Watermaker fuse burns out...

[luisasail]

The fuse on my Katalyn Powersurvior 40E watermaker constantantly burns out. I am using it on my boat in the Bahamas in salt water. I changed the fuse from 10 amps to 15 amps but they continue to burn out after about two hours of operation. Does anyone have any suggestions?

[bloodhunter]

luisasail,
Was the original 10-amp fuse the size specified by the maker? If so I would be very hesitant in upping the fuse amperage as you might do damage to what is probably a fairly expensive device.
Usually the power demands for electric motors are highest when a load is first placed on them, then as the rev up to speed the power demand drops off. Wonder if the power demands for your motor gradually builds up over the 2 hours until the fuse blows or if you get a spike that blows the fuse.
Only a couple things I could think of offhan, one is the wire being too small for the demands being put on it either because it was too small to start with or because the run is too long for that guage carrying that current demand. Or you could havea bad connection which as the motor runs is heating up and finally shorting out.

[luisasail]

bloodhunter,

Thanks for your response. The manufacture's liturature states that a 10 amp or 15 amp fuse can be used, which was why I decided to upgrade to the 15 amp fuse. The unit was working fine for the last couple of months and didn't start acting up until a few days ago. I thought maybe the higher salinity in the water may have something to do with it so I cleaned the filters again to no avail. The wire hook up to the power source is only about a foot long. The wire guage is also what the manufacture suggested, which I think was14 or 16.

[bloodhunter]

Luisasail,
Can't see how salinity of the water should make any difference. All that would happen is that you'd have to clean the filter more often. The cable run is too short to make any difference. 16-guage wire seems really light for this device but if that''s in the makers specs it should be okay. 14-guage should handle it, though 12 would be better. Since this problem occurs only after your system has been running for a while, it would almost have to be something that builds up as the motor runs and then causes a short. Only thing that I can think of is heat. I still suspect a bad connection somewhere -- even in the motor itself. What could be happening is that heat is causing wire or connector to expand just enough to arc and cause a short. Over time something may have broken or come slightly loose and is now causing you problems. I'd look for places that gets really hot for the location of your problem.
It also would be a good idea to call or e-mail the Pur folk and see what they have to say. They've probably seen most problems that can occur with their units and may very well be able to pinpoint just what and where it is.

[sailingdog]

My first guess would be that you may have low voltage going to the watermaker. Have you checked the connections and the voltage at the watermaker itself. A motor with low voltage is going to draw more amperage and heat up more than one running with the proper voltage.

Heat buildup could be a problem too, as some insulation issues are exacerbated by heat.

[redline]

If it's low voltage, you're lucky the fuse is blowing. A dockmate totally fried his pressure water pump because of low voltage; the motor stalled and cooked its windings without blowing the fuse.