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pressure drop of VAV box and diffuser not included in duct pressure loss report

3 REPLIES 3
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Message 1 of 4
HVAC-Novice
1324 Views, 3 Replies

pressure drop of VAV box and diffuser not included in duct pressure loss report

I created a duct system and am able to generate the duct pressure loss report where I see pressure drop of each fitting, duct etc.

 

I also have VAV boxes with (manually entered) pressure drop and diffusers with (calculated based on flow) pressure drop. but those pressure drops are not part of the loss report. How do i include those? Especially VAV loss is significant.

 

I attached the VAV box and diffuser families (which I took from manufacturers and modified).

Revit version: R2024.2
3 REPLIES 3
Message 2 of 4
HVAC-Novice
in reply to: HVAC-Novice

I'm still struggling to get the pressure loss report to include the device pressure drops.

 

I even called the parameter "Pressure Drop" and gave some VAV boxes a 10 in-wg pressure drop. but no matter what I do, the duct pressure loss report only contains duct pressure drop (straight duct and fittings), but none of the VAV box, diffuser etc. pressure drops.

 

Is Revit actually really capable of calculating the duct system pressure drop, or should I use a different method? It seems fairly accurate for ducts, but the device pressure drop of course is significant.

 

I have the feeling I'm doing something wrong. I also played with the family duct connector "loss method" settings to no avail.

Revit version: R2024.2
Message 3 of 4
HVAC-Novice
in reply to: HVAC-Novice

I kind of resolved half of my problem after I had an epiphany last night. For the VAV box I had to select the parameter for "Pressure Drop" to be what i wanted it to be and now the VAV box pressure drops show up.

 

I still have the problem that the diffuser (attached) doesn't seem to propagate its pressure drop. Actually it shows the pressure drop in the VAV system, but that pressured drop doesn't show in the entire AHU schedule.

 

when I just run a duct pressure loss report for the VAV system, i see the "air terminal" pressure drop. but when i run it for the entire AHU, none of the diffusers show up at all.

 

 

Revit version: R2024.2
Message 4 of 4
tanveer.aziz
in reply to: HVAC-Novice


Re: Creating Mechanical Supply System
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12-10-2015 11:50 AM in reply to: kevinaldo

Hello everyone,



here might be the easiest solution of this problem. Folow these steps:



1. Place the AHU at place

2. Place the Air Terminal At place

3. Place the VAV at place (you may adjust it later)



NO DUCT WORK TILL NOW



4. RIght click on AHU supply connection point and create a system.

5. Now click on any air terminal, right click on duct connection, add to system, click on AHU. Now the air terminal and AHU ar in the same system.

6. Now click on the VAV unit , right click on in duct connection, add to system, click on AHU.

7. Again click on the VAV unit , right click on out duct connection, add to system, click on AHU.

8. Complete all the duct connection.



DONE!

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