Sequence of Operation Gas Furnaces

1. The thermostat sends 24 volts from the W terminal thermostat when the switch is turned off to regulate the heat.

2.24 volts is returned to the furnace and then the gas valve is usually accessed via one or two safety devices.

3. When the standing pilot is lit The gas valve opens and ignites the burner gas through the indicator light

4. Heat the heat exchanger until the machine instructs the blower to turn on. Usually it is fan and limit control. See also camstat fans and restriction control.

When the thermostat is satisfied, the switch in the thermostat is opened, the gas valve is closed, the fuel is stopped, the fan continues blasting until the fan and cooling are restricted, and the blower is turned off.

4. When the vent and vacuum hose are disengaged, the pressure switch is closed. (Only 2, 3 pressure switch open to prove ventilation)

5. After the blower of the deflector sweeps out the heat exchanger, indicator light, hot surface ignition device (HSI) or spark will start

6. If the furnace is an intermittent pilot model, when the indicator light turns on, current flows through the flame sensor through the flame and when there is current through the flame the main valve opens and the burner ignites.

7. When the furnace is directly ignited, HSI or spark ignite the flame. The flame sensor conducts current to the flame. If current is flowing, the main gas valve will remain open and the heat exchanger will start warming up.

8. And most high performance furnaces use the board's electronic timer to start the blower after the burner is confirmed

Understanding the operating sequence of the gas stove saves time and expense for troubleshooting the phone. We watched over and over again that engineers ordered several parts to repair the gas stove. Has the gas valve, control panel, igniter, limit switch failed at the same time? It may not be the case. You may laugh, but we regularly receive orders for these parts. The order of operations varies by type and brand. In most cases, however, the manufacturer entered a hot surface or direct spark ignition in the following order:

Gas furnace operation order - Currently, there are various kinds of electronic ignition type high efficiency gas furnace. Some are owned by different manufacturers. One manufacturer then uses the other manufacturer's controller to control the electronic ignition portion of the gas stove. Trane gas stove is an example of a company that manufactures its own electronic ignition gas control device for that furnace. Therefore, when troubleshooting an electronic ignition gas stove, it is necessary to understand a series of operations. It is particularly suitable for all kinds of electronic ignition system. You also need to understand how the controls work. A good engineer can find basic problems in a matter of minutes by walking to the electronic ignition gas stove. Please refer to this article on the operation sequence of electronic ignition gas furnace.

Among the different types of electronic ignition gas furnaces are direct combustion gas furnaces and indirect gas combustion gas furnaces. Indirect gas stoves use indicator lights. Direct fire type gas stove will start ignition of main burner without indication light. The key to both systems is that each electronic ignition system has its own way to prove fire or prove there is fire. In the absence of a fire, the system is shut down so that no gas is injected into the space, which may be very dangerous.