People often assume that if they get a new furnace, it won't have any problems for years. Often, this is the case. But new furnaces do sometimes break. Sometimes, a part is faulty from the factory and gives out after a few years. Other times, a lack of maintenance may cause a new furnace to break prematurely. The good news is that when a new-ish furnace breaks, the part that breaks is usually a small one – and the repairs are often covered under warranty. Here's a look at some of the smaller parts that may fail on a new-ish furnace.
The ignitor is a tiny part but a very important one. It produces the spark that lights the gas (or in some cases, propane or oil) on fire. Without a functioning ignitor, your furnace burner will not kick on, and your furnace will not produce heat. You may still experience some air coming through your duct because the fan portion of the furnace is still working, but the air will be cold.
Luckily, the ignitor is a small and inexpensive part that your furnace repair contractor can simply remove and replace. Ignitors are, however, quite model-specific, so you might have to wait a few days for your HVAC company to order the proper ignitor for your furnace.
The Limit Switch
The limit switch exists to control the operation of your furnace fan. It measures the temperature inside the furnace. When the temperature drops to a certain level, it turns the blower unit off so air stops coming through your ducts. The limit switch also detects if the temperature inside the furnace gets too hot, and then it triggers your furnace to turn off. This is a safety mechanism to prevent fires.
If the limit switch fails, your furnace may keep blowing and blowing cool air, long past the heating cycle. (This happens even with the thermostat switching to "auto.") You can keep running the furnace like this, but it will waste a lot of energy. Plus, you don't have the assurance that the limit switch will turn the furnace off and prevent a fire. So, call an HVAC contractor and have them come to replace your limit switch. It's a pretty common repair in newer furnaces, and it will probably be covered under warranty.
Even newer furnaces fail sometimes. Luckily, it's usually one of these small parts that are to blame. Reach out to a professional for more information about furnace repair.