Re: Central Vac overload

[jamesgangnc <jamesgangnc@xxxxxxxxx>]

On Mar 31, 10:49=A0pm, "Robert Green" <robert_green1...@xxxxxxxxx>
wrote:
> "John Gilmer" <jlgil...@xxxxxxxxxxxx> wrote in message
> > > I am going to try a test today with my Kill-0-Watt meter
>
> Blocked and whining 8.83A, Unblocked free running inlet port - no house
> piping attached (cleanout, open actually) 12.96A
>
> External air output pipe ran free when unblocked but dropped to very low
> flow when the hose was blocked. =A0If there's an internal check valve, it=
's
> venting to someplace other than the vacuum's output pipe.
>
> I used a compresible coil type cheap plastic hose in the basement, and wh=
en
> blocked at the nozzle it contracted considerably indicating that there wa=
s
> still a serious vacuum being maintained.
>
> Another theory. =A0It takes more work to create a vacuum than maintain it=
, so
> when the hose has contracted as much as it can, the motor has less load o=
n
> it and thus the current drops. =A0With an open vacuum, the motor is const=
antly
> sucking and never achieving even a partial vacuum within the tubing.
>
> C'mon. =A0There are smart people here.
>
> Why would a plugged vacuum cleaner draw less current?
>
> --
> Bobby G.

Somebody else answered that once already.  Basically it's not moving a
bunch of air so it's not "working" any more.  Now that you know the
current you should able to design a circuit that alarms at the 8 amp
range and is off at the 12 amp range.  A 1/4ohm power resistor will
give you about a 1 volt variation between the two.