Watermaker cutting out intermitently???

[CookiesnTequila]

We have an Aquabase 130LPH, 230V watermaker. This is the 4th year we've owned and lived aboard our boat. It runs every 3 or 4 days and has worked flawlessly, until about two weeks ago, when it started cutting out for no apparent reason. It runs for a random length of time - an hour, hour and a half, half hour, etc., and then just quits. It won't start right back up after stopping, but will after about 10 or 15 minutes, and then it will run again for another period. We can run it directly off the generator (which I do by default) and we can run it off our inverter. It quits on both. I changed the filters too - no change.

Any thoughts??

[a64pilot]

Electric motor is overheating and the thermal protection is opening and shutting it down, then it cools off and the thermal protection resets.
That is my guess. Either for some reason the motor is being worked harder, it’s cooling has been compromised, or it has “worn” out.
All guesses. You ought to be able to tell from the amps it draws if it’s working harder then is use to though, although as a motor’s brushes wear out and or bearings wear, that could also draw more amps?

I’d be surprised if it was a quality motor if it’s worn out.

What has changed? Have you stacked stuff around it so that it can’t get airflow now? Are you in hotter weather than before? Maybe try putting a fan to blow on it to see if that makes a difference and confirm or deny the overheating theory.

[CookiesnTequila]

Originally Posted by a64pilot

Electric motor is overheating and the thermal protection is opening and shutting it down, ....

YES! We added a deflector above the HP pump motor over the winter! Last year I had a small T fitting break and sea water sprayed all around the engine room (cost me an alternator and our Wabasto heater controls!!), so I put a plastic cover over the unit. I left the sides open, but.... I am going right now to remove it and will give it another try!!

[a64pilot]

You may consider a small fan, something like a good Noctua 120 mm, runs direct off of 12V and will run forever and draw very little power.

[CookiesnTequila]

Originally Posted by a64pilot

You may consider a small fan, something like a good Noctua 120 mm, runs direct off of 12V and will run forever and draw very little power.

Do you know if both the LP and hp pumps have heat switches?

I took the cover off and it seemed to run longer, but then cut out again. Both tanks are full so it'll cool down completely before we try again in a couple of days. I'll try a fan also. But if removing the cover that we added doesn't do it, then I'm guessing it's time to check the motor.... It never did this before!

Thanks

[Lepke]

Thermal safeties can be replaced. Bearings getting old and not turning as freely is a common cause of motor overheating and failure. Today most motor roller bearings are sealed and not easy to regrease. Especially in hot weather the grease gets used up. I would undo the motor/pump coupling and spin the motor by hand. See if it turns easy and the bearings are silent. If the bearings make noticeable noise, they most likely are dry. Roller bearings have a number on the side of the race and can be bought online. Or the seal can be removed and hand repacked with grease - videos on Youtube.
I usually get bearings here:
https://www.primebearing.com/

[a64pilot]

Motors often have thermal protection, the bigger, more powerful and more expensive they are, the more likely they are protected.
Sometimes often tripping an overcurrent or thermal device will lower the point it trips at. When the motor turns itself off, put your hand on it, it ought to be pretty hot if it’s tripping thermal protection.
I know not scientific, but if it’s running cool, then maybe we are chasing a red herring.
DC motors may or may not be thermally protected, sort of goes back to if it’s a big expensive motor or a small cheaper one.
However since it’s been running for four years, I don’t think we can blame design or installation, or at least they ought to be pretty far down the list.
If it was sprayed with salt water, then the motor itself is more suspect I’d think, they don’t like being treated like that.

[rthompsona]

Our 120V Rainman watermaker started to cut out intermittently. It turned out that we had the Air Conditioner on. The combination of the AC and the watermaker was dropping the voltage. The watermaker ran fine once we turned the A/C off.

[SV Bacchus]

When running have you verified the fresh (RO) water output is normal? Is it possible the membrane needs a good flushing or is nearing its end of life cycle?

Just a WAG on my part, not a water maker expert and I need to learn more as our Little Wonder is acting up. The TDS reading is higher than it should be.

[CookiesnTequila]

First, like always, so great to get such good help. Thank you all.

Second, I finally figured it out!!! Last year on our last run into our winter berth the capacitor on the low pressure pump burnt out. I had it replaced by the Volvo Penta mechanic that I had service our engines. After a very painful diagnostic process that lasted most of the summer and cost well over 1000€, I remembered we had that done and checked the capacitor - the mechanic had installed the wrong capacitor!!! Problem solved as soon as I changed it..... Stupid on me for not thinking about that sooner!!

The silver lining is I now know our watermaker inside out and have a developed a serious respect for Aquabase watermakers in general. It is an elegantly simple design with very little that can go wrong and easy to repair if something does!

Thanks again