# Combustion air



## Thomas Nabors (May 24, 2017)

Ok let me start off by saying i have taken the 2015 M3 exam twice with the last time only failing
by 1 question (Still i Failed).  So I'm going to thake the 2012 M3 exam fri.  I guess my major flaw
is combustion air calculations.  Is there a difference if an appliance is located on the inside
drawing air from the outside?  And the outside combustion calculation from the IFGC says that
it can either be vertical or horizontal duct.  How to you calculate it if the exam question doesn't
tell you if its vertical or horizontal, and for either one opening or two?  And how do you calculate
Gas demand?  i know i'm new to this, but having a hard time getting help on this since i work for
a small jurisdiction and it's just me and the CBO


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## cda (May 24, 2017)

Sorry I just do nail salons

Your question, have no knowledge of 

Someone will post


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## cda (May 24, 2017)

Maybe do not read into the question?

Or do the calculations backwards ????
You have four answers 

Reverse engineer them and see if it is close to the question

Great thing about math you can move stuff around


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## Thomas Nabors (May 24, 2017)

you are right but icc does it to where the answers line up to all 4 possible answers using the 4 calculation formulas.  Just knowing which formula to use is key, so its kind of hard to make an educated guess at it


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## cda (May 24, 2017)

Is there only one of these type questions normally on the test?


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## Thomas Nabors (May 24, 2017)

no the test i took yesterday had about 6 or so combustion air calculation questions.  The exam bulletin said combustion air made up 25% of the exam.  This is the first exam i have had to take more than twice


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## cda (May 24, 2017)

Ok well than you need to know

Someone with knowledge should post


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## Thomas Nabors (May 24, 2017)

cda said:


> Ok well than you need to know
> 
> Someone with knowledge should post


thank you CDA for replying.  All Information is helpful


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## mtlogcabin (May 24, 2017)

It is an M3 exam the information should be on the plans for 1 or 2 openings along with
\vertical or horizontal ducts I suggest you slow down when reading a calculation question.
Also the infiltration rate should be on the plans and if not less than 0.40 you cannot use
304.5.2.    ICC puts a lot of useless information within a question on their exams. Read
through the junk and good luck


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## Thomas Nabors (May 24, 2017)

mtlogcabin said:


> It is an M3 exam the information should be on
> the plans for 1 or 2 openings along with vertical or horizontal ducts I suggest you slow down
> when reading a calculation question. Also the infiltration rate should be on the plans and if not less
> than  .40 you cannot use 304.5.2.   ICC puts a lot of useless information within a question on their
> exams. Read through the junk and good luck



Thank you mtlogcabin.  I wish the M3 exam consisted of more plans but i can only remember
about 4 or so questions where they gave you a drawing to look at.  The rest were word problems


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