amps used (and heat created) by the pump increases with additional pressure the pump is asked to create. So adding a bypass to a positive displacement diaphragm pump loweres the pressure of the pump and reduces the amps usage and heat. I know this from real life bench testing on our shop units that run continusouly 24hr/day....7 days/week.][/I]

I agree with this comment - however the amount of reduced amps and consequently heat is minimal - the pump motor is still operating at full speed, and the total volume of water passing through the pump is the delivery water plus the bypass water - at the reduced pressure.

Consider the benefit - no bypass valve - and the motor speed is reduced using PWM to adjust the discharge to the lower pressure. The motor is consuming much less current, is working much less hard, and is only delivering the water reaqired to pass to the RO unit.