Direct ignition gas burner control system

Claim 2

An improved method for operating a direct ignition gas burner control system which includes a burner, two electrically operated valves connected fluidically in series with the burner, an electrical resistance igniter, and a microcomputer, comprising the steps of: energizing the igniter; opening both valves so as to enable flow of gas to said burner and ignition thereof; detecting burner flame and continuing said flow of gas to said burner as long as said burner flame exists; closing one of said valves; determining if said burner flame still exists and providing an indication of valve leakage if said burner flame still exists; closing the other of said valves; and reversing order of closing said valves on alternate burner cycles.

Claim 3

The method claimed in claim 1 wherein said step of energizing the igniter includes the step of measuring voltage representative of voltage across said igniter for determining that said voltage across said igniter is sufficient to enable said igniter to attain gas ignition temperature, and the step of continuing energizing of said igniter to attain gas ignition temperature, and wherein said step of detecting burner flame and continuing said flow of gas to said burner as long as said burner flame exists includes the step of measuring voltages representative of flame gap impedance and effecting continued flow of gas to said burner when said measured voltages are indicative of existence of burner flame.

Claim 4

The method claimed in claim 2 wherein said step of continuing energizing of said igniter includes modulating said energizing of said igniter so as to prevent unnecesary heating thereof.

Claim 5

An improved method for operating a direct ignition gas burner control system which includes a thermostat, a burner, two electrically operated valves connected fluidically in series with the burner, an electrical resistance igniter, and a microcomputer, comprising the steps of: minitoring the thermostat to determine when said thermostat is calling for heat; setting a delay timer time period upon a call for heat; energizing the igniter upon timing out of said delay timer time period; measuring voltage representative of voltage across said igniter for determining that said voltage across said igniter is sufficient to enable said igniter to attain gas ignition temperature; continuing energizing of said igniter to attain gas ignition temperature; detecting and storing in a memory of said microcomputer a first voltage value representative of flame gap impedance in absence of a burner flame; opening the two valves; setting a trial ignition time period during which gas flows to said burner and said igniter is maintained energized; detecting a second voltage value representative of flame gap impedance in presence of gas flow to said burner; comparing said first and second voltage values representative of flame gap impedance and replacing said first voltage value with said second voltage value in said memory if said comparison thereof is indicative of existence of said burner flame; detecting, during the remainder of said trial ignition time period, subsequent voltage values representative of flame gap impedance, if said comparison of said first and second voltage values is not indicative of said existence of said burner flame, until comparison of one of said subsequent voltages values with said first voltage value is indicative of said existence of said burner flame, and replacing said first voltage value with said one of said subsequent voltage values in said memory when said comparison thereof is indicative of said existence of said burner flame; de-energizing said igniter when said comparison of said first voltage value with said second or said one of said subsequent voltage values is indicative of said existence of said burner flame; continuing detecting voltage values representative of flame gap impedance, comparing successive voltage values, and replacing a previously stored voltage value in said memory when said comparison thereof is indicative of existence of said burner flame, so as to effect continued flow of gas to said burner as long as said burner flame exists; and closing said valves when said thermostat is satisfied, said step of closing said valves being a sequential closing, and said sequential closing comprising the steps of closing one of said valves, determining if said burner flame exists and providing an indication of valve leakage if said burner flame exists, closing the other of said valves, and reversing order of closing said valves on alternate burner cycles.

Claim 6

An improved method for operating a direct ignition gas burner control system which includes a thermostat, a burner, two electrically operated valves connected fluidically in series with the burner, an electrical resistance igniter, and a microcomputer, comprising the steps of: minitoring the thermostat to determine when said thermostat is calling for heat; setting a delay timer time period upon a call for heat; energizing the igniter upon timing out of said delay timer time period; measuring voltage representative of voltage across said igniter for determining that said voltage across said igniter is sufficient to enable said igniter to attain gas ignition temperature; continuing energizing of said igniter to attain gas ignition temperature; detecting and storing in a memory of said microcomputer a first voltage value representative of flame gap impedance in absence of a burner flame; opening the two valves; setting a trial ignition time period during which gas flows to said burner and said igniter is maintained energized; detecting a second voltage value representative of flame gap impedance in presence of gas flow to said burner; comparing said first and second voltage values representative of flame gap impedance and replacing said first voltage value with said second voltage value in said memory if said comparison thereof is indicative of existence of said burner flame; detecting, during the remainder of said trial ignition time period, subsequent voltage values representative of flame gap impedance, if said comparison of said first and second voltage values is not indicative of said existence of said burner flame, until comparison of one of said subsequent voltages values with said first voltage value is indicative of said existence of said burner flame, and replacing said first voltage value with said one of said subsequent voltage values in said memory when said comparison thereof is indicative of said existence of said burner flame; de-energizing said igniter when said comparison of said first voltage value with said second or said one of said subsequent voltage values is indicative of said existence of said burner flame; continuing detecting voltage values representative of flame gap impedance, comparing successive voltage values, and replacing a previously stored voltage value in said memory when said comparison thereof is indicative of existence of said burner flame, so as to effect continued flow of gas to said burner as long as said burner flame exists; and closing said valves when said thermostat is satisfied, said step of closing said valves being a sequential closing, and said sequential closing comprising the steps of closing one of said valves, determining if said burner flame exists and providing an indication of valve leakage if said burner flame exists, closing the other of said valves, and reversing order of closing said valves on alternate burner cycles.