Central vacuum issues

We have a central vacuum that turns off and on when not in use. When I remove the low voltage wiring connection, it stops turning off and on....so it is being actuated by the low voltage wiring, so I'm assuming either a bad inlet valve or damaged wiring. How can I tell if an inlet valve is faulty? They all actuate the system when opened. Also, how do the inlet valves typically work?

Thanks,

Nick

 

The valve usuall has 2 terminals inside and when you insert the nozzle the metal ring around it makes the circuit, I assume this only happens when the hose is connected,does it happen at all outlets,if so there could be a problem with the hose,the metal ring on the hose could be dirty or not making a good connection in the inlet.

 

Welcome to the forums.

Since the central unit is turning itself on without the hose being inserted that would preclude the two contact shorting method.

It is possible to have a wiring short but not likely.

The most common system is a microswitch with a tiny ball bearing. When the hose is inserted the metal pipe pushes up on the ball bearing thus activating the switch. You can open the door, insert finger slightly and press up on the upper part of the fitting to confirm.

The problem is trying to find out which one is actually the culprit.

 

One of the micro switches may be a little sticky, When you put your finger in there see if one of the switches feels a little different.

 

The vacuum turns on when the door is opened, without any hose attached, so I assume there is either a magnet or some kind of micro switch activated by the door opening. Any ideas to tell which inlet is causing me the problem?

 

That's an older style inlet. You can remove the two screws behind the door and the inlet plate will pull out of the vacuum pipe with the wires still attached to the inlet cover. I'd look at all the inlets for any place where the wires may be close to shorting. If you don't see anything obvious, you can disconnect the wires from one outlet at a time and wait a while to see if the problem goes away. If you find one where the problem goes away, you can replace that outlet.

Even though those are older style inlets, I've been able to buy replacements online. If you need to use the system while you have an inlet out, you will have to replace it or block the pipe with something so you don't lose vacuum. (Don't use anything that can get sucked into the pipe!)

Good luck with your project.

 

That's a pretty old system. Most companies changed from that style because of kids playing around. Nutone or Beam may be the last to use it. The brand would be prominently displayed on the vacuum unit.

There should be a shorting bar visible on the door that hits two contacts when the door is lifted.
The plates are held on the wall with two Phillips head screws. Take all the plates off the wall and disconnect the wiring at the splice. Leave the existing wiring spliced thru.