How Carbon Monoxide Claims Are Evaluated: What Attorneys Need to Know About HVAC Expert Analysis
Carbon monoxide exposure cases involving HVAC systems require a mechanical engineer who can trace the source — flue gas spillage, backdrafting, improper venting — and establish whether the condition resulted from design error, installation defect, or deferred maintenance.
Why CO Claims Require Engineering Analysis
Carbon monoxide (CO) is produced by incomplete combustion in gas-fired appliances — furnaces, water heaters, boilers, and generators. When HVAC systems or building envelopes fail to properly vent combustion gases, CO accumulates in occupied spaces. The question courts and insurers ask is not just whether CO was present, but why it was present and who bears responsibility.
The answer requires understanding combustion chemistry, pressure dynamics within a building, flue gas temperature and buoyancy, and manufacturer installation requirements. A licensed mechanical engineer with forensic experience can trace CO exposure to its root cause — and distinguish an isolated equipment failure from a systematic design or installation defect.
Common Sources of HVAC-Related CO Exposure
In most CO cases I evaluate, the exposure traces to one of several root causes:
Flue gas spillage occurs when combustion gases escape the appliance’s heat exchanger or venting system into the occupied space before reaching the exterior. This can result from a cracked heat exchanger, negative pressure conditions in the mechanical room, or improper combustion air supply.
Backdrafting happens when stack effect, exhaust fans, or HVAC pressure differentials cause combustion gases to reverse course and flow back into the building rather than out through the flue. Tight building envelopes — common in energy-efficient construction — can create negative pressure conditions that overwhelm natural draft venting systems.
Improper venting installation is among the most common liability findings. Manufacturer installation manuals specify vent connector diameter, pitch, length, and termination clearances. When installers deviate from these specifications — using undersized vent pipe, insufficient slope, inadequate clearance from combustibles, or improper termination location — the result can be chronic or acute CO exposure.
Orphaned appliances present a subtler problem. When a high-efficiency furnace is installed and vented directly to the exterior (condensing vent), the original shared flue may be oversized for the remaining appliances, leading to condensation and backdrafting in cold weather.
What the Engineering Investigation Looks Like
A proper CO investigation involves site inspection, combustion analysis, pressure testing, and documentation review. I examine the appliances, venting systems, combustion air supply, and building envelope. I review manufacturer installation instructions, local mechanical codes, and the installation records. In many cases, I use a combustion analyzer to measure CO, CO₂, and flue gas temperatures, and a manometer to measure pressure differentials across the building envelope and within mechanical spaces.
The engineering report in a CO case needs to answer four questions: What was the CO source? What condition allowed it to accumulate? Was that condition a result of defective design, improper installation, or lack of maintenance? And does the evidence support causation between the CO exposure and the claimed injury?
How This Analysis Supports Litigation
In attorney-retained cases, I provide written opinions suitable for use in expert disclosure, and I’m prepared to testify in deposition and at trial. My analysis follows the methodology required under Daubert — observable facts, testable hypotheses, and opinions grounded in peer-reviewed engineering standards including NFPA 54, NFPA 211, and appliance-specific manufacturer documentation.
Insurance carriers and subrogation counsel retain me to evaluate whether a CO loss resulted from a covered event or from an installation or design defect that creates subrogation potential against a contractor, manufacturer, or design professional.
Jurisdiction and Availability
I hold active PE licenses in Montana, Wyoming, Idaho, Utah, Colorado, California, and several additional states. I evaluate CO cases throughout the Mountain West and nationally when the facts warrant it. If you have a carbon monoxide matter where HVAC systems are implicated, I’m available for a confidential consultation to assess whether the engineering analysis is suited to your case.