General Information
Booster Holding Coil
Secondary Coil
Coil
Function of Gas Valve System
The sensor, igniter and gas valve are interrelated and function as ignition and heat source. At the start of the cycle, the radiant sensor contacts are closed, the igniter is at room temperature and the gas valve is closed, blocking the flow of gas. NOTE: On the wiring diagram, the radiant sensor contacts are wired in parallel with the secondary coil. This bypasses current around the secondary coil when the radiant sensor contacts are closed. Valve 2 cannot open with the radiant sensor contacts closed.
Step 1: Operation: Dryer Controls calling for heat: The red wire in the gas valve harness is normally the "hot" side of the line. Voltage is routed to the gas valve assembly through the cycling thermostat located on the blower cover and the
Radiant Sensor Contact Closed
The holding coil, booster coil and igniter all receive line voltage. The holding coil and booster coil open Valve 1. Valve 2 is still closed, prohibiting gas flow to the burner. The igniter, operating at line voltage, begins to get very hot. (As the igniter gets hotter, the resistance of the igniter drops.) The igniter glow radiates heat to the radiant sensor.
Holding
Coil
Radiant
Sensor
To
Booster
MotorIgniter
Coil
Valve 1 | Valve 2 |
The booster coil and the igniter are wired in parallel.
Note: While these two components are in parallel with each other, they are wired in series with both the radiant sensor and secondary coil combination.
When the radiant sensor contacts are closed, full line voltage is available to the booster coil and to the igniter.
When the radiant sensor contacts open, current has to flow through the secondary coil on Valve 2 in order to get to the booster coil and igniter. A significant voltage drop develops across the secondary coil. While the parallel booster coil and igniter are still in the circuit, they become ineffective due to their low resistance and the resulting reduced voltage available to them.
The secondary coil on Valve 2 is bypassed because the radiant sensor contacts are closed. By not allowing voltage to the secondary coil, the second valve cannot open and prevents gas flow to burner.
Step 2: Radiant Sensor Contact Open:
The igniter is now hot and valve one (1) is open. The heat from the igniter causes the radiant sensor switch contacts to open.
With the radiant sensor contacts open, the secondary coil is no longer bypassed. The secondary coil is now in series with the parallel circuit combination of the booster coil and the igniter.
10 | 16022904 Rev. 0 | ©2004 Maytag Appliances Company |