How does VacuFlush actually work ?

[Dune]

I ask as I had one with a broken belolw.....put new bellows in and it still does nothing ! Worked perfectly for year before the bellow broke, but now even with new bellows, the pump motor does nothing. And the motor is good....I temporarily switched wiring with another unit and it works.

So the question is, what actually activates the motor to start turning ? i.e what causes 12 volts to go to that motor ? Something at the toilet, something at the pump assembly ? or ?

Just seems amazing the bellows would break and no voltage at pump problem to happen at the same time. Then again it is a boat...

 

[Maerin]

There is a vacuum switch that's located in the vacuum side of the system, between the pump and the toilet bowl. Precisely where depends on the particular system. The switch closes on a drop in vacuum, and opens when the vacuum reaches the setpoint, close to 15" of vacuum. The switch has a rubber diaphragm that can fail, usually the cause of switch problems. The remedy is a new switch. Some systems also incorporate a circuit breaker switch panel, usually identified by a switch with red and green lights. Those pilot lights are also powered by the vacuum switch, again dependent on the system you've got.

If the pump won't run, that's not generally an indicator of an electrical problem, not a bellows problem.