California B2 Residential Remodeling – HVAC
Free Exam

A line for suction line icing is low charge.

If a compressor starts but runs short cycles, any of the following can be the cause:
- low line voltage
- additional current passing through overload protection
- suction pressure high
- high discharge pressure
- run capacitor defective
- compressor too hot
- motor windings are shorted
- compressor is tight
- discharge valve being defective

Saturated steam is water vapor at the boiling point of water at a given pressure. For example, steam at sea level at 212 degrees Fahrenheit would be saturated. Saturated steam is at the lowest temperature it can be - if it were any lower it would condense.

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

In a non-condensing furnace, air is drawn directly from the mechanical room into the combustion chamber. In this type of furnace the fuel and combustion air bum less efficiently than in a condensing furnace. It is the most basic and least expensive of the two types.

Water cooled condenser scale creates higher head pressure and loss in capacity.

The relative humidity is the amount of water vapor in the air divided by the amount of water in the air at saturation at the same temperature and pressure. Direct readings of relative humidity can be obtained from a hygrometer.

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

An unloader reduces starting power demand.

1 BTU per hour is equal to 12.96 ft. lb. per minute, 0.293 watt and .00039 HP.

A British Thermal Unit (BTU)is the quantity of heat required to raise the temperature of one pound of water 1 degree Fahrenheit. It is equal to 1055 joules, 1.055 kilojoules, and 252.15 calories.

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.

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

Thermostat differential set too closely is not a cause for the compressor running continuously. Causes for the compressor running continuously are the following:
-shortage of refrigerant
-compressor too small for load
-discharge valve leaks

Atmospheric pressure is the pressure of the weight of air and water vapor on the surface of the earth. At sea level it measures 14.7 PSI.