Brownstoner.com and heatinghelp.com are fantastic sources of information for home owners and contractors. These are great tools to get information from knowledgeable contractors or experienced homeowners. Gennady is a frequent contributor to postings on both forums. Below are some recent posts that he's commented on.
http://www.brownstoner.com/forum/#!/general-discussion:boiler-installer-recommenda - Great question and answer about how to start looking for a contractor