Tips for Testing Your Furnace
Testing your furnace is an important part of maintaining a healthy and efficient home heating system. Here are some criteria to look for when testing your furnace:
Excessive Smoke from Stack: Excessive smoke from the stack is a sign that your furnace is not burning fuel efficiently. If you notice excessive smoke, you should have your furnace serviced immediately.
Three Months Since Last Efficiency Check: If it has been three months or more since your last efficiency check, it’s time to get your furnace checked out. An efficiency check will help you determine if there are any issues with your furnace that could cause it to waste energy and cost you more money each month.
High Flue Gas Temperature Reading: A high flue gas temperature reading in the furnace log or indicator in the stack is a sign that your furnace is not burning fuel efficiently. This could be caused by a number of different factors, so it’s important to have it checked out by a professional.
No Change in Operating Condition with Change of Burner Firing Rate: If your furnace’s operating condition doesn’t change when you change the burner firing rate, this could be an indication that there is a problem with the way your furnace is burning fuel.
Physical Appearance Poor: If your furnace’s physical appearance is poor, with badly sealed doors and flames escaping from the furnace, poor insulation, and refractory, it’s important to have it looked at by a professional. This could be an indication of a serious issue that needs to be addressed.
Little or No Fitted Instrumentation: If your furnace does not have any fitted instrumentation in working order, it could be wasting energy and costing you money. It’s important to have it checked out and fitted with the appropriate instrumentation.
Manually Adjusted Burners: If your burners are manually adjusted, this could be an indication that there is a problem with the way your furnace is burning fuel. It’s important to have it checked out by a professional to ensure that it is burning fuel efficiently.
Large Fluctuations in Furnace Draft Readings: If your furnace’s draft readings are fluctuating greatly, this could be an indication that there is a problem with the way your furnace is burning fuel. Have it checked out by a professional to ensure that it is burning fuel efficiently.
Installed Flue Gas Analyzer: Installing a flue gas analyzer can help you detect if there is an issue with the way your furnace is burning fuel. If the analyzer is indicating a very high percentage of carbon dioxide, very low percentage of oxygen (less than 2%), or carbon monoxide in excess of 20 PPM, you should have your furnace serviced immediately.
Produce Quality Problems: If you are experiencing produce quality problems, it’s important to have your furnace checked out by a professional. These issues could be caused by a number of different factors, so it’s important to have it looked at to ensure that it is operating efficiently and not wasting energy.
Energy Conservation Opportunities: It is usually possible to identify some energy conservation opportunities based on a quick audit of your furnace. These opportunities include reducing losses from openings and leaks, reducing losses during recycling and idle equipment shutdown, and reducing heat losses through openings. Chain curtains can be used to reduce the heat loss by 80%. Additionally, losses resulting from cold air leakage into the furnace can be serious, so it’s important to have it checked out to ensure that it is not wasting energy.
How to Reduce Heat Loss in Furnaces
Heat loss in furnaces can be reduced by making adjustments to door seals and dampers, as well as by modifying operating practices. Here are some of the steps you can take to reduce heat loss:
Door Seals and Dampers:
• Calculate the area of opening to determine the heat loss per unit area.
• Estimate or measure flue exhaust height above furnace floor.
• For furnace operating temperature and flue height, obtain heat loss from the given table.
• Heat loss per year is calculated = (area of opening)(heat loss/unit area)(operating hours/year) = watts/year.
• Savings = (percent saved)*(yearly heat consumption).
Operating Practices:
• Review operating practices to identify opportunities for reducing losses during recycling and idle equipment shutdown.
• Calculate the time needed to cool furnace to room temperature and several intermediate temperatures with the burners off.
• Estimate the rate of fuel use when idling furnace at operating and intermediate temperatures.
• Measure reheat times from room temperature and intermediate temperatures.
• Calculate the fuel needed to reheat from intermediate temperatures.
• Determine the maximum rate of temperature change that will not result in equipment damage.
Furnace Energy Audit:
• Prepare for audit with essential steps such as installing instrumentation and selecting a test day.
• Perform tests such as full commissioning test, efficiency test, efficiency test by loss method, and combustion test.
• Collect data and evaluate it.
• Calculate efficiency and determine improvements.
• Identify conservation opportunities such as tune-ups, improved control, heat recovery, and alternative fuels.
Energy input( in kJ/hr )= (fuel use) x (gross heating value)
The Benefits of Flue Gas Analysis
Flue gas analysis is an important part of any combustion process, providing valuable insights into the efficiency of the system and any potential pollutants that may be present. Here are the main benefits of conducting a flue gas analysis:
• Determining Combustion Efficiency: Flue gas analysis helps to identify any combustion inefficiencies that may be present, enabling engineers to tune the system for improved performance.
• Burner Tune Up Requirements: By analyzing the flue gas, any required burner tune-ups or adjustments can be identified and addressed.
• Pollutants Reduction: By measuring the concentrations of pollutants present in the flue gas, engineers are able to better understand the sources of pollution and how to reduce or eliminate them.
Understanding Flue Gas Analysis
Flue gas analysis is used to measure the volume of dry exhaust emissions in percentage (%), parts per million (ppm) or mg/Nm³. Since the flue gas analysis concentrations represent the ratio of certain gases in a mixture of gases, these concentrations will vary depending on the air to fuel ratio. Therefore, for the sake of comparison between two analyses at different air to fuel ratios, concentrations are usually normalized to a certain Oxygen concentration. This is usually considered at 3% Oxygen concentration in the flue gases.
Normalized Concentration = Concentration *Oxygen (%)/3%
Measuring Hydrocarbon Emissions
Hydrocarbon emissions are usually measured as the equivalent concentration of Methane (CH4), Propane (C3H8) or Hexane (C6H14). Flue gas analyzers provide precise data on these concentrations, enabling engineers to better understand the combustion process and take appropriate steps to reduce or eliminate any pollutants present.
Preliminary Energy Audit of a Boiler: How to Conduct a Successful Audit
Conducting an energy audit is the first step to understanding the energy use of a boiler and identifying potential savings opportunities. Here is a comprehensive guide to help you conduct a successful energy audit of your boiler.
Preparing for the Audit
The first step in conducting an energy audit of your boiler is to prepare for the audit. This includes obtaining the nameplate information, gathering operational details and performing a visual inspection of the boiler and auxiliaries. Obtaining the nameplate information will provide you with the boiler’s specifications, such as its maximum capacity, fuel type, and operating temperature and pressure. Gathering operational details will provide you with information on the fuel use, medium raised, temperature and pressure, and operating hours. Lastly, the visual inspection will help you to identify any potential issues with the boiler and its auxiliaries.
Identifying Test Points
The next step is to identify test points and determine the type of test and instrumentation required. There are various types of tests that can be conducted, such as a full commissioning test, an efficiency test to standards established by bodies such as ASME British Standards BS 845 or BS 2885, an efficiency test by loss method, and a combustion test only.
Identifying Conservation Opportunities
Once you have identified the test points, the next step is to identify potential conservation opportunities from improved operation. This may include tune-ups, improved control, heat recovery, and alternative fuels.
Developing an Action Plan
Once you have identified the potential conservation opportunities, the next step is to develop an action plan. This action plan should include recommendations for repairs or installation of instrumentation as necessary, as well as identifying testing positions, selecting an appropriate test day, performing the test, and collecting data.
Evaluating Data and Calculating Efficiency
The final step is to evaluate the data and calculate the efficiency of the boiler. This can be done using the total losses method, which relates all the losses to the fuel input. The losses include combustion losses, flue gas losses, incomplete combustion losses, heat transfer losses, and blow down losses. Calculating the efficiency of the boiler will allow you to determine the improvements that need to be made.
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