General
The liquid source heating/cooling split condensing units shall be ARI/ASHRAE/ISO 13256-1 loop performance certified and listed by a nationally recognized safety- testing laboratory or agency, such as Underwriter’s Laboratory (UL), or Canadian Standards Association (CSA-US). Each unit shall be water run-tested at the factory. Each unit shall be pallet mounted and shipped in clear shrink wrap for visual shipping damage inspection. The units shall be warranted by the manufacturer against defects in materials and workmanship for a period of five years on all parts, and ten years on the compressor and refrigerant circuit parts with a service labor allowance during the first 30 days. An optional extended warranty is available for the GT-GS Split Series units, which adds a labor allowance and trip charge. The liquid source units shall be designed to operate with entering liquid temperature between 20°F and 120°F.
Casing & Cabinet
The cabinet shall be designed for indoor installations. The cabinet shall be fabricated from heavy-gauge galvanized steel painted with a epoxy powder coat paint with a 1000 hr. salt spray test rating. The interior shall be insulated with 1/2" thick, multi-density, coated glass fiber with edges sealed or tucked under flanges. Three compressor compartment access panels shall be provided and shall be removable with linesets and water piping in place. The internal component layout shall provide for major service with the unit in-place for restricted access installations.
Refrigerant Circuit
All units shall contain split refrigerant circuits employing a hermetically sealed compressor, thermal expansion valve, reversing valve, coaxial tube water-to-refrigerant heat exchanger, service ports, and backseating service valves. Compressors shall be high-efficiency advanced scroll type designed for heat pump duty and mounted on spring vibration isolators. Compressor motors shall be single phase PSC with internal overload protection. A factory installed bidirectional filter drier shall be provided. The coaxial water-to-refrigerant heat exchanger shall be designed for close approach temperatures and be constructed of a convoluted copper (optional cupronickel) inner tube and a steel outer tube. The thermal expansion valve shall provide proper superheat over the entire liquid temperature range with minimal “hunting”. The valve shall operate only in the heating mode with the use of an internal check valve. The water-to-refrigerant heat exchanger and refrigerant suction lines shall be insulated to prevent condensation at low liquid temperatures. Air coil connections shall be made through brass backseating service valves with built-in Schrader ports.
Electrical
CXM Control - A microprocessor-based compressor controller (CXM) shall be provided to monitor and control unit operation. The control shall provide high and low pressure monitoring, field selectable water and air coil low water temperature sensing, over/under voltage monitoring, and unit performance sentinel (UPS). The control shall also provide for water valve connection, a test mode, short cycle protection, random start-up, as well as fault LED, fault memory, and intelligent fault retry.
The control shall employ quick attach harness assemblies for low voltage connections to the control board to aid in troubleshooting or replacement. An integral terminal block with screw terminals shall
be provided on the control for all field low voltage connections. Line voltage lugs shall be provided for unit wiring. Units shall have knockouts for entrance of low and line voltage wiring. The control box shall be harness plug-connected for easy removal.
Piping
Supply and return water connections shall be 1" swivel fittings. All water piping shall be insulated to prevent condensation at low liquid temperatures.
