Residential Energy Audit - Chapter 6

Boilers are protected from over damage caused by overheating through the use of high-limit pressure controls and temperature controls. High-limit pressure controls monitor the pressure levels within the boiler and automatically shut off the burner if the pressure exceeds a safe limit. Temperature controls, on the other hand, regulate the temperature of the water or steam in the boiler, ensuring that it does not reach dangerous levels. These controls help prevent overheating and potential damage to the boiler system.

Backdrafting refers to the reverse flow of combustion gases, such as carbon monoxide, into the living space instead of being properly vented out. This can occur due to a blocked or poorly designed chimney, where the gases are unable to escape effectively. High winds can also cause backdrafting by creating pressure differentials that disrupt the flow of gases. Additionally, suction near the furnace or boiler can create negative pressure, pulling the gases back into the living space.

Fiberglass is the proper insulation type for a steam heated system because it has excellent thermal resistance properties and can withstand high temperatures. It is also resistant to moisture and does not promote the growth of mold or mildew. Additionally, fiberglass insulation is easy to install and has a long lifespan, making it a suitable choice for steam heating systems.

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The three common burner types are atmospheric, induced-draft burners, and power burners. Atmospheric burners rely on natural air flow for combustion, while induced-draft burners use a fan to create a draft for combustion. Power burners have a forced air system to provide combustion air. These three types of burners are commonly used in various heating systems and have different mechanisms for achieving combustion.

Colder temperatures produce higher drafts. This is because cold air is denser than warm air, causing it to sink. As the cold air sinks, it displaces the warmer air, creating a draft as the warm air is pushed upwards. This phenomenon is commonly experienced in buildings during winter, where the temperature difference between the inside and outside causes drafts near windows and doors.

Electric vent dampers for gas systems with a pilot light do not close completely and only open 10% when the heating system is turned on.

The correct answer options provide different methods for fastening foil or vinyl-faced fiberglass duct insulation to sheet metal duct. These methods include using welded or glued-on pins called stuck-ups or stick pins with self-locking washers, wrapping twine or wire around the insulation and duct and anchoring it to nearby wood joists, or using plastic cable ties. These options give a range of choices for securing the insulation effectively.

Replacing oil burners with a SSE (presumably a more energy-efficient or sustainable alternative) is rarely a good return on investment when the cost-effectiveness is over 75%. This suggests that the upfront costs of replacing the oil burners and the ongoing savings from using the SSE are not significant enough to justify the investment. Therefore, it is true that such replacements rarely offer a good return on investment.

Hot water boilers do not have an air space at their water vessel's top in order to boil their water. The purpose of the air space is to allow for the expansion of the water as it heats up, preventing pressure buildup within the boiler. This air space also acts as a cushion to absorb any fluctuations in water level. Therefore, the statement is false.

A masonry chimney should be relined with a rigid or flexible chimney liner when there is no chimney liner or when the existing liner is deteriorated. This is necessary to ensure proper ventilation and prevent potential hazards such as leaks, chimney fires, or carbon monoxide poisoning. Without a liner or with a deteriorated liner, the chimney may not effectively contain and remove the byproducts of combustion, leading to safety risks. Therefore, relining the chimney with a suitable liner is essential in these situations.

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The gas furnace rated AFUE 90+ and SSE 90+ will have a Category IV chimney, no draft diverter, draft fan, low-temperature plastic venting, positive draft, electronic ignition, condensing heat exchanger, and outdoor combustion air is strongly recommended. This is because a high-efficiency gas furnace like this requires a more efficient and advanced system for venting and combustion. The Category IV chimney and low-temperature plastic venting help to safely remove the combustion byproducts, while the draft fan and positive draft assist in the proper flow of air. The electronic ignition and condensing heat exchanger further enhance the efficiency of the furnace, and outdoor combustion air is recommended to prevent the buildup of indoor pollutants.

The combustion heater should not spill combustion gases from its dilution device for longer than 30 seconds under worst case test conditions. This means that the heater should be able to effectively contain and exhaust the combustion gases within 30 seconds, ensuring the safety and proper functioning of the device.

Boilers are often oversized to provide adequate heat during the coldest weather. This is because during extreme cold temperatures, buildings require more heat to maintain a comfortable indoor temperature. By oversizing the boiler, it ensures that even in the coldest weather conditions, there will be enough heat output to meet the heating demands of the building. This helps to prevent any potential heat shortages or discomfort for the occupants.

Heating water too hot and keeping it hot for too long are common energy inefficiency factors for hot-water heaters. This is because heating water to higher temperatures than necessary requires more energy, and keeping it hot for extended periods also leads to energy wastage. By setting the water temperature to an appropriate level and minimizing the duration of hot water storage, energy can be conserved and efficiency can be improved.

SSE, or Specific Sensitivity to Ethanol, cannot be measured with CO2-sensing devices. This is because CO2-sensing devices are designed to measure carbon dioxide levels, not ethanol levels. Ethanol is a different compound and requires specific sensors or devices to accurately measure its concentration. Therefore, the statement is false.

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Vent dampers are devices that are installed in the flue of a heating system to control the flow of exhaust gases. They help to improve the efficiency of the system by preventing heat loss through the vent when the heating system is not in use. Boilers, which are used to heat water, can benefit more from vent dampers because they typically have longer periods of inactivity compared to furnaces, which provide direct heat. By reducing the heat loss during these idle periods, vent dampers can help boilers save energy and operate more efficiently. Therefore, the statement that vent dampers benefit boilers more than furnaces is true.

Back drafting, which is the reverse flow of combustion gases into a building, can be eliminated by implementing several measures. Repairing the chimney ensures that there are no leaks or blockages that could cause the gases to flow back into the building. Eliminating depressurization near the chimney involves addressing any factors that create negative pressure, such as exhaust fans or other ventilation systems. Providing outdoor combustion air ensures that there is sufficient airflow for proper combustion, reducing the likelihood of back drafting. Replacing the atmospheric heater with a sealed-combustion or power-draft heater prevents the escape of combustion gases into the building. Finally, sealing leaky ducts ensures that there are no openings through which the gases can enter the building.

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AFUE stands for Annual Fuel Utilization Efficiency, which is a measure of how efficiently a heating system converts fuel into usable heat over the course of a year. The given answer includes the factors that AFUE takes into account. Fuel burning losses refer to the energy lost during the combustion process. Chimney losses refer to the heat lost through the flue or chimney. Cycling losses refer to the energy lost when the heating system turns on and off frequently. Heat loss through a central heater's cabinet refers to energy lost due to poor insulation or leakage in the system. These factors are all considered in calculating the AFUE of a heating system.

Forced air distribution systems can waste energy in several ways. One way is through air leaks into and out of the ducts. When there are gaps or cracks in the ductwork, conditioned air can escape, leading to energy loss. Additionally, obstructions in the airways can restrict the flow of air, causing the system to work harder and consume more energy. Lastly, uninsulated ducts in unconditioned spaces can result in heat transfer or loss, further wasting energy. These factors contribute to inefficiency in the forced air distribution system, leading to energy wastage.

The term "steady state efficiency" refers to the efficiency of a system when it is operating at a constant, steady rate. In this context, "chimney losses" likely refers to the heat or energy that is lost through the chimney during the steady state operation of a system. This means that the efficiency of the system is affected by the energy that is lost through the chimney, which makes it an important factor to consider when assessing the overall efficiency of the system.

The correct answer includes all the statements mentioned in the question. Fuel burning efficiency counts losses from incomplete combustion, steady state efficiency counts chimney losses, annual fuel utilization efficiency counts cycling and jacket losses, and seasonal efficiency counts distribution losses in addition to the above mentioned.

The efficiency of a combustion heater is determined by the losses it experiences during operation. These losses include incomplete combustion, which refers to the combustion process not being fully completed and resulting in wasted fuel. Chimney losses occur when heat escapes through the chimney instead of being utilized. Additionally, losses at the beginning and end of the burner cycle refer to inefficiencies during the startup and shutdown phases. Lastly, distribution losses refer to heat being lost during the transfer of heat from the heater to the desired space.

Carbon monoxide, nitrous oxide, water vapor, and sulfur dioxide are all gases resulting from combustion heating that can affect our health. Carbon monoxide is a poisonous gas that can cause headaches, dizziness, and even death in high concentrations. Nitrous oxide is a greenhouse gas that contributes to air pollution and climate change. Water vapor, although not directly harmful, can contribute to the formation of smog and air pollution. Sulfur dioxide is a toxic gas that can irritate the respiratory system and cause breathing difficulties.

Liquid filled baseboard heaters release heat more evenly compared to other types of heaters. This is because the liquid inside the heater helps to distribute the heat more evenly throughout the room. Additionally, the heating element in liquid filled baseboard heaters only rises to about 180 degrees Fahrenheit, which is lower than the heating element in other types of heaters. This lower temperature helps to prevent overheating and ensures a safer heating experience.

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High efficiency furnaces and boilers have several improvements over older models. These include electronic ignition, which eliminates the need for a constantly burning pilot light, saving energy. Heat exchangers are designed to restrict combustion gases, allowing more heat to be extracted. Fans control the combustion air through smaller flues, optimizing the combustion process. Additionally, water condensed from flue gases is collected in a corrosion resistant heat exchanger, further increasing efficiency. These improvements contribute to the higher AFUE ratings of 80% to 97% for high efficiency furnaces and boilers, compared to the AFUE ratings of 68% to 78% for conventional models.

The main products of combustion are water vapor and carbon dioxide. During the process of combustion, a fuel combines with oxygen to produce heat and light. Incomplete combustion can result in the production of smoke and other byproducts, but in complete combustion, water vapor and carbon dioxide are the primary outputs. Water vapor is formed when hydrogen from the fuel combines with oxygen, while carbon dioxide is produced when carbon from the fuel combines with oxygen.

The gas furnace rated AFUE 78+ and SSE 80+ will have a Category 1 chimney, which means it requires a traditional masonry or metal chimney for venting. It does not have a draft diverter, which is a device used to regulate the flow of air in the chimney. Instead, it has a draft fan, which helps to control the flow of combustion air and exhaust gases. The furnace also has electronic ignition, which means it does not require a standing pilot light. It uses indoor combustion air, meaning it draws air from inside the building for combustion. There is no dilution air, which means there is no additional air introduced into the combustion process.

Heat escapes the distribution system through convection, radiation, and heating fluid escaping from the ducts and pipes. Convection refers to the transfer of heat through the movement of fluid, such as air or water, which carries the heat away from the system. Radiation is the emission of heat in the form of electromagnetic waves, which can escape through walls and other surfaces. Heating fluid escaping from the ducts and pipes can also result in heat loss from the system.

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The intensity of chimney draft can be influenced by several factors. A taller chimney creates a greater pressure difference between the inside and outside of the chimney, which increases the draft. Hotter contents of the chimney also increase the draft, as the warm air rises more rapidly, creating a stronger upward flow. Additionally, lighter contents of the chimney, such as gases or smoke, contribute to a stronger draft because they are less dense and therefore more easily displaced by the surrounding air.

Cycling losses refer to the heat that is lost when the furnace or boiler cools down without effectively warming up the house. Additionally, if air continues to circulate through the heat exchanger after the burners shut down, heat will continue to flow into the building. These losses contribute to inefficient energy usage and can result in higher energy costs.

To prevent air loss through the duct systems, it is important to insulate the ducts with fiber glass insulation. This insulation should be wrapped all the way around the duct to ensure maximum coverage. Additionally, seams should be sealed using aluminum or vinyl tape to prevent any leaks. It is crucial to ensure that the end of each piece of tape points downward, as gravity will eventually pull it off if it points upwards.

Hot fires pollute less because when the fire is burning at a higher temperature, it is more efficient in converting the wood into heat, resulting in less unburned fuel and emissions. Feeding the stove more often helps efficiency because it maintains a consistent and higher temperature, allowing for better combustion and heat transfer. Feeding the stove less often would lead to lower temperatures and inefficient combustion, resulting in more emissions and less efficiency. Smoldering, on the other hand, does not minimize emissions or fuel-burning as it indicates incomplete combustion and can lead to higher emissions.

Electric zone heating can be a realistic option for reducing heating costs in homes. Zone heating allows for heating specific areas or zones of a home, rather than heating the entire space. This can be achieved through the use of electric heaters or thermostats that control the temperature in each zone individually. By only heating the areas that are being used, homeowners can save on energy costs. Additionally, electric zone heating can be more efficient than central heating systems as it eliminates the need to heat unused areas. Therefore, the statement that electric zone heating is not a realistic option for reducing heating costs in homes is false.

Overheating in furnaces can occur due to various reasons such as duct obstruction, blower failure, and excessive fuel input. Duct obstruction can restrict the flow of air, causing heat to build up in the furnace. Blower failure can prevent proper air circulation, leading to overheating. Excessive fuel input can result in an increased flame size and temperature, causing the furnace to overheat. These factors can individually or collectively contribute to the overheating of furnaces, posing potential risks and damaging the system if not addressed promptly.

The characteristics of radiant heating include the ability to turn on and off radian panels on a room by room basis, which helps to lower energy costs. It also offers draft-free heating, providing a more comfortable environment. However, there may be possible excessive room temperature fluctuations with radiant heating. Additionally, insulation flaws do not affect the effectiveness of radiant heating.

Factory build chimneys have multiple walls to allow for closer tolerance, keep combustion gases warmer, and avoid condensation in the chimney. The multiple walls create a barrier between the hot combustion gases and the outer environment, preventing heat loss and maintaining higher temperatures inside the chimney. This helps to avoid condensation of the gases, which can lead to corrosion and damage to the chimney structure. Additionally, the multiple walls provide better support and contribute to a rigid and durable construction, ensuring the chimney's stability and longevity.

The correct answer includes solutions for duct airflow problems such as cutting off interior doors to allow air to return from rooms without a return register, installing a new return duct leading from a hard-to-heat area directly to the furnace cabinet, and cleaning the register, blowers, and air conditioning coils. These solutions address issues related to inadequate airflow and blockages in the duct system, ensuring proper circulation and ventilation throughout the space.

Passive combustion air can be supplied from adjacent indoor spaces to the confined space. This means that the combustion air can be obtained from other areas within the building, ensuring a sufficient supply of air for the combustion process. Installing combustion air vents lower down can also help in providing fresh air for combustion. Additionally, installing sealed combustion, high efficiency furnaces and boilers can ensure that the combustion process is efficient and safe. These alternatives help to address the issue of providing adequate combustion air in confined spaces.

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