Exam 14: Automatic Control Components and Applications

When a water regulating valve is used to control the head pressure of a water-cooled system, the valve's spring is acting against which pressure to modulate the water flow?

To properly set the heat anticipator, the ____  must determine what the current flow is through the heating control circuit when the furnace is operating in a steady state condition .

The cold anticipator starts the cooling system early to allow the air-conditioning system to get up to capacity when needed.

What device may be used to ensure that air is flowing through a duct before an electric strip heater is energized?

Many natural gas fired heating units operate at a manifold pressure of 3.5 in. WC .

High pressure control contacts are normally ____________________ type.

What type of control would be used to cycle compressors on and off in response to evaporator pressures that indirectly control box temperatures?

The cold anticipator is wired in ____ with the mercury bulb cooling contacts and is energized during the off cycle.

The purpose of a heat anticipator is to ____.

An oil pressure safety control usually has a 90-second time delay built into it. Why?

What is meant by the term "detent"?

Where is the thermistor motor overload device usually positioned?

The heat anticipator in a thermostat prevents the temperature in the conditioned space from rising above the thermostat setting.

To obtain an accurate reading of a fluid in a large pipe, a technician should ____.

A dual pressure control is actually a low pressure control and a high pressure control connected in parallel with each other.

Explain why the thermistor type sensor is normally embedded in the motor windings.

To prove that the combustion blower motor is operating before ignition, a ____ would be used.

Oil pressure safety controls measure the difference in pressure to establish ____.

To control ice build-up on a heat pump outdoor coil in the heating cycle, a ____ is attached to a large diaphragm.

List four reasons why low voltage controls are usually found on residential air conditioning systems?