GE GHDS830EDWS Technical Service Manual

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GE GHDS830EDWS Technical Service Manual Manual pdf 29 page image

– 29 –Ignitor Circuit OperationThe glo-bar ignitor circuit is made up of the following components: a gas valve with safety and main valves,ignitor, and a flame detector. The safety valve is actuated by a double coil that comprises a safety coil(resistance approximately 1400 ohms) and a booster coil (resistance approximately 580 ohms). Both coilsare needed to open the safety valve. Once energized, the safety coil alone will hold the valve open. The mainvalve has a single coil (resistance approximately 1300 ohms).The flame detector (< 1 ohm) is mounted on the combustion chamber. It is normally in the closed position(N.C.). The flame detector is opened by the radiant heat produced by the glo-bar and once open, the flamedetector will be held open by the radiant heat produced by the gas flame.When the control system calls for heat, the following circuits are energized:1. N- through detector, ignitor, outlet control backup, inlet safety thermostats to L12. N- through detector, booster coil, outlet control backup, inlet safety thermostats to L13. N- through safety coil and outlet control backup, inlet safety thermostats to L1When the glo-bar is heating, the booster and safety coils are both energized and will open the safety valve.The main valve is closed as its coil is bypassed by the N.C. flame detector. When the glo-bar reaches ignitiontemperature, in approximately 60 seconds or less, the flame detector is heated and opens, placing the maincoil in series with the glo-bar. The main valve opens, allowing gas to flow into the combustion chamber andignite. The main coil, now in series with the glo-bar, causes the glo-bar to cool down. However, the flamedetector is held open by the radiant heat from the gas flame. The booster coil is now also in series with themain coil and is essentially inoperative. Should a momentary power failure occur, the gas valve will shutoff and an attempt to restart will not occur until the flame detector cools and resets, in approximately 30seconds.IGNITOR(GLOWING RED) DETECTORMAINSAFETYBOOSTERL1 NIgnitor OnIGNITOR(NOT GLOWING) DETECTORMAINSAFETYBOOSTERL1 NGas Valve OpenValves Closed Valves Open