Tamu Cosc 325 exam 2
Houston/92 Questions and
Solutions
BTU - - British Thermal Unit is the amount of heat required to raise 1 lb of
water 1 degrees F.
- Ton - - amount of heat required to melt a ton of ice (2000 lb) over a 24-
hour period.
· 1 ton = 12,000 Btu/hr or 288,000 Btu per 24-hour period
- Humidity - - amount of moisture (water vapor) in the air
· Comfortable relative humidity is about 50%
- Air Velocity - - speed at which air moves from one point to another
· Measured in feet per minute (fpm)
· 40 fpm is ideal
- Registers - -
- Filtration - - process of removing particles and contaminants from air that
circulated through an air distribution system
· Located in air ductwork where air enters the heating and cooling equipment
- Ventilation - - process that occurs when outdoor air is brought into a
building
- Exhaust & make up air - - Building with exhaust has no recirculation
· Make up air: is air that is used to replace air that is lost to exhaust
- IAQ (Indoor air quality) - - is the quality of the air in the building space
· CO2 levels: well ventilated - 600 to 1000 AVG. 800
- ASHRAE (American Society of Heating, Refrigerating, and Air-conditioning
Engineers, Inc.) - - · Recommends that ventilation be increased in all
residential, commercial, and industrial buildings
- Dry bulb temperature - - measurement of a sensible heat
- Latent heat - - heat required to change liquid into a gas
- Relative Humidity - - is the amount of moisture in the air compared to the
amount it would hold if the air were saturated
, - Dew point - - The temperature below which moisture in the air begins to
condense.
- Enthalpy: - - the total heat contained in a substance measure from a
baseline of 32 degrees F and is the sum of sensible heat(dry bulb
temperature) and latent heat
- Psychrometric Chart - - chart that defines the condition of the air for any
given property
- Forced Air System - - forced air heating system is a heating system that
uses air to carry heat. The air is heated and distributed through a building to
control the temperature in the building space
- Furnace - - self-contained heating unit that includes a blower, burners, and
heat exchanger or electric heating elements, and controls.
- Types of Blowers - - Blower fan, centrifugal blower, axial flow blower
- Propeller Fan - - mechanical device that consists of blades mounted on a
central hub
- Centrifugal blower - - · consists of a scroll, blower wheel, shaft, and inlet
vanes
o Scroll is a sheet metal enclosure that surrounds the blower wheel
o Blower wheel is a sheet metal cylinder with curved vanes along its
perimeter
- Axial flow blower - - a blower that contains a blower wheel, which works
like a turbine wheel
- Venturi: - - restriction that causes increased pressure as air moves
through it
- Static Pressure - - pressure that acts through weight only with no motion
· Expressed in inches of water column
- Heat exchanger - - any device that transfers heat form one substance to
another without allowing the substances to mix
- Low-efficiency filters - - filters that contain filter media made of fiberglass.
Remove 40%
- Medium-Efficiency Filters - - · filters that contain filter media made of
dense fibrous mats or filter paper. Remove 40%-80%
Houston/92 Questions and
Solutions
BTU - - British Thermal Unit is the amount of heat required to raise 1 lb of
water 1 degrees F.
- Ton - - amount of heat required to melt a ton of ice (2000 lb) over a 24-
hour period.
· 1 ton = 12,000 Btu/hr or 288,000 Btu per 24-hour period
- Humidity - - amount of moisture (water vapor) in the air
· Comfortable relative humidity is about 50%
- Air Velocity - - speed at which air moves from one point to another
· Measured in feet per minute (fpm)
· 40 fpm is ideal
- Registers - -
- Filtration - - process of removing particles and contaminants from air that
circulated through an air distribution system
· Located in air ductwork where air enters the heating and cooling equipment
- Ventilation - - process that occurs when outdoor air is brought into a
building
- Exhaust & make up air - - Building with exhaust has no recirculation
· Make up air: is air that is used to replace air that is lost to exhaust
- IAQ (Indoor air quality) - - is the quality of the air in the building space
· CO2 levels: well ventilated - 600 to 1000 AVG. 800
- ASHRAE (American Society of Heating, Refrigerating, and Air-conditioning
Engineers, Inc.) - - · Recommends that ventilation be increased in all
residential, commercial, and industrial buildings
- Dry bulb temperature - - measurement of a sensible heat
- Latent heat - - heat required to change liquid into a gas
- Relative Humidity - - is the amount of moisture in the air compared to the
amount it would hold if the air were saturated
, - Dew point - - The temperature below which moisture in the air begins to
condense.
- Enthalpy: - - the total heat contained in a substance measure from a
baseline of 32 degrees F and is the sum of sensible heat(dry bulb
temperature) and latent heat
- Psychrometric Chart - - chart that defines the condition of the air for any
given property
- Forced Air System - - forced air heating system is a heating system that
uses air to carry heat. The air is heated and distributed through a building to
control the temperature in the building space
- Furnace - - self-contained heating unit that includes a blower, burners, and
heat exchanger or electric heating elements, and controls.
- Types of Blowers - - Blower fan, centrifugal blower, axial flow blower
- Propeller Fan - - mechanical device that consists of blades mounted on a
central hub
- Centrifugal blower - - · consists of a scroll, blower wheel, shaft, and inlet
vanes
o Scroll is a sheet metal enclosure that surrounds the blower wheel
o Blower wheel is a sheet metal cylinder with curved vanes along its
perimeter
- Axial flow blower - - a blower that contains a blower wheel, which works
like a turbine wheel
- Venturi: - - restriction that causes increased pressure as air moves
through it
- Static Pressure - - pressure that acts through weight only with no motion
· Expressed in inches of water column
- Heat exchanger - - any device that transfers heat form one substance to
another without allowing the substances to mix
- Low-efficiency filters - - filters that contain filter media made of fiberglass.
Remove 40%
- Medium-Efficiency Filters - - · filters that contain filter media made of
dense fibrous mats or filter paper. Remove 40%-80%
