FAQ

Yes, a dirty furnace filter can damage your furnace over time. When a filter becomes clogged, it restricts airflow, forcing the furnace to work harder to move air through the system. This added strain can lead to overheating, frequent shutoffs, higher energy bills, and premature wear on critical components like the blower motor and heat exchanger. Regularly checking and changing your filter is one of the simplest ways to protect your furnace and avoid costly repairs.

Many times when people call us because their furnace is not working, it’s simply because the filter is too old or dirty and not allowing proper airflow through the system. When airflow is restricted, the furnace can overheat and shut itself off as a safety measure, making it seem like a much bigger problem than it really is. Regularly checking and replacing the filter can prevent unnecessary service calls and keep the furnace running reliably.

Most furnaces should be replaced when they are 15 to 20 years old, but age alone isn’t the only factor. If your furnace needs frequent repairs, struggles to keep your home comfortable, makes unusual noises, or causes rising energy bills, it may be nearing the end of its life. Replacing a furnace before it fails completely can help you avoid emergency breakdowns during Michigan winters and gives you time to explore options that improve comfort, efficiency, and reliability.

In most homes, no. Your furnace will not run during a power outage. Even gas furnaces rely on electricity to power components like the blower motor, control board, and safety sensors. When the power goes out, the furnace shuts down as a safety measure. That’s why many Michigan homeowners consider backup power options, like generators, to keep their heating system running and their home safe during winter outages.

We don’t want to think of this as a checklist, so we reframe the question. What are we trying to accomplish during a furnace tune-up?

1. Reduce the risk of failure during peak demand.
   The furnace will be asked to perform hardest when it’s coldest. A tune-up is about identifying conditions that commonly cause no-heat calls before they do so.
2. Verify the system is operating safely.
   This is non-negotiable. Combustion appliances can create life-safety risks. A tune-up must confirm the furnace is not creating carbon monoxide risk, flame instability, or heat exchanger-related hazards.
3. Restore proper operation and efficiency where it has drifted.
   Furnaces don’t usually fail catastrophically all at once. They drift: dirty burners, restricted airflow, weak igniters, failing capacitors. A tune-up corrects normal degradation so the system runs as designed.
4. Give the homeowner clarity about the condition of their equipment.
   This is often overlooked. The customer should leave knowing: Is my furnace healthy? Is anything trending toward failure? What should I plan for?

If your tune-up does not clearly accomplish all four, you should question whether it’s worth doing at all.

With that in mind, here’s what the checklist should look like.

• Safety verification- Inspect the heat exchanger, measure carbon monoxide levels, thoroughly inspect all the venting and complete a combustion analysis when warranted.
• Reliability checks- Test and inspect ignition components, flame sensing, gas pressure and all electrical components.
• Performance restoration- Clean the burners, clean the flame sensor, check temperature rise and air flow.
• System evaluation and communication- document findings, give a clear explanation of current condition and prioritized recommendations if there are any.

A furnace can smell weird for several reasons, and not all of them are serious. At the start of the heating season, a dusty or burning smell is common as dust burns off components that haven’t been used in months. Other odors, like musty smells, can point to dirty filters or moisture issues, while a strong rotten-egg or sulfur smell could indicate a gas-related problem and should be taken seriously. If a smell is persistent, unusual, or getting stronger, it’s best to turn the system off and have it checked to ensure everything is operating safely.

To change a furnace filter, first turn the furnace off for safety. Locate the filter slot, usually in the return air duct or inside the furnace cabinet. Slide the old filter out and note the size and airflow direction arrows. Insert the new filter with the arrows pointing toward the furnace, making sure it fits snugly, then close the panel and turn the system back on. Checking the filter regularly helps ensure proper airflow and reliable furnace operation.

Cleaning a furnace starts with turning the system off and cutting power for safety. Wipe down the exterior, then carefully remove dust from around the furnace, vents, and blower area using a soft brush or vacuum. Replace or clean the furnace filter and make sure the area around the unit is clear of debris. Deeper internal cleaning and inspections should be handled by a professional, as improper cleaning can damage components or affect safe operation.

In most homes, the blower motor wheel should be cleaned every 3 to 5 years, or sooner if there is visible dust buildup. Homes with pets, high dust levels, or heavy system use may need more frequent cleaning. A dirty blower wheel reduces airflow, lowers efficiency, and puts extra strain on the furnace. Because accessing and cleaning it requires partial disassembly, this task is typically best handled during a professional maintenance visit.

A furnace may stop blowing hot air for several common reasons. Dirty filters can restrict airflow and cause the system to overheat and shut off the burners, while thermostat settings or dead batteries can prevent proper heating. Other causes include a pilot light or ignition issue, problems with the gas supply, or safety sensors shutting the system down. If the air is lukewarm or cold and the issue continues after checking the filter and thermostat, the furnace should be inspected to prevent further damage.

MERV stands for Minimum Efficiency Reporting Value. It’s a rating system that shows how effective an air filter is at trapping dust, pollen, pet dander, and other airborne particles. The higher the MERV rating, the smaller the particles the filter can capture. While higher MERV filters improve air quality, they can also restrict airflow if your system isn’t designed for them, so it’s important to choose a filter that balances filtration and proper furnace performance.

Most furnaces should be professionally serviced once a year, ideally during the heating season. Annual maintenance helps ensure the system is operating safely, efficiently, and reliably during Michigan winters. Regular service can catch small issues early, improve performance, extend the life of the furnace, and reduce the risk of unexpected breakdowns when you need heat the most.

Water in or around a furnace is usually a sign of a condensation or drainage issue. High-efficiency furnaces produce condensation as part of normal operation, and if the drain line becomes clogged or disconnected, water can back up into the unit. Other causes can include a blocked condensate pump, frozen or cracked drain lines, or excessive humidity inside the system. Because standing water can damage components and affect safe operation, it’s important to have the issue addressed as soon as it’s noticed.

You may have a bad furnace if it needs frequent repairs, struggles to heat your home evenly, makes loud or unusual noises, or causes rising energy bills. Other warning signs include short cycling, weak airflow, strange smells, or the system shutting off unexpectedly. If your furnace is older and several of these issues are happening at once, it’s often a sign the system is nearing the end of its life and should be professionally evaluated.

Yes, furnace maintenance is necessary, but not for the reason many people assume.

A furnace doesn’t usually fail without warning. Most problems develop gradually: parts wear, airflow becomes restricted, combustion drifts out of spec, or safety components begin to weaken. Maintenance exists to catch those conditions before they turn into a no-heat situation or a safety issue, typically during the coldest part of the year when the system is under the most stress.

Maintenance also matters because a furnace is a combustion appliance. Unlike many household systems, it has the potential to create carbon monoxide if something is not operating correctly. Routine maintenance is how those risks are checked and verified, not guessed at.

What maintenance does not do is guarantee that a furnace will never break down. It reduces risk, improves reliability, and confirms safe operation. Skipping maintenance doesn’t mean a furnace will fail immediately, but it does increase the likelihood that problems will show up unexpectedly, often at the worst possible time.

A furnace struggles in extreme cold because that’s when it is operating at its absolute limit. Heating systems are designed for typical winter conditions in a given area, not for prolonged or extreme cold events. As outdoor temperatures drop, heat loss from the home increases, and the furnace has to run longer and more frequently to try to keep up.

Wind and building conditions play a major role as well. High winds increase heat loss and can push cold air through gaps around doors, windows, and other leakage points, especially in older homes. In those situations, the furnace may be producing heat normally, but the home is losing heat faster than the system can replace it. This can make it feel like the furnace isn’t working properly, even when it is operating as designed.

You prevent furnace failure in winter by reducing stress on the system and identifying problems before the cold exposes them.

Most winter furnace failures are not sudden or random. They are the result of components that were already worn, dirty, misadjusted, or operating on the edge. When temperatures drop and the furnace runs longer and harder, those weak points finally show up.

The most effective prevention steps are straightforward. Have the furnace inspected and serviced before winter so safety, combustion, airflow, and high-failure components can be checked under controlled conditions. Keep airflow unrestricted by using a clean, properly sized filter and making sure supply and return vents are not blocked. Pay attention to changes in operation, such as longer run times, unusual noises, or inconsistent heat, and address them early rather than waiting for a complete failure.

No approach can guarantee a furnace will never fail, especially during extreme weather. The goal is risk reduction: catching predictable issues early, maintaining proper operation, and avoiding preventable breakdowns when the system is under maximum demand.

If a furnace stops during cold weather, the goal is to slow heat loss and protect vulnerable plumbing until heat is restored.

Start by maintaining as much residual warmth as possible. Keep exterior doors and windows closed, and open cabinet doors under sinks so warmer air can circulate around supply lines, especially on exterior walls. If there are areas of the home that are normally kept cooler, allow warm air to move into them.

Letting faucets drip slightly can also help. Moving water is less likely to freeze than standing water, and even a small, steady drip can reduce pressure buildup if freezing does occur.

If temperatures are extremely low or the outage is expected to last, temporary heat sources such as space heaters can be used cautiously in occupied areas, following all safety guidelines. In more severe situations, shutting off the main water supply and draining the plumbing system may be the safest option to prevent damage.

The key point is that frozen pipes are primarily a function of time and temperature. The faster heat is restored and the more heat you can retain in the home, the lower the risk of freezing and pipe damage.

If your furnace stops working at night, focus first on safety, then on protecting the home until heat can be restored.

Check the simple things that can be safely verified without tools. Make sure the thermostat is set correctly and has power. Check for a tripped circuit breaker or a service switch near the furnace that may have been turned off. If the furnace has a visible error code, note it rather than repeatedly cycling power.

If the system does not restart, take steps to conserve heat and reduce risk. Keep doors and windows closed, open cabinet doors under sinks to protect plumbing, and allow faucets to drip if temperatures are very cold. Use space heaters only if they can be operated safely and attended, and never as a long-term solution.

Avoid repeated resets or attempts to force the system to run. That can worsen certain failures or create safety issues. At that point, the best course is to schedule service as soon as it’s available and focus on protecting the home and occupants until the furnace can be properly diagnosed and repaired.

A new gas furnace replacement in Michigan is a significant investment, and typical installed prices are generally higher here than national low-end figures. Most homeowners in Michigan pay roughly $5,800 to $10,200 for a complete gas furnace replacement, including the furnace itself, removal of the old unit, installation labor, basic duct adjustments, and permits.

What drives that range are a few key factors: the size of the home and required furnace capacity, the efficiency rating of the furnace (higher AFUE costs more), and how straightforward the installation is (for example, whether existing venting and ductwork can be used as-is).

In Southeast Michigan specifically, typical installed costs are reported in the $4,000 to about $9,500 range for standard to high-efficiency gas furnaces.

A few points to set expectations:

• Lower-efficiency, basic gas furnaces cost less than high-efficiency models.
• Permits, inspections, and minor ductwork or vent changes add to the total cost.
• Costs can exceed these ranges if the installation is complex or if additional system upgrades are needed.

A standard gas furnace is about 80% efficient, while a high-efficiency furnace is typically around 95%. That efficiency rating describes how much of the gas you pay for is actually converted into usable heat in your home. With an 80% furnace, roughly 20% of the heat created is lost through the exhaust. With a 95% furnace, that loss is closer to 5%.

To put that into practical terms, if it costs $200 to heat your home during a cold January with an 80% efficient furnace, roughly $40 of that fuel cost is tied to heat that never makes it into the living space. A high-efficiency furnace reduces that waste, meaning less gas is required to produce the same amount of heat.

In Michigan, this difference matters because furnaces run a lot. Nighttime temperatures are commonly in the teens and 20s, daytime temperatures often stay below freezing, and heating systems may operate heavily from November through March. When a furnace runs that frequently, reducing wasted fuel has a meaningful impact over time.

In warmer climates, where heating is only needed occasionally, the same efficiency gains are far less noticeable. The value of a high-efficiency furnace depends largely on how often it runs. In cold climates like Michigan, where heating demand is high for long periods, a high-efficiency furnace is generally a very good fit.

There is no single “best” furnace brand. In real-world performance, reliability, and lifespan, the quality of the installation matters far more than the name on the equipment.

Most major furnace manufacturers build gas furnaces that can perform well and last a long time when they are properly selected, sized, installed, and commissioned. When problems show up after a replacement, they are rarely caused by the brand itself. They are far more often caused by improper airflow, incorrect sizing, poor venting, rushed installation, or skipped startup and safety checks.

Brand recognition is often driven by advertising, not by meaningful differences in how furnaces actually perform in a home. Highly advertised brands are familiar, so they are assumed to be better. In practice, familiarity does not protect a homeowner from comfort problems, higher operating costs, or shortened equipment life if the installation is not done correctly.

For homeowners, proper installation is the single most important factor. Furnaces cost contractors roughly the same regardless of brand. There is no hidden source of cheap equipment. If one replacement price is significantly lower than another, the difference is almost never the furnace—it is the work being done, or more accurately, the work not being done.

A furnace replacement is not just swapping one box for another. It involves correct sizing, proper venting, airflow setup, gas and electrical connections, safety verification, and full startup and commissioning. These steps take time and skill. Typically, two installers are in the basement for most of a day doing this work. That time is not optional if the system is going to operate safely, efficiently, and as designed.

When the goal becomes getting the job done as cheaply as possible, the only way to reduce the price is to cut corners. That often means rushing the installation, reusing components that should be updated, skipping airflow corrections, or failing to properly commission the system. The furnace may run, but it is not operating the way it was designed to.

Over time, those shortcuts show up as comfort issues, higher fuel usage, nuisance shutdowns, safety concerns, and reduced equipment life. Furnaces that fail early are often not victims of bad manufacturing, but of improper installation and setup.

The most reliable way for a homeowner to get a good outcome is not to chase a brand name or the lowest price, but to choose a company with a strong reputation for doing the work correctly. Reviews that consistently mention professionalism, thoroughness, and follow-through are a better indicator of long-term satisfaction than the name on the front of the furnace.

In short, the best furnace brand is far less important than the people installing it. A well-installed furnace from a reputable manufacturer will almost always outperform—and outlast—a poorly installed furnace from a highly advertised brand.

A good efficiency rating for a furnace depends on climate and how much the system will run, not just the number itself.

Furnace efficiency is measured by AFUE, or Annual Fuel Utilization Efficiency. An 80% AFUE furnace converts about 80% of the fuel it burns into usable heat, while the remaining 20% is lost through the exhaust. High-efficiency furnaces are typically rated around 95% AFUE, meaning much less heat is wasted.

In cold climates like Michigan, where furnaces run heavily from late fall through early spring, a high-efficiency furnace is generally a good choice. Because the system operates for long periods, reducing wasted fuel has a meaningful impact over time. For many homes, an efficiency rating in the mid-90% range strikes a good balance between operating cost and performance.

That said, efficiency ratings don’t exist in isolation. A high-efficiency furnace that is improperly sized or poorly installed will not deliver the expected benefits. Proper sizing, airflow, venting, and commissioning matter just as much as the AFUE rating itself.

In practical terms, a “good” efficiency rating is one that matches the home, the climate, and how the system will be used—and is supported by a correct installation. In Michigan, that often means a high-efficiency furnace, but the installation quality ultimately determines whether that efficiency is actually realized.

A typical furnace installation takes about one full day, but the exact time depends largely on how accessible the furnace is and how much work is required beyond replacing the unit.

In a home where the furnace is located in an open basement with good access, a standard replacement is usually completed by two installers in a single day. That timeframe allows for removing the old furnace, installing the new one, setting up airflow and venting, and properly starting up and commissioning the system.

Installations take longer when access is limited. Furnaces located in closets, attics, or crawl spaces require more time because moving equipment, working space, and safety considerations all become more challenging. In some cases, years of stored items around the furnace can also slow the process by limiting access to the work area.

Additional time may also be required if venting needs to be modified, airflow corrections are necessary, or code updates are required. These are not delays—they are part of doing the job correctly.

In short, accessibility is the biggest factor in how long a furnace installation takes. Easy access allows the work to be done efficiently in a day, while tighter or more difficult locations naturally require more time to complete properly.

A furnace is designed to protect itself and the people in the home. Modern furnaces constantly monitor their own operation and will shut down automatically if they detect a condition that could be unsafe.

A furnace will shut itself off if it believes fuel is not being burned properly, if it is overheating, or if exhaust gases cannot vent correctly. In those situations, the system may attempt to restart on its own. If the condition does not clear, it will shut down again. This process is intentional. The furnace’s priority is to prevent unburned gas, carbon monoxide, or excessive heat from entering the home.

Resetting a furnace by turning the power off and back on can sometimes clear a temporary or minor issue, such as a brief ignition failure or power interruption. If the problem was minor, the furnace may restart and operate normally. If the underlying issue is still present, it will shut itself down again.

What’s important to understand is that a reset does not fix a problem—it only clears the fault temporarily. If a furnace shuts itself off, there is a reason. Even if it restarts, the system should be inspected to determine why the shutdown occurred. Repeated resets are a sign that something is wrong and should not be ignored.

In short, a furnace that shuts itself down is doing its job. When that happens, the safest course of action is to have it checked by a qualified technician to identify and correct the cause.

Most modern furnaces do not have a pilot light. If your furnace was installed within the last few decades, it likely uses electronic ignition and does not require manual relighting. Only older furnaces use a standing pilot light.

If your furnace does have a pilot light, it can usually be relit safely by following these steps:

First, turn the thermostat to “off.” Locate the gas control valve on the furnace and turn the knob to the “off” position. Wait at least five minutes to allow any unburned gas to dissipate. If you smell gas during this time, do not continue.

After waiting, turn the gas control knob to the “pilot” position. Press and hold the knob down while lighting the pilot burner with a long lighter or match. Once the pilot flame is lit, continue holding the knob down for about 30 seconds so the safety sensor can warm up.

Slowly release the knob. If the pilot stays lit, turn the gas control knob to the “on” position, then turn the thermostat back on and call for heat.

If the pilot will not stay lit or goes out again, there is likely an issue with the safety sensor or gas control. Repeated attempts to relight it are not recommended. A pilot light going out is a safety-related event, and the furnace should be inspected to determine the cause.

If you are unsure whether your furnace has a pilot light, or if relighting attempts fail, the safest course of action is to have the furnace checked by a qualified technician.

Turning on a furnace is usually straightforward, but the exact steps depend on whether the system is already operational or has been shut off.

Start at the thermostat. Make sure it is set to “heat” and the temperature is set above the current room temperature. Many “furnace not working” calls turn out to be thermostat settings or dead batteries.

Next, make sure the furnace has power. Check that the service switch near the furnace is in the “on” position and that the circuit breaker has not tripped. Most furnaces also require the front access panel to be properly in place to operate.

Confirm that the gas supply is on. The gas shutoff valve near the furnace should be parallel to the gas line, indicating it is open. If the gas was shut off for any reason, do not attempt to turn it on if you smell gas.

Once power and gas are confirmed, the furnace should start automatically when the thermostat calls for heat. Modern furnaces handle ignition and operation on their own. You should hear the system go through a normal startup sequence and begin delivering warm air within a few minutes.

If the furnace does not start, shuts itself off, or displays an error code, do not repeatedly cycle power. That indicates the furnace is detecting a problem and is protecting itself. At that point, the safest next step is to have the system checked by a qualified technician.

Making a furnace more efficient is less about modifying the furnace itself and more about how the system and the home work together.

Start with basic airflow. A clean, properly sized air filter and unobstructed supply and return vents allow the furnace to move heat efficiently. Restricted airflow forces the system to run longer and work harder than necessary.

Routine maintenance also matters. Over time, normal operation causes components to drift out of optimal range. Cleaning, inspection, and proper setup help the furnace operate as designed and prevent efficiency loss due to wear or misadjustment.

Beyond the furnace, the home plays a major role. Heat loss through air leaks, poorly sealed ductwork, or inadequate insulation increases run time regardless of furnace efficiency. Reducing those losses allows the furnace to maintain temperature with less effort.

System setup is equally important. Proper sizing, correct airflow settings, and accurate startup and commissioning determine whether the furnace can actually achieve its rated efficiency. A high-efficiency furnace that is improperly set up will not perform efficiently in real-world conditions.

In short, furnace efficiency is a system outcome. Maintenance, airflow, installation quality, and the condition of the home itself all matter as much as the furnace’s efficiency rating.

Short-cycling always has a cause. The first step is understanding why the furnace is turning off.

If the furnace turns on and shuts off quickly and the thermostat reaches the set temperature, the most common cause—especially with newer furnaces—is oversizing. A furnace that is too large heats the space too fast, satisfies the thermostat, and shuts down before it can run a normal cycle. This is a sizing and installation issue.

If the furnace turns on and shuts off repeatedly and the thermostat never reaches the set temperature, airflow restriction is often the issue. On older systems in particular, a dirty or restrictive air filter is one of the most common causes. Restricted airflow causes the furnace to overheat, triggering safety shutoffs that lead to short-cycling. Removing the filter temporarily can help confirm whether airflow is the problem.

In both cases, short-cycling is not something to ignore. It reduces efficiency, increases wear on components, and can point to underlying design or safety issues. While checking the filter is a reasonable first step, persistent short-cycling should be evaluated to determine whether the issue is airflow, sizing, or a mechanical fault that needs to be corrected.

In very cold weather, thermostat setbacks can increase stress on the furnace, particularly in older, drafty homes. When temperatures are set back overnight, the furnace has to work much harder in the morning to recover to the set point. During extreme cold, that extended recovery run can increase the likelihood of overheating or safety shutdowns.

In those situations, reducing or eliminating nighttime setbacks can be easier on the system and help keep it running more consistently. The furnace may run longer overall, but it avoids the intense demand of a large temperature recovery during the coldest part of the day.

In newer or well-insulated homes, this is usually less of a concern. Heat loss is lower, recovery times are shorter, and moderate setbacks generally do not create the same level of stress on the furnace.

The takeaway is that thermostat strategy should match the home and the conditions. During extreme cold, especially in older or draftier houses, smaller setbacks or steady temperatures can help support reliable furnace operation.

When a furnace won’t turn on, the reason is usually something simple—or the furnace is intentionally preventing itself from running for safety.

Start with the basics. Make sure the thermostat is set to “heat,” the temperature is set above room temperature, and the thermostat has power. Check the furnace service switch and the circuit breaker to confirm the system has power. Also make sure the furnace access panel is fully in place, as many furnaces will not operate if it is not secured.

If power and thermostat settings are correct, the furnace may be shutting itself down on purpose. Modern furnaces constantly monitor safety conditions and will not run if they detect a problem. Common causes include ignition issues, overheating from restricted airflow, venting problems, or sensors that are not reading correctly.

Airflow issues are especially common. A dirty or restrictive air filter can cause the furnace to overheat and shut down. Venting issues, such as snow or ice blocking exhaust pipes on high-efficiency furnaces, can also prevent startup.

If the furnace attempts to start and then shuts off, or displays an error code, that information is important. Repeatedly resetting the furnace is not recommended, as it does not fix the underlying issue and can create additional problems.

In short, a furnace that won’t turn on is either missing power, not receiving a proper signal to run, or is protecting itself because it detects an unsafe condition. Once basic checks are done, the safest next step is to have the system inspected to determine why it is preventing operation.

When a furnace keeps turning on and off, it’s usually because something is causing it to shut down before it can complete a normal heating cycle. This behavior is called short-cycling, and it always has a reason.

In some cases, the furnace is shutting off because the thermostat is satisfied too quickly. This commonly happens when the furnace is oversized for the home. The system produces heat faster than the space actually needs, reaches the set temperature, shuts off, and then turns back on shortly afterward.

In other cases, the furnace shuts off because it is protecting itself. Restricted airflow from a dirty or incorrect air filter is one of the most common causes, especially on older systems. Poor airflow can cause the furnace to overheat, triggering safety controls that shut it down. Once it cools, it starts again—only to repeat the cycle.

Short-cycling can also be caused by thermostat problems, venting issues, or safety sensors detecting a fault. In all of these situations, the furnace is not malfunctioning randomly—it is responding to a condition it believes could be unsafe or damaging.

Because short-cycling increases wear, reduces efficiency, and can shorten equipment life, it should not be ignored. Checking the air filter is a reasonable first step, but ongoing short-cycling means the underlying cause needs to be identified and corrected.

A furnace typically lasts 15 to 20 years, but that range depends heavily on how it was installed and how it operates over time.

Most furnaces come with a 5-year parts warranty, which can usually be extended to 10 years if the installing contractor registers the equipment. That warranty applies to parts only, not labor, and manufacturers do not offer longer parts warranties than that. From a practical standpoint, that suggests manufacturers expect the equipment to operate reliably for at least that period under normal conditions.

What determines whether a furnace lasts closer to 10 years or closer to 20 is not the brand—it’s installation quality and operating conditions. A furnace that is properly sized, correctly installed, and fully commissioned will operate within its design limits. That reduces stress on components and allows the system to age normally.

Furnaces that are oversized, poorly installed, or never properly set up tend to experience more frequent cycling, higher operating temperatures, and increased wear. Over time, that shortens component life and can lead to premature failure, even if the furnace itself was well built.

In short, manufacturers design furnaces to last well beyond the warranty period, but whether they actually do depends largely on how they are installed and how hard they are forced to work. Proper installation is the biggest factor in long-term furnace life.

A furnace is usually not “bad” all at once. Most furnaces show warning signs long before they completely fail.

Common indicators include frequent breakdowns, repeated safety shutdowns, or the furnace shutting off and restarting regularly. Rising repair frequency or repairs involving major components can also signal that the system is nearing the end of its useful life.

Changes in performance are another clue. If the furnace struggles to maintain temperature, runs much longer than it used to, heats unevenly, or makes new or unusual noises, something has changed. These symptoms don’t always mean the furnace is failing, but they do indicate that it’s no longer operating normally.

Age matters as well. Furnaces approaching or exceeding 15–20 years are more likely to experience significant issues, especially if they were not installed or sized correctly. While age alone doesn’t mean replacement is required, it increases the likelihood that major repairs may not be cost-effective.

It’s also important to separate furnace problems from system or home issues. Airflow restrictions, duct problems, or thermostat issues can create symptoms that look like a “bad” furnace when the equipment itself is still functional.

The most reliable way to determine whether a furnace is truly failing is a proper inspection. A qualified technician can evaluate safety, performance, and overall condition to determine whether the issue is repairable or whether the furnace is nearing the end of its useful life.

When deciding whether to repair or replace a furnace, it’s important to understand what a furnace actually is. A furnace is not a single part—it is a collection of components working together inside one cabinet. Motors, switches, sensors, controls, and safety devices all have finite lifespans, and any one of them can fail.

When a furnace is repaired, only the failed component is being replaced. That repair restores operation, but it does not change the age or condition of the remaining components. On an older furnace, it is entirely possible for one part to fail this month and a different part to fail later in the season. Each repair solves a specific problem, but it does not eliminate the risk of future failures.

This is why age matters so much. Furnaces over about 12 years old are more likely to experience repeated component failures simply because multiple parts are reaching the end of their normal service life. Repairs on older systems are not necessarily a sign of poor quality—they are a predictable result of age.

At that point, the decision often comes down to risk tolerance. Some homeowners are comfortable repairing a furnace as issues arise, even knowing that another repair may be needed later. Others place a higher value on reliability and peace of mind, especially during cold weather, and prefer to replace the system to reduce the likelihood of unexpected breakdowns.

There is no single right answer. Repair makes sense when the homeowner accepts the possibility of future failures. Replacement makes sense when predictability and long-term reliability are the priority. The best choice balances system age, repair history, and how much uncertainty the homeowner is willing to live with.

Furnace maintenance is not about checking boxes. The purpose of maintenance is to reduce the risk of breakdowns, verify safe operation, restore proper performance, and give the homeowner a clear understanding of the furnace’s condition.

To accomplish that, maintenance focuses on four areas: safety, reliability, performance, and system condition. That includes verifying proper combustion and venting, checking components that commonly fail, correcting normal performance drift, and identifying developing issues before they lead to a breakdown.

The exact steps vary by furnace type and age, but the goal is always the same: confirm the system is operating safely and reliably before it is pushed to its limits during cold weather.

The size of furnace your home needs depends on how much heat the house loses, not just the square footage.

Many people use square footage as a shortcut, but that approach is often misleading. Two homes with the same square footage can require very different furnace sizes depending on climate, construction, and layout. Ceiling height alone makes a significant difference. A home with 8-foot ceilings has much less air to heat than the same home with 10-foot ceilings or large two-story or vaulted spaces.

Other factors matter just as much. The age of the home, insulation levels, window quality, air leakage, and overall construction all affect how quickly heat is lost. A newer, well-insulated home in Michigan may need a smaller furnace than an older, draftier home of the same size.

The most accurate way to determine the correct furnace size is through a Manual J load calculation. This is a standardized method that measures how much heat a specific home loses under design conditions for the local climate. It evaluates the structure itself rather than relying on rules of thumb or the size of the old furnace.

Proper sizing is critical. A furnace that is too large will heat the home too quickly, shut off frequently, and cycle excessively, which reduces comfort, efficiency, and equipment life. A furnace that is too small may struggle to maintain temperature during cold weather.

In short, the right furnace size is specific to the home. Square footage alone is not enough. A proper load calculation is the best way to ensure the furnace is sized correctly and performs as intended.

A humidifier is a device that adds moisture to the air inside your home.

During the heating season, especially in cold climates, outdoor air brought into the home is very dry. When that air is heated, its relative humidity drops even further. This can lead to dry skin, irritated sinuses, static electricity, wood floors or furniture shrinking, and a general feeling of discomfort even when the temperature is warm.

A whole-home humidifier works with the heating system to add controlled amounts of moisture to the air as the furnace runs. The goal is not to make the air feel damp, but to maintain a healthier and more comfortable humidity level during winter.

Proper humidity can make a home feel warmer at lower thermostat settings, reduce dryness-related irritation, and help protect wood materials in the home. Like heating equipment, humidifiers need to be sized correctly and set appropriately to avoid over-humidification, which can cause condensation or other issues.

In short, a humidifier doesn’t heat the air—it improves comfort by restoring moisture that is naturally lost during the heating season.

Whether you need a humidifier depends on how dry the air in your home becomes during the heating season.

In Michigan, winter air is naturally very dry. As cold outdoor air enters the home and is heated, its relative humidity drops sharply. It is common for indoor humidity levels to fall below 30% during the winter. For most people, comfort and dryness-related symptoms improve when indoor humidity is closer to 40–50%.

Low indoor humidity often shows up in predictable ways. Frequent nosebleeds, static electricity, dry or itchy skin, cracked wood or trim, and feeling uncomfortable even when the thermostat is set to a normal temperature are all common signs of overly dry air.

If you experience one or more of these issues, a humidifier can help restore moisture to the air and improve comfort during the winter months. If these symptoms are not present, a humidifier may not be necessary.

The key point is that dryness in winter is normal in Michigan. A humidifier doesn’t solve a heating problem—it addresses the loss of moisture that naturally occurs during the heating season.

Yes, a humidifier pad needs to be replaced, and in Michigan it’s typically a once-per-year task.

Because of mineral buildup from the water supply, humidifier pads gradually lose their ability to absorb water and evaporate moisture. As that buildup increases, the humidifier becomes less effective even though it may still appear to be operating normally.

In Michigan’s climate, replacing the humidifier pad once each year—typically in early fall, around September—is usually sufficient. Doing it at the start of the heating season ensures the pad is clean and effective throughout the winter months when humidity demand is highest.

Replacing the pad annually helps maintain proper humidity levels, prevents mineral buildup from interfering with performance, and keeps the humidifier operating as intended through the heating season.

There is no single “correct” humidifier setting. The right setting is the one that keeps the home comfortable without causing condensation or moisture problems.

In winter, especially in Michigan, most homes are comfortable somewhere in the 30–45% relative humidity range. The exact number varies by house, outdoor temperature, and personal comfort.

It’s also important to understand the limitations of different humidifier types. Bypass and fan-powered humidifiers rely on the furnace running and on evaporation. In real-world winter conditions, these systems typically top out around 30–35% humidity in most homes, regardless of how high the dial is set. Turning the setting higher doesn’t force more humidity into the home once the system reaches its practical limit.

If a homeowner wants indoor humidity closer to 45–50% during winter, that usually requires a steam humidifier. Steam humidifiers actively generate moisture rather than relying on evaporation, which allows them to raise humidity levels higher and more consistently. They are more expensive, but they solve a different problem.

The key is matching expectations to the equipment. Bypass humidifiers are effective for reducing dryness and improving comfort. Steam humidifiers are used when higher humidity levels are desired or required. The setting should always be adjusted gradually and monitored to avoid condensation on windows or other surfaces.