Home page link while using custom queries

This is just driving me crazy. I cannot get wp to return the home page/url link. I have tried various combinations of

<?php echo esc_url( home_url( '/' ) ) ?>
<?php echo esc_url( bloginfo( 'url' ) ) ?>
<?php echo home_url() ?>

But they all return the current page.

Now I should mention that 1. I am not using the loop. I have not yet got to that stage though I did write it in to test this problem. 2. I have registered custom search queries.

function add_query_vars($aVars) {
    $aVars[] = "search";
    $aVars[] = 'special';
    return $aVars;
}
add_filter('query_vars', 'add_query_vars');

The problem only seems to occur in search.php when these custom queries are in use. As you have probably guessed the returned home url is always .../wp-install/?search=foo&special=bar.

Is there any way around this problem?