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Furnace Start-up 4th Year > Furnace Start-up > Flashcards

Furnace Start-up Flashcards

1
Q

The start-up of the furnace is one of the most important steps for proper operation. List 4 main checks that must be done.

A

1) Electrical connection in the junction box and on the circuit board . 2) Leak test on all of the gas fittings ,from the gas cock to the appliance gas valve . 3) Visual inspection of all venting and duct connection .4) Follow start-up procedures set by the furnace manufacturer

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2
Q

Before inspecting any electrical connections, what must be done to prevent electrical shock?

A

Turn off electrical power at the fuse box or service panel

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3
Q

Does it matter what kind of electrical connections are made in the junction box?

A

yes it does

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4
Q

What should be done when inspecting the thermostat connections on the circuit board?

A

all screws or bolts must be inspected for tightness and proper location

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5
Q

What should be removed in the blower motor and wheel?

A

all shipping blocks and brackets have to be removed

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6
Q

Why is it important to check for gas leaks? _

A

to prevent explosions or fires

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7
Q

What are the approved methods for checking for gas leaks?

A

1) The test dial on the gas meter, 2) Commercial leak detectors (soapy water solution), 3) Electronic leak detectors

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8
Q

If a metal vent connector is used for the furnace, what things are required for proper operation?

A

Must be ULC approved and have the ULC marking clearly indicated on the vent pipe

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9
Q

What type of BH vent is approved?

A

ULC S636

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10
Q

How far should each horizontal hanger be from each other when using BH venting?

A

5 feet

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11
Q

What is undesirable or not wanted when inspecting duct connections?

A

poor duct connections,look for openings or gaps that might cause excessive leaking.

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12
Q

Is a filter required for the furnace? Why? _

A

yes, to protect the furnace especially the blower fan from all dust, debris, hair.

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13
Q

When setting up a mechanical thermostat, how would the heat anticipator be set?

A

you need a good quality thermometer and an amp meter.amp meter is used to find the amperage draw of the 24-volt control circuit,and then the heat anticipator can be set to match it.

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14
Q

When setting up a digital thermostat, how would it be set?

A

must be set to match the system to which it is attached. it is important to read the thermostats installation manual.

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15
Q

What is very important before connecting the manometer to the gas supply?

A

to turn off the gas at the shut off valve before connecting the manometer.

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16
Q

Which pressure tap will be used for checking the gas line pressure?

A

manifold pressure

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17
Q

When checking the manifold pressure, what are the important considerations that need to be made to ensure proper operation of the furnace?

A

setting the manifold pressure is a critical adjustment that is made not only to ensure that the appliance is not overfiring, but can be used to de-rate the appliance as well.

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18
Q

Why do furnaces have to be de-rated?

A

must be set for operation at the altitude in which they are installed.

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19
Q

How much does the input rating have to be de-rated for every 1000 ft above sea level?

A

must be decreased 4% for each 100 ft above sea level.

20
Q

Who designs the ratings of each furnace with regards to the amount of de-ration required at certain altitudes?

A

manufacture.

21
Q

What test is performed to calculate the BTUH input rate for any particular furnace?

A

clock the meter and convert the amount of gas consumed into btuh

22
Q

Write down the formula for calculating the firing rate of the appliance.

A

hourly consumption= [size of test dial]x360
___________________ #seconds for 1 complete revolution of test dial

23
Q

Temperature rise is important to ensure what?

A

that the heat exchangers do not overheat due to insufficient heat transfer and that the furnace is running at peak efficiency.

24
Q

What information is required to perform a temperature rise test?

A

supply air temperature, return air temperature

25
Q

What must be done to get an acceptable temperature rise?

A

you must change the speed of the blower motor.

26
Q

All safeties need to be checked for proper operation on start-up, what way can the high limit switch be checked?

A

by simply removing the motor lead from the heating terminal and placing it on a park terminal(a terminal that is never energized on the board)

27
Q

What two methods could be used to adjust the “Fan Off” settings?

A

by switching positions of dip switches or changing the location jumper.

28
Q

List the variety of test instruments that could be used for troubleshooting a furnace?

A
  1. a gas ( combustion) analyzer for different types of gases (CO2,CO,02)
  2. a manometer
  3. a tachometer
  4. multimeters ( with proper adapters to measure values)
  5. a thermometer
29
Q

Why would a combustion analyzer be used?

A

to insure that proper combustion is taking place and that gas fired equipment is operating at peak usage.

30
Q

A manometer measures gas pressures, what is the unit of measure?

A

cubit feet

31
Q

What instrument measures RPM?

A

a tachometer

32
Q

What does a multimeter have a combination of?

A

voltmeter, ohmmeter and an amp meter.

33
Q

What are two uses for a draft gauge?

A

to measure flue draft and pressure drop across air filters.

34
Q

What does AFUE stand for?

A

annual fuel utilization efficiency

35
Q

Explain AFUE.

A

it measures the amount of heat actually delivered to the enclosure, compared to the amount of fuel that you must supply to the appliance in a full season.it also takes into account the off cycle losses and associated energy losses of the heating unit as it responds to changes in the load,which in turn, is affected by changes in the weather and operator controls.

36
Q

What are the stack temperatures of the following?

Standard Eff. 
Mid Eff. 
High Eff.
A

500 Fahrenheit
350 Fahrenheit
110 Fahrenheit

37
Q

CFH stands for:

A

cubic feet per hour

38
Q

The Calorific Value of:

Natural gas: 
Propane gas: ­­­­­
A

1000 Btu
2500 Btu

39
Q

Figure 12 (ILM) shows the “sequence of operations” chart, using this chart; identify what a code 13 is.

A

open limit switch (LS)

40
Q

What would happen if the furnace is turned off before the LED diagnostics were read?

A
41
Q

List some of the problems that could arise if there is a pressure switch issue?

A

blocked vent pipes,pinched tubing from the induced draft assembly to the pressure switch,faulty induced draft motor, dirty or worn induced wiring at the pressure witch and pressure switch failure.

42
Q

What measurement is used when checking for the flame sensor current?

A

DC microamps

43
Q

Does the meter need to be in series or parallel with the flame sensing circuit when reading flame current?

A
44
Q

List the ways an igniter can be checked for proper operation.

A
45
Q

What voltage should be at the secondary side of the transformer?

A
46
Q

What does ECM stand for?

A

electronic commuted motor

47
Q

Define the following:

Direct Ignition: 
Flame sensor: 
Intermittent Pilot: 
Rectification:
A

Furnace Start-up 4th Year (1 decks)

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