Tuesday, April 12, 2016

Insulation and Interior Inspection Section#1 Insulation and Ventilation Quiz#8

This study session covers the venting of living spaces, including heat recovery ventilators.

The estimated completion time for this study session is sixty minutes.
Objectives
At the end of this study session, you should be able to:
  • Give two reasons for venting house air.
  • Explain n one sentence why venting is more important now than it used to be.
  • List three general approaches to ventilation.
  • Explain in two sentences what is meant by a balance ventilation system.
  • List nine components of a heat recovery ventilator.
  • Explain in two sentences how heat is recovered in an HRV.
  • Explain in two sentences which ducts on an HRV should be insulated and why.
  • Explain in two sentences the function and location of flow measuring stations and balancing dampers.
  • Explain in two sentences where fresh air from an HRV may be introduced to a home.
  • Explain in two sentences where exhaust air for an HRV ,may be drawn from the home.
  • Describe six characteristics of good air intake points for an HRV.
  • Describe four characteristics of good air exhaust points for an HRV.
  • List three control methods for an HRV.
  • List four defrost methods for an HRV.
  • Describe in two sentences the common relationship between an HRV and forced-air furnace.

  • Question 1

    Needs Grading
    Ungraded
    Explain how heat is recovered in an HRV.
    Selected Answer:
    Heat is recovered from the exhaust air by transferring it to the cool inlet air. 
    Correct Answer:
    Correct
    The warm, stale air is brought in one side of the heat exchanger while the cool, fresh air is brought in the other side. As the warm air passes through, it gives up some of its heat indirectly to the cool air. The warm air cools down, and the cool air warms up.
    Response Feedback:[None Given]

  • Question 2

    Needs Grading
    Ungraded
    Explain the function and location of balancing dampers on an HRV.
    Selected Answer:
    Balancing dampers are usually provided on warm-side ducts, close to the HRV. These are needed to balance the system from time to time, so we don't over-pressurize or depressurize the home. 
    Correct Answer:
    Correct 
    Balancing dampers are located on the warm side ducts, and balance the system so we don?t over-pressurize or depressurize the house.
    Response Feedback:[None Given]

  • Question 3

    Needs Grading
    Ungraded
    Explain the function and location of flow measuring stations on an HRV.
    Selected Answer:
    Flow measuring station may be installed on the warm-side ductwork to allow balancing of the system. 
    Correct Answer:
    Correct 
    These allow for balancing the fresh air supply with the warm air exhaust. There is one on the fresh air supply, and one on the warm air exhaust, both on the warm side ductwork.
    Response Feedback:[None Given]

  • Question 4

    Needs Grading
    Ungraded
    Explain which ducts should be insulated on an HRV and why.
    Selected Answer:
    cold-side ducts should be insulated. Warm house air would create condensation on the surface of cold-side ducts. 
    Correct Answer:
    Correct
    1. The duct upstream of the HRV which brings cool fresh air in from outside, and the duct downstream of the HRV exhausting the warm, stale air outside should be insulated. 2. This is because we don?t want to use the ducts as a path for heat to escape out of the house.
    Response Feedback:[None Given]

  • Question 5

    Needs Grading
    Ungraded
    How is the operation of the HRV fan and the furnace fan related in many installations?
    Selected Answer:
    In modern installations, where the HRV is interconnected with furnace ductwork, the furnace fan is often interlocked with the HRV, so that when the HRV fan is operating, the furnace fan operates as well. 
    Correct Answer:
    Correct 
    The HRV and furnace fan operate continuously at low speed. Sometimes there is a switch to operate the HRV. Switching the HRV fan to high speed may also switch the furnace fan to high speed.
    Response Feedback:[None Given]

  • Question 6

    Needs Grading
    Ungraded
    List at least three different control methods for an HRV.
    Selected Answer:
    1. Thermostat
    2. Humidistat
    3. Dehumidistat
    4. Manual switches
    5. Timers
    6. Fan speed controls
    Correct Answer:
    Correct 
    1. Manual operation 2. Automatic operation, with timers or dehumidistats 3. Continuous operation
    Response Feedback:[None Given]

  • Question 7

    Needs Grading
    Ungraded
    List four different defrosting methods for an HRV.
    Selected Answer:
    1. The incoming supply air is preheated with an electric duct heater
    2. The exhaust air leaving the HRV is recirculated through the fresh air inlet. 
    3. The exhaust fan stops and the fresh air intake is blocked with the damper.
    4. The fresh air fan is shut off and the exhaust fan continues to move warm air through the HRV.
    Correct Answer:
    Correct 
    1. Incoming air preheated with an electric duct heater 2. Exhaust air recirculated through the fresh air inlet 3. Exhaust fan stops and fresh air intake is blocked 4. Fresh air fan stops and exhaust fan continues to move warm air
    Response Feedback:[None Given]

  • Question 8

    Needs Grading
    Ungraded
    List nine components of an HRV.
    Selected Answer:
    1. A cabinet
    2. A heat exchanger
    3. Inlet and exhaust fans
    4. A duct system
    5. Flow measuring stations
    6. Controls
    7. Air filters
    8. A condensate system
    9. A defrost system
    Correct Answer:
    Correct 
    1. Cabinet 2. Heat exchanger 3. Inlet and exhaust fans 4. A duct system 5. Flow measuring stations 6. Controls 7. Air filters 8. A condensate system 9. A defrost system
    Response Feedback:[None Given]

  • Question 9

    Needs Grading
    Ungraded
    List three general approaches to venting homes.
    Selected Answer:
    1. Build an exhaust system that will remove moist, polluted air from the house. Rely on natural infiltration and leakage to bring fresh air in.
    2. Force air into the house with a fan and push the stale air out of the house through cracks, holes and other incidental openings. 
    3. Create a balanced ventilation system controlling both the exhaust air and the fresh air supply. 
    Correct Answer:
    Correct 
    1. Exhaust 2. Supply 3. Balanced
    Response Feedback:[None Given]

  • Question 10

    Needs Grading
    Ungraded
    What is meant by a balanced ventilation system?
    Selected Answer:
    It uses both supply and exhaust air fans to maintain a neutral pressure inside the house
    Correct Answer:
    Correct 
    Controlling both the exhaust air and fresh air supply
    Response Feedback:[None Given]

  • Question 11

    Needs Grading
    Ungraded
    What is the principle of a heat recovery ventilator?
    Selected Answer:
    Improve energy efficiency in a balanced ventilation system
    Correct Answer:
    Correct 
    Improve the energy efficiency in a balanced ventilation system by controlling the pressure, and transferring heat from exhaust air to the fresh air supply
    Response Feedback:[None Given]

  • Question 12

    Needs Grading
    Ungraded
    What things would you be looking for on the fresh air intake for an HRV? (List six.)
    Selected Answer:
    1. Located 6 feet away from the exhaust
    2. 18 inches above grade
    3. 40 inches away from the corners of building, to avoid turbulent air. 
    4. Three feet from gas meters
    5. Well away from driveways and garages
    6. 3 feet from clothe dryer vents, exhaust fan vent, boiler vents, furnace vents, water heater vents, and fuel oil fill and vent lines. 
    Correct Answer:
    Correct
    1. Six feet away from exhaust 2. 18 inches above grade 3. 40 inches away from corners of buildings 4. Three feet from gas meters 5. Well away from driveways and garages 6. Three feet from dryer vents, furnace, boiler or water heater vents, and oil fill and vent lines
    Response Feedback:[None Given]

  • Question 13

    Needs Grading
    Ungraded
    What things would you be looking for on the outdoor exhaust outlet for an HRV? (List four.)
    Selected Answer:
    1. Away from fresh air intake and away from attics, garages and crawlspaces.
    2. Minimum 4 to 8 inches above grade. 
    3. Should be protected from rain and snow with a hood similar to the fresh air intake
    4. Screening may or may not be provided on the exhaust but it should have a damper that opens when the system is operating and closes tightly when the system is at rest. 
    Correct Answer:
    Correct 
    1. Away from fresh air intakes, attics, garages, and crawlspaces 2. Four to eight inches above grade, and protected from the elements with a hood 3. Screens 4. A damper that opens easily when the system is running
    Response Feedback:[None Given]

  • Question 14

    Needs Grading
    Ungraded
    Where is exhaust air typically drawn from within the home?
    Selected Answer:
    1. Kitchen and bathrooms
    2. Any other rooms in the house
    3. The return air plenum of a forced-air heating system
    Correct Answer:
    Correct 
    1. Kitchens and bathrooms, through exhaust fans (i.e. over stove) 2. Any other room in the house 3. The return (cold) air plenum of the furnace
    Response Feedback:[None Given]

  • Question 15

    Needs Grading
    Ungraded
    Where is fresh air from an HRV typically introduced to a home?
    Selected Answer:
    1. Through dedicated ducts to various rooms
    2 Cold air return plenum for the furnace
    Correct Answer:
    Correct 
    1. Through dedicated ducts to various rooms of the house 2. Into the cold air return plenum of the furnace
    Response Feedback:[None Given]

  • Question 16

    Needs Grading
    Ungraded
    Why do we want to change the air in houses? (List two reasons.)
    Selected Answer:
    1. Eliminating moisture, odors and other indoor air pollutants from the home
    2. Bring fresh air into the home
    Correct Answer:
    Correct 
    1. Eliminate moisture, odours and other indoor air pollutants 2. Bring fresh air into the home
    Response Feedback:[None Given]

  • Question 17

    Needs Grading
    Ungraded
    Why is a condensate drain necessary on an HRV? Is it always needed?
    Selected Answer:
    Condensation may happen at heat exchanger. No. Some HRVs don't have this. 
    Correct Answer:
    Correct 
    1. It is needed because the warm air is often cooled to the saturation point, and we need to handle that condensation 2. It is not needed on some ERV?s, which allow some moisture transfer as well as heat transfer
    Response Feedback:[None Given]

  • Question 18

    Needs Grading
    Ungraded
    Why is venting of house air more important now than it used to be?
    Selected Answer:
    Houses are tighter these days
    Correct Answer:
    Correct 
    Newer homes are more energy efficient and tighter. We get less air changes than we used to.
    Response Feedback:[None Given]

  • Question 19

    Needs Grading
    Ungraded
    Would an HRV be more important in a cold climate or a warm climate?
    Selected Answer:
    Cold climate
    Correct Answer:
    Correct 
    It is more important in a cold climate because the temperature differential between inside and outside is greater in the winter than summer.
    Response Feedback:[None Given]
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