A combustion efficiency test performed by a qualified HVAC service technician can detect gas furnace issues that a simple visual inspection might not reveal. Combustion efficiency relates to the percentage of various gasses present in the exhaust stream discharged by the furnace up the vent pipe. By testing exhaust gasses with a combustion analyzer, the technician can identify potential issues with furnace components that affect heating peformance and safety.

A combustion analyzer measures levels of carbon dioxide and carbon monoxide, the amount of unburned oxygen and the temperature of the exhaust stream. Percentages of these gases in the exhaust should be in correct balance to support optimum efficiency.

Why Combustion Efficiency Matters

Inefficient combustion is a red flag that may be the source of several problems, including critical safety issues.

• Carbon monoxide hazards. While all furnaces emit nominal amounts of poisonous carbon monoxide gas (CO) in the exhaust stream, if a combustion efficiency test reveals excess CO it’s more than simply a combustion issue.  Carbon monoxide levels that exceed safe minimums can present an increased safety hazard to occupants of the house in the event of a cracked furnace heat exchanger—not an uncommon event with older furnaces. Ensuring that the carbon monoxide percentage of combustion gasses is at safe minimum levels reduces potential danger of carbon monoxide infiltration into the house.
• Inefficient heating performance. If analysis of combustion gases shows that natural gas fuel is incompletely combusted, you aren’t getting the maximum heating benefit from the fuel you’re paying for. Corrections by a technician such as gas valve adjustments may increase overall heating effectiveness while lowering operating costs.
• Toxic exhaust. When analysis of furnace gases shows incomplete combustion, some of the substances emitted by the furnace may be very harmful to the environment. For example, sulfur dioxide, a byproduct of incomplete combustion of natural gas, is highly corrosive and has been identified as a toxic substance with negative environmental impacts.

Ask the heating professionals at Powers Heating & Air for more about the benefits of a combustion efficiency test.