The technician has the front panel off, the flashlight is pointing at something inside, and the sentence you have been dreading arrives: “I can fix it, but you might want to think about replacing it.” Now the decision is yours, in a cold house, with a stranger waiting for an answer. The repair or replace furnace question feels like a coin flip in that moment, but it is not. It comes down to six questions, and you can answer most of them before the technician even arrives.

This is written for the way the decision actually happens in Las Vegas, where the furnace is bolted to the air conditioner, works a short winter, and is often older than the people living in the house. It does not put numbers on anything, because every house and every furnace is different, and because the right answer usually shows up before the quote does.

Question one: how old is it, really

Find the serial number on the data plate inside the front panel and work out the year. Gas furnaces are generally expected to serve 15 to 20 years, and the two ends of that range mean different things.

Under ten years old, repair is almost always the answer. The furnace is young, parts are available, and whatever failed is probably a single component rather than a pattern. The exception is a heat exchanger failure on a young furnace, which usually points to an installation problem such as restricted airflow or an oversized unit, and that needs fixing alongside the repair.

Between ten and fifteen, repair is still the default, but each repair is a prompt to look at the whole unit. Ask the technician what else is close to failing.

Past fifteen, the burden shifts. A furnace at that age can keep going, and plenty do, but a major failure is less a surprise than an arrival, and the next one is probably not far behind.

Question two: which part failed

Not all failures are equal, and this question matters more than age.

Some parts are consumables. The hot surface igniter, the flame sensor, the run capacitor, the pressure switch and its hose, a thermostat, a door switch. These wear out and get replaced on furnaces of every age. A failed igniter on a 17 year old furnace is not a reason to replace the furnace.

Some parts are major but repairable. The blower motor, the inducer motor, the control board and the gas valve are bigger jobs, and on an older furnace each one invites the question, but any one of them on its own is still a repair.

One part ends the discussion. A cracked heat exchanger means replacement. The exchanger is the barrier between the flame and the air you breathe, and a crack lets combustion gases into the house. Replacing an exchanger on an older furnace is rarely practical even where parts exist, and no responsible technician will leave a furnace with a cracked exchanger in service. If this is the diagnosis, ask to see the crack, confirm the carbon monoxide alarms are working, and move on to planning the replacement.

Question three: how often has it needed a visit

One repair is an event. Two in a winter is a trend. Think back over the last two or three heating seasons. A furnace that needed a blower motor last year, a control board this year, and is now showing an inducer problem is telling you its parts are reaching the end together, and each repair is buying months rather than years.

The pattern matters more than any single failure. A furnace that has been reliable for a decade and just lost its igniter is a repair. A furnace that has had a technician out every November is a replacement in slow motion, and the sooner you make the decision on your own schedule, the less likely you are to make it on a cold night.

Question four: is it keeping the house comfortable

A furnace can run without failing and still be done. The signs are easy to spot once you know them.

Rooms at the far end of the house that never warm up, even with the filter clean and the registers open. Long run cycles where the furnace seems to work all evening to hold the setpoint. Short cycles where it starts, runs a couple of minutes and stops, over and over. A noticeable change in how loud it is, or in how long it takes the air at the vents to warm. Energy use that has crept up winter after winter with no change in how you live.

Some of this is fixable: a duct leak in the attic, a dirty blower wheel, a thermostat in a bad spot. Have those ruled out first, because they are far smaller problems than a furnace. If the furnace is simply losing its ability to heat the house, that is age, and a repair will not restore it. The post on signs you need HVAC repair separates the fixable comfort problems from the ones that point at the equipment.

Question five: what is the air conditioner doing

In most Las Vegas homes, the furnace and the air conditioner are one system. The furnace's blower moves the cold air in summer, the evaporator coil sits on top of the furnace cabinet, and the two were sized and matched together when the house was built.

That changes the decision in two ways. If the air conditioner is also old, and in this climate an air conditioner has usually worked harder than the furnace it sits on, replacing both at once gets you a matched system with one installation, one set of warranties and one refrigerant line set, rather than two separate projects a few years apart. The post on how long AC units last in Las Vegas is the other half of this question.

If the air conditioner is newer, say five years old and healthy, then the furnace can often be replaced on its own with a unit matched to the existing coil, and the decision stays focused on the furnace. Either way, ask the technician whether the blower in the current furnace is sized for the air conditioner, because an undersized or failing blower is a common reason a Las Vegas AC underperforms in July.

Question six: can it be repaired at all

This one is practical. Furnaces that are 20 years old or more may use parts that are no longer manufactured, and a control board or gas valve that has to be sourced from a salvage supplier is a repair with a short shelf life. A furnace with a refrigerant coil of a type no longer produced creates the same problem on the cooling side. If the technician says the part is available but backordered for weeks in the middle of winter, that is part of the answer too.

Permits and code also play in. A furnace replacement typically needs a permit and an inspection, and an older installation may need venting, gas line or electrical updates to pass. That is not a reason to avoid replacement, but it is a reason to plan it rather than have it forced on you.

Where a home warranty takes the decision off your plate

A home warranty changes who makes the first call, and in a useful way. When a covered furnace fails from normal wear and tear, you file a service request, a licensed local contractor is dispatched, and the contractor diagnoses the failure and reports it. The contract then sets the rule: repair when the unit can be repaired, replacement under the contract's terms when it cannot. The decision follows the diagnosis rather than a sales conversation, and the technician's job is to fix the covered breakdown, not to sell a new furnace.

Heating is covered in every Dwellness plan, and a furnace that has aged out of its manufacturer's warranty is exactly the furnace a home warranty is meant for. Dwellness approves 97 percent of claims, no maintenance records are needed to buy a plan, and the contract spells out how replacement works, including coverage limits for each item. On the Enhanced Plan and above, the permits and code upgrades that a furnace replacement can trigger are covered too, which removes one of the surprises from question six. The heating home warranty page lists what counts as a covered heating breakdown, and the post on whether a home warranty covers a furnace explains the exclusions, including pre-existing conditions and damage from an unlicensed repair.

What a warranty will not do is replace a working furnace because it is old. The trigger is a covered breakdown. So if you are weighing a planned replacement of a furnace that still runs, that is a decision you make on your own terms, and the post on what goes into replacing an HVAC system is the place to start.

Putting the six answers together

Repair when the furnace is under fifteen, the failure is a single wear part, it has been reliable, it still heats the house evenly, the air conditioner is in good shape, and parts are available.

Replace when the heat exchanger is cracked, full stop. Lean toward replacing when the furnace is past fifteen and has needed repeated repairs, when it no longer keeps the house comfortable after the fixable causes are ruled out, when the matching air conditioner is also at the end, or when the part that failed cannot be sourced.

Most furnaces land clearly on one side. The ones in the middle, a 14 year old unit with a failed blower motor and a tired AC, come down to how much you value doing it on your schedule. A warranty takes the cold-night version of this decision off your plate, because the repair or replace call follows the diagnosis and the contract. If your furnace is into its second decade, request a free quote at dwellness.house and see what coverage would look like, or call (702) 509-7007 and ask a person.

Frequently Asked Questions

There is no fixed age. Gas furnaces generally serve 15 to 20 years, and a well-maintained furnace past 15 can keep going as long as its heat exchanger is sound and it still heats the house evenly. Replacement becomes the likely answer when an older furnace needs repeated repairs, loses capacity, or suffers a major failure such as a cracked heat exchanger.

For a small wear part such as an igniter, flame sensor or capacitor, yes. For a major component such as a blower motor, control board or gas valve on a 20 year old furnace, it depends on the unit's recent history and the condition of the heat exchanger, and the technician's inspection should drive the answer. A cracked heat exchanger at that age means replacement.

No. A cracked heat exchanger allows combustion gases, including carbon monoxide, into the air stream, and the furnace must be taken out of service. On an older furnace, replacing the exchanger is rarely practical, so a crack almost always means a new furnace.

If both are near the end of their lives, replacing them together gives you a matched system installed once, which usually performs better than mismatched equipment. If the air conditioner is relatively new and healthy, a new furnace matched to the existing coil and blower requirements is usually the sensible route.

Both, depending on the diagnosis. A Dwellness plan covers heating breakdowns from normal wear and tear; the contractor repairs the furnace when it can be repaired, and when it cannot, replacement is handled under the contract terms, including coverage limits. The decision follows the technician's findings and the contract rather than the age of the unit alone.

The licensed contractor dispatched on the service request diagnoses the failure and reports whether the unit can be repaired. The warranty provider then applies the contract. You are not asked to choose between a repair and a replacement on the spot, and the furnace is not replaced simply because it is old if it can be fixed.

Close the main water shutoff first, then open a faucet to relieve pressure. Move anything that can be damaged away from the water and get the area drying. A burst pipe from freezing is a plumbing repair, and the water damage it causes is typically a homeowners insurance matter, so document it with photos before cleanup.