Carbon Monoxide Testing in Lexington, KY

Carbon monoxide is the rare household hazard that gives no warning before it harms. The gas is colorless, odorless, slightly less dense than air, and produces symptoms (headache, dizziness, nausea, confusion, drowsiness) that overlap with common illnesses including the flu — meaning the cause goes unrecognized until exposure becomes severe enough to be unmistakable. The CDC reports that more than 400 Americans die each year from accidental, non-fire-related carbon monoxide exposure, with tens of thousands more sent to emergency departments. The majority of these incidents trace back to gas appliances inside homes: furnaces, water heaters, boilers, gas ranges, generators, sometimes vehicles idling in attached garages. The good news is that proper combustion testing of gas equipment catches the conditions that cause CO exposure before they become emergencies. Lexington Heating and Air provides combustion-analyzer-based carbon monoxide testing across Fayette County — on every heating tune-up, on suspect equipment, and on the homes of customers who want the reassurance.

How Carbon Monoxide Actually Harms You

The mechanism is specific and worth understanding. Hemoglobin in your red blood cells is the protein that picks up oxygen at the lungs and delivers it to your tissues. Hemoglobin binds carbon monoxide roughly 200 times more readily than it binds oxygen. When you breathe air containing CO, the gas displaces oxygen on the hemoglobin molecules and forms carboxyhemoglobin — which can’t deliver oxygen. Your body becomes progressively starved of oxygen at the cellular level even though you’re still breathing normally. The brain and heart, with the highest oxygen demand of any tissue, suffer first.

At low concentrations — 50 parts per million sustained over hours — headache, fatigue, and impaired judgment appear gradually. At 200 ppm, severe headache and disorientation within two to three hours. At 400 ppm, unconsciousness becomes possible after one to two hours. At 800 ppm, unconsciousness within 45 minutes and death within two hours. Above 1,000 ppm, death within an hour. The dose-response relationship is steep and the early symptoms are deceptively mild, which is why detection matters more than treatment.

What Causes CO in Homes

• Cracked heat exchanger on a gas furnace. The metal wall separating combustion gases from supply air develops a crack; combustion gases (including CO) mix into the supply air and circulate through the ductwork into living spaces. The classic scenario, and the one our combustion testing on furnace tune-ups specifically catches. See our heat exchanger repair page for more on this failure mode.
• Blocked or improperly vented flue. A vent blocked by a bird’s nest, ice, snow drift, debris, or a structural problem prevents combustion gases from leaving the home. Gas appliance produces CO; CO accumulates indoors instead of exiting through the chimney or vent.
• Backdrafting. A combustion appliance in a tightly built home loses its natural draft because exhaust fans, dryers, or other appliances pull more air out of the home than can be replaced. Combustion gases reverse direction and spill into the room rather than going up the flue. Particularly relevant in modern tight construction.
• Improperly installed or unmaintained gas appliances. Incorrect burner adjustment, dirty burners, inadequate combustion air, or improper venting can all cause incomplete combustion and elevated CO.
• Vehicles idling in attached garages. Even with the door open, CO can infiltrate the home through the door connecting the garage to the living space.
• Portable generators operated indoors or near openings. A leading cause of CO poisoning, especially during power outages. Generators must be operated outdoors, at distance from any opening, every time.
• Gas stoves and ovens used for heat. A practice that occasionally appears during heating emergencies; can produce elevated CO and is unsafe.

Why CO Detectors Are Necessary But Not Sufficient

Working CO detectors on every level of the home (and outside each sleeping area) are essential — the EPA, CDC, NFPA, and every fire marshal agree on this. Modern CO detectors alarm reliably when CO concentrations reach dangerous levels in the immediate area of the detector. They’ve saved countless lives.

What detectors don’t do is detect a slow-developing problem in a furnace early enough to prevent the exposure that triggers the alarm. UL 2034, the consumer CO alarm standard, requires detectors to alarm only after specific concentration-times-duration thresholds are crossed — for instance, 70 ppm for 60-240 minutes. The standard was set this way deliberately to prevent nuisance alarms from brief, low-level exposures that aren’t dangerous to most people. The trade-off is that detectors aren’t designed to catch the slowly emerging cracked heat exchanger or the gradually worsening backdrafting condition before exposure occurs.

That’s where combustion testing fills the gap. A calibrated combustion analyzer detects CO in flue gas and supply air at levels well below what a residential detector will alarm on — meaning we can find a developing problem before it produces a dangerous exposure event. The detector is the last line of defense; combustion testing is the first.

Our Combustion-Analyzer-Based Testing Process

1. Calibrated combustion analyzer. A professional analyzer (Bacharach, Testo, or similar) calibrated against known gas samples, measuring CO, O₂, CO₂, and stack temperature, with computed combustion efficiency.
2. Flue gas measurement. CO measured directly in the flue gas during steady-state combustion. The number provides a fingerprint of combustion quality: clean combustion shows CO in the single-digit ppm range, while problematic combustion can show hundreds or thousands of ppm.
3. Supply-air measurement. The critical test: CO measured at supply registers throughout the home. Clean supply air confirms no exchanger leak; elevated supply-air CO confirms one.
4. Draft and pressure measurement. Verifying the appliance is drafting properly and not backdrafting under any operating condition (which can require running other appliances like the bathroom fan and dryer to simulate worst-case depressurization).
5. Visual inspection. Heat exchanger visible surfaces with a borescope camera. Burner condition. Flue and vent integrity. Combustion air pathway.
6. Documentation. Test results recorded in writing, with photos of any findings. You see the numbers and the images.

When We Recommend Combustion Testing

• As part of every heating tune-up. Included in our standard fall furnace tune-up — it’s the only routine moment when someone with a calibrated analyzer looks at your gas appliance and confirms it’s burning cleanly.
• When your CO detector has alarmed. Even if the alarm appears to have stopped, find the cause. Detectors don’t alarm without reason.
• After a near-miss. Headaches, fatigue, or nausea that improve when you leave the home and return when you come back — classic CO exposure pattern that warrants immediate testing.
• Following any HVAC repair or installation. Especially heat exchanger work, vent modifications, or appliance changes.
• When buying or selling a home. Combustion testing on gas appliances can be a useful adjunct to a standard home inspection.
• On older equipment. Particularly furnaces past 15 years where thermal fatigue in the heat exchanger becomes statistically more likely.
• For peace of mind. Households with infants, elderly residents, anyone with cardiovascular or respiratory conditions, or anyone genuinely concerned about combustion safety.

CO Detector Guidance We Stand Behind

• Install one on every level of the home, including the basement, and outside each sleeping area. Bedrooms benefit from a dedicated alarm immediately outside their door.
• Test detectors monthly using the test button. Confirm they alarm; confirm batteries function.
• Replace detectors per manufacturer recommendation, typically every 5–10 years. The sensor element degrades over time even when the detector still passes its test cycle.
• Combo smoke / CO detectors are fine and increasingly common. Standalone CO detectors are also fine. Both meet current code.
• Plug-in CO detectors with battery backup address one of the most common failure modes — depleted batteries leaving the detector inoperative.
• If a detector alarms, leave the home immediately, taking everyone with you. Call 911 or the fire department from outside. Don’t return until authorities confirm it’s safe.

Frequently Asked Questions

Should I test my home for carbon monoxide?

Yes, particularly if your home uses gas appliances (furnace, water heater, boiler, range, dryer, fireplace). The CDC reports more than 400 Americans die annually from accidental CO exposure, and most cases involve home gas appliances. Annual combustion testing on heating equipment, paired with working CO detectors on every level, is the standard recommendation for households with gas appliances.

Why aren’t CO detectors enough?

Detectors are essential but they’re the last line of defense, not the first. The UL 2034 alarm standard requires detectors to alarm only after specific concentration-and-duration thresholds are crossed (for example, 70 ppm sustained for 60 to 240 minutes). The standard was set to prevent nuisance alarms, but it means detectors aren’t designed to catch a developing problem early. Combustion testing with a calibrated analyzer detects CO at levels well below what a detector will alarm on, catching problems before exposure occurs.

What are the symptoms of carbon monoxide exposure?

Headache, dizziness, nausea, fatigue, confusion, and drowsiness are the most common early symptoms, often mistaken for flu. A characteristic pattern: symptoms improve when you leave the home and return when you come back, while other household members or pets experience similar symptoms. At higher exposures, unconsciousness can follow within hours. If you suspect CO exposure, leave the home immediately, call 911 from outside, and arrange combustion testing before returning to the home.

How does CO get into a home from a furnace?

Most commonly through a cracked heat exchanger that allows combustion gases including CO to mix into the supply air and circulate through the ductwork. Other causes include blocked or improperly vented flues, backdrafting in tight homes where exhaust fans depressurize the space, and improperly maintained or installed gas appliances. Combustion testing identifies all of these conditions.

How often should I have my CO detectors replaced?

Per manufacturer recommendation, typically every 5 to 10 years. The sensor element in CO detectors degrades over time even when the unit still passes its self-test cycle. Replace detectors on schedule rather than relying on them indefinitely. Test the units monthly, and replace any unit that has reached or passed its rated end-of-life regardless of whether it appears to still function.

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Get Combustion Testing on Your Lexington Home

Detectors are the last line of defense; combustion testing is the first. Schedule professional testing with a calibrated analyzer, across Lexington and Fayette County.

• Phone: (859) 215-5241
• Address: 343 Cassidy Ave, Lexington, KY 40502
• Email: [add business email before publishing]

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