Learn How Furnaces Work

First a draft motor for the exhaust turns on. Then an electronic igniter ignites main burners and heats up the heat exchanger. Once heated a fan turns on and circulates warm air thought the ventilated area. Once the set temperature is met the furnace turns off and circulates air for a short time to cool off the heat exchanger.

In the greater Sacramento area the majority of gas furnaces are fueled with natural gas. When you up the heat on the thermostat a signal is sent to the furnace to turn on.

Working Properly

A properly working furnace will produce a temperature rise range typically between about 35-65 degrees. The temperature from room to room should be within a few degrees of each other. The furnace should run constantly until the set temperature is met. Once the desired temperature is met the system should stay off before turning on again. If the furnace turns of and then shortly after turns on again this is called short cycling and can likely be resolved by adjusting the heat anticipators setting on the thermostat.

Red Flags

  • Turning off before the set temperature is met
  • Blowing room temperature air when there is a call for heat from the thermostat
  • Any burning smell when the system is running(dust will burn on the heat exchanger the first time its turned on every year)
  • Any loud noise or strong vibrations when the furnace is running
  • A dirty air filter