Heat pump unit shall include Reverse Cycle Defrost that automatically begins a defrost cycle when microprocessor determines criteria for defrosting has been met. Defrosting shall be accomplished by systematically ceasing heat pump operation, pausing to allow internal refrigerant pressures to equalize, then operating the compressor with the flow of refrigerant reversed to allow the hot gas to flow through the outdoor coil melting the accumulated frost. The unit shall automatically resume heat pump operation, after pausing to allow refrigerant pressures to equalize, at conclusion of defrost cycle.
The unit shall be equipped with a temperature-activated drain valve to allow water generated in heat pump operation and defrost cycles to drain into the wall case rather than being deposited on the outdoor coil.
In the event of compressor failure during heat pump operation, The unit shall automatically switch to electric resistance heat to maintain selected room temperature regardless of outdoor temperatures.
The unit shall have a switch concealed from room occupant to allow heat pump operation to be overridden and heat provided by electric resistance heat regardless of outdoor temperature.
In the event of compressor failure during heat pump operation, unit shall automatically switch to electric resistance heat to maintain selected room temperature regardless of outdoor temperatures.
Specifications for Optional Internal Condensate Removal (ICR) system for 3900 or 5800 series heat pump units.
The unit shall have a factory-installed Internal Condensate Removal (ICR) system to permit unit to automatically dispose of heat pump generated condensate water with no overflow to outdoors during heating under outdoor ambient of 55°F Dry Bulb, 90% Relative Humidity; indoor ambient 70°F Dry Bulb, 52% Relative Humidity, for four hours of continuous run time.
(Wall Cases and Grilles are needed for new installations.) (Alternate specification for steel wall case.)
Wall Case. The wall case shall be constructed of heavy-gauge, insulated, zinc-coated phosphated steel with a protective baked-on enamel finish. Bottom critical points of the steel wall case shall be coated with petroleum microcrystalline wax for added corrosion protection and shall meet ASTM B-117, 1800-hour hot air aerated salt spray test.
(Alternate specification for molded wall case.)
Wall Case. The wall case shall be constructed of a non-corroding fiberglass-reinforced polyester compound.
Cases shall be installed through exterior walls where
shown on the plans and shall be installed per manufacturer’s installation instructions. In no instance shall fasteners be used through the bottom in order to retain the water integrity of the bottom of the wall case.
Outside weather panels shipped with the cases shall remain in place until the outdoor air louvers and chassis are installed, at which time they are to be removed and discarded by
the installer.
Outside Grille. Each unit shall be equipped with a standard exterior grille that has been designed to allow unit operation in high ambient conditions. Grilles shall be of material and design specified.
Special grilles or customer louver sections to be supplied by others will conform to a minimum of 65% free area to allow for proper unit operation and shall be submitted to the PTAC/ PTHP manufacturer, if requested, for feasibility and airflow characteristics.
Specifications for Sub-Base (if required)
Sub-Base.Each unit shall have a field-installed UL-listed electrical sub-base. The sub-base shall be attached to the lower inside flange of the wall case prior to installation in the exterior wall. It shall include adjustable screws at the bottom corners to permit exact leveling of the wall case. The sub-base shall have a factory-installed receptacle to allow unit line cord to plug into mating receptacle and shall have a chaseway to contain and conceal the line cord. The sub-base shall have side panels adjustable from a minimum of 2-3/8" to a maximum of 13-3/4" to enclose the area under the wall case.
Weather Resistance. Complete unit including outside louver shall be submitted to an independent agency for weather resistance tests.
Air infiltration test to be conducted in accordance with ASTM E283-91. With static air pressure differential of
1.57lb./ft.2 (.3" H2O) equivalent to 25 mph wind, allowable air infiltration shall not exceed 7 ft.3/min.
Approvals. Units shall be certified under the ARI and cUL certification program and listed by UL.
Service. Submit complete information with bid covering service availability to whom service on units will be assigned, along with complete address and phone number, including phone number of emergency service personnel.
Start-Up, Adjust, Demonstrate. Contractor shall be responsible for the initial starting of units, adjustments thereto, etc., to place the units in required operating condition. Contractor shall demonstrate to the owner or his representative the operation of units for both summer and winter functions.
Warranty. The warranty shall be a full one-year parts and labor on the entire unit, plus an additional full four years parts and labor for the sealed refrigerating system, including service call for diagnosis and transportation to and from service shop (if necessary) at no charge to the customer. The warranty shall also include a limited second through fifth year parts only warranty for fan motors, switches, thermostat, heater, heater protectors, compressor overload, solenoids, circuit boards, auxiliary controls, thermistors, frost controls, ICR pump, capacitors, varistors and indoor blower bearing.
Installation Responsibility. Units shall be installed according to the manufacturer’s recommendations and the manufacturer shall not be responsible for unit failure as a result of improper installation, or unit performance when installed with accessories not approved by the manufacturer.