<table cellspacing="0" cellpadding="0" border="0" ><tr><td valign="top" style="font: inherit;">Hi...............<br>                  what is the difference between PTAC and PSZ.<br>                  what AC ia used for residential purpose.<br>                   Thanks in advance<br>Regards<br>vipin sharma<br>student <br>Energy Engg.<br></td></tr></table>