|
Central Vacuum Cleaning Systems
QUESTION: Does anyone know the equivalence (and differences) among the three types of
power ratings I have encountered with central vacuum cleaning systems? One
brand has 518 air watts, a second has 178 inches of water lift and a third
has 3 horsepower.
ANSWER: Sounds like specmanship to me, Alan...But here's what I think they might
mean...
The 178 inches of water lift refers to the maximum vacuum the system will
create, presumably when all entrance of air is blocked off. This spec by itself
is meaningless, as you could create 178 inches of water lift with a tiny pump,
but the flow rate with the system opened to air would be insignificant,
certainly not enough to move much dirt.
The 3 horsepower rating presumably relates to the power output of the motor
under maximum load, which probably occurs at minimum air flow, i.e. with the
inlet port blocked, but I may be wrong there, as the maximum load might occur
at maximum air flow instead. The efficiency of the fan moving the air through
comes into play here, as you could have a very wasteful fan design which uses
up a lot of horsepower just heating up air inside it without moving much air
through the syetem!
The 518 air watts is a new one for me, but I guess it refers to an air flow
rate, i.e. "x" pounds of air times a velocity of "y" feet per second, I think
that would fit the definition of horsepower, which is dimensioned in pound feet
per second.
Might be better to seek comments from users of these systems, or check out
Consumers Reports for this kind of equipment.
|
|
|
|
