Module 2 Test Cooling Study Cards Flashcards
List 10 items that affect the amount of air conditioning needed in a home.
outdoor temp, outdoor humidity, insulation levels, single/double/triple window panes, whether windows are low e, window coverings open/closed, amount of shade from trees, roof overhang, awnings, amount heat generated inside by people, amount of east/west facing glass.
How many square feet can one ton of A.C. cool in Florida?
450 to 750 sgft
How many square feet can one ton of A.C. cool in Michigan?
700 to 1000 sqft
Oversized distribution ductwork is a common problem with central A.C. T/F
False
An undersized AC is better than an oversized one. T/F
True
The typical temperature drop from outdoors to indoors with a properly operating AC system would be about 15 degrees F. T/F
True
What kind of temperature drop would you expect to find in the house air as it passes over the evaporator coil?
15-20 degrees F
A compressor can be thought of as a pump. T/F
True
Compressors are typically located indoors on an air-to-air split system AC system. T/F
False
What is the function of a sump or crankcase heater?
It keeps the oil at the base of the compressor warm enough to boil off the refrigerant
List 8 common compressor problems:
excessive noise/vibration, short cycling/running continuously, out of level, wrong fuse or breaker size, electric wires too small, missing electrical shut off, inoperative, inadequate cooling
The condenser coil in a split system is typically located_.
outdoors
The evaporator coil in a split system is typically located _.
indoors (above furnace)
The condenser fan in a split system is located __.
outdoors
List 4 condenser problems
dirty, damaged or leaking, corrosion, dryer or water heater exhaust too close
List 3 common configurations of evaporator coils.
A-coil, slab coil, vertical coil
Evaporator coils should be upstream of furnace heat exchangers. T/F
False
List 6 common evaporator problems:
no access to coil, dirty, frost, top evaporator dry, corrosion, damage
In 1 sentence, describe the function of a capillary tube
The capillary tube acts as an obstruction in the line, reducing the pressure and temperature of the liquid refrigerant
In one sentence, describe the function of a thermostatic valve.
A TXV, or TEV acts as a more precise expansion device on larger AC or heat pumps.
List 4 common expansion device problems
capillary tube defects, thermostatic expansion valve connections loose, clogged orifice, expansion valve sticking
List 5 possible causes of leaking condensate drain pans.
- pan cracked or open seam
- opening to drain line may be obstructed
- drain line may be missing or disconnected
- pan may not be sloped properly, allowing water to overflow rather than run to the drain
- pan may be rusted through
- pan may not be properly located below the coil
- pan may be filled with debris, restricting the amount of water it can hold
When is an auxiliary condensate drain pan needed?
auxiliary pan is needed when the evaporator coil is located in attic, or anywhere over a finished living space.
What are condensate drain lines usually made of?
plastic or copper
Do condensate drain lines ever have a trap?
condensate line from the primary pan may or may not have a trap. Lines from secondary pans should never be trapped.
If condensate drain lines have a trap, what is its purpose?
- trap may be required if the condensate pan is upstream of the house air fan, b/c the water is under negative pressure.
- if the condensate is allowed directly into waste plumbing, a trap is required.
List 2 acceptable discharge points for condensate drain lines and one generally unacceptable discharge point.
acceptable: outside the building directly into the ground, near the basement floor drain
unacceptable: into the granular fill beneath the basement floor slab, into the waste plumbing stack
List 3 common condensate pump problems
inoperative, leaking, poor wiring
Refrigerant lines are usually made of:
copper
The larger refrigerant line contains a liquid. t/F
False
The smaller refrigerant line is called the suction line. T/F
False
The larger refrigerant line is called the return line. T/F
True
List 5 common refrigerant line problems:
- leaking
- damage
- missing insulation
- lines too warm or cold
- lines touching each other
How would you normally identify a leak in a refrigerant line visually?
This may be identified by an oil residue below the line set, typically at valves or coil connection
Which line should be cold when the system is operating?
suction line
Which line should be warm when the system is operating?
liquid line
Which refrigerant line should be insulated?
suction line
Where is the condenser fan in a split system?
outside in the condenser unit
What is the typical inlet & outlet temperature of air across the condenser fan?
inlet temperature is outdoor air temperature, & outlet temperature is roughly 15 to 20 degrees F higher than the outdoor temperature
List 4 common condenser fan problems.
excessive noise/vibration, inoperative, corrosion or mechanical damage, obstructed air flow
Where is the evaporator fan typically located in a split system.
Indoors
The amount of air that must cross an evaporator coil in a heating climate is less than the amount of air that must cross a conventional furnace heat exchanger coil. T/F
False
Oversized ducts are a common problem. T/F
False
High level returns are more appropriate for heating and cooling. T/F
False
Ducts passing through unconditioned spaces such as attics or crawlspaces should be___.
Insulated, with appropriate vapor barriers
List 7 common problems with thermostats.
- Inoperative
- poor location
- not level
- loose
- dirty
- damaged
- poor adjustment/calibration
How long do AC compressors typically last in your area?
- 8 to 10 years-southern USA
- 10 to 15 years-moderate climates
- 15 to 20 years-northern climates
What is the typical warranty period for a compressor?
5 years typically
Heat pumps are generally sized based on the:
a. heating load
b. cooling load
c. other
cooling load
The implication of an oversized heat pump during summer months is:
It would cool the house down too fast without dehumidifying the air, resulting in a cool, damp environment
You should not operate the heat pump in the heating mode when the outdoor temperature is above __
65 degrees F
You should not operate the heat pump in the cooling mode when the outdoor temperature is below__
65 degrees F
List at least 8 clues that would suggest that you are looking at a heat pump rather than a central AC system.
- data plate may say “HP” or Heat Pump
- Thermostat has an emergency heat setting
- both refrigerant lines are insulated
- presence of a reversing valve
- compressor is indoors & its
‘s an air-to-air system - presence of an outdoor thermostat connected to control wiring
- If it is winter & the unit is operating, it’s a heat pump
- You find a two-stage thermostat
- You find 2 expansion devices
