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  1. #1

    Studying for my G2 and need help with some questions !!

    so i am studying for my Gas-2. I live in Ontario Canada and was hoping to get someone who has done the same type of test to help me out with a few questions i am having trouble with. here we go.

    1. It has been determined that a free air opening of 152 square inches is required for an installation. How large would the opening have to be if the grill has 75% free area? the answer is 203 square inches.. how did they get the answer?

    2. There are two appliances in a 10ft x 10ft x 20 ft structure which has an equivalent
    leakage area greater than 0.05 square meters. A furnace has a draft hood and an input
    of 50,000 Btuh. The second appliance has an input of 75,000 Btuh, and does not have a
    draft hood. The required combustion air opening size is: answer is 9 square inches, how did they get that?

    3. A one-half cubic foot test dial on a meter makes one revolution ever 22 seconds.
    Approximately how much heat is being generated? answer is 82,000 btu, how do you calculate that again?

    4. A water heater with a draft diverter is to be connected to a masonry chimney using a single wall
    vent connector. The vent connector rise R will be 2 feet, H is determined to be 25 feet, the water
    heater is rated at 50,000 Btuh and will be located 3 feet from the chimney. Determine the vent size and
    maximum input of the vent if the house is 25 years old. (Do not use interpolation.) ( no idea on how to do this question, the answer is 4" diameter 67cfh)

    5. how do you determine the pitch of a chimney? i had a few questions on this and i have no idea how to do it?


    If someone can help me out or refer me to something to study for my G2 it be greatly appreciated

  2. #2
    Join Date
    Jun 2009
    Location
    Ontario, Canada
    Posts
    1,029
    1. did you pass high school math? (100/75)*152=203
    2. you need to read the code book. that math is at the annex section. i haven't done it in a while and don't have the code book with me. in real life you almost never had to do the calculation, unless the engineer screw up big time.
    3. clocking the meter. (3600/22)x.5( it's .5 cf dial) = 82MBH
    4. this is at the code book also. it's at the annex section
    5. chimney pitch? you mean roof pitch?
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  3. #3
    Quote Originally Posted by blitz View Post
    1. did you pass high school math? (100/75)*152=203
    2. you need to read the code book. that math is at the annex section. i haven't done it in a while and don't have the code book with me. in real life you almost never had to do the calculation, unless the engineer screw up big time.
    3. clocking the meter. (3600/22)x.5( it's .5 cf dial) = 82MBH
    4. this is at the code book also. it's at the annex section
    5. chimney pitch? you mean roof pitch?
    wow, thanks alot man ! yes sorry i meant roof pitch, i have written the test once and have had a few questions on it, cant seem to find it in the code book

  4. #4
    Join Date
    Feb 2010
    Location
    Calgary, Alberta
    Posts
    1,101
    If you don't know how to use the venting tables and pipe sizing tables in the code book you're in real trouble.
    As far as #2 goes, there's a table for that as well. Refer to tables 8.2 and 8.3.

    Knowing how to pull info from the B149 is crucial to the stupid TSSA's test

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