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About to take PE hvac


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Hi guys. I have been preparing for pe exam in the past 3 months. I put about 200 hours serious studying in. Right now I can finish the three 80 questions practice exams I have (ppi, 6 minutes and ncees practice exam) within 4 to 6 hours, each. And I can manage to get at least 90% (ncees practice exam I can get 100%). Should I buy some more practice exams? Or this should be enough. My exam is in 2 weeks. 

Thank you!

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It sounds like you're prepared. But ultimately I can't give you a firm answer. Everyone is different. Some people want to work as many problems as possible. I'm Mechanical, but not HVAC, so I can't really recommend any specific problems to work.

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Thank you. I think I will spend the rest of the days familiarize with the reference material.  Found a mistake on the NCEES reference manual. Gonna post it here. If anyone is taking the exam recently, keep this in mind. I contacted Ncees, but didn't really get a confirmation other than they will look at it. 

It's on page 293, STEAM TABLES.
At temperature 64 F, the saturation pressure should be around 0.295 psi instead of 0.36 psi given on the reference table. Since this is the only reference allowed for the new CBT exam, If we use the wrong data, we will get a wrong answer.

Screenshot_20200814-160624~2.png

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50 minutes ago, Jorge T said:

Good afternoon Lim,

Is there any way you could help me out with problem 80 from the NCEES practice exam? It pertains to acoustical control throughout a ductwork.

Thank you. 

I had the same problem. Seems like we need some data on the noise control liner material. And I looked up on the Internet, different material really has very different properties. Also, there isn't any reference data on Ncees reference manual. So I came up with this solution, If we really come cross this question during exam. 

Just remember at 1000 hz it has the highest noise reduction, about 2.3 dB/ft 

So for this specific  problem, at 1000 hz, it goes down to 96-23=73. And towards 2 directions of frequency the per foot reductions are all less than 2.3. Option C matches the pattern.

Just memorize 2 numbers. 2.3 dB/ft and 1000 hz. Without reference, I think this is the best  we can do.

Since we are talking about noise control, there is another formula I memorized. 

Experienced sound level.

Say there is a printer in an office, giving out 100 dB noise, frequency is 1000 hz . You sit 25 feet from it. Room volume is 250 cft. What noise level down you experience?

I don't think I could find the formula on the reference manual. But any way, this is the formula.

Lp=Lw-5logV-3logF-10logR+25

Lp: experienced level

Lw: sound source level 100 dB

V: room volume 250 cft

F: frequency 1000 hz

R: distance from sound source 25 ft

So the answer should be 90 dB.

Hope I'm helping. My exam is on the 22nd this month. What about you?

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On 9/14/2020 at 2:07 PM, Lim said:

I had the same problem. Seems like we need some data on the noise control liner material. And I looked up on the Internet, different material really has very different properties. Also, there isn't any reference data on Ncees reference manual. So I came up with this solution, If we really come cross this question during exam. 

Just remember at 1000 hz it has the highest noise reduction, about 2.3 dB/ft 

So for this specific  problem, at 1000 hz, it goes down to 96-23=73. And towards 2 directions of frequency the per foot reductions are all less than 2.3. Option C matches the pattern.

Just memorize 2 numbers. 2.3 dB/ft and 1000 hz. Without reference, I think this is the best  we can do.

Since we are talking about noise control, there is another formula I memorized. 

Experienced sound level.

Say there is a printer in an office, giving out 100 dB noise, frequency is 1000 hz . You sit 25 feet from it. Room volume is 250 cft. What noise level down you experience?

I don't think I could find the formula on the reference manual. But any way, this is the formula.

Lp=Lw-5logV-3logF-10logR+25

Lp: experienced level

Lw: sound source level 100 dB

V: room volume 250 cft

F: frequency 1000 hz

R: distance from sound source 25 ft

So the answer should be 90 dB.

Hope I'm helping. My exam is on the 22nd this month. What about you?

Hey Lim,

Thank you for your input, that is exactly what I was planning to do based on similar problems from the engineering pro guides. 

I will be taking the exam this Friday!

Best regards.

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4 hours ago, Jorge T said:

Hey Lim,

Thank you for your input, that is exactly what I was planning to do based on similar problems from the engineering pro guides. 

I will be taking the exam this Friday!

Best regards.

You will pass! Let me know! 

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On 9/15/2020 at 7:03 PM, Lim said:

You will pass! Let me know! 

Lim,

The test was very similar to the NCEES practice exam concept wise. There were some practical questions relevant to the field experience as well. There were 37 questions in the AM and 43 in the PM session with the difficulty level. I would say, if you review the concepts from the NCEES practice exam and the Engineering Pro Guides you should be in great shape.

I should be getting my results later this week, I will keep you posted!

Good luck tomorrow!

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On 9/21/2020 at 11:01 AM, Jorge T said:

Lim,

The test was very similar to the NCEES practice exam concept wise. There were some practical questions relevant to the field experience as well. There were 37 questions in the AM and 43 in the PM session with the difficulty level. I would say, if you review the concepts from the NCEES practice exam and the Engineering Pro Guides you should be in great shape.

I should be getting my results later this week, I will keep you posted!

Good luck tomorrow!

Just saw your post..i took my exam today. Just like you said, it's very similar to the practice exam. Some practical/experience type of problems are the hard ones for me. But I feel good about it. Should get the result next week. Fingers crossed! I passed FE first try 3 months ago. I hope the good luck extends. Keep me posted! 

Best  regards.

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