I have the Stweart Warrner model. It gets hot so much you don't want to touch it and smoke comes out the exhaust as well as when you turn it. Off through the vents. I was wondering if the metal is closed till it hits temp then opens to allow it to. Know it's ok to got to run and when you bypass it it does not tell it it is hot enough to go to run???
The device responsible for switching on the pilot light on the control box is the flame detector switch shown in the image below.
When the light comes on, you must flip the start switch from "START" to "RUN" without hesitation (if you let it stay in the "OFF" position for any length of time, the fuel pump will shut off).
This heater relies on a wick for igniting. This wick soaks up fuel and brings it to the igniter, which is not unlike the cigarette lighter in your car. The igniter glows red hot and will start a small flame, which in turn ignites the atomized fuel in the combustion chamber.
The calibration of the fuel control valve is important and should be about 15cc/min in "LO". If too much fuel is supplied, the wick may not ignite. The "HI" mode of operation is locked out during "START".
So, if too much fuel is supplied, the heater will not ignite, but fuel will begin to fill the combustion chamber and may create a situation later if not removed. You will have smoke from the exhaust even if there is no flame.
The normal shut-down procedure includes a run time without the fuel pump running, so that any excess fuel will burn off. Any time the heater is turned off after a failed start, fuel will remain in the combustion chamber and should be removed. The TM will tell you not to try to start the heater more than 2 or 3 times for this reason.
At this point, I'd suggest that the calibration of the fuel control valve is checked...