HVAC for addition
 

I tried to explain in another post a few weeks ago but that didn't work out too good.

This time I even have a mini picture I did in MS Paint.

The main trunks are the black line in the back. They sit about 10 feet from the addition.

Assuming I can run the supply (s) into the wall right above the foundation and of course the new floor. And then can I run the return into the foundation wall in the corner which you see in this illustration? There is going to be a massive girder so can't really run it into the room. And can't go through the side wall because the joist is going to be there.

Also assuming 8 inch lines on both.

Looking for advice and clarification from an HVAC guy. I don't do HVAC, usually hire out which I may still end up doing but want to be able to discuss this with them too.

http://img696.imageshack.us/img696/9533/hvac.png

You can do that. But only someone that see's what you have to work with can tell you what will or won't work for sure.

Have you considered a mini split?

how big is the addition