Common furnace problems
from simple to complex

Joeseph T. Prock - Author

Joseph T.Prock

October 2019 • 5 min read

Simple fixes that can save customers a service call

Common furnace problems range from simple fixes homeowners can perform to complex repairs that require the expertise of a technician. A clogged filter is one of the biggest causes of a furnace and A/C problems. When dust builds inside a filter it reduces airflow through the system causing the furnace to shut off. You might mention to homeowners to check their air filter first to see if it’s clogged or if they’ve changed the filter within a reasonable timeframe.

Another easy check for homeowners is the thermostat. Sometimes the furnace doesn’t work because the thermostat hasn’t been set correctly. This is more common with programmable thermostats because the homeowner might have set up a program last spring and forgotten about it when they tried to turn the heat on in the fall. The homeowner needs to verify the temperature setting and make sure the thermostat is set to “heat” rather than “air” or “off”.

Circuit breakers are another area homeowners can check. Every so often something will cause the circuit breaker to the furnace to trip, turning it off. Also, there is usually a switch that looks like a light switch near the furnace that turns it on and off. Check to see no one has turned it off by mistaking it for the attic light.

Lack of routine maintenance

Regular maintenance is key to ensuring the furnace operates properly throughout the year. It’s best if homeowners consider servicing their furnace at least one to two times a year. Getting a maintenance agreement is a great way to address any issues before they become major problems. During routine maintenance, the tech might discover a problem with the heating system and suggest ways of dealing with it before it becomes serious.

Common furnace problems that require a technician:

Ignition Problem

Modern gas furnaces no longer use standing pilot lights. Instead, they use either intermittent pilot or hot surface ignition to start the furnace. These are more efficient than a standing pilot light because they’re not constantly burning a small amount of gas just to keep the furnace ready to start.

The most common is the hot surface ignition system. It’s sort of like the filament in a standard light bulb. When the thermostat signals the furnace to switch on, electricity runs through the igniter and heats it. Just like a standard light bulb, the igniter is a thin piece of metal and will not last forever.

Other problems can occur with the ignition in modern gas furnaces. Safety switches can break, computer boards can fail or other malfunctioning parts of the furnace can keep the ignition system from working. If the furnace isn’t turning on and you’ve checked the thermostat, there is a good chance the problem is somewhere in the ignition system

If you have an older furnace, you might still have a standing pilot light. Sometimes the pilot light has gone out for some reason and you can just light it again. If you have a furnace with a pilot light, it isn’t nearly as efficient as a modern furnace and you should be able to save quite a lot on your heating bills by replacing it with a new one.

For any hot surface ignitor replacements, LennoxPros offers kits, ignition integrated furnace controls, ignition modules, and more.

Burner Needs Adjustment or Cleaning

Once the furnace is lit it relies on a burner to heat the air that’s blown through air ducts and delivered to the rooms in the home. Sometimes the ignition system will work fine but the burner won’t light. Other times the burner won’t work properly. This could also lead to no heat or very poor efficiency meaning the homeowner will have higher energy bills.

Figuring out that the burner is dirty or needs adjustment requires looking inside the furnace. There are safety concerns when making repairs to gas appliances, especially as you don’t want to accidentally cause a gas leak or carbon monoxide.

LennoxPros offers a variety of burner replacements available online or in-store pickup.

Belt and Blower Problems

The most common blower problems are usually belt problems, sometimes a more serious problem creates similar symptoms. If the furnace is making a high-pitched sound it is likely the blower belt or the blower itself. The best way to resolve this problem is to have a qualified technician inspect and diagnose the system. Sometimes fixing this problem can be as simple as lubricating it. The belt could also be worn. Both situations can usually be avoided with annual maintenance inspections. Sometimes, the problem is with the blower motor or another mechanical part which will either need repair or replacement.

Whether you’re replacing a motor or a belt, LennoxPros has a wide variety of replacements to help you get the job done right so you can restore comfort to your customers.

Lennox, engineered for perfect warmth and savings

If your customer needs to replace their furnace, make sure you recommend a Lennox. Engineered to deliver perfectly consistent temperatures and unprecedented, quiet high-efficiency, warmth and savings, Lennox has been designated as one of the most efficient Energy Star qualified products in 2019. LennoxPros offers a variety of gas or oil furnaces designed for different budgets that’ll help your customer save on utility bills without sacrificing comfort.