Testing and Troubleshooting

Question 1

What three items does a combustion analyser sample when testing efficiency?

Answer 1

CO2, O2, and Excess air

Question 2

What is a draft gauge used for?

Answer 2

To measure flue draft and pressure drop across air filters

Question 3

What are four types of efficiencies?

Answer 3

Combustion, steady state, thermal, and annual fuel utilization

Question 4

Which dial is used for the purpose of clocking the meter

Answer 4

The proving dial

Question 5

What is the calorific value of natural gas?

Answer 5

1000 BTU

Question 6

What is the calorific value of propane gas?

Answer 6

2500 BTU

Question 7

What are the conditions that could possibly cause low O2 in the flue gas?

Answer 7

Insufficient combustion air, burner over firing, and low vent (stack) draft

Question 8

What are 3 conditions that may cause low vent draft in an appliance?

Answer 8

Improperly sized vent, vent system blocked, and poor workmanship

Question 9

On the PCB, What can be used to aid in the diagnosis of a fault in a furnace?

Answer 9

The LED

Question 10

Every manufacturer uses LED fault codes on their circuit boards. True or False?

Answer 10

True

Question 11

Should the power be turned on or off before you read the fault codes?

Answer 11

Turned on

Question 12

What are the possible causes for a pressure switch not closing?

Answer 12

Blocked vent pipe, faulty tubing, faulty induced draft motor, and dirty or worn induced fan wheel

Question 13

What are the possible causes for a limit switch to open?

Answer 13

Plugged filter, restriction in the duct work, loose blower wheel, faulty blower motor, and faulty switch or electrical connections.

Question 14

Where is the rollout switch located?

Answer 14

Beside the burner

Question 15

A flame sensor is checked by measuring the amount of ___ flowing through it.

Answer 15

DC microamps

Question 16

All HSI are supplied with 110 V. True or False?

Answer 16

False

Question 17

What can happen to an HSI if the furnace is oversized?

Answer 17

It can shorten the life of the HSI

Question 18

The troubleshooting procedure for a direct drive multi-speed motor is exactly the same as it is far an electronically commuted motor. True or False?

Answer 18

False

Question 19

What are the variety of test instruments used for testing a furnace?

Answer 19

A gas analyzer, manometer, tachometer, multimeter, and thermometer

Question 20

What is the air to gas ratio?

Answer 20

10/1

Question 21

What device is used to measure gas pressure and pressure drops in ductwork?

Answer 21

A manometer

Question 22

What device is used for measuring the speed of motors and fans in HVAC equipment?

Answer 22

A Tachometer

Question 23

What device combines a voltmeter, ohmmeter, and an amp meter in one to perform service and electrical readings?

Answer 23

A multimeter

Question 24

What device is used for taking temperature readings?

Answer 24

A Thermometer

Question 25

What gauge is used for determining draft pressure?

Answer 25

A draft gauge

Question 26

What is Annual Fuel Utilization Efficiency (AFUE) ?

Answer 26

A thermal efficiency measure of combustion equipment like furnaces, boilers, and water heaters.

Question 27

What is combustion efficiency?

Answer 27

It is a calculated measurement in percent of how well the appliance converts the fuel into useable heat at a specific point in time.

Question 28

What is steady-state efficiency?

Answer 28

It used to describe combustion efficiency

Question 29

What is running efficiency?

Answer 29

It is defined as the point at which combustion gas content reaches equilibrium and stack temperatures stabilize.

Question 30

What is annual fuel utilization efficiency (AFUE)?

Answer 30

It is the off cycle losses of equipment

Question 31

What is the stack temperature and running efficiency in a standard low-efficient furnace?

Answer 31

Stack temperature 500 degrees F and a running efficiency of 70 - 79 percent

Question 32

What is the stack temperature and running efficiency in a mid-efficient furnace?

Answer 32

Stack temperature 350 degrees and a running efficiency of 80 - 83 percent

Question 33

What is the stack temperature and running efficiency in a high-efficient furnace?

Answer 33

Stack temperature 110 degrees F and a running efficiency of 90 - 98 percent

Question 34

What is the smallest dial on the gas meter?

Answer 34

The test dial

Question 35

What is the formula for flow rate?

Answer 35

Vol of dial X 3600 / time

Question 36

With less gas would you have a larger or smaller orfice?

Answer 36

A smaller orfice

Question 37

How do you convert the amount of gas used into Btuh?

Answer 37

You must multiply the cubic feet of gas consumed by its calorific value.

Question 38

What is the difference between low oxygen and high oxygen O2 and High CO levels?

Answer 38

Low oxygen has insufficient combustion gas, burner is over firing. and has a low vent draft. High oxygen combustion has too much combustion air, burner is underfiring, and has loose access panels.

Question 39

How do you diagnose a pressure switch?

Answer 39

By checking both the electrical and the diaphragm that is in the switch.

Question 40

What is a limit switch?

Answer 40

A simple auto resetting, on-off switch that opens due to excessive heat in the heat cabinet.

Question 41

What is a rollout switch?

Answer 41

It is a manual reset switch that is normally closed that opens when the temperature at the burners gets too high.

Question 42

A flame sensor has power going to it all the time. True or False?

Answer 42

True

Question 43

What are some causes of excessive on/off cycling?

Answer 43

Installation of an over-sized furnace, dirty filter or squirrel cage blower, or a dirty evaporator coil or heat exchanger.

Question 44

What are the two types of gas valves?

Answer 44

Solenoid and diaphragm

Question 45

What are the two basic types of indoor blower motors?

Answer 45

Direct drive and belt drive

Question 46

What is an electronically commuted motor (ECM)?

Answer 46

It is an ultra-high efficiency programmable brushless DC motor that uses a permanent magnetic rotor and built-in inverter.