It is important to look out for common furnace warning signs in order to make the necessary adjustments. A qualified HVAC technician should perform a furnace inspection and tune-up to avoid system failure just when it is needed. Generally, a properly maintained furnace lasts around ten years, after which efficiency declines and repairs become more frequent. The energy and repair costs associated with an old furnace can be high even if some high-quality furnaces last for more than 20 years. Unusual odors and sounds coming from the furnace are definitive warning signs. In fact, odors, rattles, creaks, and other strange noises may be signs of a more serious problem. Particularly odors indicate a serious problem with a furnace, since they shouldn’t emit odors. Technicians with experience can diagnose the problem and fix it quickly. The color of the flame from a furnace can indicate whether it has a problem. If the flame is yellow or orange instead of a clean, stable blue, it is a sign that there is dirt in the burner. Obstructed airflow to the system can cause an inappropriate mixture of oxygen and gas, thereby causing diminished heating effectiveness, which is why it is the first items a service technician will check. A simple miscommunication between the thermostat and the furnace is one of the most common problems. If the furnace keeps turning on and off, or if some rooms feel too cold no matter how high one turns up the thermostat, then it is a clear sign of a thermostat problem. An HVAC technician should be able to fix this problem easily.