In article , David Williams
writes
My rough calculations agreed with yours- about 50% of what I should expect.

Would it suffice to turn it up full and measure the Voltage across it?
(pardon my ignorance)

I notice it has the usual high and economy settings. In spite of the
electronic tag on the unit I bet these are achieved with 2 elements in the
heater can and also that one of these is not being fed when it is on the
high setting. You'd be able to check this with your multimeter. You might
also find that there is no difference in heat between the high & economy
settings.
--
fred