Fuel burning heater, voltage dependent?

[cranetruck]

The Stewart Warner heater uses a series of resistors with positive temperature coefficients to regulate the voltage to the igniter and fan motor. Higher voltage results in higher temperature (higher power dissipation) and higher voltage drop. The Benmar heater, which I'm "playing" with on the 8x8, uses a simple voltage dropping resistor, so the voltage applied to its igniter and motor, varies with the battery voltage...

I noticed yesterday that the Benmar heater started more reliably when the engine was running and producing 28 volts.
Suggestion, if you have trouble starting your heater, try a higher supply voltage (28 vs 24 volts).

Also, if you heater doesn't start, you may be dumping raw fuel into the combustion chamber. For a properly calibrated control valve, this can amount to 1/2 cup (about 100 cc) in 5 minutes. If it starts with this much fuel, the combustion will be out of control and the unit will shut down on its own due to overheating. That's why the TM says to have the heater serviced when it doesn't start properly.
That's right, my playing around with it dumped a lot of fuel into the combustion chamber and running it repeatedly to try to burn off this extra fuel, just caused it to shut down on its own. I'll be working on getting it cleaned now...probably on the work bench...