9 Furnace Troubleshooting Tips to Prepare for Winter

September 22, 2023

9 Furnace Troubleshooting Tips to Prepare for Winter


Getting your furnace ready for the winter? A little preparation will get your furnace and home ready before the big chill.

Want to know how you can save money, and stay warm this winter? Don't wait for the cold weather to hit, prepare for winter by troubleshooting your furnace yourself today.

Here are 9 furnace troubleshooting tips to prepare for winter to get you started:

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1. Check and Change Your Clogged Filter and Breathe Healthier Air

Replacing your furnace filter regularly is a quick and simple task, and goes a long way in protecting HVAC components and improving your inside air quality. Air filters are a vital part of every HVAC system and often overlooked as to their importance.

Cleaning the debris that builds up on your filters will aid with the flow of air. When your air filter is clogged, your air handler must work harder to compensate for the blockage of air flow. In addition to driving up your utility bill, the reduced air flow through your heating and cooling system can cause your heat exchanger to overheat and shut off too quickly.

"In addition to driving up your utility bill, the reduced air flow through your heating and cooling system can cause your heat exchanger to overheat and shut off too quickly, preventing your house from warming up".

Not a good thing! Your filter should not look like this:

dirty air filter.png

Photo credit: Dirty Air Filter

This one tip alone can save you all sorts of problems of what can go wrong when you have a clogged air filter. Dust and debris will restrict your air flow and put unnecessary strain on your furnace.

A new filter costs so little, while a furnace costs so much more. Why risk damaging it?

You should change your air filters according to your manufacturer's recommendations. Some suggest monthly, others every 3 months. Not all air filters are built the same. A MERV rating is assigned to air filters to rate the effectiveness of an air filter removing air particles from the air.

It's important to know the difference between furnace filters.

Take a look at your filter every 30 days to determine if you need a new one.

2. Switch Your Thermostat From Cooling to Heating

In a panic you might have not switched or toggled from cooling to heating. Don't laugh it's been done, especially with the newer programmable thermostats.

If you're a household with a Nest, How-to-Geek simplifies your life with their step by step instruction on How to Switch Your Nest Thermostat from Heating to Cooling (and Vice Versa)

Troubleshoot the problem. Often the solution can be very simple.

3. Take Out Window Screens and Install Storm Windows

As the colder air approaches so does the draft from windows and doors. By installing storm windows you will be able to decrease the amount of heat leaking through your windows and into the outdoors or vice versa cold air coming in.

According to Energy.gov, field studies have found that they can help reduce air movement into and out of existing windows. Therefore, they help reduce heating and cooling costs.

You can improve the energy efficiency of existing windows by adding storm windows, caulking and weatherstripping, and using window treatments or coverings.

4. Inspect Your Chimney for Safety and Efficiency

Inspecting and cleaning fireplaces and chimneys is essential for safety and efficiency. A clogged chimney presents risks of carbon monoxide poisoning or fire.

wikiHow shows you exactly in 10 steps How to Inspect a Fireplace Chimney. You should be checking for any obstructions, such as bird nests or debris. Furthermore, you should also make sure there is no significant soot buildup, as it can be a dangerous fire hazard.

  • Excess creosote, over 18 inch (0.3 cm) or 3 mm, can ignite in the flue and send flames shooting out the top of the chimney, even causing the home itself to catch on fire.

With a flashlight, inspect the flue damper to make sure it opens, closes, and seals properly.

“If the damper doesn’t seal well, you’ll lose a tremendous amount of heat from the home when the fireplace isn’t in use,” explains Gary Spolar, a licensed sweep and owner of Century Chimney in northeast Ohio.

You want to remove the dangerous, flammable creosote from inside the chimney. If your chimney hasn't been inspected in a long time, call a professional to check it and clean the ducts.

And on another note, if you have a gas-burning fireplace, it needs an inspection as well.

  • Inspect the glass doors for cracks or latch issues.
  • Check that gas logs are in the proper position.
  • Turn gas off at the shut-off valve and test the igniter.
  • Ignite the fire and look for clogged burner holes. If present, turn off gas and clear obstructions with a pin or needle.

(Inspecting a Gas-Burning Fireplace)

Any precautions and steps you take now will help your furnace work more efficient later.

5. Burners Must be Free of Debris and Dust

Dust can accumulate during the summer. Therefore, it's very important to check and clean the furnace burners before the start of the colder seasons.

A combination of condensation and soot can cause burners to function improperly, and may cause other furnace problems as well. The burner assembly should be cleaned annually or replaced if the existing one is in poor condition.

Your burners should display blue flames, if you see excessive yellow when turned on...

it’s time to call for service.

gas furnace flame.png

photo credit: gas furnace flame

While cleaning the burners, check for signs of misalignment and rust.

You can use a shop vac with a small nozzle to clean both the burner channels and exchanger tubes. If your furnace is an older model and has a pilot, turn off the gas first and be careful not to pull out any wires before you clean.

6. Oil the Furnace Blower Once a Year

When preparing your furnace for winter it is important to make sure all the components of your heating system are clean and in working order.

The furnace blower’s main function is to draw heat from the furnace and distribute it throughout the house. Keeping a furnace blower lubricated will extend the life of your furnace.

Here are 8 easy and detailed steps How to Oil a Furnace Blower Motor, courtesy of SFGate:

oil your furnace blower motor.png

The furnace blower motor plays a big role in how your heating system functions. It should be oiled once a year and it shouldn't make any unusual noises when started.

A quick furnace troubleshooting tip is to simply listen to your furnace.

7. Make Sure Your Thermostat is Working Properly

Having a thermostat that functions correctly is essential to keeping your home comfortable during any time of year.

If a thermostat is not working correctly, your heating system may not be working efficiently. Turn on your thermostat and monitor how it responds, it should start up immediately without any problems.

If you have an old thermostat that must be controlled manually you should consider updating it. Set-back thermostats are the best choice because they allow you to completely control the temperature in your home. A set-back thermostat can be automatically turned down when you're asleep or away, which can save you a lot of money.

Modern homes are being equipped with the capability to control many functions by wireless communication devices. You can operate your garage door, lighting, and control your HVAC system from anywhere that has access to the internet.

You can read more on the Pros and Cons of Smart Thermostats.

8. Check Your HVAC Vents for Proper Air flow

Throughout the year, furniture is often moved around and new furniture is brought into the home. Double-check around your house to make sure that nothing is blocking your heating vents.

Blocked vents are not only useless since heat can't get out, but they can also drive your heating up. In addition, a blocked vent can result in an overheated furnace.

Check both your supply registers, heat blows out of these, and your return registers, the air is drawn into these.

Do you ever close vents in unused rooms to save money?

The Energy Vanguard Blog did an excellent and comprehensive job at explaining why you really shouldn't close those vents. They went on to clarify unintended consequences of closing your vents.

In a nutshell it can do more harm than good. A few of the after-effects are:

  1. Increased duct leakage
  2. Comfort problems because of low air flow
  3. Cracked heat exchanger, with the potential for getting carbon monoxide in your home
  4. Condensation and mold growth in winter due to lower surface temperatures in rooms with closed vents

You can read the full article here: Can You Save Money by Closing HVAC Vents in Unused Rooms?

9. Tune Up Your Heating System

Since your furnace has been idle for several months, a yearly tune up will let you know if it is in working condition or may need replacing.  HVAC technicians may check:

  • Burners are set to correct combustion settings
  • All parts are lubricated to avoid breakdown
  • No signs of wear and tear
  • Thermostats are running adequately
  • Blower access door has a snug seal at the furnace
  • Heat exchanger inspected for rust and corrosion
  • Drainage system is checked for blockage and leaks


Schedule an Appointment to Clean Your Furnace Early in the Season

Professional companies get very busy at the onset of winter, so it's a good idea to schedule your appointment ahead of time. The best way to save money in the long run is to have a professional clean your heating system.

Systems cleaned by professionals will work better and more efficiently. Check with your local BBB (Better Business Bureau). Make sure the company you want to call is an Accredited BBB member with an A+ rating.

These tips are a great start, but keep in mind that you should contact a professional if you aren't familiar with how your heating system works. Keep your furnace clean, and replace equipment as needed.

With proper maintenance, your furnace will work more efficiently, and save you money on expensive energy costs.

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