If your house depends on an old furnace to keep it warm, you may wonder whether or not it is still working properly given its age. Before the heater fails completely, you may be able to detect a couple of early warning signs that there are issues which warrant a service call to determine if the furnace is repairable or needs replacing.

1.  Certain Rooms or Spots Always Seem to Stay Cold

One warning sign that there is an issue with your home's old furnace is the presence of cold spots in certain areas of rooms or even entire rooms that constantly stay cold. Normally, if you have the right-sized furnace for your house, it should be powerful enough to transport warm air into all rooms and areas.

If there is an issue with the motor or blower fan that caused the furnace to lose power, however, it will prevent the warming of certain areas, especially those that are furthest away from the vents or the furnace itself. And, since these cold areas will cause a general decrease in the ambient temperature read by the thermostat, you may also notice that your heater is running more often than usual.

Walk around your home to see if you notice any cold, drafty spots that have no other explanation, such as a window that is cracked open. If you find several of these areas, you should have your furnace checked for issues.

2.  Strange Odors Are Detected While the Furnace Is Running

Another sign that there could be a problem with your old furnace is when you start to detect strange odors whenever the furnace is running. Aside from the initial musty odor that fills your house when you first turn the heater on for the season, you should not smell anything unusual.

If you start to smell odors resembling burning metal, the motor may have an electrical issue, such as fraying wires or a short. Since this has the potential to cause an electrical fire, you should have the unit inspected as soon as possible.

If you have noticed either or both of the above signs, there may be a problem with your furnace. Contact a heating service to schedule a time for someone to come out and inspect your unit so that the issue can be found. They can then discuss with you whether the furnace can be repaired or should be replaced.