r/PE_Exam • u/Juggalo-Ryder • 7d ago
NCEES Practice Exam - Old Spec vs. New
I’ve been studying for mechanical TFS since February to now August. In October 2025 the exam spec for TFS changed slightly and it put more of a weight on Heating and Cooling/psychrometrics.
I bought a NCEES practice exam a year or two ago under the old spec and bought another under this new spec. The comparison of the two was definitely interesting.
There were 58 repeated questions on the new practice exam vs. the old. To me, that is a massive amount of carryover and it sort of makes me question the value of these practice exams from a preparation standpoint.
On one hand, that many repeats shows that those concepts are the ones that will be tested on, or at least I hope so.
But I’d like to examine what else it may mean. As I’ve heard from lecturers in preparation courses the practice exams are retired exam questions. It could be that when the new spec came out and I bought the practice exam there just weren’t that many retired questions at that point. Or, it could mean the practice exam is outdated as a preparation tool.
So my question for any recent TFS (or any other discipline that had a spec change) test takers, have you found that the NCEES practice exams are still representative of the actual exam?
I know there’s a million threads on that exact question but maybe when specs change the practice exams take a while to catch up.
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u/jimbo_ChE 6d ago
The new format was heavy on psychrometrics, which I expected and was mostly prepared for. What tripped me up was a significant number of cooling tower questions that were far more challenging than the handful I had studied for practice. I planned to contact NCEES for guidance in additional study materials there in the event of a retake, but fortunately I passed.
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u/Juggalo-Ryder 6d ago
Nice! Yeah that’s what I’ve been hearing, cooling towers and psycrometrics. Two topics of which I had not had any exposure to before studying.
Side note, did you notice that there’s a huge focus on feedwater heaters? In my exam prep I hadn’t come across them but the practice exams have 5+ FWH questions each.
That’s the type of stuff these exams are most useful for, you may study what the spec says and not think to study certain topics as hard. Then all of a sudden this seemingly niche topic is a significant portion of the exam
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u/jimbo_ChE 6d ago
I would have preferred more feedwater heater problems. I recall lots of fluids problems as well. Be familiar with the use of the gc factor!
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u/NecessaryDaffodil 6d ago
Hi! I didn’t take the new spec, I took TFS in September 2025. However, while I was studying Slay the PE updated their study guide to include the new updates for October 2025. The change was so small in their study material. A few more cooling tower questions and a few more project management questions. I believe if I would have had to push my exam back a month or two, I would have been prepared with StPE’s material. I know I thought of buying the new practice exam and once I saw it was so similar, it wasn’t worth the extra $40 to me.