California B2 Residential Remodeling – HVAC
Free Exam

Each 5 percent reduction in air flow results in a 1 percent reduction in capacity.

If the compressor is not starting and there is no hum, any of the following can be a reason:
-open power switch on blown fuse
-broken electrical connection
-the overload is stuck
-frozen defective
-tight compressor
-high head pressure
-thermostat set too high
-solenoid valve closed

Insufficient gas in the system is not a cause of the compressor having high suction pressure. Causes for the compressor having high suction pressure include the following:
-compressor too small for evaporation
-overfeeding of expansion valve
-leaky suction valves

A line for suction line icing is low charge.

A leak in a length of copper tubing should be repaired by brazing over the leak.

When working with wiring controls, the indoor fan motor will turn on when you join the red wire to the green wire.

As water evaporates, it cools. This is the basic principal behind evaporative cooling. The wet bulb temperature is caused by the evaporation of water at a given pressure.

Ducts come in a variety of shapes and sizes. The difference in the elbows comes mostly from the manufacturing technique and the materials used. Turning vanes are used to present a smoother turning radius.

When working with wiring controls, the compressor will turn on when you join the red wire to the yellow wire.

It takes a certain amount of heat to raise the temperature of the air. The amount of heat needed to warm a given amount of air is called the specific heat. For most HVAC applications, the specific heat of air at one atmosphere can be taken at 0.24 Btu/lb. degrees F. This means it takes 0.24 Btu to raise the temperature of one pound of air by one degree Fahrenheit.

The average winter temperature difference is found by subtracting the average low temperature from the average high temperature.

When installing metal ducts in the ground, it is necessary to ensure that they are not in or within four inches of the ground.

1 boiler HP is equal to 33,480 BTU per hour, 34.5 lb. water evap. per hour from and at 212 degrees Fahrenheit, and 9.8 KW. 1 KW equals 3413 BTU per hour.

The temperature at saturation for a given humidity ratio and given pressure is the dew point. If moist air encounters a surface at or below the dew point, water will condense out of the air. This is how a cooling coil removes water from the supply air stream to a building.

The maximum amount of carbon monoxide allowed in a building is 20 PPM.