desuperheater of vented double-wall construction and factory
installed within indoor heat pump cabinet.]
[i.
Field-Installed Domestic Hot Water Desuperheater: Provide units
factory assembled, designed, tested, and rated. Units shall
include double-wall vented refrigerant-to-water heat exchanger,
water pump powered by a sealed magnetic drive motor, water line
thermostat, secondary safety thermostat to prevent scalding,
internal fuse, internally mounted disconnect switch, air bleed
port, and refrigerant ports. Units shall be UL listed. Units
shall be provided by the ground source closed loop heat pump
manufacturer.]
j.
Emergency Heater: Provide UL or ETL listed, electric resistance
heater with internal fusing integral with heat pump unit; fan
shall run until heater cools. Locate downstream of indoor coil.
k.
Hose Kits: Kits shall include two 0.6 m 2 foot long metal braided
hoses with swivel connectors on one end, an manual flow control
valve with test ports, two shutoff ball valves with memory stops
(one with test port), blow down ball valve, and Y-strainer. Hoses
shall be fire rated to meet UL 94. Hoses shall have a maximum
working pressure of 2067 kPa 300 psi.
l.
Hanger Kits: Provide horizontal units with hanger kits consisting
of galvanized steel brackets, bolts, washers, and vibration
isolators. The hanger kit shall be designed to support the unit
from below and suspend from threaded rods.
**************************************************************************
Note: Microprocessor based controls should normally
be utilized on large projects. Electromechanical
controls should be used on small installations,
housing, and remote location projects.
**************************************************************************
m.
Controls: Controls and safety devices shall be factory wired and
mounted within the control box of the unit cabinet.
(1) Provide a microprocessor based controller that communicates
with an electronic multi-stage space thermostat. The
microprocessor shall control sequencing, high and low pressure
switch monitoring, freeze protection, lockout control, night
setback, emergency shutdown, short cycle protection, random start,
LED mode and fault indicators, fault memory, input and output
diagnostics, and a communications port. Provide a
factory-installed low voltage terminal block for field control
wiring and a low voltage transformer. [Provide communications
capability for remote direct digital control (DDC).] [Provide a
hand held, remote service terminal from the heat pump manufacturer
capable of interfacing with heat pump unit microprocessor
controller to perform diagnostics, data retrieval, and calibration
functions.]
[(2) Provide 24 volt electromechanical controls supplied with a
low voltage transformer, controls for compressor, reversing valve,
and fan motor operation. Controls shall include a random start
relay, a night setback relay, a compressor cycling relay for
demand load shedding, and a condensate overflow switch. Provide a
SECTION 15741N
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