37 HVAC contractor services; Installation, maintenance and repair of HVAC systems, plumbing installations, refrigeration and water treatment systems; Installation, maintenance and repair of heating, ventilating and air conditioning equipment; Installation, maintenance and repair of polyvinylidene fluoride (PVDF) pipes, hydronic pipes, hydraulic pipes, chiller system pipes, biotech high purity pipes, environmental chamber pipes and tubing; Repair and installation services, namely, the installation of heating, cooling and environmental control systems