Which of the following is NOT a safety device that manufacturers use to provide extra protection for the compressor on condensing units with complex control systems?

For each sentence, mark True or False. 1. Refraction is the change in direction of wave propagation due to a change in transmission medium. 2. The index of refraction compares how much a material bends light relative to air. 3. The iris in the eye acts as a diaphragm, expanding and contracting to control the amount of light entering the eye. 4. Ciliary muscles adjust the shape of the cornea to help focus light on the retina. 5. The retina converts light into electrical signals, similar to how a CCD in a digital camera works.

A technician is pulling a 500 micron vacuum on an air conditioner after a compressor replacement.  After blanking off the pump, the technician observes that the micron reading would rise slightly and then stop periodically.   Which of the following is the most likely problem with the system?

When gas pipe passes through an outside wall, it must be

When sizing gas pipe systems using the tables, you will chose the table based on 

Repair work on HVAC equipment must not alter the nature of the appliance or equipment in violation of the listing and label.

The IFGC applies to the installation of all ________

Exceptions excluded, the maximum design pressure for indoor gas pipe systems shall not exceed

Using the multiple appliance vent tables, determine the furnace vent connector capacity for the illustration above.    (Use single-wall connector pipe if applicable)

Natural gas is made up primarily of (CH4) methane, is colorless, tasteless and odorless and lighter than air. it has a flamability range of approximately _________ % volume in air