Having walked into a freezing cold house in two consecutive Januaries when the ignitor on our furnace broke, I can confirm that the furnace is something you just expect to work but immediately notice when it doesn’t.
A furnace is one of the most important aspects of a home especially for those who experience cold winters. It’s an expensive appliance to buy, can be costly to fix but also provides instant heat during the coldest months of the year.
Once a furnace has reached 50% of its expected lifespan of 15-20 years and it requires a repair that will cost 50% of its initial cost, replacement is better than repair. By that time a newer model will be more energy efficient and cheaper in the long run to operate.
Whereas an older furnace may have an energy efficiency rating of around 78%, modern high efficiency furnaces are around 95% efficient and can go as high as 98%. This means that older furnaces may be wasting up to 22% of energy produced.
When should you replace a furnace
Once a major appliance in your home has reached or exceeded half of its expected lifespan and you are facing a repair that is expected to cost at least half of its original cost, it’s usually better to replace than repair it. In the case of a furnace, 15 – 20 years is the expected lifespan before it will need to be replaced.
How expensive are furnace repairs? I recently had to call emergency service on a holiday to fix our rental house’s 5-year old furnace which had a broken flame sensor. A fairly pedestrian and quick fix. Parts and labor including the extra charge for the holiday visit was $308. I also had to pay a bit more on top of that since the house is managed by a property management company and they added their fee, too.
Beyond just the age of your furnace, symptoms to look for that indicate that a replacement might be order include:
Increased heating bill: Your gas and heating bills are going up even if gas costs are relatively stable. Over time your furnace loses efficiency and has to run more frequently to produce heat which increases the cost to you.
Uneven heating: You may experience different temperatures in parts of your home. Vastly different temperatures in various rooms of your house indicate a potential problem with your furnace. This is particularly true on the highest floors of your home which are furthest away from the furnace itself in the basement.
Furnace can’t keep up: You may find that no matter how high you set the thermostat you can’t keep a reasonable temperature in the home. The furnace runs constantly and can’t keep up with the heating requirements.
Furnace makes frequent noises: Clicking, humming, booming and screeching sounds can indicate various problems that might require expensive fixes or replacement.
New furnace technology reduces energy usage and costs
By the time 15 – 20 years has passed, not only is your furnace likely to experience costly repairs, newer models on the market have been released that are more energy efficient than the one you have. With HVAC costs often running as high as 40% of a home’s electrical bill, this is not insignificant.
Recent improvements of furnace and home technology has seen a number of new developments that older furnaces can’t match including:
Better built and insulated homes: New green initiatives result in more insulated and better built homes that reduce the need for as much heating and cooling which impacts how your furnace operates in your home. New energy analysis software also helps homeowners figure out what system makes the most sense for them given their situation and needs.
New technology: New developments in ventilation and increased usage of heat pumps and solar technologies can be used in conjunction with your heating and cooling systems to lower your reliability on your furnace and AC to heat and cool your home respectively.
Smart features: Most thermostats are now built with WiFi technology and smart home monitoring capabilities so that you can operate your furnace and adjust home temperature remotely from anywhere with your cellphone.
Remote monitoring: Traditionally, a furnace problem or breakdown meant you had to call your HVAC repair service and they had to physically show up to your home to diagnose the problem and possibly return with parts on a second visit. As with other technologies in our lives, furnace and HVAC systems are getting smarter with sensors and monitoring features that can help you predict problems before they occur and diagnose them remotely, saving time and money and allowing HVAC repair staff to reduce the number of visits to fix a problem.
Information about your air ducts
A forced air heating and cooling system uses air ducts to move hot and cold air from the basement furnace or AC unit throughout each room of the house to moderate the temperature. Air ducts are enclosed metal passages that run throughout the home to deliver this air. Over time ducts may get dirty or damaged which can reduce your HVAC system’s efficiency.
As mentioned above, an older furnace may operate well below the standard 95% efficiency of modern high efficiency units meaning that it loses around 5% of energy to waste. Your air ducts can be responsible for losing significantly more energy. The US Department of Energy reported years ago that leaky air ducts can lose 30% – 40% of the air that travels through them.
If you notice visible damage to your air ducts in your basement or throughout your home, have an HVAC specialist repair them if you’re unable to do it yourself. Older homes may also have outdated or poorly designed air duct systems that can be corrected.
Adjusting your air ducts and air returns
Another consideration regarding your air ducts is to close off or at least restrict air flow from the air returns in certain rooms that are not being used to instead move warm or cool air to other rooms of your room that are in use. Close doors of your home that are not in use such as a spare room that is empty to further better use the heated and cooled air produced by your furnace or air conditioner.
Conversely you can open up other air returns to rooms that are heavily used. I’ve also found that air returns that are located on a floor directly on top of your furnace have a strong airflow and can be slightly closed off to direct more air to the higher floors of your home that are further away from the furnace.
If after adjusting and closing off some air returns don’t result in improvements of air flow, you may want to schedule a visit with an HVAC company to check out your entire system, especially if you own an older home.
Cost to replace a furnace
The cost to replace a furnace is generally in the $2,500 – $6,592 range for an average unit but the most expensive high efficiency furnaces can go higher. Your total cost will also depend on whether you choose a gas, electric or oil furnace.
You will see furnaces rated by Annual Fuel Utilization Efficiency (AFUE) as a percentage. It refers to the efficiency of the furnace so the higher the number the more efficient. Furnaces range in efficiency as follows:
- Minimum standard: 78% AFUE
- Mid-efficiency furnace: 80% – 85%
- High-efficiency furnace: 90% – 98%
Here are considerations for each type of furnace to compare one against the other:
| Gas Furnace | Electric Furnace | Oil Furnace | |
| Unit Cost | Most expensive to buy up front. $1,200 – $2,400 unit cost plus installation is reasonable. | Cheapest to buy up front. $700 – $2,000 unit cost plus installation is reasonable. | Most expensive. $1,900 – $5,900 unit cost plus installation is reasonable. |
| Energy cost | Natural gas is cheapest. $640/year in heating costs is a reasonable average. | Electricity is cheaper than oil. $960/year in heating costs is a reasonable average. | Oil is most expensive. $1,851/year in heating costs is a reasonable average. |
| Efficiency | Most efficient. Up to 98% currently. | Less efficient than oil. | More efficient than electricity. Generally 80% – 90% currently. |
| Heating of air | Fastest. Gas-fired furnaces heat air the quickest. | Slowest. Tends to deliver the coolest air, too. | Delivers the hottest air as oil burns hotter than gas. |
| Considerations | Works during a power failure. Natural gas delivery is generally very reliable, constant, and automatic. | Won’t work during a power failure. | Heating oil is delivered to your home by truck not through a pipe so it can run out. |
| Safety | Natural gas fumes can kill as it produces carbon monoxide. Flammable. | No fumes to worry about and electricity is not flammable like a gas. | Inhaling oil fumes is not life-threatening like natural gas. Is flammable but will not explode. |
| Popularity* | Around 48% of US homes have a gas furnace but it’s decreasing. | 37% of US homes have an electric furnace or other electrical heating but it’s increasing. | About 8% of US homes have an oil furnace as it’s generally not a popular option anymore. |
| Maintenance | Natural gas burns cleaner than heating oil so maintenance is generally not required. | Burns very clean unlike gases so maintenance is not generally required. | An oil tank generally requires cleaning every 5 years and possibly other maintenance. |
The major established furnace brands you will frequently see include Lennox, Trane, Heil, Carrier, Rheem, Goodman and Maytag among others.
Cost to replace a furnace filter
Your furnace filter is an easy to replace, DIY “project” that you should be doing typically four times per year ie. every 3 months. Changing a furnace filter only takes a few seconds. Popular disposable furnace filters cost $10 – $50 for standard pleated and non-pleated filters commonly used in modern furnaces.
Choosing a furnace filter that meets your household’s needs is easy once you’ve determined the furnace filter size you need. To get this size, simply check the label on your furnace for a three digit size that will typically look like 16 x 20 x 1 where 16 is the length in inches, 20 is the width in inches and 1 is the depth in inches. You can also check to see the measurements of the current filter used in your furnace, assuming it’s correct.
Please check out my complete page on How Often To Replace A Furnace Filter for more information. Your furnace filter is an important part of your heating and cooling system and should be replaced on schedule.
Both hot air (furnace usage during the winter) and cold air (air conditioning during the summer) passes through the air filter so it should be replaced throughout the year.
Installing a furnace humidifier
With forced air heating systems, delivering warm air throughout your home during the coldest months of the winter often leads to dry, dehumidified air. If during the coldest months of the year you experience a sore or dry throat particularly when you wake up, get frequent nose bleeds for no reason and get dry hands and skin, it’s likely that the humidity level in your home is low.
Get a home thermometer with humidity reading so that you can measure humidity in each room of your home to determine if you have a problem. Humidity should be 30% – 40% inside the home for optimal comfort.
A humidifier can be attached to your furnace which will add moisture to the heated air before it gets distributed throughout your home.
Here’s a short video that illustrates the mechanics behind the various kinds of furnace humidifiers that exist. While you can install a humidifier yourself, it’s also a job that an HVAC pro could easily do for you, too.