Chapter 12: Air-Conditioning & Heat Pumps

If so, what is it's purpose?

1. A trap may be required if the condensate pan is upstream of the house air fan because the water is under negative pressure. 2. if the condensate is allowed directly into waste plumbing, a trap is required.

List 3 common configurations of evaporator coils.

1. A-coil 2. slab coil 3. vertical coil

List 4 common expansion device problems.

1. capillary tube defect 2. thermostatic expansion valve connections loose 3. clogged orifice 4. expansion valve sticking

List 4 condenser problems.

1. dirty 2. damaged or leaking 3. corrosion 4. dryer or heater exhaust too close

List 4 common condenser-fan problems.

1. excessive noise/vibration 2. inoperative 3. corrosion or mechanical damage 4. obstructed air flow

List 5 common refrigerant line problems.

1. leaking 2. damage 3. missing insulation 4. lines too warm or cold 5. lines touching each other

List 6 common evaporator problems.

1. no access to coil 2. dirty 3. frost 4. top of evaporator dry 5. corrosion 6. damage

What kind of temperature drop would you expect to find in the house air as it passes over the evaporator coil?

15-20 degrees

How many square feet can 1 ton of air-conditioning cool in Florida?

450-700 square feet

What is the typical warranty period for a compressor?

5 years typically

You should not operate the heat pump in the cooling mode when the outdoor temperature is below _________.

65 degrees

You should not operate the heat pump in the heating mode when the outdoor temperature is above _________.

65 degrees

How many square feet can 1 ton of air-conditioning cool in Michigan?

700-1,000 square feet

How long do air conditioning compressors typically last in your area?

8-10 years: southern US 10-15 years: moderate climates 15-20 years: northern climates

Describe the function of a thermostatic expansion valve.

A TXV or TEV acts as a more precise expansion device on larger air conditioners or heat pumps.

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 (must be an air gap) Unacceptable: Into the granular fill beneath the basement floor slab Into the waste plumbing stack

Do condensate drain lines ever have a trap?

Condensate lines from the primary pan may or may not have a trap. Lines from secondary pans should never be trapped.

Heat pumps are generally sized base on ______________.

Cooling load

Refrigerant lines are usually made of ____________.

Copper

List at least 8 clues that would suggest you are looking at a heat pump rather than a central air conditioning system.

Data plate may say "HP" or "Heat Pump" Thermostat has an emergency heat setting Both refrigerant lines are insulated A reversing valve is present The compressor is indoors and it's an air-to-air system. The presence of an outdoor thermostat is connected to control wiring. If it is winter and the unit is operating, it's a heat pump. You find a two-stage thermostat. You find two expansion devices.

List 8 common compressor problems.

Excessive noise/vibration Short cycling or running continuously Out of level Wrong fuse or breaker size Electric wires too small Inoperative Inadequate cooling

Compressors are typically located indoors on an air-to-air split system air conditioning system. True or False?

False

Evaporator coils should be upstream of furnace heat exchangers. True or False.

False

High level returns are more appropriate for heating than cooling. True or False?

False

Oversized distrubution ductwork is a common problem with central air conditioning. True or False?

False

Oversized ducts are a common problem. True or False?

False

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. True or False?

False

The larger line contains liquid. True or False?

False

The smaller line is called the suction line. True or False?

False

Where is the evaporator fan typically located in a split system?

Indoors

List 7 common problems with thermostats.

Inoperative Poor location Not level Loose Dirty Damaged Poor adjustment/calibration

Ducts passing through unconditioned spaces should as attics and crawlspaces should be ____________.

Insulated with appropriate vapor barriers

What is the function of a sump or a crankcase heater?

It keeps the oil at the base of the compressor warm enough to boil off the refrigerant.

The implication of an oversized heat pump during the summer months is what?

It would cool the house down too fast without dehumidifying the air, resulting in a cool, damp environment.

Which line should be warm when the system is operating?

Liquid line (small uninsulated one)

List 10 items that affect the amount of air-conditioning needed in a home.

Outdoor temp Outdoor humidity Insulation level in the house Single-, double-, triple-pane windows Whether windows are low e Whether window coverings are open Amount of shading from trees Roof overhang Awnings or buildings nearby Amount of heat generated inside by people and equipment Amount of east- and west-facing glass

List 7 common heat pump problems distinct from common air-conditioning problems.

Oversized for cooling and/or undersized for heating. Heat pump inoperative in heating or cooling mode Poor outdoor coil location Outdoor coil iced up Airflow problems No backup heat, or backup heat does not work Old

Which line should be cold when the system is operating?

Suction line (large insulated one)

Describe the function of a capillary tube.

The capillary tube acts as an obstruction in the line, thereby reducing the temperature and pressure of the liquid refrigerant.

Where is the condenser fan in a split system located?

The condenser fan is outdoors in the condenser unit.

What is the typical inlet and outlet temperature of air across the condenser fan?

The inlet temp is outdoor air temp, and outlet temp is roughly 15-20 degrees higher than the outdoor temp

List 5 possible causes of leaking condensate drain pans.

The pan may be cracked or have an open seam in it. The opening to the drain line may be obstructed. The drain line may be missing or disconnected. The pan may not be sloped properly, allowing water to overflow rather than run to the drain. The pan may be rusted through. The pan may not be properly located below the coil. The pan may be filled with debris, restricting the amount of water it can hold.

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 connections.

A compressor can be thought of as a pump. True or False?

True

An undersized air conditioner is better than an oversized one. True or False?

True

The larger line is called the return line. True or False?

True

The typical temperature drop from outdoors to indoors with a properly operating air-conditioning system would be about 15 degrees. True or False

True

When is an auxiliary condensate drain pan needed?

When the evaporator coil is located in an attic or anywhere over a finished living space.

The evaporator coil in a split system is typically located _______________.

indoors (above the furnace)

List 3 common condensate pump problems.

inoperative; leaking; poor wiring

The condenser coil in a split system is typically located _______________.

outdoors

The condenser fan in a split system is located _________________.

outdoors

What are condensate drain lines usually made of?

plastic or copper

Which line should be insulated?

suction line