HVAC Gas 2 Test

Building System Components

• Key components include the building envelope, external environment, mechanical systems, and occupants.

Occupancy and Humidity

• As the number of occupants increases in a tightly-constructed building, relative humidity increases.

Winter Vapor Barrier

• In winter, if a vapor barrier is not continuous, heat gain will increase indoors.

Poor Insulation Effects

• Poor building insulation could lead to increased fuel consumption.

Building Skin Purpose

• A building's skin protects the underlying materials.

Forced Air Furnace Heat Transfer

• Forced air furnaces utilize conductive heat transfer.

Conduction Defined

• Conduction is the transfer of heat from particle to particle.

Sources of Building Heat Gain

• Windows, doors, and walls are sources of heat gain in a building.

Wind Effect on Buildings

• The wind's effect involves positive pressure on the windward side and negative pressure on the leeward side.

Causes of Excess Moisture

• Excess moisture is caused by new construction materials, open sump pits, and poor air barriers.

Ventilation in Heating Season

• Introducing ventilation air in the heating season decreases the moisture content.

Effect of Heating Air

• When air heats up, relative humidity decreases.

Vapor Barrier Placement

• Vapor barriers should be installed on the warm side of the insulation.

Air Barrier Purpose

• Air barriers prevent moisture travel through building walls.

Common Building Construction

• Today, platform construction is the most common building construction type.

Reducing Heat Loss

• Reducing heat loss is most effectively achieved by sealing air leaks.

Sealing Air Leaks for Heat Loss

• Windows are the most important to seal against air leaks to prevent heat loss.

Sealing Air Leaks Method

• Caulking is the best way to seal against air leaks.

Combustion Requirement

• Air is the most important element for proper combustion in a gas appliance.

Cause of Negative Pressure

• A lack of makeup or combustion air causes negative pressure in a building.

Flue Gas Spillage Cause

• Negative air pressure caused by mechanical systems is the most common cause of flue gas spillage from gas appliances.

Source of Replacement Air

• If combustion air comes from inside, it's replaced by outside air through infiltration.

Depressurization Testing Instrument

• A magnehelic gauge performs passive depressurization tests.

Minimum Ventilation in Bedrooms

• The Ontario Building Code requires a minimum ventilation air supply of 10 cfm in master bedrooms.

Harmful Effects of Moisture

• Excessive moisture can harm building construction.

Odor Removal

• The best way to remove household odors is to ventilate the house.

Dust Removal

• Filtration is the most effective method for removing dust.

Air Leaving a House

• Air leaves a house through exfiltration.

Air Entering a House

• Air enters a house through infiltration.

Bathroom Fan Function

• Bathroom exhaust fans reduce excessive moisture buildup.

Combustion Air Opening Size

• The minimum size of an outdoor combustion air opening for an appliance with a draft hood having an input of 125,000 BTU in a structure with a continuous vapor barrier, leakage area of 0.05 m2, and dimensions of 10 ft x 10 ft x 20 ft is 18 square inches (116 cm2).

Combustion Air Opening Size (No Draft Hood)

• For an appliance without a draft hood and with an input of 50,000 BTU in a structure (leakage area > 0.05 m2, dimensions 10 ft x 10 ft x 20 ft), the minimum combustion air opening size from outdoors is 0 square inches (0 mm2).

Combustion Air Opening Size (Two Appliances)

• Two appliances in a 10 ft x 10 ft x 20 ft structure (leakage area > 0.05m2), the furnace has a draft hood and an input of 50,000 BTU and the second appliance has an input of 75,000 BTU but does not have a draft hood. The required combustion air opening size is 9 square inches (5800 mm2)

Outdoor Air Supply Opening Location

• Air supply openings from the outdoors should be located at least 12 inches (300 mm) above the outside grade level.

Air Supply Duct Termination

• Air supply ducts providing outside air should terminate within 1 foot above and 2 feet (0.3 m, 0.6 m) horizontally from the burner level of the highest input appliance.

Combustion Air Dampers

• Automatic combustion air dampers must be interlocked with the burner control system to ensure the main burner operates only when dampers are fully open.

Baffle Effect on Air Supply

• A baffle is required, it cannot reduce the required free area of the opening or 0%.

Combustion Air Duct Size

• The smallest dimension of a combustion air supply duct must be at least 2" (50 mm).

Air Supply Opening Dimensions

• For all appliances with draft diverters in a newer building, with close-fitting windows and doors, vapor barrier, and drywall, with a 310,000 BTU total input, the minimum required air supply opening dimension is 47 square inches (30000 mm2).

Negative Pressure Cause

• Volume of air leaving the building exceeding volume of air entering the building leads to negative building pressure.

Negative Pressure Effect on Venting

• Negative pressure may cause a downdraft condition at gas appliances.

Minimum Combustion Air

• A boiler room contains two hot water boilers each firing at 750,000 BTU. A single water heater firing at 270,000 BTU and one also firing at 30,000 BTU. The minimum required combustion air opening is 200 square inches.

Grill Size for Boiler Room

• A boiler room as detailed above requires a grill needs to have an 80% free area, the grill size should be 250 square inches.

Ventilation Air Opening Location

• Ventilation air openings for gas appliances shall be at the highest practical point communicating outdoors.

Furnace Room Ventilation

• A furnace and conventional water heater are enclosed in the new furnace room. A house ~25 years old has a door separating the space from upper levels. Furnace is 100,000 BTU, water heater is 25,000 BTU, the enclosure is 10'x20'x7' with structure dimensions of 20'x30'x7'x3(levels). Air opening required for the furnace door is 18 square inches.

Supply Opening Dimension in New Buildings

• A recently constructed building with close-fitting windows, vapor barrier, and drywall, a single water heater with a draft diverter firing at 48,000 BTU, requires a supply opening of 0 square inches.

Recommended Humidity

• To maintain the proper indoor air quality and structural integrity of the house, the recommended relative humidity range is between 30% and 50%.

Air Changes per Hour

• A residence requires a minimum of 1 ACH to maintain a healthy indoor air quality.

Reducing Mould Growth

• Covering earthen floors and open water surfaces (sumps, aquariums, etc.) will have the greatest effect on reducing mould.

Elevated CO2 Causes

• Elevated carbon dioxide levels may be caused by occupant activities, spillage of flue gasses, and lack of ventilation.

Radiant Heating Systems

• Recommend the installation of a mechanical ventilation system if a customer reports "wet walls and windows" after a direct vent radiant heating system is installed.

"Systems Approach"

• The "systems approach" considers how fuel-fired appliances affect and are affected by the occupants, outside environment, and the building.

Stack Effect Cause

• The "stack effect" results from the mechanical ventilation system.

Flue and Ventilation Effect

• The flue and ventilation effect in a building results increases infiltration of air to replace that which is exhausted through vents and exhaust devices.

Distribution Effect

• A forced air furnace with no return air openings in the furnace room would be expected to cause problems due to the "distribution effect".

Negative Building Pressure

• The maximum negative building pressure a natural draft vented appliance should be exposed to is -5 Pa (-0.02" WC).

Effect of Temperature Difference on Stack

• When the temperature difference between the indoors and outdoors increases, the stack effect always increases the draft action of vented appliances.

Problems with Stack effect

• Seal the lower building envelope with an air barrier and caulking to limit the problems caused by the "stack effect" on vented appliances

Limiting Problems Caused by Distribution Effect

• To limit the problems caused by the "distribution effect", one should balance return and supply air, ensure a tight seal around the furnace filter/blower door, and seal the ductwork around the furnace area.

Negative Building Pressure

• One can avoid pressure-induced backdrafting by utilizing sealed combustion, direct vent appliances.

Furnace Replacement

• For a house requiring a furnace replacement, with a heat loss requirement of 100,000 BTU/h, the best choice is a 120,000 BTU/h input furnace with an AFUE rating of 85%.

Depressurization Test

• Conducting depressurization tests on a house is helpful for determining the potential for pressure-induced backdrafting.

Gas Solenoid Symbol

• Symbol "6" represents the gas solenoid.

Dryer Heat Thermostat Symbol

• Symbol "1" represents the dryer heat thermostat.

Dryer High Limit Switch Symbol

• Symbol "3" represents the dryer high limit switch.

Dryer Centrifugal Switch Symbol

• Symbol "7" represents the dryer centrifugal switch.

Dryer Pilot Switch Symbol

• Symbol "2" represents the dryer pilot switch.

Timer Motor Symbol

• Symbol "5" represents the timer motor.

Dryer Motor Operation

• A centrifugal switch proves a dryer motor is running.

Moisture Exhaust Ducts

• Moisture exhaust ducts from clothes dryers should never be screwed together.

Dryer Exhaust Duct Termination

• A dryer moisture exhaust duct should terminate 36'' (90cm) from a service regulator.

Venting a Gas Dryer

• A gas dryer has to always be vented outdoors.

Joining Dryer Ducts

• Ducts on a residential dryer shall be joined with duct tape.

Shutting Off Spark Igniter

• The ignition sensor shuts off the spark igniter in a spark ignition dryer.

Modulating Oven Control

• The bypass or minimum burner flame maintains a minimum oven temperature on a direct acting modulating oven control.

Therm-O-Disc Activation

• A Therm-O-Disc on a self-cleaning oven activates at 650 degrees F (340 degrees C).

Corrugated Connector Length

• The maximum length of a corrugated flexible connector installed on a range is 6 feet.

Clearance for Domestic Clothes Dryer

• A domestic clothes dryer requires 6 inches (15 cm) of clearance from the sides to combustible materials, unless otherwise approved.

Range Protection from Combustible Material

• If a range is certified to have zero side clearance on either side from combustible material, then 28 MSG (0.3 mm) sheet metal spaced out 0.25 inch (6 mm) of protection is needed.

Minimum Clearance Range

• The minimum clearance to combustible materials from the sides of a domestic range, unless otherwise specified, is 6 inches (150 mm).

Mantle of a Gas Lamp

• The mantle of a gas lamp changes a blue flame to a luminous flame.

Gas Lamp Clearance

• An 18 inches (450 mm) is the required clearance above a pendant type gas lamp.

Lava Rocks in Barbeque

• The burner will burn out prematurely if too many lava rocks are in the rack of a barbeque.

Barbeque connectors

• An approved hose gas connector may be used to connect a barbeque to house piping.

Component Components of a Gas refridgerator

• Main components of Gas-fired refrigerator: generator, evaporator, absorber, condenser

Propane Refridgerator Usage

• Use of a propane refrigerator is not permissible in a recreational vehicle while the vehicle is in motion.

Propane Refridgerator Installation

• An approved direct vent type or equivalent propane refrigerator can be installed in a recreational vehicle.

Refidgerator Service Schedule"

• A refrigerator must be serviced and cleaned every year or as suggested by the manufacturer.

Refrigerator Operation

• A three-way refrigerator runs on propane, 12 volts d., and 120, volts a.c/.

Evaporator Frost

• When a refrigerator develops excessive frost on the evaporator, it becomes less efficient.

Heater Installation

• To be installed in a bathroom, a room heater should use a direct vent heater.

Room Heater Installation Standards

• A room heater installed in either a sleeping area or a public area shall be equipped with a regulator.

Gas Log Fireplace

• Installing a gas log fireplace: secure the chimney damper in the open position.

Combustibles Clearance

• The required clearance from combustibles above a free-standing radiant room heater is 36"(900 mm).

Bedroom Installation

• Natural draft decorative appliances should only be installed in bedrooms if certified for it.

Wall Furnace Vent

• For a wall furnace concealed in a partition wall, a BW vent must be used.

Construction Heater Procedure

• Prior to using a certified hose to connect a construction heater to temporary piping, a lever handle shut off valve is installed upstream of the hose.

Fireplace Insert Installation

• When installing a fireplace insert, provide a metal chimney liner.

Use of Infra-red Heaters

• An unvented infra-red heater can be installed in industrial, warehouse, or commercial appliances.

Dirt Pockets

• Dirt pockets are not required on gas logs, room heaters, or decorative appliances.