Dear Marwan,

I personally find it tedious and confusing to change HVAC Equipment types
using parametric runs. There are just too many BDL keywords that have to
be manaaged when changing between different equipment types. I choose to
lessen my own hassles and risk for errors and bad output data in this way:

1. I get my model file set with all the base inputs that I want to look
at in both comparisons.
2. I do a "save as" of my file with all the other ECM parametrics already
in them (everything but the HVAC changes.)
3. With this new copy of my file I go ahead and change the HVAC systems
and equipment within the model file directly (not in the parametric runs).
4. With this newly adjusted file you have two options to work from:
- First you can continue working from two files for your comparison,
knowing which file is representing what project case.
- OR--you can take the newly created .inp file from the adjusted file,
and go back to your originial model file and then reference this new
adjusted .inp file as the .inp file for the parametric run for
this ECM that
is a change in chiller types. By referencing the adjusted inp.
file in your
parametric case you have accomplished setting up your system change as an
ECM parametric with in your model file, but you avoided all the
difficulty
of looking up BDL key-words that you would have had to use for the
parametric inputs.

This explanation maybe a little vague, especially if you are not familiar
with how to reference other .inp files into your model file. But if I were
in your shoes---these are the two options I would consider and attempt to
use to complete the task at hand. I hope it is helpful to you.

Regards,
Pasha