Specifications

Page 64 of 76 SmartSource 2-Stage Water Source Heat Pumps Catalog 1114-1
Engineering Guide Specications
The unit mounted control system shall allow economizer operation for either supplemental to mechanical unit cooling or
independent, based on entering uid temperature and refrigerant suction temperature operating conditions. Economizer
operation shall be permitted when entering uid temperature is below 55°F yet adjustable between 70°F to 50°F. Economizer
operation shall be initiated from a 3-stage wall mounted thermostat or room temperature sensor. Economizer operation shall
not be permitted when entering uid temperature is below 35°F.
Motorized Water Isolation Valves
The optional 2-way motorized isolation valves shall be factory-installed inside the compressor compartment. The valve actua-
tor shall be factory wired to the MicroTech III SmartSource unit controller and be controlled when there is a call for heating
or cooling. The valve shall have an end switch to ensure valve is fully opened prior to compressor operation.
External Loop Pump(s)
This option includes the addition of an externally mounted water pump on unit sizes 2 tons and larger. The pump shall be
similar to a Grundfos U26-99 or U26-116, or equivalent. Single pump or dual pumps available. Pumps shall be piped in se-
ries. The pump(s) shall be able to produce nominal GPM (3 GPM/ton) and be able to overcome the internal pressure drop of
the coax HX, plus 30 feet additional water pressure drop with 25% PG antifreeze solution.
Fan and Motor Assembly
All units shall have a direct drive centrifugal fan. The fan housing shall have a removable orice ring to facilitate fan mo-
tor and fan wheel removal. The fan housing shall protrude through the cabinet to facilitate eld supply duct connection. The
standard fan motor shall be ECM type isolated from the fan housing and shall have internal thermal overload protection. The
fan and motor assembly must be capable of overcoming the external static pressures as shown on the schedule. The ECM mo-
tor shall deliver precise speed and economical performance regardless of system static pressure. PSC motor shall be available
as an option for single-stage units only.
Disconnect Switch
This factory-installed option shall include the addition of a 2 or 3-pole switch mounted inside the unit and the knob or handle
protruding through the corner post. The switch shall have a lockout/tag out feature. The switch shall be rated to be added to
all units to handle the unit only (not to include additional amperage from eld installed accessories). The switch shall be rated
to handle all the voltages available for the unit. 460/3/60requires4-wirepowerservice.
Compressor Disable Switch
This factory-installed option shall allow the ability to bypass compressor operation in the event of compressor failure and al-
low the fan and electric heat to operate as a means of emergency heat.
Sound Package
Available as a factory installed option, units shall utilize sound attenuating compressor blankets combined with high tech-
nology sound attenuating material that is strategically applied within the air handling compartment to further reduce sound
transmitted by the unit while in operation.Coaxial Coil Supply Liquid Auto Flow Regulator
This factory-installed option includes the addition of an automatic ow control valve to set and limit the GPM through the
unit. The valve shall have a “replaceable cartridge” capability. The valve shall be rated for 600 psig. Note:Thisoptionwill
notbeavailablewithExternalWaterPumpoption.
Electrical
A control box shall be located within the unit and shall contain controls for compressor, reversing valve and fan motor opera-
tion and shall have either, a 50VA or 75VA transformer and a terminal block for low voltage eld wiring connections. Unit
shall be name-plated to accept time delay fuses or HACR circuit breaker for branch over-current protection of the power
source. Unit control system shall provide heating or cooling as required by the set points of the wall thermostat. The unit con-
trol scheme shall provide for fan operation simultaneous with compressor operation (fan interlock) regardless of the thermo-
stat type. The unit shall be capable of providing an output signal to an LED on the thermostat or to a central monitoring panel
to indicate a “fault” condition from the activation of any one of the safety switches.