function serwisTab(id) {
	document.getElementById('link-kotly-co').className = '';
	document.getElementById('link-ogrzewacze').className = '';
	document.getElementById('link-wymienniki').className = '';
	document.getElementById('kotly-co').className = '';
	document.getElementById('ogrzewacze').className = '';
	document.getElementById('wymienniki').className = '';
	document.getElementById('link-' + id).className = 'selected';
	document.getElementById(id).className = 'selected';
	return false;
}