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Why is a combustion analysis Necessary?
When installing a new gas furnace, it is critical to ensure that it operates efficiently and safely. One of the essential steps in commissioning a new gas furnace is performing a combustion analysis. A combustion Analysis of your Gas Furnace helps determine whether the furnace is operating within the manufacturer’s specifications, whether it is using fuel efficiently, and whether it is producing dangerous levels of carbon monoxide. This article will explore the importance of performing a combustion analysis on a new gas furnace while commissioning the unit. Following the manufacturer’s installation instructions, appropriate natural gas pressures should be established. The top priority for any technician should be the protection of the appliance. The production of carbon monoxide in the exhaust must be maintained beneath 100 parts per million, even though the permissible concentration in the stack is 400 parts per million.
- Ensure efficient operation: Performing a combustion analysis on a new gas furnace while commissioning the unit helps ensure that the furnace is operating efficiently. The analysis measures the ratio of air to fuel in the combustion process, which affects the furnace’s efficiency. If the ratio is not correct, the furnace may consume more fuel than necessary, which will result in higher energy bills.
- Ensure safe operation: Carbon monoxide is a deadly gas produced by incomplete combustion of fuel. It is odorless and colorless, making it impossible to detect without special equipment. Performing a combustion analysis helps detect dangerous levels of carbon monoxide and ensures the furnace operates safely.
- Comply with regulations: Performing a combustion analysis on a new gas furnace while commissioning the unit is a regulatory requirement in many regions. Failure to comply with regulations can result in fines, voided warranties, and potential legal action.
- Identify potential problems: Performing a combustion analysis helps identify potential problems with the gas furnace before they become significant issues. The analysis can detect issues such as dirty burners, incorrect fuel-to-air ratios, and inadequate combustion air supply. Identifying these issues early can prevent costly repairs down the line.
- Ensure customer satisfaction: Performing a combustion analysis on a new gas furnace while commissioning the unit ensures customer satisfaction. A well-tuned furnace operates efficiently, safely, and quietly, providing a comfortable living environment for the homeowner.
Checking the draft
In order to be safe, it is essential to check the draft. All appliances in which the flue gases are removed by the heat exchanger or draft hood, as well as those with power burners, must have draft present. In compliance with the ANSI (American National Standards Institute), any appliance needing a draft has to be able to show reliable draft during use and must do so within five minutes.
When the system is running under normal conditions, the draft should remain constant. As the flue temperature rises, the draft should grow until it reaches its highest point and stabilizes. The analyzer will capture the draft reading and save it for the display and output of the flue gas measurement. It may take up to 10 minutes for a draft to be created if both the appliance and the chimney are cold; however, if the system has been running, the draft should be quickly established.
This is the maximum amount of time the appliance is allowed to spill before the spill switch trips. If draft-induced and atmospheric appliances are vented together, always make sure that the atmospheric one is not leaking when both are running.
When the atmospheric one is functioning alone, confirm that the flue gases are not exiting by the draft hood. If the two appliances are vented together, both should be tested for draft.
Any changes to the kitchen, such as exhaust fans or opening and closing basement doors, should not have an effect on the draft. When a number of appliances that are affected by draft are vented concurrently, be certain that no spilling happens from the heat exchanger and through the burner openings of the other appliance when it is in its off position.
At the beginning and end of any review of a fossil fuel appliance, a combustion test should be conducted.
How is a combustion analysis performed?
Combustion analysis is performed using specialized equipment such as a combustion analyzer, a manometer, and a thermometer. The combustion analyzer measures the furnace’s oxygen, carbon dioxide, and carbon monoxide levels, while the manometer measures the pressure of the flue gases. The thermometer measures the temperature of the flue gases.
The results of the combustion analysis are compared to the manufacturer’s specifications to determine whether the furnace is operating efficiently and safely. The technician can then make adjustments to the furnace as necessary to ensure it operates within specifications.
Since measuring the theoretical temperature of a combustion process on site is not feasible because of the gases being diffused and the heat being dissipated to the environment, the combustion equation is used to ascertain if the combustion is managed appropriately. The combustion efficiency is an estimator of the appliance’s thermal efficiency, however, it is not equivalent to the published AFUE. This calculation takes into account the theoretical heat value of the fuel burned and the associated stack losses, but it does not consider how efficiently the heat produced is used.
The most critical measurement taken by an analyzer related to combustion is the oxygen (O2) reading. The oxygen content in the air does not change, at 20.9 percent, and is the only stable factor in the burning process. Although there is always 20.9 percent O2 by percentage, the mass of oxygen supplied to the burners fluctuates in line with air density.
Ensure that the O2 measurement is regularly monitored in order to create a flame with the least amount of excess air while still keeping the CO levels in the stack safe. All readings should remain within the maker’s recommended specifications. Additionally, all burner shields must be in place to stop additional air from entering.
Manufacturers of residential furnaces have opted not to include provisions for combustion air adjustment, as the safety benefits of providing more air to support full combustion far exceed the potential cost savings. Furthermore, the mixing of additional air with the flue gases leads to a decrease in the dew point, thus diminishing the likelihood of condensation in noncondensing systems.
The CO2 concentration in the exhaust can give an indication of how well the combustion is being conducted. When there is only a small amount of extra air present and CO2 is produced to its highest degree, the flue gas heat losses become as low as possible. To obtain the CO2 reading, the O2 reading must be calculated by the analyzer.
FAQ’s
What is combustion analysis?
Combustion analysis is a way to figure out what elements, like carbon, hydrogen, and oxygen, are in an unknown substance. It’s mainly used in chemistry to learn more about new or unknown materials.
The process works by burning a small amount of the substance with a lot of oxygen. When it burns, the elements inside the substance turn into other things like carbon dioxide (CO2), water (H2O), and sometimes nitrogen gas (N2) or sulfur dioxide (SO2). We then collect and measure the amount of these new substances created during the burning.
By knowing how much of these new substances are made, we can figure out how much of each element was in the original substance. This helps us learn more about the substance’s structure and makeup. Even though there are more advanced ways to study unknown substances today, combustion analysis is still a useful method to find out what elements are in a compound.
How often should a combustion analysis be performed?
Combustion analysis is a crucial part of ensuring the safety and efficiency of fuel-burning appliances, such as furnaces, boilers, and water heaters. The frequency at which combustion analysis should be performed varies depending on the specific appliance, its age, and the conditions it operates under.
As a general guideline, combustion analysis should be performed:
• During installation: To make sure the equipment is set up correctly and operating safely and efficiently.
• Annually: For routine maintenance and to detect any changes in performance or potential issues. This may be more frequent for older or high-use systems.
• If there is a noticeable change in performance, fuel consumption, or signs of incomplete combustion (e.g., soot buildup or unusual odors).
However, it is essential to consult the manufacturer’s recommendations and local regulations for more specific guidance. Regular combustion analysis is a critical component of preventive maintenance and can help identify potential problems before they become more severe or costly to fix.
Can I perform a combustion analysis myself?
No, performing a combustion analysis requires specialized equipment and training. It should only be performed by a licensed and trained technician.
Combustion produces high temperatures and can generate toxic gases, so it is important to have proper ventilation and protective equipment. Additionally, handling and working with combustible materials requires care and attention to minimize the risk of fire or explosion.
If your furnace isn’t being maintained by an HVAC professional, call us at Silicon Valley Comfort so we can offer the most in-depth and comprehensive air conditioning & heating preventive maintenance programs in Santa Clara County.
Conclusion
Performing a combustion analysis on a new gas furnace while commissioning the unit is critical to ensuring its efficient and safe operation. It helps detect potential problems before they become significant issues, ensures regulatory compliance, and provides customer satisfaction. By investing in a combustion analysis during the commissioning process, homeowners can enjoy a comfortable living environment and lower energy bills.
Citations
| ACHR News
| “ACHR News”. 2023. Achrnews.Com. https://www.achrnews.com/articles/106070-performing-a-combustion-analysis.
| Why Combustion Analysis is Better Than a Visual Check
| “Why Combustion Analysis Is Better Than A Visual Check”. 2021. Trimark, Falls Church. https://www.trimarkmechanical.com/combustion-analysis/.
| Combustion analysis of the gas furnace
| “Combustion Analysis Of The Gas Furnace”. 2023. Gray Furnaceman Furnace Troubleshoot And Repair. http://www.grayfurnaceman.com/combustion-analysis-of-the-gas-furnace.html.