Message text written by INTERNET:Chip19474@aol.com
>I just cleaned, painted and reassembled my heater box - checked, cleaned,
>oiled the motor, etc. as part of the restoration on my '76 TR6 which was
>built on 7/5/76 - 10 days shy of the last TR6 build date.....it's
definitely
>a 4 blade unit - not a squirrel cage fan.
I seem to have put my foot in it (again) and spoke from (unreliable)
memory. My TR8 definately has a squirrel cage as did my 1965 MGB. Sorry
for any confusion.
>I think I'd go to Grainger or some other industrial/commercial retailer
that
>sells electrical components and attempt to match one up with an
>over-the-counter motor. It doesn't appear to be an unusual size. As far
as
>finding one with the exact rpm specs for the 2 speeds - I'd get one with
as
>close as possible rpm ranges. I don't know how you'd get a squirrel cage
to
>work effectively (using the same motor mounting) since the motor shaft and
>air flow are both vertical....doesn't a squirrel cage generally blow air
away
>from the plane of the shaft by 90 degrees? I'm relating to my furnace
>fan.....
This is exactly the problem. Bladed fans such as those used in the TR6
heater generate airflow that is parallel to the fan axis. These are
sometimes refered to as axial fans. Squirrel cage fans use the centrifugal
effect to generate are flow. The vanes are moved in a circle. Air moved
by the vanes will be pushed out by centrifugal force. Hence these fans are
sometimes called centrifugal blowers. By their nature the exiting air flow
is radial to the fan axis. Hence sometimes these fans are referred to as
radial blowers.
Optimum housings for each of these fans are markedly different and
retrofitting a squirrel cage type blower into a housing for an axial fan is
somewhat problematic. An approximation of an optimum configuration will
entail mounting the fan motor rotated 90 degrees from the way it is now
which requires a different motor mount, and building a housing around the
blower to duct all the air emenating from the blower in a 360 degree arc
and duct it to the discharge port.
Perhaps a more efficient fan blade would be easier.
My humble opinion
Dave
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