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Scott Flanders of Fort Lauderdale, FL asks:

I own 46#74. To solve the Naiad cooling problem, I increased the inlet line to the cooling pump to 3/4". I then replaced the toy water-puppy with an Oberdorfer 172ba85 12 volt continuous duty centrifugal pump. Out of the 3/4" discharge I plumbed in an in-line March LC3CPMD115 AC pump. The discharge is 1/2", original size, and used the same hose to the Niads. Both pumps are full flow so if either fail I simply turn on the appropriate breaker. I have about 300 hours on the system. To date I have used the 115V pump off the invertor exclusively. I confirmed this with the Naiad folks first and their only criteria was a 3 GPH flow. For spares I carry a spare head for the AC pump and could also scavenge any one the three complete AC pumps on board.

Dan Streech responds:

We have used both the centrifugal Orberdorfer and a centrifugal 120VAC pump in previous applications, but never together in series - and that is what I think I am reading in your report. A quite interesting approach and a pretty good idea. What discourages me about the centrifugal pumps is their propensity to lose prime when they ingest air in heavy conditions. We have lost prime on NORDHAVN’s air conditioning pump several times since leaving Barbados.

 

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