First fire of the season in Fort Collins: the September checklist before you need it in October

September 8, 2026

The busiest week of the year for Fort Collins hearth techs is the one after the first hard freeze in October, and almost none of it is emergencies. It is six months of dust, a thermocouple that finally gave up, and a battery pack that went flat in July, all discovered by several thousand households on the same evening. Everything on the list below is findable in September, when you can pick the appointment instead of taking one.

Here is the case for doing it now, in numbers. The Colorado Climate Center’s station on the CSU campus, which has been recording since 1889, puts the 1991 to 2020 January normal at a 45.0 degree high and an 18.3 degree low, and NOAA’s normals give Fort Collins 51.4 inches of snow a year. This is a town that genuinely burns its fireplaces, four or five hours an evening for four months. Then from April to October most of them sit completely cold. That cycle, not age, is what breaks gas fireplaces here.

Week one: the safe checks you can do yourself

None of this involves gas fittings, and none of it needs tools.

1. Open the bottom louver and look. On most units it lifts off or unclips. You are looking for dust, cobwebs, mouse evidence, and anything that has been stored in the cavity since spring. A vacuum with a brush attachment on the visible surfaces is fine. Do not vacuum the burner ports or the pilot assembly.

2. Change every battery while you are in there. Three places: the handheld remote, the receiver box behind the louver, and on an electronic ignition unit the four-AA backup battery pack. Weak batteries in the receiver are the single most common cause of a fireplace that appears completely dead, and they are the cheapest fix in this trade. Taking them out in April is a habit worth forming.

3. Confirm the gas valve handle is on. A lever or knob marked ON, OFF and PILOT, usually behind the louver or at a shutoff in the wall. Plenty of first-fire failures are simply a valve somebody closed in spring.

4. Check the ON, OFF, REMOTE switch. Many units have a three-position rocker behind the louver. In the wrong position the wall switch does nothing and the remote does nothing.

5. Look at the logs. Every log set has locating pins or notches and exactly one correct layout. A log nudged into the flame path or resting on a burner port will soot the glass in one evening. If someone rearranged them for looks, put them back or photograph them and ask.

6. Look at the glass gasket. The rope or tape gasket around the glass on a sealed direct-vent unit is a combustion seal, not trim. If it is flattened, hard, or missing a section, that is a repair before the first fire, not after.

7. Check the vent termination outside. Walk around the house and look at the coaxial cap on the wall or the roof. Birds’ nests, a wasp nest, mulch, snow guards, and new landscaping all end up blocking terminations. Clear what you can safely reach.

8. Test the carbon monoxide alarm. New batteries, and check the manufacture date on the back. Most units expire at seven to ten years, and an expired alarm is decoration.

Week two: the first fire

Light it on a mild evening while it is still easy to get help, not on the first cold night.

Expect a burning-dust smell for the first thirty to sixty minutes. Six months of house dust on a hot firebox smells alarming and is not. Open a window and let it burn through.

Expect some haze on the glass. Combustion residue is normal, especially on a new unit or a new log set. It cleans off cold glass with a ceramic-glass fireplace cleaner, never with an ammonia cleaner, which permanently etches the glass. The white film page has the method.

Give the blower fifteen or twenty minutes. Nearly every fireplace blower is on a thermal snap switch that only closes when the firebox is genuinely hot, and it keeps running after shutdown until the metal cools. That delay is the design, not a fault.

Two lighting attempts, five minutes apart, then stop. Each failed attempt leaves a little unburned gas in the box.

Now watch what it does, because these are the four symptoms that decide your October:

• Pilot lights but will not stay lit. Thermocouple, or a pilot too small and yellow to heat it. $200 to $400 for the sensor, $300 to $600 for a full pilot assembly. See pilot will not stay lit.
• Clicks and never lights. Electronic ignition sparking without finding gas: batteries, then a pilot orifice with a summer of spider webbing in it, then the module at $350 to $700. See clicks but will not light.
• Runs ten minutes and shuts off. A thermopile that starts strong and sags as it heats, or a flame sensing rod on an electronic unit. $200 to $400, or $300 to $600. See shuts off after a few minutes.
• Lazy yellow flames or soot inside a week. Usually the burner needs cleaning, and sometimes the orifice is wrong for our elevation.

The altitude item nobody checks

Fort Collins sits at 4,997 feet. The National Fuel Gas Code (NFPA 54 / ANSI Z223.1) calls for derating gas appliances installed above 2,000 feet by about 4 percent per 1,000 feet, and manufacturers publish high-altitude orifices and conversion kits by elevation band, with natural-gas kits typically starting above 4,500 feet. Making that adjustment is the installer’s job, and it is the most commonly skipped step in this trade.

Every town this site covers is in the band: Milliken at 4,810 feet, Severance at 4,876, Johnstown at 4,994, Loveland at 4,997, Berthoud at 5,033, Laporte at 5,109, Wellington at 5,194, and Estes Park at 7,743. A unit that never got its kit burns rich forever: lazy flames, soot that returns a week after cleaning, delayed ignition with a whump, and more carbon monoxide. The tell is soot coming back fast. If a previous contractor cleaned your glass and it went black again in days, nobody checked the orifice. The permits and altitude page covers the code side.

What the September service visit actually includes

At $175 to $350 per fireplace, with a multi-unit rate for a second or third one in the house, annual service is: burner ports and pilot assembly cleaned, logs vacuumed and reset to the manufacturer’s layout, glass cleaned properly, blower cage cleared, thermopile output measured in millivolts against the 300 to 750 millivolt band, inlet and manifold pressure checked in inches of water column, orifice size checked against your elevation and fuel, vent termination and clearances inspected, gasket inspected, and a combustible gas and carbon monoxide check. You get the readings.

The value is not the cleaning. It is finding the thermopile reading 280 millivolts in September, at a price you agreed to, instead of at nine on a Sunday night in December with the house at 58 degrees.

Stop immediately for these

A smell of gas means leave the house, leave the door open behind you, do not touch a light switch or a garage door opener, and call your gas utility’s emergency line or 911 from outside. Xcel Energy is the natural gas utility named on Larimer County’s provider list; Greeley and parts of Weld County are Atmos Energy. Do not call a contractor first.

Also stop and leave it off for: ignition with a bang you feel through the glass, flames rolling out at the front of the opening, fresh soot on the wall or mantel above the fireplace, or a carbon monoxide alarm sounding, which means everyone outside and 911 from outside.

Everything else is a scheduling problem, and September is when it is cheapest to schedule. The repair cost estimator will put a range on your symptom in twenty seconds, and the pricing page has the full table.