Wrong in Duc Size !???

[just_vip2003]

Hi guys.

I have problem in Duct Size in Revit MEP, aftre finished from create the system and go to the duct size tool and select the equal friction methed for example, then compare these value of the duct sizes with another program (McQuay) for duct size, we have a differnt in these valua. (Revit have oversize)

Knowing that the air density and viscosity are same.

Please anyone can help me.......

[m20roxxers]

You would have to look at the calculations both programs recognise to be able to pinpoint where the changes are occuring. Also the calculation type the terminals and equipment are connected to as well as fittings and so forth can make a big difference.

[just_vip2003]

The value of flow is the same but the size is different?
for example: in the attachment file this duct has (470 L/s) in Revit MEP on 0.65 Pa/m pressure drope the size is 700x200 mm. but in another program and the same input the size is 600x200mm as shown in the second picture in the attachment.

[tys90]

The value of flow is the same but the size is different?
for example: in the attachment file this duct has (470 L/s) in Revit MEP on 0.65 Pa/m pressure drope the size is 700x200 mm. but in another program and the same input the size is 600x200mm as shown in the second picture in the attachment.

Look at my post here I made yesterday: http://forums.augi.com/showthread.php?t=110667

I have the same exact problem, especially when I restrict width or height. I opened a support ticket on Autodesk Subscription but have not received a reply yet. Your guess is as good as mine as to why this happens.