- Isolate the approximate location of the clog by determining the inlet furthest from the
vacuum unit that is not suctioning well.
- Run numbered paper towels or Styrofoam balls through each inlet and check which
paper towels/balls made it to the power unit.
- Once the location of the clog is located, insert the hose into the wall inlet as usual,
hold hand over other end, and let the pressure build up. Quickly release hand and let air
rush in. Try this multiple times from various inlets, even those that are close and working
properly. This process creates rhythm and movement in the pipes and often dislodges the clog
in the central vacuum system pipe.
- Lift the inlet valve lid and inspect the first elbow in the wall. Also, inspect the last
fitting entering into the vacuum tank and any elbows within the tank. The tank
connection should not be glued and it should come loose by wiggling the first fitting.
These are common areas for clogs.
- Run a Free Flow
or paper towel through the clogged inlet valve. This larger bulk item can often dislodge
objects by building up pressure and pulling debris through.
If the cloth gets stuck, continue to the next method.
- Run electrician's fish-tape through the pipe and try to hook object/clog. We do not
recommend using a plumber's snake because vacuum pipe has a much thinner wall than plumbing
- Reverse suction backwards through the pipe and inlet valve by connecting a portable
vacuum or shop vac directly into the wall valve. Let pressure build, then release.
Repeat multiple times. Be sure to allow air to flow backwards without the central vacuum
running and remove the central vacuum unit's bucket or top to expose the filtration.
- Alternatively, the central vacuum tank itself may be used. Remove from wall, set
next to wall inlet, plug into electrical, connect hose to tank port or tank
intake, put hose handle end into wall inlet, and seal with hand. It may be necessary
to suck multiple directions: toward the unit, then toward the inlet, then towards
unit again to loosen the object.
- Whichever machine you use, also try placing a
Flow Maintenance Sheet or paper towel inside the pipe where it enters the
canister and then try sucking it back toward the inlet to catch the object in the
- Consider any recent construction or other work where someone may have driven a nail into a
(especially closet organizers, phones, alarms, or recent pictures hung).
- If the clog will not dislodge, then find its exact location by one of several ways:
Once the exact location is found, cut the pipe and pull out the clog. Use a
to easily put the pipe back together.
- Run paper towel through and listen for humming or vibration.
- Create louder noise using a ping-pong ball. Insert into inlet, turn on unit,
then remove inlet to get ball in.
- Endoscopy cameras can be attached to an electrician's fish-tape to view the
interior of the pipe.
- Important: Once the clog is removed, verify by running a
through each inlet. If they don't all show up, do it again with numbers on each to
determine which valve is clogged. The clog may have migrated to another section of pipe
that is out of the air pathway.
- Pipes that run underground can sometimes coagulate with debris from moisture. Proper
underground installation installs the central vac pipe inside three-inch irrigation
pipe. Run 10 pounds of rice through system into the unit, repeat. If ineffective,
trench old lines and replace.
- In rare cases, the old vacuum pipe might need to be abandoned and a new pipe run from a
working section to the valve location.
- If the suction remains poor, you will need to replace/install
new pipe &
Contact a local MD authorized dealer for assistance.
NOTE: Proper installation of a central vacuum virtually guarantees no
clogging. Large objects should get stuck at the first elbow just behind the wall valve which
is designed to catch items. A sloppy installation can create opportunities for
debris to catch over time. Specific installation errors include Tee's that are installed
backwards, pipes rough-cut with a hacksaw, excessive elbows, and pipes not fully inserted
into the cuffs of the fittings. Many times, the build-up will eventually get large enough to
break way but in rare instances, the clog remains.