Seawater pump (engine room) and hose blockage to toilets

Duane Siegfri

I recently overhauled the Jabsco Par4 pump for the forward head.  On testing I noticed that quite a lot of flow was diverted to the engine room sump (bilge) compared to the aft head, and the flow into the fwd toilet looks pretty low volume.

I'm wondering why Amel put the small pipe into the siphon break draining to the bilge.  It's not on top of the anti-siphon loop like a relief valve, but is on the pipe going to the top of the loop.  In this location some of the water pumped is always going to go to the bilge.

I'm guessing this is to prevent a deadhead condition for the pump, since it does not have a pressure sensor, in case the hose becomes plugged.  But why is roughly half of the forward head pump output going to the bilge?  It seems odd that I didn't notice it until the new pump.  

The only thing I can think of is that the hose has become partially plugged:  with BARNACLES?  Is the solution to run Barnacle Buster into the line and let it sit overnight?

Is there something else?

Any thoughts would be appreciated.


Wanderer, SM#477

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