On Sat 15 Aug 2009 12:24:29a, Robert Green told us...

I want to truly silence my Hayden central vac. I bought a muffler for
it, but it's not really of much use since I've already vented the
exhaust to the outside via an unused dryer vent. The facts are that it's
a high RPM motor and it whines and wakes people up when it's in use when
someone's sleeping. My plan is to box it inside something lined with
acoustical foam and to provide two auxilliary fans (one low mounted
push, one high mounted pull and thermal monitoring) to keep the motor
cool and shut if off if the temperature in the box gets too high. I
know the motor's got a built in thermal shutoff, but since I am going to
be running it in an abnormal environment and what a replacement costs,
I'd feel safer with two.

I am going to make some preliminary and crude sound measurements
wrapping in a different material to see if any has particularly good
sound deadening properties. Anything I am missing? What sort of
materials (I was thinking 3/4" ply and that bumpy acoustic foam) should
I use? How much distance to leave around the unit for good airflow?
What CFM rate? What sized fans? I intend to use 120MM 12V PC case
fans, but I'm worried that a lot of sound will leak out through the fan
ports. I thought perhaps "top hatting" them the way chimneys and vent
pipes are covered would reduce the leakage, especially if the cap had
some acoustical foam facing the fan.

Any thoughts appeciated. Any flames will be cheerfully ignored!

Bobby G.

Bobby, the truly simplest approach is to relocate the unit outside the
living space. My parents had central vacuums in their homes since the
first ones were introduced. There were three scenarios of their
installations. (1) Garage, (2) Basement, (3) Spare Closet, where the
interior walls of the closet were heavily insulated. Another possibility
would be the attic. At least half of those years I was living at home. I
could never tell when the unit was running unless I entered either the
garage, basement, or opened the closet.

It shouldn't be that difficult to run an inlet pipe to the new location, be
it through closets, hollow walls, etc. The other upside to doing this is
not tampering with the environment that the vacuum naturally requires. I
would never consider enclosing it in a box, despite the efforts to
ventilate it with fans.

--
Wayne Boatwright
------------------------------------------------------------------------
We are living in a world today where lemonade is made from
artificial flavors and furniture polish is made from real lemons.
Alfred E. Newman