Electric toilet water intake sucked dry by venturi effect when sailing

[OS2Dude]

I have an issue with my A/C that if I heel past a certain point on a port tack, the intake lifts high enough so that the water drains and I have to bleed the hose when I get back to the dock. (I really need to remember to close the A/C inlet to prevent this.)

After several attempts at trying to build a venturi, my guess is it is not actually a venturi effect that is your issue.

[transmitterdan]

The air conditioning intake water hose should be routed so the pump is below the water line and the hose should fill up with water all the way to the pump when the boat is on even keel. Check your hose routing. Something is wrong if you have to prime your air conditioning water pump.

[model 10]

Didn't somebody already suggest a scoop and then dissed right away?

[accomplice]

Originally Posted by transmitterdan

Something is wrong if you have to prime your air conditioning water pump.

While the intake shouldn't run dry, potentially it can -- whether it be venturi effect (doubtful), being heeled far over, or rough seas.

With a self-priming pump, why would this be an issue?

One wouldn't want it to run dry for a long time, but a few seconds to prime should be fine.

[transmitterdan]

Originally Posted by accomplice

While the intake shouldn't run dry, potentially it can -- whether it be venturi effect (doubtful), being heeled far over, or rough seas.



With a self-priming pump, why would this be an issue?



One wouldn't want it to run dry for a long time, but a few seconds to prime should be fine.

Air conditioner pumps are not self priming. Thus the hose from thru-hull to pump inlet must be below the waterline and be flat or slightly down hill. You want water to flow by gravity to the pump inlet.

[accomplice]

Originally Posted by transmitterdan

Air conditioner pumps are not self priming. Thus the hose from thru-hull to pump inlet must be below the waterline and be flat or slightly down hill. You want water to flow by gravity to the pump inlet.

Ours are (self-priming). The OP's probably could be too if they wanted them to be. Some AC A/C are setup to run DC powered pumps, of which many are self-priming; if you want a self-priming AC powered pump those exist too.

The only non-self-priming pumps we have aboard are for our pressurized fresh water system. I find them it inconvenient when they need priming. I suppose one could argue that the submersible bilge pumps are not self priming, but I've never needed to prime them

The OP's original question was about head supply, not AC, but the same applies -- except I'm used to head supply being DC.

[sdowney717]

I dont have this problem the rubber impeller prevents water flowing past it unless the motor runs.
Maybe the rubber impeller is really worn out and leaking internally the water.

I have seen the bowl sucked down due to a suction developed in the outflow from the Lectrasan, but all my hoses and things are above the thru hull, so the water wants to naturally run down hill out the exit. I always have plenty of intake water available at the electric pump.