We added two ports to an existing system and a year later they called me up and stated it hadn't worked right since we left. I can't confirm the issue was caused by us because we were able to isolate the run by capping it off and it still had low pressure. Do you guys have any suggestions for troubleshooting low pressure on a central vac system? Assuming the inlets are all operating the way they should.

Are you saying you were able to separate the new outlets from the rest of the system?

First thing I would do is disconnect all the outlets and test pressure at the vacuum unit. If the pressure is good reconnect the vacuum and check suction at each outlet. While doing this I would also listen to the sound of the vacuum cleaner as you open each port. If there is an obstruction in the line between two outlets you should hear a higher pitch from the vacuum when you go from the closest outlet to the next one further away. If there is no pitch change from the closest outlets to the ones further away there could be an obstruction between the vacuum and the first outlet.

I was able to clear an obstruction by using my fish tape in a client's system.

Hope this helps.

Start by working at the outlets closest to the pump. Check the suction at the pump if it's good, you've probably got an obstruction. (Or the pump is too small for the house)  Once you determine where the suction starts to "suck". (sorry, I couldn't help myself).  Cut into the pipe, and break out the fish tape with a hook on it, or a Sewer snake.  Make sure you bring a bunch of couplers with you to put the pipe back together.  

In my experience, it's generally a sock.  And it's usually fairly close to the pump.  It seems the Vacs are generally powerful enough to get the obstruction almost all of the way through the system, but as you get closer to the pump, you generally have more elbows, the obstruction generally can't make the twists and turns.  

You didn't name the brand, but most do have an outlet on the unit, or at least right by it.

Check there first.

A. Vacuum low (at the unit)?

Pretty common for a secondary filter to get clogged. Clean or remove (removing it is the better solution, as that secondary filter is a design flaw).

B. Vacuum high (at the unit)?

Begin by checking all outlets starting with the closest one.

(a). Vacuum low at one outlet as you work your way farther from the unit?

1. Remove inlet cover and use a small 25' drain snake at that point. If the pipe has been installed properly (flow). the snake will get to the problem.

2. Use the vac unit to help pull the obstruction out (only if the outlets are close enough together) by trying to suck the obstruction out.




All else fails, you'll at least know approximately where the clog is (measure how much snake you've inserted).




Been there, done that. Many, many times.

Don't forget the possibility that there is a break in the line.

If the motor winds close to the same with one inlet open vs all inlets closed you probably have an open line.

I just thought of something to add from my previous statement.  I don't think it would've taken them a year to call if the vacuum didn't have decent suction. Maybe it's not so much an obstruction as it is a poorly seated outlet and it's leaking?  Just throwing it out there.

Unless they're just filthy human beings and only vacuum once a year, you'd think they would've called sooner.  

Thanks for all of the suggestions guys! They truely gave up using it a year ago and never called. Now we are back doing another remodel and said, "oh by the way." I think it would be super important to get something to pressurize the system. That way I would tell if it's a leak or not. It could have been a sawzall blade or a picture that was hung that they took down that is causing this issue.

They have great pressure at the garage outlet the rest of the house isn't good. We tried working our way around the house cutting and capping the trunkline to isolate the issue but there was only one unfinished spot in the house. That's why it will be critical to pressurize the system first and work our way back from there.

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It's the ol' Banana in the Vacpipe trick.... 

People are famous for cleaning out their cars and sucking up some crap (kids sock, underwear) under the seat of the minivan... friggin' kids.  They're nasty little buggers.  

I keep hammering home socks and underwear, everytime I ever had to unplug a vac pipe it was a sock or underwear.  Nothing like pulling some used underwear out of a vac pipe.  

I stopped installing those damn things a decade ago.  

Not to be a pen!s but they are inlets, not outlets.

I have found a plethora of things stuck in central vacs. If you have 2 people you can use tissue at each inlet to find where the obstruction is. Then you should tape closed all of the inlets and reverse the air flow.

Just coming onto RC making waves with everyone! JK

I called them inlets in the OP but was flying through on the last response.