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ICA > Module 2 Section 2 Gas Furnaces > Flashcards

Module 2 Section 2 Gas Furnaces Flashcards

1
Q

List 5 components of a gas furnace

A

fuel s system, system, combustion air delivery, burner assembly, heat exchanger, controls, venting system, distribution system

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2
Q

Purpose of the drip on gas piping:

A

To collect dirt & moisture, separating it from the gas before it gets to the gas valve.

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3
Q

One-half-inch diameter black steel piping should be supported every __feet, unless it is rising vertically, in which case it must be supported every __feet.

A

6 feet, and every floor

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4
Q

List 6 gas piping problems you should watch for

A

leaks, no drip leg, missing shut off valve, rusting, plastic pipe exposed above grade, improper connections

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5
Q

Incomplete combustion of natural gas produces:
a. nitrogen dioxide
b. carbon dioxide
c. ozone
d. carbon monoxide
e. sulfur dioxide

A

sulfur dioxide

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6
Q

Describe briefly how the pilot light & thermocouple work to ensure safety

A

pilot flame heats the thermocouple, which senses the flame, allowing the gas valve to open. If flame goes out, the gas valve is automatically closed.

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7
Q

The flame wavers over one burner in a gas furnace when the blower comes on. What is the likely cause?
a. heat exchanger failed
b. gas valve faulty
c. blower motor running too slow
d. airflow across heat exchanger is insufficient
e. vent partially blocked

A

heat exchanger failed

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8
Q

List 6 problems you’ll find on gas combustion equipment.

A

rust, scorching, inoperative, delayed ignition, short cycling, flame wavers, dirt or soot

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9
Q

What is meant by spillage & back drafting on a gas furnace?

A

spillage (back drafting) is when the combustion products flow out of the furnace into the room through the burner or draft hood, rather than up the vent. Life threatening situation

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10
Q

Using a mirror & flashlight to view the heat exchanger on a gas furnace allows you to see:
a. less than 20% of heat exchanger
b. 20-40% of heat exchanger
c. 40-60% of heat exchanger
d. 60-80% heat exchanger
e. all of heat exchanger

A

less than 20% of heat exchanger

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11
Q

Where possible, why should you watch the flame pattern of a gas furnace?

A

Look for changes in the flame pattern when the house air fan turns on. This indicates heat exchanger failure.

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12
Q

How many panel covers do most conventional gas furnaces have?

A

2- the blower compartment door, and the burner compartment door

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13
Q

List 6 problems commonly found with furnace cabinetry

A

rust, mechanical damage, missing components, inadequate combustible clearances, obstruced air intakes, scorching

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14
Q

List & describe the 3 settings on the fan/limit switch

A

Fan off-indicates the temp at which the house air fan stops (80 degrees to 110 degrees)
Fan on-indicates the temp at which the house air fan starts (120 degrees to 150 degrees)
High limit-indicates the temp which combustion is stopped for safety (170 degrees to 200 degrees)

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15
Q

List 6 problems commonly found with limit switches

A

set wrong or defective, scorching, rusting, mechanical damage, improperly wired, missing cover

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16
Q

List 6 problems you may find with a mechanical thermostat

A

poor location, not level, loose, dirty, damaged, poor adjustment/calibration

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17
Q

A heating thermostat located in a kitchen will tend to:
a. keep rest of house cooler than you want it
b. keep rest of house warmer than you want it

A

keep rest of house cooler than you want it

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18
Q

List 3 components of the venting system

A

draft hood, vent connector, vent

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19
Q

List 6 problems found with vent connectors

A

sections not secured together, rusted, poor support, poor slope, too long, too small/big furnace, inadequate combustible clearances

20
Q

Should the smaller appliance vent connect into the chimney above or below the vent from the larger appliance?
a. Above
b. Below

A

above

21
Q

If there is a chimney clean-out below the vent connection to the chimney, you should look up it to see ___ (2 points)

A

obstructions in chimney, connection between vent connector & chimney, if vent connector extends too far into chimney

22
Q

The vent connector should slope:
a. downward going away from the furnace at a minimum of a quarter inch per foot
b. upward going away from the furnace at a minimum quarter inch per foot
c. downward going away from the furnace at a minimum half inch per foot
d. upward going away from the furnace at a minimum half inch per foot
e. not at all; should be horizontal

A

upward going away from the furnace at a minimum quarter inch per foot

23
Q

We like to see vent connectors:
a. less than 3 feet long
b. less than 5 feet long
c. less than 8 feet long
d. less than10 feet long
e. length is not a concern

A

less than 5 feet long

24
Q

A. What is the typical combustible clearance for a single wall vent?
B. What is the typical combustible clearance for a single B vent?

A

A. What is the typical combustible clearance for a single wall vent: 6 inch clearance
B. What is the typical combustible clearance for a single B vent: 1 inch clearance

25
Q

List 6 common problems with furnace blowers

A

dirty, noisy, inoperative, overheating, rust, poorly secured

26
Q

List 2 clues that the blower motor may be too small

A

excessive temp rise across the heat exchanger; poor airflow at remote registers

27
Q

How much should a belt deflect when it is under proper tension?
a. 1/2”
b. 1”
c. 1 1/2”
d. 2”
e. 3”

A

1”

28
Q

Do our standards require us to look at electronic air cleaners? Y/N

A

No

29
Q

List 5 problems that could be found with mechanical filters in furnaces.

A

Missing, dirty, installed backwards, wrong size, loose or collapsed

30
Q

Starting at the supply plenum, list the components of the duct system the air travels through to deliver heat to the room, & to re-enter the furnace at the return side.

A

The heated air is pushed through the supply plenum, along the supply ducts, out the registers into the room. The air travels across the room from supply register to return grille, through the return ducts to the return plenum, where it re-enters the furnace to be reheated.

31
Q

List 3 things that cause friction loss in duct system

A

Duct size, elbows, high velocity, duct shape, length of duct

32
Q

List 6 common problems with duct systems

A

disconnected, dirty, removed during renovations, leakage, rust, no air or weak air flow, registers obstructed

33
Q

In a heating only climate, an uninsulated heating duct running through a garage will deliver__ air to the room at the end of the duct
a. warm
b. cool

A

cool

34
Q

The vapor barrier on an insulated duct in a heating-only climates should be
a. on the side of the insulation closest to the duct
b. on the side of the insulation furthest away from duct

A

on the side of the insulation closest to the duct

35
Q

Why is it unsafe to have a supply register supplying heat to a garage?

A

Exhaust fumes can enter the house when the furnace is not running

36
Q

List 6 components that would be found inside the cabinet of a conventional gas-fired forced air furnace

A

gas valve, burners, heat exchanger, exhaust flue passages, draft hood, fan/limit, blower, air filter

37
Q

The off-cycle losses of a conventional efficiency furnace total___% of the fuel consumed.

A

20%

38
Q

List 8 common problems you may find with mid-or-high-efficiency furnaces

A

vent dampers stuck open/closed, ignition problems, condensate problems, induced draft fan problems, venting problems, differential pressure switch problem, spillage switch problem, poor outdoor combustion air intake location

39
Q

It is impossible for a vent damper to fail in the closed position. T/F

A

False

40
Q

List 5 reasons why an electronic ignition system may not work.

A

no electrical power, loose connections, poor electrical ground, no spark, flame sensor fails to detect flame, hot surface, hot surface ignitor cracked

41
Q

Does condensate leakage out of the induced-draft fan housing cause corrosion problems with the primary heat exchanger? Y/N

A

No

42
Q

List 5 problems commonly found with condensate systems.

A

blocked, leaking, poor discharge location, no neutralizer bath, clogged neutralizer

43
Q

List 3 common induced-draft fan problems

A

damaged, worn bearings, inoperative

44
Q

List 4 concerns with mid- or high-efficiency furnace vents.

A

Inappropriate materials, poor location for vent termination, mechanical damage, inadequate combustible clearance, improper slope

45
Q

Do the standards require that we report on the life expectancy of furnaces? Y/N

A

No, although we have to advise our client if the system is near the end of its normal life expectancy

46
Q

What is the typical life span for a conventional gas furnace?
a. 5 to 10 yrs
b. 10 to 15 yrs
c. 15 to 20 yrs
d. 20 to 25 yrs
e. 25 to 30 yrs

A

20 to 25 years

ICA (26 decks)

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