HVAC Flashcards
What are the 3 methods of heat transfer?
Convection
Radiation
Conduction
What 4 factors affect human comfort?
Humidity
Temperature
Air movement
Radiation
What is cold 20?
When any of the 3 variables affecting human comfort are not at their ‘comfort’ condition.
What are the 4 main reasons for automatic control?
Comfort
Safety
Economy
Convenience
What is a closed loop system?
A control system that uses feedback to make the control process automatic.
What are the 6 basic components of a forced air heating system?
Main burners Fan or blowers Load devices Controlling devices Heat exchangers Flue or stack
What are the 4 secondary basic components of a forced air heating system?
Filters
Supply plenum
Ducts
Power supplies
What is another name for a manual override switch?
Summer/ winter switch
What are the typical fan temp settings?
Fan-on 49 and 60^
Fan off 32 and 38^
Differential 17 and 22 ^
What does a diaphram valve operate by?
Gas pressure
Name the 5 parts incorporated with a combination gas valves
Gas regulator Safety gas valve Power unit Main gas valve Manual gas shut off (On/off pilot valve)
What is the load that the thermocouple powers?
Power unit
What is the purpose of the thermocouple?
To shut off the flow of fuel through the gas valve if the pilot flame goes out
What does the thermocouple prove?
The presence of flame.
What is the typical range for a highlimit switch?
80 - 120
