You can only use constants in an IF statement, no variables.
Working:
<tmpl_if name=if_condition op=> value=5>
<tmpl_if name=if_condition op=== value=3.57>
Not working:
<tmpl_if name=if_condition op=> value={tmpl_var name=Capacity}>
<tmpl_if name=if_condition op=== value={tmpl_var name=Capacity}>
I hope I could help you.
Regards,
Claus