Res furn 2

Question 1

What is the main difference between an intermittent pilot gas valve and a direct ignition gas valve?

Answer 1

The direct ignition gas valve has no pilot connection.

Question 2

When using electronic ignition, what is the process of proving the flame called?

Answer 2

Flame rectification

Question 3

What is the minimum flame rode to ground electrode area that is immersed in the flame?

Answer 3

1:4

Question 4

Why have flame conductivity systems not been used for proving the flame?

Answer 4

The system will not distinguish between a flame and a short to ground.

Question 5

What is the first step in the sequence of operation for any heating application with electronic ignition?

Answer 5

There is a call for heat at the thermostat.

Question 6

What is the importance of the connection diagram?

Answer 6

It shows where the wires go and the colour of the wires.

Question 7

What is the importance of the ladder diagram?

Answer 7

It shows how the appliance works for troubleshooting.

Question 8

What is the function of the device identified as ILK?

Answer 8

The ILK device shuts off the appliance if the blower door is removed.

Question 9

What device has a capacitor connected to it?

Answer 9

The blower motor.

Question 10

How many speeds does the blower motor have?

Answer 10

4

Question 11

What color wires are connected to the limit switches?

Answer 11

Red

Question 12

What is the voltage output of the transformer?

Answer 12

24 VAC

Question 13

Which motor speed is not used as the unit is received from the factory?

Answer 13

MED HI

Question 14

What size of fuse should be used as a replacement?

Answer 14

A three-amp fuse

Question 15

How many trials for ignition does this unit have?

Answer 15

Four

Question 16

5 parts of a Relay

Answer 16

Coil
Core
Return spring
Armature
Contacts

Question 17

List four most common arrangements for the contacts of a relay

Answer 17

“SPST - NO” single pole throw normally open contacts
“SPST - NC” single pole single throw normally closed contacts
“SPDT” single pole double throw
“DPDT” double pole double throw

Question 18

Two most common capacitors used in HVAC systems

Answer 18

Run capacitor

Start capacitor

Question 19

What is the material called that is used to separate the two plates in a capacitor?

Answer 19

Dielectric

Question 20

What activates a pressure switch?

Answer 20

The pressure switch is activated when the IDM starts turning and creates enough pressure, it will force the diaphragm to move toward the microswitch, closing it.

Question 21

What is flame rectification?

Answer 21

Flame rectification is an AC electrical circuit that sends a very small current from the furnace electronic board-up to the flame rod. When the flame is established, the flame acts as a path or conductor, which allows the current to flow across the flame from the flame rode to ground (burner), thus completing the circuit.

Question 22

Where is the CPU located?

Answer 22

The electronic control board contains the CPU in most modern day HVAC equipment.

Question 23

In a cooling unit, where is the high pressure switch located?

Answer 23

The switch is located in the tubing between the discharge side of the compressor and the condensing coil.

Question 24

Explain the function of the low pressure switch.

Answer 24

The low pressure switch monitors the refrigeration system for a loss of refrigerant charge and may also be helpful in stopping the evaporator (indoor) coil from freezing up due to a dirty filter or low airflow over the coil.