Gally Maid vacupump?

[thoward]

Is there a way for water to flow across the intake directly to the output?

When I open the onboard blackwater holding tank and run the boat the holding tank fills with seawater. I did have the overboard valves shut......

 

[LIBERTY]

Each of the Galley Maid head pumps on my boat is actually two pumps, one intake the other output/macerator, located on opposite ends of a single electric motor. These pumps are connected by a 1/4 inch copper line that I assume serves some priming or anti-airlock function. If the intake thru-hull is left open and the pump is below the water line, due to loading or planning angle, the holding tank - over time - will back-siphon and fill with sea water. Installing a cut-off in the 1/4 inch line or shutting off the intake thru-hull are possible “fixes”.

 

[thoward]

Right on! Thank you, that is what I was wondering. Then I guess I will be installing a valve in there. I am getting ready to replace the impellers in the first of three so I will have a better idea of how they work once I get in there.