How to favour one file type over another in search results?

You can favor one file type over another by appending contenttype:filetype in a search term

eg: test contenttype:pdf

will yield results with pdf files on top.

You can also search level boosting to favor the file type as below

eg: test contenttype:pdf^10

Examples:

If you need html files to be displayed on top the search should be as follows

test contenttype:html

If you need jpg files to have a greater preference the search should be as follows

test contenttype:jpg

To learn about Search in SearchBlox read: Search Syntax and Semantics in SearchBlox