Carbon Monoxide Testing Draper UT | Draper Heating & Air

Carbon Monoxide Testing in Draper, Utah

Carbon monoxide poisoning is the most preventable gas appliance hazard in residential HVAC — and the one most consistently underdiagnosed before a serious event occurs. CO is colorless and odorless. Low-level chronic exposure (50–150 ppm in ambient air) produces headaches, fatigue, and cognitive impairment that are consistently misattributed to illness, allergies, or stress until someone makes the connection between symptoms and a malfunctioning appliance. By the time CO detector alarms trip at 70 ppm sustained for four hours (the UL 2034 alarm threshold), occupants in a sealed winter home may have been experiencing effects at sub-alarm concentrations for weeks.

In the south Salt Lake Valley, two local conditions elevate the CO risk profile above the national baseline. The first is altitude: gas appliances installed at SunCrest (6,200 ft) and Traverse Ridge (6,400 ft) that were not altitude-derated at installation run rich-burn combustion conditions that produce elevated CO in the flue gas — and, if a heat exchanger breach is present, elevated CO in the return air stream. The second is building tightness: modern tight-envelope construction in Daybreak, Rosecrest, and newer Herriman builds reduces natural air infiltration and concentrates indoor CO from any source faster than older leaky construction at the same appliance output.

Our CO testing service uses calibrated electrochemical sensor instruments to measure CO at the appliance flue gas, at the return air grille, and in ambient living areas, producing a written report that documents the findings and supports any appliance service or replacement decisions that follow.

What Carbon Monoxide Testing Includes

Furnace Combustion Analysis

Combustion analysis is performed with a Testo 320 Basic flue gas analyzer inserted in the flue gas sampling port or draft hood after the furnace reaches steady-state operation. We measure and record:

  • CO air-free (ppm): The CO concentration in the flue gas corrected for excess air dilution. Target under 100 ppm for a properly operating gas furnace. Our action threshold: if CO air-free exceeds 200 ppm, we shut the furnace down and investigate the cause before returning it to operation.
  • O₂ percentage: The oxygen percentage in the flue gas. Target 5–9% for properly tuned combustion. O₂ below 4% at SunCrest or Traverse Ridge elevation is the signature of a furnace running at sea-level gas valve settings — the rich combustion condition that produces elevated CO.
  • Stack temperature: Compared against manufacturer specification. Elevated stack temperature on a condensing furnace indicates secondary heat exchanger fouling; elevated stack on a non-condensing furnace with correct gas pressure may indicate a heat exchanger breach allowing return air dilution of the flue gas stream.
  • Flue gas CO at all firing stages: For two-stage and modulating furnaces, we test at each firing stage separately. A furnace with clean combustion at high fire and elevated CO at low fire (common on systems with burner port deposits from altitude-related rich burn at SunCrest) has a different repair path than one with elevated CO at all stages.

Return Air CO Measurement — The Critical Safety Test

The combustion analysis measures CO in the flue gas circuit, which should stay in the flue and exit through the vent. The return air CO measurement is more clinically important for occupant safety: it measures whether CO from the flue gas circuit is entering the conditioned air stream through a heat exchanger breach, a draft hood backdraft, or a combustion appliance in an underpressurized mechanical room.

We use a Bacharach MGS-150 or equivalent electrochemical CO detector (not a residential CO alarm, which has response thresholds deliberately above acute exposure levels) to measure CO at:

  • The return air grille directly (the air being drawn into the system — elevated CO here indicates a path from the combustion circuit to the conditioned air)
  • The supply air registers (the air being delivered to occupants — CO here means the contaminated return air has passed through the system and is reaching the living space)
  • At breathing height in occupied rooms (5 feet above the floor, in the rooms most occupants spend the most time during the heating season)

Background CO in a well-maintained home from non-appliance sources is typically 0–2 ppm. CO at the return grille above 5 ppm on a furnace call, or CO at breathing height above 5 ppm, triggers immediate investigation of the combustion appliance circuit before the home is reoccupied by vulnerable individuals.

Heat Exchanger Borescope Inspection

When return air CO or elevated flue gas CO cannot be explained by altitude derate error or burner conditions alone, we perform a borescope inspection of the heat exchanger cells. As documented on our Heat Exchanger Repair page, the borescope is the only instrument that can visually confirm a heat exchanger crack or perforation. CO in the return air without a visible heat exchanger breach may indicate a cracked cell not accessible to the probe’s viewing angle, a leaking flue connector, or a combustion air depressurization issue rather than a structural heat exchanger failure.

Water Heater and Fireplace CO Testing

Gas water heaters and gas fireplaces are CO sources that are often overlooked when a home is tested for CO concerns. Atmospheric-draft water heaters in mechanical rooms adjacent to the furnace share the same combustion air supply; a water heater running at rich-burn conditions (common on water heaters at SunCrest elevation that were never derated) produces CO in the same flue pathway as the furnace. Gas fireplaces with partially blocked flue dampers or deteriorated firebox gaskets can backdraft CO into the living space when the HVAC system creates depressurization in the room.

Our CO testing scope includes:

  • Gas water heater: combustion analysis at the draft hood with CO air-free measurement and visual inspection of the draft hood for evidence of backdrafting (soot staining, discoloration)
  • Gas fireplace: CO measurement at the firebox opening and in the room air adjacent to the fireplace, with visual inspection of the damper condition and firebox gasket
  • Gas range or cooktop: ambient CO measurement in the kitchen during operation (gas ranges are not flue-connected; they exhaust directly into the kitchen air, making them a significant CO source in tightly sealed kitchens with inadequate range hood ventilation)

Altitude Derate Verification for SunCrest and Traverse Ridge

The majority of elevated CO findings we document in the south Salt Lake Valley on furnaces above 5,000 feet elevation trace to a single root cause: the gas valve manifold pressure was never adjusted for altitude at installation. A furnace delivering sea-level gas pressure at SunCrest elevation has too much fuel relative to the available oxygen at 6,200 feet air density. The combustion is rich. The flue gas CO is elevated. This condition is repairable — we adjust the manifold pressure to the manufacturer’s altitude-corrected specification during the CO testing visit if the combustion analysis confirms the derate was not performed.

Altitude derate verification steps included in our CO test scope for addresses above 5,000 feet:

  • Confirm installation address elevation by GPS measurement at the equipment location
  • Pull the furnace installation manual and confirm the manufacturer’s altitude correction table for the specific model
  • Measure the existing manifold pressure and compare to the altitude-corrected target
  • Adjust manifold pressure if out of specification and re-run combustion analysis to confirm correction
  • Document pre-correction and post-correction combustion readings in the written report

When to Request CO Testing

CO testing is appropriate in the following situations:

  • CO detector alarm: Any CO detector alarm in a home with gas appliances warrants a professional CO source investigation, not just resetting the detector. The detector alarm is confirmation that a CO source is present. Identifying which appliance and why is the purpose of the testing visit.
  • Unexplained symptoms: Persistent headaches, fatigue, nausea, or flu-like symptoms in household members that improve when occupants are away from home and worsen during the heating season. Low-level CO exposure (30–70 ppm) produces symptoms that are indistinguishable from seasonal illness without CO measurement.
  • Furnace over 12 years old with no recent service: Heat exchanger thermal fatigue risk is meaningfully elevated in furnaces past 12 years of continuous cycling, particularly at SunCrest and Traverse Ridge elevations where altitude derate errors have accelerated heat exchanger fatigue.
  • New home purchase: Pre-purchase CO testing is a standard IAQ due diligence item that many home inspectors cannot perform with the instrument precision required to distinguish low-level appliance CO from background. We provide pre-purchase CO testing with written reports for real estate transaction documentation.
  • After any work on the gas appliance venting: Any modification to furnace venting, water heater venting, or the gas supply that could affect combustion air or draft should be followed by a CO test confirming normal appliance operation in the modified configuration.
  • SunCrest or Traverse Ridge home where altitude derate status is unknown: If you do not have documentation confirming your furnace’s gas valve was altitude-derated at installation, CO testing that includes a combustion analysis and manifold pressure verification is the appropriate way to confirm or correct this.

CO Detector Requirements and Limitations

Residential CO detectors (Kidde, First Alert, Google Nest Protect) are safety devices, not diagnostic instruments. Their response characteristics are defined by UL 2034, which requires the alarm to activate within a specific time window at specific CO concentration thresholds:

  • 70 ppm: alarm within 60–240 minutes
  • 150 ppm: alarm within 10–50 minutes
  • 400 ppm: alarm within 4–15 minutes

These thresholds are set to prevent nuisance alarms from brief CO exposure while providing protection against acute poisoning. They do not protect against chronic exposure at concentrations below the alarm threshold. A home with sustained ambient CO at 25 ppm — below the UL 2034 alarm trigger — will not alarm but is exposing occupants to CO concentrations above the NIOSH (National Institute for Occupational Safety and Health) recommended 8-hour ceiling of 35 ppm.

Electrochemical CO detectors should be replaced according to the manufacturer’s schedule, which is typically every 5–7 years. An expired CO detector may display a flashing low-battery indicator but is not reliably sensing CO. We verify CO detector age and replacement status during every CO testing visit and document findings in the report.

What a CO Test Report Includes

Our CO testing service produces a written report that documents:

  • Date of testing, technician name and license number, property address and GPS elevation
  • All gas appliances tested (furnace model and serial, water heater, fireplace, range)
  • Combustion analysis readings for the furnace (CO air-free, O₂, stack temperature) at each firing stage
  • Manifold pressure measured versus altitude-corrected target
  • CO readings at the return air grille, supply registers, and ambient breathing height locations
  • Heat exchanger borescope findings if performed (cell-by-cell notation, photos attached)
  • Water heater and fireplace CO readings
  • CO detector status (age, model, battery condition)
  • Findings summary: pass / advisory / action required
  • For action-required findings: specific recommended service with estimated cost range

The written report is provided at the conclusion of the testing visit and emailed in PDF format within 24 hours. For pre-purchase testing, a copy is provided directly to the buyer’s agent on request for inclusion in the real estate transaction file.

Frequently Asked Questions

How much does CO testing cost in Draper?
A complete CO testing visit (furnace combustion analysis, return air and supply air CO measurement, water heater draft hood inspection, ambient room air testing, and written report) typically runs $125–$195 for a single gas appliance system and $175–$250 for homes with multiple gas appliances (furnace, water heater, and fireplace). Pre-purchase testing with written report formatted for real estate transaction documentation runs $175–$250. If the CO test reveals a condition requiring service (altitude derate correction, furnace repair, or heat exchanger inspection), the testing fee is applied to the repair or inspection cost if the work is performed on the same visit.
My CO detector went off but it is not alarming now — should I be concerned?
Yes. A CO detector alarm that cleared itself indicates a CO source produced enough CO to trigger the alarm at the time of activation, and the concentration has since dropped — either because the appliance cycled off, a door or window was opened, or ventilation diluted the CO below the reset threshold. The CO source is still present. A reset alarm without identifying and correcting the source is a temporary clearing, not resolution. Call us for a CO testing visit. Do not defer this if the alarm occurred during furnace operation in the heating season.
Is CO testing the same as a furnace tune-up?
No — though a furnace tune-up includes a combustion analysis as one of its components. CO testing is a safety-focused diagnostic visit specifically aimed at confirming or ruling out CO exposure pathways in the home. It is more comprehensive in its CO-source scope (water heater, fireplace, range, ambient rooms) and more specific in its documentation than a tune-up’s combustion analysis. For a home with no CO concerns, the combustion analysis in an annual furnace tune-up provides adequate safety monitoring of the furnace. For a home with a CO alarm event, unexplained symptoms, or a high-risk profile (SunCrest, older furnace, no service history), a dedicated CO testing visit is the appropriate scope.
Can I test for CO myself with a consumer CO detector?
Consumer CO detectors will alarm at the UL 2034 thresholds described above, which protects against acute poisoning but does not detect chronic sub-alarm exposure. They also cannot tell you which appliance is the CO source, what the concentration is at the appliance versus in the room air, or whether the furnace combustion chemistry is producing elevated CO that has not yet leaked into the conditioned space. Professional CO testing with an electrochemical instrument (Bacharach MGS-150 or equivalent) provides ppm-resolution measurement at 0–500 ppm rather than the binary alarm/no-alarm of a consumer detector. If you have a consumer CO detector in the home and no symptoms, its function is adequate for alarm-threshold protection — but it will not tell you that your SunCrest furnace is producing 185 ppm CO air-free due to a missing altitude derate.
What should I do if I think I have a CO leak right now?
Immediately: (1) Open windows and doors. (2) Get all people and pets out of the home. (3) Call 911 — the fire department has professional CO detection equipment and is equipped to identify and isolate the source safely. (4) Do not re-enter the home until the fire department clears it. (5) Once the immediate emergency is resolved and the fire department has identified the source, call us for the appliance repair or replacement that the emergency revealed. If the CO source was the furnace, do not operate the furnace until the combustion issue is diagnosed and corrected.

Contact Draper Heating & Air Conditioning

For CO testing across Draper, Sandy, Bluffdale, Riverton, South Jordan, and Herriman — including SunCrest and Traverse Ridge altitude derate verification — contact us to schedule a testing visit. We provide written reports, same-visit repair authorization where appropriate, and 24/7 emergency dispatch for active CO alarm events.

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