G2 Gas Technician Module 13 Revised (2024/2025) Already Passed

G2 Gas Technician Module 13 Revised (2024/2025) Already Passed If inadequate combustion air is in a tightly sealed house what happens? Potenially leads to severe indoor air quality problems When changing a part of the heating system what 4 factors must the gas technician take into account? The building envelope, external environment, mechanical systems, and occupants What comprises the building envelope? Foundation and floor slabs, walls, roofs, and windows and doors What does the skin in the building envelope do? Protects the underlying material, maintains building integrity and reduces heat loss and heat gain What is the function of the vapour barrier? It is used to maintain proper humidity levels inside the house. In winter if not present the relative humidity will decrease causing it to feel colder then it is. What does insulation do? It is a poor conductor of heat and will prevent the ex filtration indoor heat to the outside. Name 2 signs of poor attic ventilation. Curling shingles in summer and icicle dams in the winter What is the function of the air barrier and where is it located? The air barrier is located between the bricks and wood studs. It allows moisture to be removed through venting. What are three types of building construcion? Balloon frame, Double/solid brick, platform (most common) How do occupants affect the building system? What are some actions that do this? As the more occupants increase the relative humidity will also increase. Cooking, bathing, smoking and plain old breathing. Mechanical impact consist of equipment and appliances within the building. Name a few. What should the gas tech consider? Water heaters, dryers, motors, fireplaces, wood stoves and air cleaners. They may require more combustion and ventilation air for air exhausted and used in combustion. External Environment affects on the building. If in a windy area it can cause cooling in the winter or a similar affect can be caused by tree shade in the summer What part of the building has the greatest heat loss? The walls due to them having a higher surface area then the rest of the building parts. How does an HRV work? Preheats fresh outdoor incoming air and expels stale warm indoor air. Used to improve air quality and be efficient at the same time. Master Bedroom - 20 cfm What cfm ventilation does the ontario building code require in the master bedroom and all other rooms? Other rooms - 10 cfm What is latent heat? Change in state with no change in temperature What is sensible heat? Change in temperature with no change in state If a house has poor ventilation what would the affect be on indoor air quality? High relative humidy Pollution sources in the building envelope Biological(mold, mildew, bacteria), chemicals (off -gasing of furniture, carpets and building materials), dust from inside and outside, any combination of these How would you control pollution? Remove the source, Balanced hvac throughout house, local exhausts (bath, kitchen), substitute chemicals for non-polluting ones, and Filtration is best for remove dust pollutants How can positive pressure affect the building envelope? Conditioned air will be forced from the building envelope, inefficient How does negative pressure affect the building envelope? Potential concerns? Outdoor air will be sucked into the house by path of least resistance. Sometimes this is your appliances exhaust vent. Can lead to spillage and CO poisoning What is stack effect in building pressure? Hot air will rise to the top of the building and escape through the cracks. This may cause negative pressure in the basement starving gas fired appliances What is mechanical or natural ventilation effect? Mechanical exhausting of building air can cause a negative pressure situation by means of the path of least resistance. This can be your gas fired appliance exhausts causing spillage. What is Duct Effect? Improperly designed or installed HVAC can cause air to leak from ducts short cycling the furnace. This can lead to poor occupant comfort and removal of combustion air from appliance rooms. What is Wind Effect? Buildings exposed to high winds can cause positive pressure on the windward side and negative on the leeward side. Can lead to occupant discomfort and starved gas fired appliances. What is Flue Effect? Appliance venting is often path of least resistance. So reconsider using natural draft appliances if a large capacity air-exhausting appliance is used in the structure. What principal does a natural draft appliance rely on? The buoyancy of hot air. What is the most common cause of flue gas spillage into the building envelope? Negative pressure. Name 3 things that can cause spillage? Negative pressure, down draft and blocked venting. How will a poorly insulated build effect furnace run time increase/decrease? increase How is insulation added to balloon type construction? Blowing into attic or wall cavity Heat and moisture will always from from a area of ________ concentration to a area of _________ concentration. From high to low What is the most effective way to reduce heat loss? Seal air leaks Relative humidity increases/decreases when air is heated? Decreases Introducing ventilation air in the winter will increase/decrease relative humidity? Decrease Best way to reduce odors from inside the building is? Ventilate New construction requires combustion air be brought into the furnace room? T/F? True What energizes the high speed fan in an HRV? Humidistat How do filters clean air? Impingement, straining and electrostatic precipitation What principal is electrostatic filtration based on? Opposites attract A method for minimizing negative pressure in a combustion appliance? By using a sealed combustion appliance What does a passive depressurization test measure? The buildings differential pressure When sizing combustion air what must a gas tech know? Appliance btuh input, type of building construction, and method of venting flue products What is required when an appliances input is greater than 400000 btuh? Outside air be brought in for combustion and ventilation What year did the OBC start making houses tighter? 1993 Can appliance with a draft hood use combustion air from inside the building structure? Yes What is the difference in an ERV and HRV ERV uses an aluminum core giving greater heat transfer and moisture control. HRV uses a plastic core What speed does a HRV use for continuous ventilation? Low speed