Quest M3 Roaster

[Bendo]

Apparent power = V x A. Real power (Watts) = V x A x PF. The PF is the power factor. It occurs when the V and A are out of phase in an alternating current.

The kill-a-watt reads both powers. You simply need to push the button a second time to get W rather than VA. In most resistive devices the PF is unity, so you may not notice it. But on my Quest, I get a PF from 0.30 to 0.80, so my 1200 VA is only 960W.

[ecc]

Bendo, that doesn't make sense to me. 

Inductive loads that develop magnetic fields and collapse them (like heavy motors) can give you a nasty power factor like that, but I would think that the majority of your load would be purely resistive from the heaters.  In big 3 phase power systems, you will see poor power factor if the load on the 3 phase legs are largely imbalanced.

It might be interesting to see if there is voltage on your neutral and/or ground.

EDIT: And since it is AC, watts really aren't V * A, since V is only equal to 120 a small amount of the time, but that's picky.

[Bendo]

Could it have something to do with the power control method?

[Bendo]

This graph provides a good idea of how the phase fired controller works on the Quest.

You can see at my usual 9.5A and 1150VA I'm only getting about 850W of real power to the heaters.

[ecc]

My Quest stock heater control is a basic variable resistor, (rheostat) not a pulse wave modulator.   Maybe this link will help. http://www.ultracad.com/articles/rms.pdf

[Bendo]

Not sure what you're trying to say. The manufacturer clearly states "Power Control: Traditional frequency transistor circuit".

[ecc]

Not sure what you're trying to say. The manufacturer clearly states "Power Control: Traditional frequency transistor circuit".

You are correct, I checked it with my kill-a-watt.  I've had the roaster apart a few times, apparently never paid  enough attention. 

In this case, the reading does not indicate inductance or capacitance, just a limitation in the way the kill-a-watt measures the V part of VA.