Title: Unit 11 Outline
Course: HET 119 HVACR Electricity II > Section: HET 119 HVACR Electricity II

Unit 11 Outline

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Unit 11 Outline

1. Operation Controls
  - Thermostats
  - Solid-state Time Delay
  - Low Ambient Fan Controls
2. Limit and Safety Controls
  - High Limit Controls
  - Fan Limit Switches
  - Static Pressure Switches
3. Sequence of Operation
  - Call from the thermostat
  - Time Delay Circuit
  - Energizing the Compressor Contactor
  - Condenser Fan Motor Operation
  - Satisfying of the thermostat
4. Troubleshooting Heating Controls
  - Knowing What Should be Happening at any time
  - Using the Volt/Ohm Meter to Troubleshoot
  - Eliminating unnecessary Information and Concentrating on the Task at Hand
  - Replacing the Correct Component
  - Servicing Controls

Summary

- Control Devices are the part of an electrical system to operate when, how, where, and what will be turned on, off, and by a variable signal.
- HVAC/R systems need to control the temperature, pressure, flow, humidity, and level for the comfort of humans; thereby, it will be necessary to know all possible sequence of operations of a HVAC/R system.
- Controls can be binary (off and on), analog (variable), or integral (variable and adjusting) controls to give the most efficient control of a HVAC/R system.
- Most control system use low voltage operating at 24 Volts and uses a transformer to step down the voltage.
- Safety controls are used to protect the system, the occupant, and the structure.
- Operating Air Conditioning controls are used to maintain the correct temperature during the cooling season.
- Heat-pumps use a reversing valve during the air conditioning season to operate the compressor for cooling. The Reversing Valve will reverse the flow of refrigerant during the heating season.

Review the vocabulary terms listed below and look up their definitions / descriptions before taking the Vocabulary Quiz.

Vocabulary

- Pressure Switches
- Liquid Solenoid
- Time Delay Control
- Contactor
- Compressor
- Condenser Fan Motor
- Condensing Unit
- Reversing Valve