pageHeader shouldn't be a page, but you have to define the content that replaces it in each page that uses your template:
<ui:define name="pageHeader"> .... </ui:define>
Why don't you put the charset declaration in the html head (which should be in your template file)?
<head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" /> .. </head>
When you said, that pageHeader shoudn´t be a page, you meant it shouldn´t be a separate file? I did redifine it for every page because I import different css and js files for each one.
I did try to put
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" />
on the main page put it didn´t help.
Any other ideas?
Thanks for your help