Allan's Heating, Cooling & Appliance Repair (916) 425-7754

Furnace repair

If you live where it gets cold during the winter season you will have to deal with a furnace repair at some point. Repairing of a heating system in a modern home can be very complicated. These modern HVAC units are computer controlled and this can be a little intimidating to the non technical person. There are several sub-systems within a heating and cooling unit. Let’s use a gas furnace for example.

  1. The first sub-system that we are all familiar with is the control system or thermostat. The thermostat takes the settings that the homeowner enters into it and sends those signals to the main control board on the furnace. This signal is transmitted over a low voltage circuit supplied by the main control board. This is accomplished by wires that connect the thermostat to the main control board. This is a low voltage that is used, 24 volts which is the same as the voltage that operates the doorbell in the home.
  2. The second sub-system is the burner. The burner has a gas valve that is controlled by the main control board. The control board will start the burner by first energizing an electric igniter. Once the control board proves that the igniter is hot enough it will send a signal to the gas valve. When the gas valve opens, gas will flow into the burner and the igniter will light the fuel. The control board senses that the flame is burning it will keep the gas valve open. If the burner fails to ignite, the control will shut down the gas valve and the gas flow goes off.
  3. The third system is the fan that blows the heated air into the duct system that in turn distributes that air throughout the home. The blower comes on after the burner has been running long enough to have heated up the firebox. This ensures that the furnace doesn’t blow cold air into the ducts. After the burner shuts off, the blower will continue to run long enough to remove the last bit of heat from the firebox.

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