As a home inspector, ensuring the safety and health of a home is paramount. One critical aspect of this responsibility is measuring carbon monoxide (CO) levels in household furnaces. Carbon monoxide is a colorless, odorless gas that can pose serious health risks if not adequately monitored and controlled. In this blog, the home inspection specialists at HomePro Inspections will explore the importance of measuring air-free CO levels in furnaces, the methods for doing so, and why home inspectors must pay close attention to this aspect during home inspections.
Air-free CO reading of 25 ppm
What is Air-Free CO?
Air-free CO refers to the concentration of carbon monoxide in a furnace's flue gas, adjusted to remove the dilution effect of excess air. This measurement provides a more accurate indication of the CO levels produced solely by the combustion process, making it a crucial factor in assessing a furnace's safety and efficiency.
The Importance of Measuring Air-Free CO
Health Risks
Carbon monoxide is a hazardous gas that can cause a range of health issues, from mild headaches and dizziness to severe poisoning and even death. Because it is both colorless and odorless, CO can go undetected without proper monitoring. High levels of CO in a home can result from a malfunctioning furnace, making it essential to measure and control air-free CO levels to prevent health risks to inhabitants.
Efficiency and Performance
Beyond health concerns, measuring air-free CO can provide insights into a furnace's efficiency and performance. Elevated CO levels may indicate incomplete combustion, which wastes fuel and leads to higher operating costs and increased wear and tear on the furnace. By ensuring that a furnace operates within safe CO limits, homeowners can save on energy costs and extend the life of their heating systems.
Methods of Measuring Air-Free CO
Using a Combustion Analyzer
A combustion analyzer is a specialized tool home inspectors use to measure the levels of various gases produced by a furnace, including air-free CO. This device samples the flue gas and calculates the CO concentration, adjusting for excess air to provide an accurate air-free CO reading. When using a combustion analyzer, following the manufacturer's instructions and ensuring the device is correctly calibrated for precise measurements is crucial.
Manual Calculations
While combustion analyzers provide a convenient and accurate way to measure air-free CO, manual calculations are also an option. This involves directly measuring the CO concentration from the flue gas and adjusting the reading according to the excess air levels. The formula for calculating air-free CO is as follows:
Air-Free CO = (Measured CO ppm) x (20.9) / (20.9 - O₂%)
In this formula, O₂% represents the percentage of oxygen in the flue gas. By adjusting the measured CO concentration, this calculation yields an air-free CO value that eliminates the diluting effect of excess air.
Understanding Air-Free CO Levels
Acceptable Limits
Understanding acceptable limits of air-free CO is crucial for home inspectors and homeowners. The Environmental Protection Agency (EPA) and other regulatory agencies establish guidelines for safe CO levels in residential environments. Air-free CO concentrations should not exceed 400 parts per million (ppm). Levels above this threshold may signal an issue with the furnace that requires immediate attention.
While 400 ppm is considered the upper limit, our home inspectors recommend advising service if the reading exceeds 100 ppm. We occasionally face pushback from HVAC contractors who argue that this level has no problems. Our stance in the home inspection industry is that a lower number is preferable for safety and efficiency.
Troubleshooting High CO Levels
If air-free CO levels exceed acceptable limits, an HVAC technician should thoroughly examine the furnace to identify the root cause. Common issues that can lead to elevated CO levels include:
· Blocked or restricted flue vents
· Cracked heat exchangers
· Inadequate combustion air supply
· Incorrectly adjusted burners
· Excessive soot buildup
Addressing these problems promptly can help reduce CO levels, improve furnace efficiency, and ensure the safety of the home's occupants.
Best Practices for Home Inspectors
Regular Inspections
Our home inspectors incorporate regular CO measurements into their inspection routines. This helps identify potential hazards and gives homeowners peace of mind, knowing that their heating systems are operating safely and efficiently.
Proper Documentation
Documenting the results of CO measurements is essential for maintaining accurate records and providing homeowners with valuable information about the condition of their furnaces. Detailed reports should include the air-free CO levels, identified issues, and recommended remediation actions.
Summary
Measuring air-free CO in furnaces is a crucial aspect of home inspection that directly impacts homeowners' health, safety, and comfort. Home inspectors can play a vital role in ensuring the well-being of the homes they inspect by understanding the importance of air-free CO, utilizing proper measurement techniques, and adhering to best practices. Remember, a safe home is a happy one, starting with accurate CO measurements and diligent inspections.
At HomePro Inspections, our home inspectors are trained to inspect your attic and ventilation systems and identify defects. Any issues are documented in your home inspection report and recommended for resolution by a qualified professional.
Visit our website or schedule your home inspection in the areas of Rochester, Owatonna, and Faribault, MN. You can also contact us today at (507) 202-8942, email us, or use our online “Schedule Now” feature to schedule an appointment.