We paid $3500 to reconfigure an installation of a Navien boiler that this firm professed to be capable of installing. Among other problems Navien corporate technicians cited an explosion hazard in the company's work. That is but the start of our problems with this firm. Westchester County licensing officials have summoned CNS for a hearing in September regarding work on our home. If you insist on hiring this firm check Westchester County clerk's website online for licensing violations, lawsuits and liens. Forewarned is forearmed.