On 7/11/2013 4:54 PM, Jim Wilkins wrote:
....

... I posted only the free-flow and fully blocked
readings for a small impedance-protected motor that doesn't represent
the loading curve of a larger one. The shape of the blades strongly
affects the pressure the fan can produce and the full-load power.
You'd need a wattmeter and a gage like this:
http://www.dwyer-inst.com/Product/Pr...ges/Series2000
to determine the conditions of that specific installation. I've done
it for the cooling fan for vacuum tube and solid-state radio
transmitters, not for HVAC.

So then why are you hounding me over suggesting a possible area for the
OP who's looking into motor problems w/ sizable vent fans in a greenhouse?

I don't have his fan curve; we don't even have pictures of the
installation; all I'm trying to do is give the guy some things to go
investigate that could help him get to the bottom of his problem.

Certainly he needs far more data than has provided here to have any hope
of learning anything specific unless it's truly obvious and then it
would seem would already have known...

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