Why Does My Furnace Blow Out Cold Air?
There are some common causes for a furnace blowing cold air that you may be able to correct yourself before making a service call.
Does your furnace blow hot air, then cold air, and then no air at all? If so, your furnace may be overheated. The cool air is your furnace’s way of trying to cool itself down while operating. It’s likely caused by a dirty or clogged air filter that needs to be changed.
Another common reason for your furnace to be blowing cold air is because the pilot light is out. There are three solutions for this problem:
- Relight the pilot light (if it stays on, that’s all you’ll need to do!)
- Be sure that your furnace’s gas valve switch is in the correct position (e.g., in line with your gas supply pipe)
- The copper rod your pilot light flame hits (thermocouple) needs to be adjusted or replaced (this isn’t a DIY fix if you’re not familiar with how to do this)
Why Is My Furnace Leaking Water?
The most common reason for a furnace to be leaking water is condensation, especially if you have a high-efficiency furnace. Units like this have cool exhaust, which produces condensation. You likely have a high-efficiency furnace if your vent pipe is white plastic. Water pooling from condensation could be due to a clogged floor drain or clogged or broken condensation tubing.
With a standard furnace (metal exhaust pipe), you shouldn’t have any condensation. If you are seeing water from condensation with this type of furnace, it usually means the flue pipe isn’t sized correctly. Water leaks around your furnace may also be caused by:
- A faulty secondary heat exchanger
- Problems with your humidifier
- An internal drain system clog (if your AC unit shares an internal drain with your furnace and you’re at a point where you are still using your air conditioning for warmer days)
Why Does My Heater Smell Like Burning Dust When I First Turn It On?
A strong burning dust smell when you first turn your furnace on after a long period of not using it may simply mean that the system is just burning off the dust that has accumulated from the off-season. If this is the case, the smell should go away within a few hours of operation. if it doesn’t, check to see if your filter needs to be changed.
Should you smell an electrical burning odor that would indicate a problem which should be addressed immediately. Turn the system off and call a professional to identify and fix the problem.
Why Does My Furnace Make a Small Explosion Noise When It Starts?
If you’re hearing a scary “boom” when your furnace starts, it’s definitely not a sound you can or should ignore. Determine which one of these two issues is causing your furnace to make a small explosion noise by standing near your furnace after you turn it on. Pay attention to where the sound seems to be coming from.
If you hear a clicking noise like your furnace is trying to turn on before you hear the “boom” sound, it’s likely a delayed ignition problem. This is often caused by dirty burners, too much gas, or too much primary air. This condition is not good for the system and can become unsafe. A well-trained technician can locate and fix the problem before the condition gets worse.
Expansion of Your Air Ducts
If the noise sounds like it’s coming from a few feet away from your furnace after it starts and the blower turns on, it may be coming from your ducts. This is caused by too much static pressure in your ducts, which may result from closed vents, dirty air filters, or ducts that aren’t properly sized for your home.
Why Does My Furnace Make Clicking Noises?
Clicking noise usually mean your furnace is trying to start a cycle. With this problem, you may experience a delayed ignition, or you may not get any heat at all if your furnaces’ spark igniter isn’t able to start your pilot light or burners. This means you have an ignition system malfunction, which isn’t a DIY type of repair.
What If I Suspect a Gas Leak?
If you smell natural gas in your home or near your furnace, take immediate action. Turn off the gas supply valve (usually located by your gas meter). Err on the side of caution and evacuate your home. Do not turn on or off any lights while exiting the home. Call the gas company or fire department from a safe location.