Furnace Operation Review

Question 1

Once a force is applied to an atom this particle of an atom will release causing flow. What particle is it ?

Answer 1

Electrons

Question 2

What particles in the atom are positively charged and which ones are negatively charged ?

Answer 2

Positive =protons
Negative= electrons

Question 3

What device is used to measure flow of electrons ?

Answer 3

Amp
Meter

Question 4

What device is used to measure the force applied to electrons ?

Answer 4

Volt meter

Question 5

What are the two different types of voltages ?

Answer 5

Ac meaning positive to negative
Dc meaning constant voltage (car batteries)

Question 6

When an electrical circuit does not have a load and the circuit is closed with power, what is it called ?

Answer 6

Short circuit

Question 7

What is the formula used to calculate watts ?

Answer 7

Volts x amps = watts

Question 8

What are the 2 diffrent types of electrical wiring diagrams used ?

Answer 8

Schematic (ladder)
Connection (pictorial)

Question 9

What is voltage ?

Answer 9

Force in a circuit

Question 10

What is amperage ?

Answer 10

Current flow

Question 11

What are ohms ?

Answer 11

Resistance

Question 12

What is watts ?

Answer 12

Power

Question 13

Operating controls used in residential hvac ?

Answer 13

Thermostat
Fan switch
Gas valve
Humidistat

Question 14

Saftey switches used in hvac

Answer 14

Pressure switch
High limit
Flame roll out (near burners)
Door switch
Spill switch (venting blocked)
Fuse

Question 15

What’s the function of a standing pilot ?

Answer 15

Lights main burner
Heats the thermocouple

Question 16

What components are used to heat up the flame safeguard in a standard furnace ?

Answer 16

Pilot assembly
Thermocouple
Pilot stat

Question 17

Which part of the gas valve adjusts gas pressure to the main burner

Answer 17

Regulator

Question 18

What is the sensing element used in temperature sensing switch ?

Answer 18

Bi-metal

Question 19

Why is a heat anticipator used in thermostats

Answer 19

Prevents over shoot

Question 20

What’s other names for 120vac ?

Answer 20

Primary
Line side

Question 21

What are other names for 24vac ?

Answer 21

Control circuit
Secondary
Load side

Question 22

R on thermostat terminal ?

Answer 22

24vac/power (red)

Question 23

W on thermostat terminals ?

Answer 23

Heat (white)

Question 24

Y on thermostat terminals ?

Answer 24

Cooling (yellow)

Question 25

G on thermostat terminals ?

Answer 25

Fan (green)

Question 26

C on thermostat terminals ?

Answer 26

Common (black) Helps eliminate batteries

Question 28

What is fan on temp range ?

Answer 28

120-140 degrees farenhite

Question 29

What is the off temp range ?

Answer 29

90-110 degrees Fahrenheit

Question 30

What is the max temp setting for a high limit switch ?

Answer 30

250 degrees Fahrenheit

Question 31

How are transformers rated for power and class ?

Answer 31

Va ratings = volt amps Class 2 transformer

Question 32

What are the 4 thermocouple tests and what are they used for ?

Answer 32

Open circuit test : 17-32mvdc Closed circuit test: 10-17mvdc Dropout test: 0.75-6mvdcv Flame response time: 180 seconds

Question 33

What are heat exchangers used for ?

Answer 33

Transfer heat from one medium (fire) to another medium (room air)

Question 34

What is a draft diverter (draft hood) used for ?

Answer 34

Dilution air(cools products of combustions) and breaks the stack effect

Question 35

Two diffrent types of burners used ?

Answer 35

Inshot ( loud, horizontal burner,more efficient) Upshot ( old furnaces, quite, not as efficient)

Question 36

What is important about rating plate?

Answer 36

Btuh input /btuh output Temp rise Altitude rateing Model number Serial number Voltage rateing External static pressure Gas pressure rateing Amperage Csa approved

Question 37

What is the recommended manifold pressure for a natural gas furnace ?

Answer 37

3.5 water column

Question 38

What instruments can be used to measure gas pressure ?

Answer 38

Digital manometer, u-tube , analog

Question 39

What needs to be done if there is a crack in the heat exchanger in a residential furnace ?

Answer 39

Replace it

Question 40

What wire gauge is used for 120vac to a furnace ?

Answer 40

14ga (solid copper)

Question 41

What wire gauge is used for a 24vac thermostat ?

Answer 41

18ga (strand or solid copper)

Question 42

What materials can be used to connect natural gas ?

Answer 42

Iron Copper Corrugated stainless steel tubeing Aluminum (only for pilot ) Poly ethylene (underground only)

Question 43

How much clearance is needed in front of a furnace for servicing ?

Answer 43

24” (2’)

Question 44

How much air (cu.ft) is required for theoretical combustion of natural gas ?

Answer 44

10 cuft

Question 45

Can flexiabke gas connectors be used on a residential gas furnace ?

Answer 45

Yes maximum 2ft long and only from drop to appliance

Question 46

Calorific value of natural gas ?

Answer 46

1000btu/cuft

Question 47

Calorific value of propane gas ?

Answer 47

2500btu/cuft

Question 48

What needs to be done when installing a gas appliance at high altitudes ?

Answer 48

Derate

Question 49

What is max gas pressure allowed going to a residential dwelling?

Answer 49

2psi

Question 50

What are the installer’s responsibilities before leaving a furnace install job ?

Answer 50

Leave literature(owner Manuel) Explain how appliance operates

Question 51

What are the 5 main components needed when sizing gas lines ?

Answer 51

Btu load Longest run Material used Pressure Fuel