Furmace Start Up And Testing And Trouble Shooting

Question 1

It is considered safe practice to inspect the electrical connections with the power turned on ? (True or false?)

Answer 1

False

Question 2

A typical circuit board on any furnace will have only one voltage ? (True or false ? )

Answer 2

False they will have 24v and 120v

Question 3

What should be checked on the blower assembly when performing the start up ?

Answer 3

Confirm shipping blocks and brackets are takeing out

And check the wheel inside housing to make sure it’s running in the center of the housing and secured to shaft of the motor properly

Question 4

What are 3 acceptable methods to check for gas leaks ?

Answer 4

Test dial
Commercial leak detection (soapy water )

Electronic leak detection

Question 5

What direction must the venting on the furnace slope ?

Answer 5

Upwards and away from furnace

Question 6

What is the maximum distance the supports can be apart on system 636 venting ?

Answer 6

5 feet

Question 7

What should u be looking for when checking duct connections ?

Answer 7

Openings and gaps that cause excessive leaking

Question 8

What should the heat anticipator setting match?

Answer 8

Amperage draw of the 24volt circuit

Question 9

What are the 2 reasons for setting the manifold pressure ?

Answer 9

Ensures appliance is not over fireing

Derates the appliance as well

Question 10

What are the two formulas for converting gas quantity’s into btuh

Answer 10

Hourly consumption =

(Size of test dial/ #of seconds for 1 reveloution of test dial ) x 3600

Btuh= hourly consumption x calorific value of the gas

Question 11

What are the calorific values for natural gas and propane gas ?

Answer 11

Ng= 1000/ftcubed

Propane = 2500/ft cubbed

Question 12

How is temp rise calculated ?

Answer 12

Difference of return air temp and supply air temp

Question 13

When do the blower speeds have to be changed ?

Answer 13

When temp rise is to high or to low

Question 14

What is the most important part of a furnace install?

Answer 14

Furnace start up

Question 15

The first thing you as an installer must do before performing any system start up is ?

Answer 15

Turn off the power supply

Question 16

The furnace must be wired electronically and grounded in accordance with local codes. (True or false)

Answer 16

True

Question 17

Feild wireing connections must be made where ?

Answer 17

Inside the furnace connection box

Question 18

What must u not use as a way to check for a gas leak ?

Answer 18

Open flame

Question 19

When Useing the test dial method you must ?

Answer 19

Turn off gas to all appliances except the one you are working on

Question 20

Electronic leak detectors work in two different ways what are they ?

Answer 20

Use of a sensor that detects mercaptin

Senses the high frequency sound that the gas makes when it’s pushed between the metal of the two fittings

Question 21

Filters that have reinforced backing must be installed up stream or downstream of the filter rack ?

Answer 21

Downstream (furnace side)

Question 22

How do u check for gas supply pressure ?

Answer 22

Connect gas manometer to the inlet side of the gas valve

Question 23

How to test for manifold pressure (single stage )

Answer 23

Connect manometer to the outlet pressure port on the gas valve

Question 24

High altitude gas conversions should be done by a qualified service agency in accordance with ?

Answer 24

Manufactures instructions and all applicable codes and requirements

Question 25

What happens if u fail to set the air temp rise properly?

Answer 25

May result in reduced furnace life

Question 26

Pcms are characterized by ?

Answer 26

A smooth and quiet operation and may also be multispeed

Question 27

How to change blower speeds on permanent split capacitor motors ?

Answer 27

Switching the wires that run from the motor to the circuit board

Question 28

Ecms have distinct advantages when the furnace is being used for either heating or ventilation? (True or false ?)

Answer 28

True

Question 29

How to change speeds on ecms?

Answer 29

Dip switches

Question 30

What does ecm stand for ?

Answer 30

Electronically commuted motor

Question 31

What does pcm stand for ?

Answer 31

Permanent split capacitor motor

Question 32

How to test a high limit ?

Answer 32

Remove motor lead from the heating terminal and placing it on a park terminal. Turn on power and turn up thermostat to call for heat If the limit control is working the burners will remain on until the temp of high limit is reached and will then shut down

Question 33

2 common methods of adjusting fan on and fan off settings

Answer 33

Switching positions of dip switches Changing locations of a jumper

Question 34

What 3 items does a combustion analyzer sample when testing efficiency ?

Answer 34

Co2 carbon dioxide O2 oxygen Excess air

Question 35

What do u use a draft gauge for ?

Answer 35

Measure flue draft pressure drop across filter

Question 36

4 types of efficiencies ?

Answer 36

Combustion Steady state Thermal Annual fuel utilization

Question 37

What is annual fuel utilization efficiency?

Answer 37

Measures amount of heat Accutalky delieverd to the enclosure, compaired to the amount of fuel you must supply to the appliance in a full season Also takes into account the off cycle losses and associated energy losses of the heating unit as it responds to change in the load , which, in turn, is affected by changes in weather and operator controls

Question 38

What dial is used for the purpose of clocking the meter ?

Answer 38

The proving dial

Question 39

List 3 conditions that could possibly cause low o2 in the flue gas ?

Answer 39

Insufficient combustion air Burner over fireing Low vent (stack) draft

Question 40

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

Answer 40

Improperly sized vent Vent system blocked Poor workmanship

Question 41

The led on the pcb can be used to aid in the diagnosis of a fault in a furnace. (True or false?)

Answer 41

True

Question 42

Every manufacturer uses led fault codes on his/her printed circuit boards. (True or false)

Answer 42

True

Question 43

You should turn off power to appliance before you read the faukt codes. (True or false )

Answer 43

False

Question 44

What are 4 possible causes for a pressure switch not closing ?

Answer 44

Blocked vent Tubbing from the induced draft assembly to the pressure switch Faulty induced draft motor Dirty or worn induced draft fan wheel

Question 45

5 possibles reasons for a limit switch to open ?

Answer 45

Plugged filter Restriction in ductwork Loose blower wheel Faulty blower motor Faulty switch or electrical connections

Question 46

Where is the roll out switch located ?

Answer 46

Beside the burner

Question 47

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

Answer 47

DC Microamps

Question 48

All hsi are supplied with 110v. True or false ?

Answer 48

False

Question 49

Having an oversized furnace can shorten the life of an hsi. True or false

Answer 49

True

Question 50

The troubleshooting procedure for a direct drive multi speed motor is the same as it is for an electronically commuted motor ? True or false

Answer 50

False

Question 51

Why are combustion analyzers used ?

Answer 51

Ensure that proper combustion is takeing place Gas fired equitment is operating at peak usage

Question 52

Combustion analysis look at the chemistry of the flue gase and determines the appliances fuel efficiency by measuring ?

Answer 52

Oxygen Carbon monoxide Carbon dioxide Flue gas temp Combustion air temp Nitric oxide Nitrogen dioxide Sulfur dioxide

Question 53

What are the two types of tachometers ?

Answer 53

Non contact- Digital with reflective strips Contact - mechanical with pulley wheel

Question 54

What are tachometers used for ?

Answer 54

Measuring the speed (rpm) of motors and fans in hvac equitment

Question 55

What is a manometer ?

Answer 55

Used to measure gas pressure, pressure drop across cooling coils, pressure drop across filters, pressures created by induced draft motors and pressures in duct work. Measures pressure

Question 56

What do u use to measure ohms ?

Answer 56

Ohmmeter

Question 57

What do u use to measure amps ?

Answer 57

Amp meter

Question 58

What do u use to measure volts

Answer 58

Voltmeter

Question 59

What is a multi meter ?

Answer 59

Single meter that combines a voltmeter ohmmeter and amp meter

Question 60

2 types of efficiency ratings ?

Answer 60

Combustion efficiency Steady state efficiency

Question 61

Standard efficiency furnace (natural draft ) Running efficiency Afue Stack temp Off cycle loses

Answer 61

RE= 70%-79% Afue= 45%-58% ST= 500 degree Fahrenheit OCL= draft diverted and standing pilot

Question 62

Mid efficiency furnace (fan assisted draft) Running efficiency AFUE Stack temp Off cycle losses

Answer 62

RE=80-83% AFUE=80-83% ST= 350 degrees Fahrenheit OCL= negligible

Question 63

High efficiency furnace (condensing furnace ) Running efficiently AFUE Stack temp Off cycle losses

Answer 63

RE=90-98% AFUE=90-98% ST= 110 degree Fahrenheit OCL= negligible

Question 64

Why is a high efficiency furnace stack Tempature so low ?

Answer 64

Because that much more heat is staying inside the home

Question 65

What is a printout used for when doing combustion testing ?

Answer 65

Help customers understand the nature of additional costs Establishes a history of burner performance and may provide an early indication of a failing component

Question 66

Why should u install a tee in venting with a clean out on it ?

Answer 66

So u can uses it as an opening for the probe when doing a combustion analysis

Question 67

Where will you find what led codes mean ?

Answer 67

Insulation manuels

Question 68

A pressure switch should have 24 volts on call for heat on each terminal ? True or false

Answer 68

True of not there’s a problem with switch

Question 69

Limit switch should have 24volts on both sides of limit switch true or false

Answer 69

True if you do not u need to replace it

Question 70

Rollout switch should have 24 volts on both sides true or false ?

Answer 70

True if not u need to replace it

Question 71

Two types of gas valves ?

Answer 71

Solenoid Diaphragm

Question 72

What is an electronically commutated motor ?

Answer 72

Ultra high efficiency programable brushless DC Motor that uses a permanent magnetic rotor and a built in inverter

Question 73

Who just all metal vents be approved by ?

Answer 73

ULC and must adhere to gas code

Question 74

When derateing an appliance that is past 4500 feet above sea level you must derate it by ____% for every 1000ft ?

Answer 74

4%

Question 75

What is combustion efficiency ?

Answer 75

Calculates how well the fuel is put into usable heat

Question 76

What is steady state efficiency?

Answer 76

Often refers to as running efficiency When combustion gas reaches a balance