A furnace that quit on a 28-degree Ocala morning: the repair, step by step

Step one: the 6:15 a.m. call from East Fort King Street

Picture a two-story Victorian in the Ocala Historic District, one of the preserved homes on the brick streets east of the downtown square. It has a gas furnace, which puts it in the minority in a mostly all-electric county, fed by the Peoples Gas Ocala division. The owner wakes to a 61-degree house on the first hard freeze of the year, a 28-degree morning in the second week of December. The thermostat is calling for heat. The furnace clicks, hums, and goes quiet. It tries again four minutes later. Same result.

She calls 866-266-5709 at 6:15 and a person answers. Dispatch asks three things: does the furnace try to start, is there any smell of gas, and does the house have a carbon monoxide detector and is it quiet. The answers (it tries, no smell, detector silent) make this an urgent call rather than an evacuation. A technician is routed from Palm Coast, west on SR 40 through the Ocala National Forest, and gives her an arrival window.

The signs that were there before the cold night

Furnaces in Ocala rarely fail without warning; they fail without anyone noticing the warning, because the heat runs so few weeks a year. Looking back, this one had been telling her for two winters:

• Longer and longer to light. Several clicks before the burners caught, where it used to be one.
• A short run, then a stop. Burners lighting, running a minute, shutting down, then trying again. The classic sign of a dirty flame sensor or a failing ignitor.
• A faint scorched-dust smell the first time it ran each December, lasting longer each year.
• One room never warming, the back bedroom at the end of a duct run added in a 1980s renovation.
• A yellow tinge to the burner flame, where it should have been blue.

Any one of those in November is a service call on a mild afternoon. All of them together on a 28-degree morning is this page.

What a dead or half-working furnace costs while you wait

In an all-electric house, waiting on heat means running space heaters and watching the Ocala Electric Utility bill. In a gas house it’s different. A furnace that short-cycles, lighting and quitting every few minutes, is burning gas and wearing its ignitor on every attempt, delivering little heat for the fuel. A furnace with a yellow flame may be burning incompletely, which is a carbon monoxide question, not a comfort question. And a house in the Historic District with plaster walls, tall ceilings and original windows loses heat fast; the pipes won’t freeze on a 28-degree night, but the cold settles in and takes a day to chase out.

The cold snaps here come in clusters. Ocala’s first freeze arrives around December 12 in an average year and the coldest January nights settle in the upper twenties, with a record low of 11. A furnace that limped through one night is going to be asked again tomorrow.

Steps two through five: safety check, diagnosis, the fix, the test

The technician arrives a little after 8:30. Here is the order of the next ninety minutes, and it is always this order on a gas furnace.

Step two: safety first. Gas shutoff located, carbon monoxide reading taken at the furnace and in the living space, a look at the venting for blockage or disconnection, and a visual on the heat exchanger for cracks or rust-through. A furnace that fails this step doesn’t get repaired; it gets shut off and the conversation changes. This one passes.

Step three: diagnosis. Power and thermostat signal confirmed. The furnace is asked to start while the technician watches the sequence: inducer motor runs, pressure switch closes, ignitor glows dim and uneven, gas valve opens, burners light raggedly, flame sensor fails to prove flame within its window, gas valve closes. Twice. The ignitor is cracked and the flame sensor is coated. The yellow flame traces back to burners furred with the dust of nine idle months.

Step four: the price, then the fix. The written number comes before the parts. She approves it. New hot-surface ignitor. Flame sensor cleaned. Burners pulled and brushed. Filter, which turns out to be a summer’s worth of oak pollen and dog hair, replaced.

Step five: the test. Three full cycles from a cold start. Flame blue, steady, proven on the first attempt each time. Temperature rise across the furnace measured and within the nameplate range. Carbon monoxide rechecked at the registers: zero. Supply air at the far bedroom register measured and noted as low, a duct problem for another day, written on the report.

Call for furnace repair at any hour

Step six: making sure next December is boring

Before leaving, the technician does the part that keeps him from coming back on the next cold morning.

He shows her the old ignitor and explains why Florida furnaces eat them: nine months idle in a damp closet, then asked to glow orange on the one morning a year it actually freezes. He marks the filter size on the cabinet and suggests checking it monthly from January through May, when Ocala’s oak and pine pollen loads filters faster than anywhere the box’s three-month figure was written for. He notes that the back bedroom’s duct run should be looked at in daylight, and that a fall furnace check in October, before the first freeze, would have caught the ignitor reading weak and the flame sensor dirty on a 75-degree afternoon instead of a 28-degree morning.

He also says the quiet thing: the furnace is past twenty years, and while this repair will hold, the next failure on a heat exchanger that age won’t be a repair. When that day comes the quote costs nothing, and the house may be a candidate for a heat pump paired with the furnace as a dual-fuel system, which in Ocala’s short winter often makes the gas the backup rather than the main event.

The price she paid at 10 a.m. on a freezing Thursday is the price she’d have paid at 10 p.m. on a Saturday. Cook’s has no after-hours charge, and a furnace call on the coldest night of the year dispatches like any other.