Bruce class

Question 1

What light is produced by the hottest part of the flame

Answer 1

Infrared light

2/3 of flame

Question 2

Open cct test voltage

Answer 2

17-32 mvDC

Question 3

Closed cct test voltage

Answer 3

8-17 mvDC

Question 4

Drop out time for propane (CH4)

Answer 4

90 sec

Question 5

What’s the difference between intermittent and interrupted pilot

Answer 5

Interrupted shuts off after flame is proven

Question 6

What is the time out setting for proving flame with DSI and HSI systems

Answer 6

4 seconds

Question 7

Silicon carbide strength and resistance

Answer 7

Fragile
40-80 ohms

“Carbide = Crack”

Question 8

Silicone nitride strength and resistance

Answer 8

Strong
15-20 ohms

“Nitride = No crack”

Question 9

Gap on ignition systems

Answer 9

1/8”

Question 10

According to CSA B149 what is the max pressure drop from no load to full load

Answer 10

No more than 1” W.C.

Question 11

Ground rod to flame rod ratio

Answer 11

4: 1 for ground rod
10: 1 is recommended

Question 12

HSI temperature

Answer 12

2600F

Question 13

Natural gas ignition temperature

Answer 13

1200F

Question 14

Propane ignition temperature

Answer 14

950F

Question 15

Micro amp reading on flame sensing

Answer 15

2-6 micro amps

Question 16

Micro amp drop out signal

Answer 16

Less than 1 micro amp

Question 17

What is the closing force on a draft pressure switch

Answer 17

Negative pressure from draft fan

Question 18

How many BTu’s in 1 cubic foot of propane

Answer 18

2500 BTU

Question 19

Weight of 1 US cubic foot

Answer 19

62.4 pounds

Question 20

Another name for natural draft burners

Answer 20

Atmospheric burner

Question 21

B149.3 flame failure response time for gases heavier than air less than 400 MBH on standing pilot

Answer 21

20 seconds

Question 22

AIT flame failure response time for gases lighter than air on standing pilot

Answer 22

180 seconds

Question 23

Natural draft appliances need to remove products of combustion to the outdoors through the flue(chimney). Under what category do these fall under

Answer 23

Category 1 (i)

Question 24

Question needed

Answer 24

Category 4 (iv)

Question 25

What category is an atmospheric burner with a draft hood

Answer 25

Category 1(i)

Question 26

How to convert btuh to kilowatt

Answer 26

Divide by 3.412

Question 27

Describe process for determining office hole sizes

Answer 27

Derate btu/h based on elevation (2% per 1000 ft)
Divide by number of burners
Select orfice size and gas pressure to 0.1 “wc without over firing

Question 28

How to read dial consumption

Answer 28

(3600 seconds / seconds in 1 revolution) x dial size = cubic ft per hour consumed

Question 29

B149

Closest you can install a DFMAH to combustible gases

Answer 29

20 ft

Question 30

What is AFUE

Answer 30

Efficiency rating for stand by losses

Question 31

2 most common wiring diagrams

Answer 31

Connection and schematic

Question 32

Maximum CO2 exposure in an 8 hour period

Answer 32

25 ppm

200ppm for 15 min period

Question 33

What would cause the burner flame to become unstable in a high efficiency furnace

Answer 33

Cracks in heat exchanger

Question 34

What type of light is generated in the first 1/3 of the flame

Answer 34

Ultra violet

Question 35

Optical sensors increase or decrease darkness

Answer 35

Increase

“More blacks equal more resistance for the Fuzz”

Question 36

Restrictive flow in mid and high eff furnaces allow for what

Answer 36

Increased heat transfer

Question 37

Negative result of unregulated flow through heat exchanger

Answer 37

Premature cracking

Question 38

Define B51 code

Answer 38

Pressure vessels