Carrier 50PQ - Manual (Page 15)

Application notes
Filters — Plenum filter racks for 008 size units can accom­
modate 2-in filters for higher filtration efficiency and/or
longer filter life. Filters other than 1-in standard must be field
supplied
Ductwork — At installer's option, ductwork may be attached
to the curb on 50PQ units (and 50RQ units with accessory
plenum) interior installation may proceed before unit is set in
place on roof
Field power connections — Accessory (field-installed) electric
heaters may require separate power entry to comply with local
codes Factory-installed electric heat allows single power entry
to unit for both heating and cooling
Condensate trap — Evaporator is draw-thru configuration. A
trap (minimum 4 in deep) must be field provided prior to
start-up on cooling cycle
Static pressure limits — When return air ductwork systems are
used, return side static pressures should be limited to 0 4
in. wg
Operating limits — Cfm values indicated illustrate the oper­
ating range of the indoor fan Operation above or below these
limits is not recommended Exception Operation of the
50RQ008 460-3-60 unit with 15 10 electric heat ratio,
minimum cfm is 2800 at 80 F return air temperature
Remote control panel - When use is required with emergency
heat, emergency heat switch, Carrier Part No HR59JP115
must be used Emergency heat subbase cannot be used with the
remote control panel
Low ambient cooling operation — Units are designed to
operate at outdoor temperatures down to 35 F At tempera­
tures below 35 F, accessory Motormaster® will permit opera­
tion at outdoor temperatures as low as —20 F
Roof curb — All curb installations must be counterflashed to
prevent water leakage.
Guide specifications
Base unit — Furnish and install a one-piece, air-to-air electric
heat pump designed to function as a year-round air condi­
tioning system. Unit shall be completely assembled, and tested
complete with refrigerant charge and ready to operate The
total unit shall be U L listed and carry a U.L label Unit shall
be designed for either slab mount (RQ) or single-piece curb
mount (PQ) PQ unit to have outdoor air inlet with filter, plus
factory-supplied 1-in throwaway return air filters
Cooling capacity (net) — Unit cooling cycle capacity shall be a
NET capacity with indoor fan motor heat deducted and shall
be_____ Btuh or greater total,_________ Btuh sensible at condi­
tions of______cfm air entering indoor coil, ________ F dry bulb.
___ F dry bulb entering outdoor coil
EER shall be______ .or greater when
_____ _ F wet bulb, and _
The total unit cooling
rated in accordance with ARI Standard 240 for air-to-air heat
pumps
Heating capacity — Heating cycle capacity shall be_______ Btuh
or greater (integrated rating) when rated at_______ ,F db outdoor
ambient, with_______cfm and______ F air entering the indoor
(heating) coil The total unit C.O.P at above conditions shall
be____ or greater The ARI heating C.O.P. shall be__________ at
47 F db outdoor ambient (hi-temp),_________ at 17 F db outdoor
ambient (low temp) or greater when rated in accordance with
ARI Standard 240 for air-to-air heat pumps
Electric resistance heat — Electric resistance heaters shall be
supplied to offset building heat loss (at winter design
conditions) when the heat pump heating cycle capacity cannot
satisfy space requirements. Fleaters shall consist of open wire
nichrome elements with controls necessary for operation
Safety controls shall include primary overtemperature and
overcurrent protection. Heaters shall be U.L. listed when
factory installed
Unit compressor(s) shall be welded, fully hermetic with
crankcase heater(s) and suitable vibration isolators Com­
pressors shall be of the same manufacture as unit and shall be
tested and designed in unit to operate to —20 F OAT on
heating cycle without shutting off. The standard unit shall be
capable of operating to 35 F OAT. on cooling cycle Com­
pressors shall have a 5-year warranty
Coils — Indoor and outdoor coils shall be of nonferrous
construction with aluminum plate fins mechanically bonded to
seamless copper tubes with all joints brazed.
Fans and motors — Indoor air fan shall be forward curved,
centrifugal, belt-driven type capable of delivering___________ cfm
at_____ in. wg external static pressure Motor pulley shall be
adjustable pitch. Indoor fan shall be____________ hp with per­
manently lubricated bearings. Outdoor fan shall be of the
propeller type, with direct driven permanently lubricated
motor of_____ _hp or less. Fans shall discharge upward
Unit cabinet shall be constructed of galvanized steel, bonder-
ized and coated with a baked enamel finish Cabinet interior
shall be insulated with 1-in. thick neoprene coated fiberglass.
Cabinet panels shall be easily removable for service to' all
operating components. A condensate drain for the indoor coil
shall be provided.
Controls — The heat pump cooling/heating system shall be
protected with high pressurestat, low pressurestats, loss of
charge protection, indoor coil freezestats, and current and
temperature sensitive overload devices
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