Nordic R-45, Installation And Service Manual, Page: 6 / 91

1-Nov-2021 Page 6 001200MAN-09
R/RH-Series System Description
General Overview
The Nordic R/RH-series is a package water source heat
pump that can heat or chill air in a forced air duct system. The
duct system can be zoned, but only to limited extent (see Wiring
and Ductwork chapters).
Being a ‘ground source’, ‘water source’, ’geoexchange’, or
‘geothermal’ heat pump, the R/RH-series does require either a
closed ground loop or open loop water well for a heat
source/sink. There is no outdoor fan unit for ground source heat
pumps.
The air heating and cooling functions are controlled by a
standard 3H/2C 24V room thermostat.
In additional to space heating/cooling, there is a double-
wall desuperheater for pre-heating domestic hot water with ~5%
of the heat pump’s capacity. This function is only active when
the heat pump is running for space heating or cooling purposes.
An energy-efficient bronze head ECM circ pump for the desu-
perheater circuit is built in, along with a temperature control.
A two-stage scroll compressor with suction accumulator is
standard. The blower motor is a premium constant-airflow
ECM. The outdoor loop refrigerant to water heat exchanger is a
heavy duty coaxial copper / steel model, with optional CuNi in-
ner tube available for open loop applications. A single thermo-
static expansion valve (TXV) regulates superheat. The cabinet
is constructed from powder coated galvanized sheet metal.
1. Heating Mode
In heating mode, the heat pump heats warm air in a duct
system. As the unit operates, heat is extracted from the ground
loop or well water. The heat pump is activated by by a standard
3H/2C 24V room thermostat, which will call for stage 1 or stage
2 heat according to its own algorithm. The thermostat can also
call for stage 3 (due to air temperature falling further below the
setpoint, or after a certain run time), which will activate the op-
tional electric plenum heater. The plenum heater accessory is
available in different sizes to provide either full backup or partial
auxiliary heat.
If a closed ground loop is used, the circulation pumps are
powered and controlled by the heat pump; if open loop, a water
valve is opened by the heat pump during heating operation and
closed when the heat pump is idle.
2. Cooling Mode
In cooling mode, the heat pump cools air in the duct sys-
tem. As the unit operates, heat is extracted from the ducted air
stream and rejected to the ground loop or well water.
Factory Options
Looking at the main service panel and piping connections,
the heat pump can be ordered as a left or right hand air return
from the factory. This must be specified at time of order as the
physical construction of the two configurations is different.
* See Piping chapter for an
annotated copy of this diagram