Wordpress feeds showing crazy characters

My Wordpress blog use the charset UTF-8 and when I try to display the feed through a RSS feed reader on my VBulletin forum (that is encoded with ISO-8859-1), the output show weird characters like: †etc. I tried to put this code: header('Content-Type: text/html; charset=VALUE'); in my feed_reader.php and fix the problem, I can see the feeds correctly but now all the vBulletin shows that crazy characters.

How can I fix this? Thanks!

This is my feed_reader.php by the way:

<?php...

PHP:

Wordpress feeds showing crazy characters

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