Testing a VacuFlush vacuum switch

This video describes a method for testing the vacuum switch on the Vacuflush toilet system used on narrowboats.
The vacuum pump that I used was a Broco DC 12V Micro Vacuum Pump Electric Mini Air Pump ( £8.39 from Amazon ).which I powered from a variable power supply.
I used the gauge from a Neilsen vacuum and fuel pump test tool.
I believe the switch is intended to operate at 10-12 inches ( Hg ) of Vacuum, so the switch turns off at this level.
If the microswitch needs to be replaced it is a Square D9007 A01 model which is available from various component suppliers.

[@markjacobsen3860]

I'm in the US having problems with Vacuflush, would cleaning the inside of the switch be any benefit. My system keeps running and if I tap on the tank it will stop. Could you please give me the micro switch replacement info.

[@bobvecchi304]

That is a common problem, one which I am experiencing as well. I substituted another switch from a second unit and it didn’t solve the problem,. I think that the differential between when the switch is supposed to close and when it opens is a very small difference in vacuum. So a slight vacuum leak is causing the switch to not reach a level of vacuum that would open the switch and stop the pump. I would look for a slight vacuum leak at the fitting where the toilet drain hose connects to the top of the tank. Of course, you malls need to verify that the Jose clamps are tight. Also make sure the bowl is holding water when under vacuum. If it isn’t, there is your leak.

[@bobvecchi304]

The only thing you proved is that the vacuum switch mechanism moved when the vacuum is applied. You haven’t proven whether the switch itself I’d transferring. Oh, you also proved that the vacuum is not holding for very long, but since you are only testing the switch mechanism it doesn’t matter..