Central Vacuum Issue

[1990C4S]

Not my house helping a friend.

If I unplug the central vacuum main suction line in the garage I seem to have good suction right at the unit. Inside the house I would describe the suction as 'anemic'.

Thinking it was clogged I sucked a piece of string through all the lines , then pulled a plastic bottle cap backwards through the outlet. Nothing, all clear.

I did the same with the hose. Not clogged.

Now I am stumped. Possible reasons

a) there is leaking tube somewhere - but I can't hear a leak, and the tubes are all buried in the walls, why would they leak now?

b) an open outlet - but she swears there are only three outlets in the house.

I am stumped now...any ideas?

[GH85Carrera]

I installed my system myself.

I had one connection come loose and the idiot that put the system in forgot to glue one joint. It was of course in one of the most inconvenient places. The system worked fine for a couple of years. I guess several cycles of hot attic to cold attic popped the connection.

You are likely going to have to go up into the attic and trace out the system.

[stomachmonkey]

Try the string thing but with a larger object that almost fills the tubing.

Start it at the vacuum end and pull thru feeling for a change in tension.

If the leak is after the split, assuming all three feed into one collector at the same spot, you'll draw the same length of string for two of the runs and a longer length for the 3rd with the leak.

In theory.