Finals Flashcards
which direction does heat always travel
warm to cold
how is a principal ventilation fan sized
number of bedrooms
define dew point
temperature at which moisture in the air begins to condense
what happens when air is heated
relative humidity decreases
what is not a type of hrv heat exchanger core
Pannel
why do we set a lower relative humidity in our home when the temperature drops
to prevent condensation
how do we measure intensity of heat
degrees measured by a thermometer
absolute zero is -273c, what else is it?
0 degrees kelvin
what method of heat transfer uses natural motion of a fluid medium
convection
one British thermal unit will raise?
55 cubic feet of air one degree farenheight
when does heat stop flowing between objects
when they reach the same temperature
what method of heat transfer requires physical contact between two bodies to occur
conduction
what is not a function of a make up air system
Control temperature of a home
a grain is a measure of
weight
what effects does low humidity have on people
sore throats and dry skin
sensible heat is
The amount of heat required to produce a change in temperature of a substance, but not a change of state.
Heat transfer by Radiation can be described as
The transfer of heat by energy waves similar to light waves.
hrvs can recover what percent of heat loss
85
what was the source of ventilation in the 70s
leakage
how many cfms for a master bedroom
20
what is heat
energy
how do we measure the volume of heat
btus
what is not a type of furnace
side boy
what are the 2 most common heating fuels in Alberta
natural gas and propane
what separates the air that circulates in a house from the products of combustion
heat exchanger
what is the efficiency of a furnace that has 15% of the heat it produces going up the chimney
85 perecent
what is the purpose of an inducer motor
to regulate combustion air
a furnace that condenses water vapour in its flue gases is known as what type of furnace
high efficiency
why do we filter the air upstream of the furnace
to protect the equiptmentb
what is the recommended humidity in the home
30-55 percent
a humidistat is activated by what
moisture
what does cfm measure
amount of air a fan will exhaust or supply in one minute
why do we reduce our duct in an extended plenum system
to keep pressure levels at what is required
what was the method of supplying combustion air for appliances prior to 1976
leakage
Special fresh air ventilation fittings must be used to connect the fresh air duct to the return trunk duct.
no
the combustion air termination is used to…
keep cold air from dropping into the furnace room
Both factory built chimneys and vents have a system of parts that are _____ by a recognized testing agency.
certified
Installations requiring you to run forced air heating under the concrete slab are known as:
under slab heating
roofjacks used on dryer vents are available without bird screens
true
the fitting used to connect the return air branch to the main duct is
nothing
The material used for venting of the fan to the outside must be metal duct with insulation and a vapour barrier, such as foilback insulation.
false
Furnaces require air to fuel the fire inside of them. This is called _____ air.
combustion
The entire underslab ducting system must slope (back to/level/away from) the furnace.
back to
When a return air branch run is finished on the bottom with a drywall ceiling, the bottom of the branch run is finished with:
drywall
_____ is the uncontrolled leakage of air from a building.
exfiltration
Type L-vent construction consists of:
an outer casing of Galvalume® / airspace / inner liner of stainless steel.
The ductwork coming off the plenum for underground heating installations will be round for strength and to make it easier to seal against moisture in the ground.
true
a 14x8 return air grill covers a 14x8 hole
true
what’s the heart of the hvac system
air recirculation fan
The air is ______ from the central heating or cooling unit by the supply air system.
distributed
he return air part of an HVAC system consists of the parts to bring air back from the _____ to the furnace.
occupied space
Rectangular duct takeoffs include all of the following except:
saddle takeoffs
duct ratio should not exceed
4 to 1
