1. How Long Does a Furnace Last?

A properly installed and regularly maintained furnace can typically last around 15 to 20 years, although the actual lifespan depends on the type of equipment, installation quality, maintenance history, how heavily it is used, and the conditions it operates in. In Michigan, furnaces work hard through long heating seasons, so regular maintenance can be especially important. Age isn't the only factor to consider. An older furnace that has been well maintained and is operating safely may still have useful life left. However, as a furnace approaches the 15-year mark and beyond, homeowners should pay closer attention to increasing energy bills, frequent repairs, unusual noises, uneven heating, and declining performance. If your furnace is getting older, August is a great time to have it professionally inspected. Finding out that your furnace is nearing the end of its life before winter gives you time to consider your options instead of making a rushed decision during a freezing Michigan night.

2. How Often Should I Have My Furnace Serviced?

For most homeowners, having your furnace professionally serviced once a year is a good rule of thumb. The ideal time is generally before the heating season begins, which makes late summer and early fall an excellent time to schedule maintenance in Michigan. A professional furnace inspection can help identify potential problems before they turn into unexpected breakdowns. A technician can evaluate important components, check system operation, inspect safety controls, look at airflow, and identify signs of wear that may affect performance during the winter. Regular maintenance doesn't guarantee that a furnace will never break down, but it can help keep the system operating properly and give homeowners an opportunity to address smaller problems before they become larger ones. Homeowners should also stay on top of routine maintenance between professional visits, particularly replacing the furnace filter as recommended for their particular system and keeping supply and return vents unobstructed. Most importantly, don't wait until the first cold snap to discover your furnace needs attention. Scheduling maintenance before winter gives you time to address problems while your home doesn't depend on the furnace every minute of the day.

3. Should I Repair or Replace My Furnace?

There isn't a single answer that applies to every furnace. The decision to repair or replace your system depends on several factors, including the age of the furnace, the cost of the repair, how frequently it has needed repairs, its efficiency, its overall condition, and any safety concerns. If your furnace is relatively young and needs an isolated repair, fixing it may be the most practical option. However, if your furnace is 15 or 20 years old and you're repeatedly spending money on repairs, replacement may make more sense in the long run. It's also important to consider what you're getting for your money. Continuing to repair an aging, inefficient furnace may mean putting money into a system that is approaching the end of its service life. A newer furnace may provide improved efficiency, reliability, and comfort while potentially reducing operating costs. The best approach is to have a qualified HVAC professional evaluate the system and explain both options. A trustworthy contractor should be willing to tell you when a repair makes sense rather than automatically recommending replacement. For Michigan homeowners, August and early fall are ideal times to have this conversation. If replacement is ultimately the right choice, you have time to compare equipment, explore financing options, and schedule the installation before the heating season begins.

Is Your Furnace Ready for Another Michigan Winter? 7 Warning Signs You Shouldn’t Ignore

Michigan homeowners know that winter has a way of sneaking up on you. August can still bring hot, humid days, but before long, the leaves will begin to change, temperatures will drop, and your furnace will become one of the most important appliances in your home.

That makes late summer and early fall the perfect time to take a closer look at your heating system.

A furnace that worked perfectly last winter may not necessarily be ready for another Michigan heating season. Furnaces often give homeowners warning signs before a major breakdown occurs. Recognizing those signs now can give you time to address a small problem, schedule maintenance, or make an informed decision about replacement before you're left without heat on the coldest day of the year.

At Mulligan Heating, Inc., we've been helping families across Southeast Michigan stay comfortable since 1955. Here are seven furnace warning signs Michigan homeowners shouldn't ignore, along with answers to some of the most common furnace questions homeowners ask.

1. Your Furnace Is Making Strange Noises

Most furnaces make some noise when they start and operate. However, if your furnace suddenly sounds different than it did last heating season, it's worth paying attention.

Banging, rattling, squealing, grinding, or repeated popping noises can indicate that something isn't operating properly. A worn component, loose part, blower problem, ignition issue, or airflow restriction could be contributing to the noise.

That doesn't automatically mean your furnace needs to be replaced. In many cases, catching a problem early can prevent a relatively small repair from becoming a much larger one.

If your furnace is making a sound you've never heard before, don't simply turn up the thermostat and hope it goes away.

2. Your Furnace Keeps Turning On and Off

Have you noticed your furnace starting and stopping constantly?

Frequent cycling, sometimes called short cycling, is another warning sign that shouldn't be ignored. Your furnace should run through normal heating cycles to maintain the temperature in your home. If it is repeatedly starting and shutting down after only a short period, something may be wrong.

A dirty filter, restricted airflow, thermostat problem, improperly sized equipment, or mechanical issue could be contributing to the problem.

Frequent cycling can also place additional stress on the furnace because the system is repeatedly starting instead of operating normally.

If you've noticed your furnace cycling more often than it used to, it's a good idea to have it inspected before winter.

3. Your Energy Bills Are Increasing

Your furnace doesn't necessarily need to be completely broken to tell you something is wrong.

One of the more subtle warning signs is an increase in heating costs without a corresponding change in your home's comfort or usage.

As a furnace gets older, components can wear down and efficiency can decline. Dirty filters, restricted airflow, ductwork problems, and other HVAC issues can also force your furnace to work harder and run longer.

An increase in your utility bill doesn't automatically mean your furnace is failing. However, if you're also noticing longer run times, uneven heating, unusual noises, or other problems, it's worth having your system evaluated.

4. Some Rooms Are Warm While Others Stay Cold

If your thermostat says 70 degrees but certain rooms in your home still feel cold, your furnace may not be the only thing to blame.

Uneven temperatures can be caused by airflow restrictions, ductwork problems, insulation, blocked registers, thermostat location, or issues with the heating equipment itself.

This is an important reminder that whole-home comfort isn't simply about how much heat your furnace produces. That heat also needs to be distributed properly throughout your home.

If you're constantly adjusting the thermostat, using space heaters, or closing and opening vents because certain rooms aren't comfortable, it's worth having the entire system evaluated.

5. Your Furnace Is Getting Older

One of the most common questions homeowners ask is, “How long does a furnace last?”

While there isn't one exact answer, a properly maintained furnace can often provide roughly 15 to 20 years of service, depending on the equipment, installation, usage, maintenance, and operating conditions.

Once a furnace begins approaching the end of its expected service life, homeowners should pay closer attention to its efficiency, repair history, reliability, and overall condition.

Age alone doesn't mean you need a new furnace. An older system that has been properly maintained and is operating safely may continue to provide reliable heat.

However, if your furnace is older and you're also experiencing frequent repairs, increasing energy costs, or declining comfort, it's a good time to have a professional evaluate your options.

The important part is planning ahead rather than waiting for the furnace to fail completely.

6. You're Having to Repair Your Furnace More Often

A furnace repair isn't necessarily a reason to replace your system. Every heating system will eventually need repairs.

The bigger question is how often those repairs are happening and how much you're spending to keep an aging system running.

This leads to another common homeowner question:

“Should I repair or replace my furnace?”

The best answer depends on several factors, including the age and condition of the furnace, the cost and type of repair, its repair history, efficiency, reliability, and whether there are safety concerns.

If you have a relatively newer furnace with an isolated repair and the rest of the system is in good condition, repairing it may make perfect sense.

On the other hand, if an older furnace requires increasingly expensive or frequent repairs, replacement may provide better long-term value. Local HVAC guidance commonly considers system age, repair frequency, safety, and declining performance when evaluating repair versus replacement.

A good HVAC company should explain both options and help you understand why one may make more sense for your particular home.

7. You Notice a Yellow or Orange Flame or Other Safety Concerns

Some furnace warning signs aren't simply about comfort or efficiency. They're about safety.

If you have a gas furnace and notice that the burner flame looks yellow or orange instead of the expected blue appearance, your furnace should be professionally inspected.

Homeowners should also take unusual odors, soot around the furnace, abnormal combustion, or concerns about carbon monoxide seriously.

Never attempt to diagnose or repair gas combustion equipment yourself. Gas furnaces contain electrical, gas, and combustion components that require the proper tools and training to safely inspect.

Make sure your home also has functioning carbon monoxide detectors, particularly near sleeping areas.

If you ever suspect a carbon monoxide emergency, leave the home immediately and contact the appropriate emergency services or your local gas utility.

How Often Should a Furnace Be Serviced?

Another question we hear from homeowners is, “How often should I have my furnace serviced?”

For most homeowners, professional furnace maintenance should be performed at least once a year. Having your furnace inspected before the heating season gives a technician an opportunity to check the system's operation, identify potential problems, and address issues before the furnace is working continuously during a Michigan cold snap.

Late summer and early fall are particularly convenient times to schedule this service because you're getting ahead of the heating season instead of waiting until everyone else turns on their furnaces.

Homeowners should also keep up with routine tasks such as changing the furnace filter according to the filter manufacturer's recommendations and keeping supply and return vents clear.

Professional maintenance goes beyond simply changing a filter. A proper inspection can include checking important operating and safety components, airflow, electrical connections, controls, and combustion-related components.

Why August Is a Great Time to Check Your Furnace

You may be wondering why we're talking about furnaces when Michigan is still experiencing summer weather.

That's exactly why August is such a good time.

Your furnace probably isn't running much right now, which means you have time to identify potential problems before you actually need the system.

Waiting until the first freezing night to discover that your furnace isn't operating properly can turn a manageable repair into an emergency. It can also leave you making a major replacement decision when you're uncomfortable and under pressure.

Taking care of your furnace before winter gives you choices.

You can repair a problem, perform necessary maintenance, compare replacement options, or simply have peace of mind knowing your heating system has been inspected and is ready for another season.

Don't Wait for the First Cold Snap

Your furnace doesn't have to completely stop working before it needs attention.

Strange noises, frequent cycling, rising energy bills, uneven heating, an aging system, repeated repairs, and combustion or safety concerns can all be reasons to have your furnace evaluated.

And if you're asking yourself how long your furnace has left, whether it needs maintenance, or whether you should repair or replace it, the best time to get those questions answered is before winter—not during it.

At Mulligan Heating, Inc., we've been helping families across Southeast Michigan with their heating and cooling needs since 1955. Our goal is to help homeowners understand their HVAC systems and make informed decisions about their comfort.

Is Your Furnace Ready for Another Michigan Winter?

If your furnace is showing any of these warning signs, don't wait until the first cold snap to find out whether it's ready.

Schedule your furnace service with Mulligan Heating, Inc. and get ahead of winter.

From furnace maintenance and repairs to complete system replacement, our team is here to help keep your home comfortable through another Michigan winter.

Mulligan Heating, Inc.

Quality You Can Feel

Serving Southeast Michigan Since 1955

Visit www.MulliganHeating.com to learn more or schedule your HVAC service.

Frequently Asked Questions

1. How Long Does a Furnace Last?
A properly installed and regularly maintained furnace can typically last around 15 to 20 years, although the actual lifespan depends on the type of equipment, installation quality, maintenance history, how heavily it is used, and the conditions it operates in. In Michigan, furnaces work hard through long heating seasons, so regular maintenance can be especially important.

Age isn't the only factor to consider. An older furnace that has been well maintained and is operating safely may still have useful life left. However, as a furnace approaches the 15-year mark and beyond, homeowners should pay closer attention to increasing energy bills, frequent repairs, unusual noises, uneven heating, and declining performance.

If your furnace is getting older, August is a great time to have it professionally inspected. Finding out that your furnace is nearing the end of its life before winter gives you time to consider your options instead of making a rushed decision during a freezing Michigan night.
2. How Often Should I Have My Furnace Serviced?
For most homeowners, having your furnace professionally serviced once a year is a good rule of thumb. The ideal time is generally before the heating season begins, which makes late summer and early fall an excellent time to schedule maintenance in Michigan.

A professional furnace inspection can help identify potential problems before they turn into unexpected breakdowns. A technician can evaluate important components, check system operation, inspect safety controls, look at airflow, and identify signs of wear that may affect performance during the winter.

Regular maintenance doesn't guarantee that a furnace will never break down, but it can help keep the system operating properly and give homeowners an opportunity to address smaller problems before they become larger ones.

Homeowners should also stay on top of routine maintenance between professional visits, particularly replacing the furnace filter as recommended for their particular system and keeping supply and return vents unobstructed.

Most importantly, don't wait until the first cold snap to discover your furnace needs attention. Scheduling maintenance before winter gives you time to address problems while your home doesn't depend on the furnace every minute of the day.
3. Should I Repair or Replace My Furnace?
There isn't a single answer that applies to every furnace. The decision to repair or replace your system depends on several factors, including the age of the furnace, the cost of the repair, how frequently it has needed repairs, its efficiency, its overall condition, and any safety concerns.

If your furnace is relatively young and needs an isolated repair, fixing it may be the most practical option. However, if your furnace is 15 or 20 years old and you're repeatedly spending money on repairs, replacement may make more sense in the long run.

It's also important to consider what you're getting for your money. Continuing to repair an aging, inefficient furnace may mean putting money into a system that is approaching the end of its service life. A newer furnace may provide improved efficiency, reliability, and comfort while potentially reducing operating costs.

The best approach is to have a qualified HVAC professional evaluate the system and explain both options. A trustworthy contractor should be willing to tell you when a repair makes sense rather than automatically recommending replacement.

For Michigan homeowners, August and early fall are ideal times to have this conversation. If replacement is ultimately the right choice, you have time to compare equipment, explore financing options, and schedule the installation before the heating season begins.

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September Is the Best Time for Early Fall Furnace Maintenance in Michigan

By Mulligan Heating, Inc. • September 3, 2026

September in Michigan is a transition month. The hot summer days are starting to fade, mornings are getting cooler, and before long, homeowners across Oakland County will be turning their furnaces on for the first time of the season. That makes September one of the smartest times of the year to schedule early fall furnace maintenance .