Engineering Guide Specifi cations
General
The water-source heating units shall be high temperature water-to-
water heat pumps. Units shall be performance rated in accordance
with EN 14511-2 or ARI/ISO/ASHRAE 13256-2, and listed by a
recognized safety-testing laboratory or agency, such as ETL. Each unit
shall be water run-tested at the factory. The quality control system
shall automatically perform via computer: triple leak check, pressure
tests, evacuate and accurately charge system, perform detailed
heating mode tests, and quality cross check all operational and test
conditions to pass/fail data base. Each unit shall be pallet mounted
and shipped with appropriate protective packaging to help avoid
damage in transportation.
The units shall be warranted by the manufacturer against defects
in materials and workmanship for a period of 10 years on all parts,
and 10 years on the compressor and refrigerant circuit parts with a
service labor allowance for 5 years on refrigeration components and
2 years on other parts. An optional extended warranty is available
for the 50YEW Series units, which increases the labor allowance to
10 years on all parts. The water source units shall be designed to
operate with entering Source temperature between 20 and 110°F
[-7 and 43°C], and entering Load temperature between 50 and
130°F [10 and 54°C] with a maximum leaving load temperature of
145°F [63°C].
Casing & Cabinet
The cabinet shall be fabricated from heavy-gauge galvanized steel and
painted with a polyester powder coating. Access door shall be hinged
for easy access. The interior shall be insulated with 1/2” [13mm]
thick, multi-density, foil-backed coated glass fi ber. Three access panels
shall be provided and shall be removable with piping in place. The
internal component layout shall provide for major service with the
unit in place for restricted access installations. The units shall have
an insulated compressor section to minimize the transmission of
compressor noise.
Refrigerant Circuit
All units shall contain Puron
®
(HFC-410A) sealed refrigerant circuit
employing a hermetic motor-compressor, thermal expansion valve,
coaxial tube water-to-refrigerant Source heat exchanger, brazed plate
Load heat exchanger, compressor discharge muffl er, 100% molecular
sieve fi lter drier with XH-11 desiccant, and service ports. An optional
Domestic Hot Water mode shall be available. Compressors shall be
scroll type designed for heat pump duty and shall be double isolated
from the cabinet with two sets of compressor mounting hardware.
Compressor motors shall be single-phase PSC with internal over
load protection.
The coaxial water-to-refrigerant heat exchangers shall be designed
for close approach temperatures and be constructed of a convoluted
copper (optional cupro-nickel) inner tube and steel outer tube. The
brazed plate heat exchanger shall be designed for close approach
temperatures and shall be constructed with stainless steel plates. The
thermal expansion valve shall provide proper superheat over the
entire fl uid temperature range with minimal “hunting”. The coaxial
heat exchangers and refrigerant suction lines shall be insulated to
prevent condensation at low liquid temperatures.
Electrical
CXM Control – A microprocessor-based compressor controller
shall be provided to monitor and control unit operation. The control
shall provide compressor enable, high and low pressure monitoring,
fi eld selectable water coil low temperature sensing, and over/under
voltage monitoring. 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 connection to other low
voltage controls. The control system microprocessor board shall be
specifi cally designed to protect against building electrical system noise
contamination, EMI, and RFI interference.
MPC Control – A programmable controller shall be provided to
monitor buffer tank temperature, Domestic Hot Water (DHW)
tank temperature, outdoor air temperature, and other inputs to
determine when to operate the compressor, pump(s) and hot water
valve. The MPC shall be factory-wired to the CXM compressor
control module and user interface. MPC programming shall include
outdoor temperature reset, warm weather shutdown, cooling enable,
heat pump staging, emergency DHW output, pump control, vacation
mode, DHW time schedule, advanced diagnostics, user interface
communication, and sensor monitoring.
Digital User Interface – A panel-mounted backlit digital user interface
shall be factory installed and wired for customization of the MPC
programming. Four arrow keys and a select key will be used to
control a large dot-matrix style 2” x 2” (5 x 5 cm) backlit display. The
main screen shall display current outdoor and water temperatures,
and allow the user to change settings by selecting from one of
the menus at the bottom of the screen. A special installer set up
mode will allow the technician to change some of the default MPC
parameters. The user interface shall include a time schedule for
DHW operation, Fahrenheit/Celsius selection, vacation mode for
DHW, and other user preference options.
12-point terminal block – A low voltage terminal block with a blue/
gray pattern for ease of identifi cation shall be provided to connect
thermistors and external wiring. The MPC, user interface, CXM
board and other relays/components shall be factory-wired to the
terminal block.
Line voltage lugs shall be provided for unit wiring. A circuit breaker
protected 75VA transformer shall be employed. Units shall have
knockouts for entrance of low and line voltage wiring.
Piping
Source/Load supply and return water connections, as well as
Domestic Hot Water supply and return connections shall be FPT
(Female Pipe Thread) copper fi ttings and shall be securely mounted
fl ush to the cabinet allowing for connection to an MPT (Male Pipe
Thread) fi tting without the use of a back-up wrench. All Source
water piping shall be insulated to prevent condensation at low liquid
temperatures.
50YEW
20
GT-PW Water-to-Water (50YEW) Series
Carrier : Turn to the Experts.
