US 5,567,144 AGranted

Hot surface ignition controller for fuel oil burner

AssigneeDESA International, Inc.

InventorHugh W. McCoy

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Abstract

A fuel oil burner utilizing a hot surface ignition with an ignitor that is fully sintered and has essentially no porosity, a circuit for applying AC line voltage to the ignitor and to a blower motor, an AC-to-DC converter for providing twelve volts DC for operation of a control circuit that has a first time constant circuit for preheating the ignitor and maintaining the ignitor at an ignition temperature for a predetermined ignition trial period of time, a second time constant circuit for starting the blower motor and providing fuel to the combustion chamber for a predetermined time concurrent with the ignition trial period, and a third time constant circuit that either maintains the fan blower in its energized state if a flame of sufficient magnitude and frequency is detected and for de-energizing the blower motor if the flame is not detected in less than one second after the ignitor is de-energized. A lock-out circuit is provided such that if no flame is detected, the unit cannot be restarred without first removing power and then reapplying power to the unit.

Claims12

Dependent claims

A fuel oil type burner including:

a fuel oil combustion chamber;
a power source for providing at least 100 volts AC;
a hot surface ignitor electrode associated with said combustion chamber, said ignitor electrode being sintered to full density with essentially no porosity;
a fan blower driven by a motor for providing fuel oil and air to said combustion chamber;
an AC/DC converter coupled to said AC power supply for providing a DC voltage output;
a first controllable switch coupled between said AC power source and said hot surface ignitor;
a second controllable switch coupled between said AC power source and said fan blower motor;
a flame detector associated with said combustion chamber for generating an electrical signal if a flame is detected;
and
a control assembly coupled to said DC output voltage, said flame detector and said first and second controllable switches for energizing said first controllable switch to heat said hot surface ignitor with said AC voltage for both a first predetermined preheat period and a second predetermined trial ignition period, energizing said second controllable switch to operate said blower motor with said AC voltage only during a second predetermined trial ignition period, said fan blower motor being energized with said AC voltage only at the beginning of said trial ignition period and continuing for a flame test period immediately following said trial ignition period and de-energizing said fan blower motor if no ignition occurs during said flame test period.

7 more elements

Dependencies are inferred from the claim text.