Dear Srinarayana,
The way I learnt this was to take a simple example in the examples folder and hand draw the schematics for the node connections.
I must disswade you from building a model from scratch. I've never done it, well almost never. Take an existing working model and adapt it.
I would also recommend using tools which simplify the process, such as OpenStudio, or a commercial software.
Your statement is confusing as you said that you had both a splitter and a mixer on the return path. This doesn't make sense. The mixer is on the return and the splitter is on the supply side right?
Mit freundlichen Grü�en- Sent from my iPhone (excuse the brevity)
i. A.
Jean Marais
b.i.g. bechtold
Tel. +49 30 6706662-23
Srinarayana