Revit MEP users have been waiting for a long time ever since the inception of Revit Building Systems now called Revit MEP for Manufactured Specific Content.
Well wait no longer as more and more manufacturers on the mechanical side are creating content for Revit MEP. I have compiled a list of the ones I know of. If you know of more please let me know and I will add them as well. Be careful when using manufacturer content, as some content may be bloated and slow down your model. It is difficult to know who actually build the families for these manufacturers.
Below click on the manufacturer and you will be taken to the Revit content page. Some of the sites require you to create a login.
I hope I have been able to help some Revit MEP users with these links. My posts have been far and few between lately, however I will post topics as I find them interesting enough to share.