Abstract: A test circuit for testing all lamps in a system monitor for a hot water heater. The comparator includes a amplifier having a reference input connected to a reference voltage and a second control input connected to power through a plurality of different circuit elements in a voltage coupling network. A timer is connected in the circuit to the control input to provide a timed drive signal to a power switch unit connected to the comparator amplifier for energizing all of the lamps. The timer is a simple resistor-capacitor network with the comparator connected to the signal control input. The signal branch circuit includes components selectively inserted to produce a test signal to the timer and comparator amplifier. A thermostat monitor is connected by a diode to the comparator amplifier and a demand for hot water creates a turn-on signal to the comparator for the period of the timer to energize all lamps for a short period at the initiation of the demand.

Abstract: A gas fired burner includes a pilot gas valve and a burner gas valve sequentially operated to light the burner. A monitor includes individual monitoring of the status of the valves and the burner as well as other components and systems associated with the burner and includes separate lamps for each components. A test circuit monitors the sequential ignition cycle and includes a timing circuit having a timing period somewhat longer than the selected ignition period. An indicator lamp is connected to the timing unit. A sensing device is connected to the pilot gas valve and to the burner gas valve and each establishes an output in response to activation of pilot gas valve and burner valve. The pilot valve signal turns on the timing unit and the burner valve signal turns off the timing unit such that the indicator lamp is actuated only if ignition of the burner is not established within said selected ignition period.