Spectra Catalina 300 False Alarms?

[belizesailor]

Hola Tellie!

About 10 days ago, I purged my Catalina 300 (Spectra rebuilt Clark pump a few years ago, upgraded to MPC5000 controller) , changed all the filters, flushed it (no pressure), and ran it briefly pressurized to test. Everything was fine. PPM quickly dropped to about 250. Yahoo!

Now, about 10 days later (longer than planned), I fire it up to make water and it throws a "SERVICE PREFILTER" alarm. The prefilter is like new and water is flowing thru the system with no obvious issues (I can see flow in the prefilter, the feed pump is not overloaded, and the brine discharge appears to be normal volume visually).

I change the almost pristine prefilter just to make sure and it throws the same error again. No biggee, Ive got an MPC 5000, by pass that silly error. Run it again and it halts on a "HIGH PRESSURE" error. Geez...

If I force manual run, just by throwing the switch on the control box, everything looks/sounds fine (feed pump sounds normal, I can see flow into the prefilter, Clark pump has a nice symetrical thump, brine discharge looks normal volume and cycles with Clark pump).

I had a similar issue many years ago before the MPC upgrade...fired up my Spectra one day after being away, and it wasnt sure whether it was a toaster oven or a microwave...doing lots of wierd stuff. I reset the firmware and BAM..it remembered it was a water maker. My theory was nearby lightening strike scrambled its brains but did no damage.

However, Im not finding any such "reset" ability on the MPC 5000.


Looking for troubleshooting suggestions. Thanks in advance.

[belizesailor]

More info...

Shut down system, opened pressure relief valve, closed it, ran system again and no High Pressure error. It ran and made water at about 340 PPM.

The pre filter bar graph gradually crept up to max and feed water pressure declined from 50+ PSI to 41 over only about a 6 minute run. Feed pump sounded like it was working a bit harder. Output (old stroke sensor type) dropped to 10.5 but held steady.

This is an older system with 3 stages of filtration. I changed all 3 when I serviced about 10 days ago and it has not been run since. Could this be a blockage in one of the down stream filters?


[emoji848]

[belizesailor]

Next run...

Shut down system, opened pressure relief valve, closed it, ran system again and no High Pressure error, but also feed water pressure reads 00 at the MPC and no bars shaded on prefilter graph. Otherwise, after about 6 minutes run, its making water at 304 PPM, 10.4 GPH.

Pressure sensor in its death throes?

[emoji848]

[belizesailor]

Originally Posted by belizesailor

Next run...

Shut down system, opened pressure relief valve, closed it, ran system again and no High Pressure error, but also feed water pressure reads 00 at the MPC and no bars shaded on prefilter graph. Otherwise, after about 6 minutes run, its making water at 304 PPM, 10.4 GPH.

Pressure sensor in its death throes?

[emoji848]

Continued this run for a full hour, no problems. Held steady at around 300PPM, sometimes a bit less, and about 10.5 GPH output. Feed water pressure reading at MPC remained zero (though it obviously wasnt). Prefilter graph remained zero too.

Hmmm, bad cable connection, bad sensor?

[Rivatar]

Disconnect the 2 sensors pre-filters, they always give false readings.

[belizesailor]

Always? Mine have been working properly since 2004.

With the MPC 5000 control board you can just by pass the alarm via a software option, no need to physically disconnect, which is what Ive done for now.

Would like to ultimately sort this out though.

[Tellie]

Hi belizesailor,



Sorry I missed this thread, I've been busy with the boat show">Miami boat show so I'm a week or so behind. I would say that the absolute pressure sensor has probably failed. Did you pull the sensors out to inspect? I'd bet that if you do you'd quickly see why it has failed. These sensors eventually crud up over the years. Even though they are quality SS they live for the most part in an oxygen deprived environment when the system is sitting and not running. This leaches nickle from SS and my guess is you will see some crevice corrosion on your sensors once you wire brush away the black corrosion. You did the right thing by using the MPC5000 to bypass them. Bypassing them like this will eliminate the feed pump pressure reading and the filter condition reading on the MPC control panel and the red light next to the "Alarm Display button will flash on and off indicating that something in the program has been disabled. There are two ways to resolve this. Obviously replacing the sensors is an option, but unfortunately this same thing can happen again in the future. There are two sensors that would need to be replaced (If ones bad the other most likely is right behind it) these sensors are $220 each. A bit of an ouch factor for something that may fail again in the future. I have people just not replace them and live without the feed pump pressure readings and the clean filter readings. Instead of two new sensors I'd prefer a 0-200psi pressure gauge in line if you don't already have one. This is far more accurate for trouble shooting than the pressure readings on the MPC controls. Also, I usually tell customers with older systems like yours that use a 50Micron pre-filter that this can be eliminated altogether. The newer models of the NP400s have been using only the 5 and 20 Micron pre-filters for years now. I usually tell customers that go without to just change the pre-filters every 30-45 days and their fine. I'd like you to do a flow test on the product water as well. This is a far more accurate reading on production than the MPC controls, especially a system with the older stroke sensor on the Clark pump. Let me know what you find.


Best Regards
J.T. Halden

[belizesailor]

Thanks much Tellie!

Busy making ready to take off now, but will do a flow test soon and post the results.

My sensors have lasted 15 years so not so bad amortized over that time, but $220 is still spendy for a simple sensor. I do have a gauge in the system, but its not covenient to view...maybe I will relocate...and hack around the sensor issue. [emoji6] plenty of inexpensive pressure sensors out there. Would be good for Spectra to find a polymer replacement sensor.

Thanks again.

[belizesailor]

Update: did a flow test and it matched the MPC numbers within 0.1 gallons.

All good I thought, but....

Yesterday after an extended run, my water tank was still near empty...not good.

Test tun today: the product water flow and quality start off good, but in about 10 minutes both start to degrage. PPMs climb slowly from 300-400 up to about 800 and output volume decreases to nothing more than a dribble.

I suspect something in the Clark pump, but dont know what. Troubleshooting suggestions much appreciated (Esp since we are now going to have to take in water for the first time in years).

[belizesailor]

And another update:

Opened up the compartment where the water maker is installed to investigate further. I found a fitting on the vaccum side of the feed pump leaking air into the system, easy fix, snugged it up. Also found a cracked and leaking pressure vessel end cap...oooh, bad. I do not have a spare end cap and had low expectations for a successful field repair, but gave it a shot...wrapped the end cap in silicon tape, siezed over that with doubled monel wire and a big hose clamp...much to my surprise it worked! Only an occassional drip now.

Successful one hour test run at about 10.3 GPH and 350 PPM. Less output than usual, but sure beats the snot out of jerry jugging water of questionable quality!

[emoji41][emoji322]

Pic of my Franken-cap: