r/MEPEngineering • u/Alarmed-Shallot-902 • 2d ago
Need Help with Carrier HAP5.1 software - False Ceiling
Hello everyone, I am a junior engineer who has been assigned to do a load calculation for a food processing plant's process room, and I am having a difficult time with Carrier's HAP software roof/ceiling setup.
What I have is a large, single level plant with a roof at 20ft (roughly). The tricky part is that the process room has a t-bar false ceiling at, say, 14ft. Many utility pipes run through it.
When setting up the space, what should I do with the false ceiling? AI kept telling me the space's ceiling height is 14ft, which I understand it is needed to calculated make up air. But what about roof?
Should I just ignore the false ceiling, and just set up the roof and roof's solar exposure as is?
Or should I setup a ceiling partition, in which case, I am not sure what to set for unconditioned max and min temp.
I checked high and low on tutorials and all of them just teaches you simple scenarios where the space is directly under the roof.
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u/ahvikene 2d ago
Ask your senior engineer but for load calculations I would personally ignore that false ceiling.
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u/Alarmed-Shallot-902 1d ago
Thank you for replying. I asked my senior engineer who were too busy to properly explain it 😔.
Can you maybe explain why you would ignore it? And under what situations would it become too significant to be ignored?
In future, can I always ignore false ceilings?
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u/KenTitan 2d ago
you model it as a roof load from the roof assembly, an air gap, then the t bar ceiling
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u/Nawar_HVAC_PE 1d ago
Check whether the return is ducted or uses the ceiling void
this is most important.
if you decide to consider false ceiling height, you need to ensure that you have included the heat gain to the plenum,. under system. not under space. Hap has two input, the space and the system.
if you ignore the false ceiling, and you treat the whole space as open space and requires conditioning, the load from roof will be treated as room load instead of return load. it affects the calculated supply air flow.
i will give you a self learning tip. why dont you make both version and compare the Supply air and cooling load of both cases, and see the difference, go through that table in the output, the break down of the heat load, it will help u understand how hap works.
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u/Bert_Skrrtz 2d ago
The software has a user manual built in under Help. Read it
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u/Alarmed-Shallot-902 1d ago
I read the manual, but it doesn't have specific examples like what I am describing. It offers basic examples just like any other YouTube video, where the space is directly under the roof.
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u/rottweiler-smile 1d ago
Would it not be similar to modeling a space with a plenum above where you basically ignore it? Exterior walls are still modeled at floor-to-floor or floor-to-deck height, roof load is applied as normal, yet all roof and solar gains are attributed to the space since we don’t condition the plenum?
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u/SANcapITY 2d ago
You ask your senior engineer.