Despite the seeming simplicity of your home's furnace, it does far more than you may realize and in a more complex and fine-tuned way. This is especially true for furnaces within the last few years. Some of the latest, higher-end furnace systems can regulate the humidity of the air, reduce the presence of pathogens and toxins, and even neutralize cooking smells that would otherwise linger. However, most people are plenty happy to see their basic, single-stage furnace last longer than 10 years without any major upsets. Every once in a while, though, the level of comfort inside your home may be negatively affected by your aging furnace, despite still being able to work in a relatively normal fashion. Here are three obvious symptoms of a faulty furnace, each with causes that are much harder to detect without a little help.

1. Inconsistent Heating

This symptom could be caused by something as simple as closed vents when they ought to be opened, but it could be far more severe. Certain problems with your pilot light could cause the furnace's flame to burn only intermittently. Not only does this problem waste valuable gas, but the gas could build up within the flue and ignite all at once, potentially necessitating extensive repairs to your furnace's burner. If you find that the heating is inconsistent throughout your home and it's not caused by closed vents, take a look inside the furnace housing to be sure that the tiny pilot light is still burning. If it isn't, shut off the furnace and call a professional immediately.

2. Insufficient Heating

This symptom might not indicate any problem with your furnace at all, but with your ductwork. Because the heated air needs to travel through the ducts before it gets to each room of the house, any disruption to the ducts, walls, joints, seams, or sheeted insulation will make for a curiously cooler house. If the insulation on your ductwork has not been inspected or replaced within the last five years, then it may be due for a replacement.

3. Allergies

That's right; some problems with your heating can produce allergy-like symptoms or make existing allergies much worse. When your furnace burns natural gas, chemicals such as nitrogen dioxide and carbon monoxide will be found in the exhaust. Normally, these chemicals are vented harmlessly outside, but any breach in the furnace's flue will leak these toxic gases into your home. You can detect these dangers quickest by installing a toxic chemical detector, which will sound an alarm when concentrations of these chemicals reach harmful levels.

As you can see, the problems of a faulty furnace can reach far beyond mild discomfort; potentially wasting thousands of your dollars, introducing or exacerbating respiratory problems. Call a heating professional (such as Alliance Heating & Cooling LLC) to look into these symptoms, because the possible downsides to forgoing preventive service far outweigh the cost of the service itself.