The first cold night of the year: furnace and heat pump warning signs worth a call

Signs that deserve a call before the first cold front

Your furnace or heat pump needs service before winter if it makes new noises, such as banging, grinding or squealing, turns on and off every few minutes, blows cool air when it should be heating, gives off a smell that lingers past the first few minutes of the season, shows a yellow or flickering flame where it should burn steady blue, or trips a breaker. Headaches, dizziness or nausea in the house that ease when people leave are the most serious sign of all, because they can point to carbon monoxide. If a carbon monoxide alarm sounds, get everyone outside first and call for help from there.

I am Brandon Quigley of Quigley Heating & Air, a Farmers Branch company my grandfather started in 1945. Heating calls in our part of Texas tend to arrive all at once, on the first genuinely cold morning, when everyone turns the heat on for the first time in months. Many of those calls could have been a calm fall appointment. Here is how to tell what is normal, what is not, and what to do about it.

What is normal on the first chilly morning

Some things look alarming and are not. The first time a furnace runs after a long summer, it usually gives off a dusty, slightly burnt smell for a short while as dust on the burners and heat exchanger burns off. That should fade quickly. You may hear a sequence of sounds at startup: a click, the hum of the small inducer fan, then ignition and the larger blower. That routine is normal.

Heat pumps have their own normal habits. The air from the vents feels warm rather than hot, because a heat pump delivers a steady stream of moderately warm air instead of short blasts of very hot air. On cold, damp days the outdoor unit periodically goes into a defrost cycle, pauses, and may give off a cloud of steam. That is the system clearing frost from its coil, and it should resume heating within a few minutes.

Noises, smells and cycles that are not normal

The signs below are the ones I would not ignore. None of them means the system is about to fail tonight, but each one tells you something is wearing out or working outside its design, and heating problems rarely get cheaper while you wait. Write down when it happens and what you noticed, because that detail shortens the diagnosis.

Short cycling deserves a word of its own, because people tend to live with it. A furnace that lights, runs for a minute or two and shuts down is often protecting itself: a dirty flame sensor, an overheating heat exchanger from a clogged filter, or a thermostat problem can all cause it. Each start and stop adds wear, so a system that short-cycles all winter tends to fail sooner, and usually on a cold night.

• A loud bang or boom at ignition, which can mean delayed ignition
• Grinding, scraping or squealing from the blower or motors
• The system turning on and off every few minutes
• Cool or barely warm air from a gas furnace
• A burning, electrical or gas smell that does not fade
• A yellow, orange or flickering burner flame
• A breaker that trips when the heat comes on

Carbon monoxide: the warning sign you cannot see or smell

A gas furnace that is working properly vents its combustion gases outside. One that is not can leak carbon monoxide into the house. The EPA lists leaking chimneys and furnaces and back-drafting from furnaces and gas water heaters among the household sources of carbon monoxide. At higher concentrations it causes headaches, dizziness, confusion and nausea, and the EPA notes flu-like symptoms that clear up after leaving home. Very high levels are fatal.

Two protections matter. First, the EPA recommends having a trained professional inspect, clean and tune up a central heating system, including furnaces, flues and chimneys, every year. Second, the EPA page cites the Consumer Product Safety Commission's recommendation that every home have carbon monoxide alarms on each level, outside each sleeping area. Every heating tune-up in our Q Club program includes a carbon monoxide test, and we install and maintain smoke and carbon monoxide alarms. Our technicians still find homes with a gas furnace and no CO alarm at all, and it is the cheapest safety fix in the house.

Heat pump trouble looks different

Many homes in our service area heat with a heat pump, and its warning signs are not the same as a furnace's. Watch the thermostat. If it shows auxiliary or emergency heat running much of the time on mild days, the heat pump may not be carrying its share, and the electric heat strips are doing the work at a much higher operating cost. Your first clue is often a power bill that jumps for no obvious reason.

Look at the outdoor unit as well. Light frost that clears during defrost is normal. A thick layer of ice that keeps building, a fan that is not turning, or an outdoor unit that is silent while the indoor blower runs all mean it is time to call. If you are deciding whether your next system should be a heat pump, a gas furnace or a dual-fuel combination of both, my guide on heat pumps versus gas furnaces walks through the tradeoffs.

Five minutes of checks before you call

A few heating calls turn out to be simple, and you can rule them out yourself. Confirm the thermostat is set to heat, the set point is above room temperature, and the batteries are fresh. Pull the filter and replace it if it is dirty. Check the breaker for the furnace or air handler, and the outdoor unit if you have a heat pump. On a furnace, make sure the front panel is fully seated, because many furnaces have a door switch that keeps them off when the panel is loose.

Walk the house and make sure supply vents and return grilles are not blocked by furniture or rugs. Outside, clear leaves from around a heat pump. If none of that helps, stop there. Do not take apart burners, gas valves or electrical controls. My guide to HVAC maintenance you can safely do yourself draws that line clearly. And if you smell gas, leave the house and call your gas utility from outside before you call anyone else.

What a fall heating tune-up actually covers

ENERGY STAR recommends checking the heating system in the fall and the cooling system in the spring. On the heating side, its checklist includes checking gas connections, gas pressure, burner combustion and the heat exchanger, and it warns that a dirty burner or cracked heat exchanger can make equipment less safe and less efficient. It also includes tightening electrical connections, lubricating moving parts and checking the controls so the system starts, runs and shuts off properly.

Our Q Club heating visits follow the same logic. Depending on the membership tier, the visit covers the items below. Doing this in October means the technician finds the weak flame sensor or the worn inducer motor while it is still a scheduled repair instead of an emergency on the coldest night of the year.

• Carbon monoxide test
• Furnace ignition and gas operation
• Electrical controls checked for safe operation
• Blower and inducer draft motor inspected
• Heat pump operation, including heat strips
• Supply and return air temperatures measured and thermostat checked
• Flame sensor cleaned or inspected, and one standard filter replaced

Age, bills and the repair question

Our winters are mostly mild, which lulls people into forgetting the heating system exists. Then a hard freeze arrives, like the one that hit Texas in February 2021, and the furnace that has been limping along for years is suddenly the most important appliance in the house. Age matters. ENERGY STAR suggests having a furnace evaluated once it is more than 15 years old, and a heat pump once it is more than 10, and it notes that an ENERGY STAR certified furnace is about 15 percent more efficient than a conventional one.

Age alone is not a reason to replace a system that runs safely and well. Frequent repairs, rising bills, rooms that never warm up and any safety concern found during an inspection are the real signals. When we find a problem on an older system, we give you the repair price and, if it makes sense, the replacement options side by side, so you are deciding with numbers rather than with a cold house pushing you.

There is a local wrinkle here. In Dallas a furnace may sit idle from April to November, so its age shows less in hours than in parts that dry out, corrode or collect dust while it waits. That is one more reason the fall inspection matters more than the calendar age on the nameplate.

When our technician comes out

You get a text naming your technician when they are on the way. They arrive in a marked van with shoe covers and drop cloths, ask what you have noticed, and run a full system diagnostic, including the safety checks. Before any work starts, they explain what they found and give you the repair options and the price. Many repairs are finished on the same visit when the part is on the truck.

If you would rather not think about this every October, our Q Club plan schedules a heating visit every fall and a cooling visit every spring, with priority service when something does go wrong; I explain what a good plan should include in my maintenance plan guide. We serve Dallas, Farmers Branch, Carrollton, Coppell, Frisco, Garland, Highland Park, Plano, Richardson and University Park, and we service all brands of furnaces and heat pumps.

Questions people ask me