Nordic R-Series Manual

11-May-2021 Page 1 002512MAN-01
Maritime Geothermal Ltd.
P.O. Box 2555, 170 Plantation Road
Petitcodiac, NB E4Z 6H4
[phone]
R/RH-Series
Liquid to Air
Heat Pumps
Single-Stage R410a
Model Sizes 09-24
[email protected]
www.nordicghp.com
002512MAN-01
11-May-2021
Installation and Service Manual

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WARNING: Ensure all access panels are in place and properly secured before applying power to the unit.
Failure to do so may cause electrical shock.
WARNING: Before performing service or maintenance on the heat pump system, ensure all power sources
are DISCONNECTED. Electrical shock can cause serious personal injury or death.
WARNING: Heat pump systems contain refrigerant under high pressure and as such can be hazardous to
work on. Only qualified service personnel should install, repair, or service the heat pump.
CAUTION: Safety glasses and work gloves should be worn at all times whenever a heat pump is serviced.
A fire extinguisher and proper ventilation should be present whenever brazing is performed.
CAUTION: Venting refrigerant to atmosphere is illegal. A proper refrigerant recovery system must be
employed whenever repairs require removal of refrigerant from the heat pump.
SAFETY PRECAUTIONS
Model Nomenclature
Series:
R = liquid to air, vertical config.
RH = liquid to air, horizontal config.
Nominal Size:
09 = 0.75 Ton
12 = 1 Ton
18 = 1.5 Ton
24 = 2 Ton
Functions:
H = Heating
AC = Active Cooling
Refrigerant:
P = R410a
Voltage Code:
1 = 230-1-60 VAC
3 = 265/277-1-60 Outdoor Loop Exchanger:
C = copper
Z = CuNi coil
Air Coil:
S = standard (non-coated)
K = e-coated
Blower Type:
D = direct drive
Blower Motor:
E = ECM
Air Return Orientation:
L = left return
R = right return
Air Supply Orientation:
T = top
Revision:
01, 02 etc.
R—24—HAC—P—1L—C—SDELT—01
Compressor:
L = 1 Stage Rotary

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APPLICATION TABLE
SERIES MODEL
SIZE FUNCTION REFRIGERANT VOLTAGE COMPRESSOR OUTDOOR COIL FAN/CASE REVISIONS
R 09 HAC P 1
3 L C Z
SDELT
SDERT 02 03
R 12 HAC P 1
3 L C Z
SDELT
SDERT 02 03
R 18 HAC P 1
3 L C Z
SDELT
SDERT 02 03
R 24 HAC P 1 L C
Z
SDELT
SDERT 02 03
RH 09 HAC P 1
3 L C Z
SDELT
SDERT 03 04 05
RH 12 HAC P 1
3 L C Z
SDELT
SDERT 03 04 05
RH 18 HAC P 1
3 L C Z
SDELT
SDERT 04 05
RH 24 HAC P 1 L C
Z
SDELT
SDERT 02 03
This manual applies only to the models and revisions listed in this table.
Maritime Geothermal Ltd. has a continuous improvement policy and reserves the right to modify specification
data at any time without prior notice .

11-May-2021 Page 4 002512MAN-01
Tables, Figures, & Documents ................................. 5
R/RH-Series System Description ............................ 6
General Overview ................................................................... 6
1. Heating Mode ..................................................................... 6
2. Cooling Mode ...................................................................... 6
Factory Options ...................................................................... 6
R-Series Sizing ................................................................ 7
Heat Pump Sizing ................................................................... 7
Plenum Heater Sizing ............................................................. 7
Installation Basics ......................................................... 8
Sample Bill of Materials - Ground Loop Installations .............. 8
Sample Bill of Materials - Open/Building Loop Installations .... 8
Unpacking the unit .................................................................. 8
Unit Placement ....................................................................... 8
Air Outlet Orientation .............................................................. 9
Air Return Orientation ............................................................. 9
Plenum Heater Installation (Optional) ..................................... 9
Wiring ................................................................................ 10
Power Supply Connections ................................................... 10
Outdoor Loop Pump Module Wiring (Ground Loop Only) ..... 10
Control Transformer .............................................................. 10
Domestic Hot Water (Desuperheater) ................................... 11
Thermostat Requirements ..................................................... 10
Blower Motor ......................................................................... 10
Safety Controls ..................................................................... 11
Open/Closed Loop LPC Selection ........................................ 11
Piping ................................................................................ 12
Condensate Drain ................................................................. 12
Outdoor Loop ........................................................................ 12
002513PDG - Typical Loop Connections .............................. 13
Ductwork .......................................................................... 14
Blower Motor ......................................................................... 14
Duct Systems - General ........................................................ 14
Duct Systems - Grill Layout .................................................. 14
Thermostat Location ............................................................. 14
Plenum Heater ...................................................................... 14
001201CDG - Typical Duct and Condensate Connections ... 15
Duct Sizing Guide ................................................................. 16
Ground Loop Installations .................................. 17
Circulator Pump Module ....................................................... 17
Flushing & Purging ............................................................... 17
Adding Antifreeze Solution .................................................... 18
Initial Pressurization .............................................................. 18
Pipe Insulation ...................................................................... 18
Low Pressure Control Selection ............................................ 18
000608INF - Typical Horiz. Ground Loop Configuration ........ 19
000609INF - Typical Vert. Ground Loop Configuration .......... 20
000906CDG - Circulator Pump Module Installation .............. 21
002336PDG - Pump Module Inst - 2 Units on 1 Loop ........... 22
Open Loop Installations ....................................... 23
Well Water Temperature ....................................................... 23
Well Water Flow .................................................................... 23
Well Water Quality ................................................................ 23
Water Discharge Methods .................................................... 23
Water Valve .......................................................................... 24
Low Pressure Control Selection ............................................ 24
Water Flow Control ............................................................... 25
Submersible Pump Selection ................................................ 25
Plumbing the Heat Pump ...................................................... 25
Pipe Insulation ...................................................................... 25
000619INF - Ground Water Disposal Methods ..................... 26
Table of Contents
Startup Procedure ....................................................... 27
Pre-start Inspection ............................................................... 27
Unit Startup ........................................................................... 28
Startup Record ...................................................................... 29
General Maintenance .................................................. 30
General Maintenance Schedule ............................................ 30
Coaxial Heat Exchanger Flushing Procedures ..................... 30
Troubleshooting Guide ............................................. 31
Repair Procedures ....................................................... 38
Pumpdown Procedure .......................................................... 38
General Repair Procedure .................................................... 38
Vacuuming & Charging Procedure ....................................... 38
Compressor Replacement Procedure ................................... 39
Model Specific Information ...................................... 40
Refrigerant Charge ............................................................... 40
Shipping Information ............................................................. 40
Operating Temperature Limits ............................................... 40
Pressure Drop Data .............................................................. 41
Standard Capacity Ratings ................................................... 42
Performance Tables: R-09 ..................................................... 43
Performance Tables: R-12 ..................................................... 44
Performance Tables: R-18 ..................................................... 45
Performance Tables: R-24 ..................................................... 46
Electrical Specifications ......................................................... 47
Plenum Heater Electrical Specifications ................................ 47
Wiring Diagram (208/230-1-60) ............................................ 48
Wiring Diagram (265/277-1-60) ............................................. 49
Refrigeration Circuit - Heating Mode ..................................... 50
Refrigeration Circuit - Cooling Mode ..................................... 51
Dimensions: R-09/12 Left Return .......................................... 52
Dimensions: R-09/12 Right Return ....................................... 53
Dimensions: R-18/24 Left Return .......................................... 54
Dimensions: R-18/24 Right Return ....................................... 55
Dimensions: RH-09/12 Left Return ....................................... 56
Dimensions: RH-09/12 Right Return ..................................... 57
Dimensions: RH-18/24 Left Return ....................................... 58
Dimensions: RH-18/24 Right Return ..................................... 59
Warranty ......................................................................... 60

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Tables, Figures, & Documents
Table 1 - Heat Pump Size vs. Heated Area for a Ground Loop System .................................................. 7
Table 2 - Heat Pump Size vs. Heated Area for an Open/Building Loop System ..................................... 7
Table 3 - Plenum Heater Sizing ............................................................................................................... 7
Table 4 - Power Supply Connections (Heat Pump) ............................................................................... 10
Table 5 - Power Supply Connections (Plenum Heater) ......................................................................... 10
Table 6 - Control Signal Description ...................................................................................................... 10
Table 7 - Airflow ..................................................................................................................................... 10
Table 8 - Control Board Fault Codes ..................................................................................................... 11
Table 9 - Heat Pump Size vs. Hot Air Grills ........................................................................................... 14
Table 10 - Duct Sizing Guide ................................................................................................................. 16
Table 11 - Antifreeze Percentages ........................................................................................................ 18
Table 12 - Volume of Fluid per 100ft. Of Pipe ....................................................................................... 18
Table 13 - Required Open Loop Flow .................................................................................................... 23
Table 14 - Refrigerant Charge ............................................................................................................... 40
Table 15 - Shipping Information ............................................................................................................. 40
Table 16 - Operating Temperature Limits .............................................................................................. 40
Table 17 - Loop Pressure Drop Data ..................................................................................................... 41
Table 18 - Standard Capacity Ratings - Ground Loop Heating 60Hz .................................................... 43
Table 19 - Standard Capacity Ratings - Ground Water Heating 60Hz ................................................... 43
Table 20 - Standard Capacity Ratings - Ground Loop Cooling 60Hz .................................................... 43
Table 21 - Standard Capacity Ratings - Ground Water Cooling 60Hz ................................................... 43
Table 22 - Electrical Specifications ........................................................................................................ 47
Table 23 - Plenum Heater Electrical Specifications ............................................................................... 47
Figure 1 - Ground Loop Accessories & Tools ........................................................................................ 16
Figure 2 - Open Loop Accessories & Tools ........................................................................................... 24
Dimensions: R-09/12 Left Return .......................................................................................................... 52
Dimensions: R-09/12 Right Return ........................................................................................................ 53
Dimensions: R-18/24 Left Return .......................................................................................................... 54
Dimensions: R-18/24 Right Return ........................................................................................................ 55
Dimensions: RH-09/12 Left Return ........................................................................................................ 56
Dimensions: RH-09/12 Right Return ..................................................................................................... 57
Dimensions: RH-18/24 Left Return ........................................................................................................ 58
Dimensions: RH-18/24 Right Return ..................................................................................................... 59
002513CDG - Typical Loop Connections - R/RH Commercial .............................................................. 13
001201CDG - Typical Duct and Condensate Connections .................................................................... 15
000608INF - Typical Horizontal Ground Loop Configuration .................................................................. 19
000609INF - Typical Vertical Ground Loop Configuration ...................................................................... 20
000906CDG - Geo-Flo Circulator Pump Module Installation ................................................................. 21
002336PDG - Circulator Pump Module Installation - Two Units on One Ground Loop........................... 22
000619INF - Ground Water Disposal Methods ...................................................................................... 26
001954SCH - R/RH-09/12/18/24 Schematic Diagram 208/230-1-60 ..................................................... 48
002124SCH - R/RH-09/12/18/24 Schematic Diagram 277-1-60 ............................................................ 49
001766RCD - R(H) 09-24 Refrigeration Circuit - Heating Mode ............................................................ 50
001767RCD - R(H) 09-24 Refrigeration Circuit - Cooling Mode ............................................................ 51
Tables
Figures
Documents

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R/RH-Series System Description
General Overview
The Nordic vertical R-series and horizontal RH-series,
geothermal standards for more than 30 years, are package wa-
ter source heat pumps that can heat or chill air in a forced air
duct system. Being ‘ground source’, ‘water source’, ‘geo-
exchange’, or ‘geothermal’ heat pumps, the R and RH-series do
require a building loop, ground loop or open loop water well
for a heat source/sink. There is no outdoor fan unit for ground
source heat pumps.
The residential NORDIC R/RH product line, with premium
features expected in a central heating/cooling system, runs from
size 25 to 80. The smaller R/RH-09 to 24 described in this doc-
ument aim to economize on price while still maintaining high
reliability and many premium features. They are normally con-
sidered a ‘commercial’ product for multiple-unit installations,
although they can be employed residentially.
On R/RH-09 to 24, there is no desuperheater for DHW
heating. A single stage rotary compressor with built in accumu-
lator is used. The blower motor is an ECM, which has 5 fixed
constant torque airflow settings which are selected during instal-
lation. The outdoor loop refrigerant to water heat exchanger is a
heavy duty coaxial copper / steel model, and an optional CuNi
inner tube may be available for challenging water applications
(check with factory). A single thermostatic expansion valve
(TXV) regulates superheat. The cabinet is constructed from
galvanized sheet metal, partly powder coated.
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, well water, or building loop. The heat pump is activated by
by a standard 2H/1C 24V room thermostat, which will call for
heat from the compressor first. The thermostat can also call for
stage 2 (due to air temperature falling further below the setpoint,
or after a certain run time), which will activate the optional elec-
tric 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, 230v circulation pumps
can be powered and controlled by the heat pump; if building
loop or 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

11-May-2021 Page 7 002512MAN-01
R/RH-Series Sizing
TABLE 2 - Heat Pump Size vs. Heated Area
for an Open / Building Loop System
Model ft2 m2
R/RH-09 375 35
R/RH-12 500 46
R/RH-18 750 70
R/RH-24 1000 93
Heat Pump Sizing
The following table is a rough guideline as to the size of
space each heat pump size can handle for ground loop (closed
loop) installations.
The following table is a rough guideline as to the size of
space each heat pump size can handle for ground water (open
loop) or building loop installations.
THE TABLES ABOVE ARE FOR ESTIMATION ONLY.
THEY SHOULD NOT BE USED TO SELECT A FINAL UNIT
SIZE. They simply show what size unit is required for a
residential installation with typical construction: R20 walls, R40
ceiling, and average size and number of windows. The heated
area is the area of the above grade main level; the tables ac-
count for a basement the same size as the heated area.
MARITME GEOTHERMAL LTD. HIGHLY RECOM-
MENDS THAT A PROPER HEAT LOSS/GAIN ANALYSIS BE
PERFORMED BY A PROFESSIONAL WITH APPROVED CSA
F-280 SOFTWARE BEFORE SELECTING THE HEAT PUMP
SIZE. For heating dominant climates, we recommend sizing
the unit to 100% of the heating design load for maximum
long term efficiency with minimal supplementary heat. The
unit should be installed as per CSA standard 448.2-02. For
ground loop applications, the ground loop should be de-
signed using suitable software with a multi-year analysis.
The analysis will result in a heat load for the coldest day,
which is influenced by, for example, the number of levels, the
size of the windows, the orientation of the home, attached gar-
age, bonus rooms, walk-in basement, and coldest outdoor tem-
perature for the region.
A heat pump model size can then be selected by compar-
ing the calculated heat load to the heat pump capacity at the
design indoor loop temperature, which can be found in the per-
formance tables in the Model Specific Information section. For
these heat pump series, the Standard Capacity Ratings rather
than detailed performance tables can be used for simplicity. For
100% heat pump sizing, choose a heat pump with a standard
capacity rating that matches or just slightly exceeds the calculat-
ed heat load.
Some background on Standard Capacity Ratings: closed
ground loops are normally designed to reach a minimum tem-
perature of just below freezing at the end of the heating season,
in order to take advantage of the latent heat of groundwater (at
least in northern climates). Hence, the Standard Capacity Rat-
ings for Ground Loop Heating should apply in all northern cli-
mates. Conversely, the Standard Capacity Ratings for Ground
Water (open loop) heat pumps assume a well water temperature
of 50°F (10° C). In more southerly climates, the groundwater or
ground loop will probably be at a warmer minimum temperature,
and it will be necessary to consult the more detailed perfor-
mance tables for heat pump output at a different ELT.
In cooling dominant climates, the heat pump should be
similarly sized using the Ground Loop Cooling or Ground Water
Cooling Standard Capacity Ratings. Even in northern heating
dominant climates, it should be ensured that 100% of the
cooling load will be covered when sizing the heat pump,
since there is normally no auxiliary or backup cooling avail-
able.
Plenum Heater Sizing
The plenum heater is available as an accessory in 5, 7, 10,
15 and 20 kW sizes. If full backup is desired, choose a size that
covers 100% of the coldest day heat load, according to the heat
loss analysis mentioned in the last section. If that is not availa-
ble, use the following recommendation:
Be sure to order the ‘internally mounted’ type of plenum
heater, even though on these units it is mounted externally.
This is because the “internally mounted” model has a narrower
cage that is more suitable for the smaller discharge ductwork
used with smaller heat pump sizes.
TABLE 3 - Plenum Heater Sizing
Model Plenum Heater Size
for full backup
R/RH-09 5 kW (or smaller)
R/RH-12 5 kW (or smaller)
R/RH-18 5 kW
R/RH-24 7 kW
TABLE 1 - Heat Pump Size vs. Heated Area
for a Ground Loop System
Model ft2 m2
R/RH-09 300 28
R/RH-12 400 37
R/RH-18 600 56
R/RH-24 800 74

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Installation Basics
Unpacking the Unit
When the heat pump reaches its destination it should be
unpacked to determine if any damage has occurred during
shipment. Any visible damage should be noted on the carrier's
freight bill and a suitable claim filed at once.
Unit Placement
Ducted or forced air heat pumps should be centrally located
in the building with respect to the conditioned space. This
provides the best in economy and comfort and usually can be
accomplished in harmony with the design of the space. A
heating system cannot be expected to produce an even temper-
ature throughout the space when it is located at one end of the
structure and the heated or cooled air is transmitted with
uninsulated metal ductwork.
For vertical R-series units, the front access panel (on the
side where pipes are connected) should remain clear of
obstruction for a distance of 2 ft (0.7 m) to facilitate servicing
and general maintenance. No access is required on the left,
Sample Bill of Materials -
Ground Loop Installations
FROM MARITIME GEOTHERMAL
• R/RH SERIES HEAT PUMP (L OR R RETURN)
• PLENUM HEATER 5/7kW
• 2H/1C THERMOSTAT (OR SOURCED ELSEWHERE)
• P/T PORTS AND HOSE ADAPTERS (2)
• 1 PUMP PACK
• PIPE ADAPTERS FOR PUMP PACK
OPTIONAL FROM MARITIME GEOTHERMAL
• ANTI-VIBRATION PAD
• SOUND JACKET
DUCTWORK
• OUTLET PLENUM ADAPTER W/ FLEXIBLE COLLAR
• RETURN AIR ADAPTER W/ FLEXIBLE COLLAR
• FIBREGLASS INSULATION (FOR NOISE, IF REQ’D)
• TRUNK DUCT W/ JOINERS (IF NOT EXISTING)
• 6” ROUND DUCT W/ADAPTERS (IF NOT EXISTING)
• ALUMINUM TAPE
• SHEET METAL SCREWS
GROUND LOOP
• ¾” PE PIPE
• 1-1/4” PE PIPE
• PE PIPE FITTINGS
• 1” CLEAR HOSE (HEAT PUMP TO PUMP PACK)
• HOSE CLAMPS
• ANTIFREEZE: METHANOL OR PROP. GLYCOL
ELECTRICAL
• HEAT PUMP SERVICE WIRE: 14-2 OR 12-2
• PLENUM HEATER SERVICE WIRE
• HEAT PUMP BREAKER
• PLENUM HEATER BREAKER
• THERMOSTAT WIRE 18-8
• THERMOSTAT WIRE 18-2 (PLENUM HEATER)
• FORK TERMINALS FOR TSTAT WIRE (10)
• CONDENSATE PUMP & HOSE (IF REQUIRED)
• 2” STYROFOAM INSUL. (IF PAD NOT PURCHASED)
Sample Bill of Materials -
Open/Building Loop Installations
FROM MARITIME GEOTHERMAL
• R/RH SERIES HEAT PUMP (L OR R RETURN)
• PLENUM HEATER 5/7kW
• 2H/1C THERMOSTAT (OR SOURCED ELSEWHERE)
• P/T PORTS AND HOSE ADAPTERS (2)
• DOLE/HAYS FLOW RESTRICTOR VALVE
• SOLENOID WATER VALVE
OPTIONAL FROM MARITIME GEOTHERMAL
• ANTI-VIBRATION PAD
• SOUND JACKET
DUCTWORK
• OUTLET PLENUM ADAPTER W/ FLEXIBLE COLLAR
• RETURN AIR ADAPTER W/ FLEXIBLE COLLAR
• FIBREGLASS INSULATION (FOR NOISE, IF REQ’D)
• TRUNK DUCT W/ JOINERS (IF NOT EXISTING)
• 6” ROUND DUCT W/ ADAPTERS (IF NOT EXISTING)
• ALUMINUM TAPE
• SHEET METAL SCREWS
WATER SYSTEM (OPEN LOOP ONLY)
• 1” BLACK PLASTIC WATER PIPE
• 1” BARBED FITTINGS & HOSE CLAMPS
• VSP SUBMERSIBLE PUMP (IF NOT EXISTING)
• PRESSURE TANK (IF NOT EXISTING)
• CYCLE STOP VALVE (IF FIXED SPEED PUMP)
ELECTRICAL
• HEAT PUMP SERVICE WIRE: 14-2 OR 12-2
• PLENUM HEATER SERVICE WIRE
• HEAT PUMP BREAKER
• PLENUM HEATER BREAKER
• THERMOSTAT WIRE 18-8
• THERMOSTAT WIRE 18-2 (PLENUM HEATER)
• FORK TERMINALS FOR TSTAT WIRE (10)
• CONDENSATE PUMP & HOSE (IF REQUIRED)
• 2” STYROFOAM INSUL. (IF PAD NOT PURCHASED)
right, or back sides. Raising the indoor unit off the floor a few
inches is generally a good practice since this will prevent rusting
of the bottom panel of the unit from concrete floors, and deaden
vibrations. An anti-vibration pad, available as an accessory, or
a piece of 2” styrofoam should be placed under the unit.
Horizontal RH-series units are normally mounted in a con-
cealed ceiling, and securely hung using the built-in hangers (or
floor mounted in a crawl space). The front access panel, the
access panel opposite the air return, and the access panel on
the end or side which is the same size as the fan discharge pan-
el should remain clear of obstruction for a distance of 2 ft (0.7
m) to facilitate servicing and general maintenance.
For both R and RH units, ensure the unit is level to elimi-
nate condensate draining issues.
The heat pump comes equipped with an air filter rack which
can be installed with the removable end (where the filter is in-
serted) on either side to facilitate changing the filter. Be careful
not to run piping in front of the filter rack access cover, since
access is required in order to change the air filter.

11-May-2021 Page 9 002512MAN-01
Air Outlet Orientation
For vertical R-series units, the air discharge location is in a
fixed position, blowing upwards.
For horizontal RH-series units, as is typical for heat pumps
of this type, the air discharge can be field installed in either the
side (default position, opposite the air return) or the end (90° to
the air return). To switch it to the end position, before ductwork
is installed:
1. Ensure power to the unit is off.
2. Remove the screws that hold the access panel adjacent to
the blower panel in place and remove the access panel by
pulling up on the handle and then outward from the bot-
tom.
3. Repeat for the access panel with the blower mounted in it.
Ensure the wiring harnesses move freely while removing
the blower.
4. Disconnect the wiring harness plugs from the motor, and
the ground wire from the fan housing.
5. Place the blower in front of its new ‘end’ location, making
sure the motor is facing toward the adjacent access panel.
Flip the blower and panel over if required. Reconnect both
motor plugs and the housing ground wire.
6. Install the blower and secure panel with the screws.
7. Install the adjacent access panel and secure with the
remaining screws.
Note for both R and RH units, for blower motor servicing
the entire blower can be removed out the adjacent access panel
by removing two bolts:
Air Return Orientation
The heat pump can be ordered as left or right air return
from the factory. This must be specified at time of order as the
physical construction of the two configurations is different. Re-
fer to the Dimensions section toward the end of this manual for
physical dimensions of the units.
LEFT RETURN RIGHT RETURN
Plenum Heater Installation (Optional)
Be sure to order the ‘internally mounted’ type of ple-
num heater, since the plenum heater intended for external
installation in larger heat pumps has a cage which is too
wide for the smaller ductwork used with these smaller heat
pumps.
Plenum heater should be installed in the air discharge duct
outside the heat pump cabinet in a manner that allows all of the
airflow to pass through it to prevent any hot spots in the heater
elements. Ensure that the plenum heater is mounted in an ap-
proved position as per its instructions. (If there is an airflow
direction arrow on the plenum heater, it can be disregarded.)
R
RH

11-May-2021 Page 10 002512MAN-01
TABLE 4 - Power Supply Connections (Heat Pump)
Line Description Voltages
L1 Line 1 208/230-1-60, 277-1-60
L2 Line 2 208/230-1-60, 277-1-60
GND Ground 208/230-1-60, 277-1-60
N Neutral No Connection
TABLE 5 - Power Supply Connections
(Plenum Heater)
Line Description Voltages
L1 Line 1 All
L2 Line 2 All
N Neutral No Connection
GND Ground All (connect to ground lug)
Wiring
NOTE: A properly qualified electrician
should be retained for all connections to the
heat pump and associated controls. The
connections to the unit MUST CONFORM TO
LOCAL CODES.
Power Supply Connections
The heat pump has a 0.875” knockout for main power sup-
ply connection from the breaker panel to the electrical box.
There are also 0.875” knockouts and a plastic grommet for con-
nections to plenum heater power supply, thermostat, and water
valve or ground loop pump pack.
NOTE: Two separate power supplies are required, one for
the heat pump and a second one for the plenum heater.
Each must have its own supply wires and breaker.
Electrical diagram can be found on the electrical box cover
as well as in the Model Specific Information section of this man-
ual. The Electrical Tables in the Model Specific Information
section contain information about the wire and breaker size.
Outdoor Loop Pump Module Wiring
(Ground Loop, or Single Pipe Building Loop)
The circulator pump or pump module should be wired so
that they will be turned on whenever the compressor operates.
Unlike other NORDIC model series, there is no dedicated
terminal strip for circulator pump connection in the heat pump,
and there is no neutral wire connection to the heat pump to al-
low 115v circulators to be powered from the heat pump. Circu-
lators may be externally powered and controlled, using a relay
or contactor activated by the Y signal from the thermostat.
However, 230v circulators may be connected to the load
side of the heat pump’s compressor contactor using ring termi-
nals or female disconnects, as long as they do not exceed 1.5A
maximum current draw. Ground wire should be connected to
the ground lug in the electrical box.
Control Transformer
The low voltage controls for 208/230-1-60 and 208-3-60
models are powered by a class II transformer with impedance
protection. Should the 24v side be accidentally shorted out and
impedance protection tripped, it will be necessary to replace the
transformer.
IMPORTANT NOTE: For 208/230VAC-1-60
units, if connecting to 208VAC power supply
move the red wire connected to the 240 ter-
minal of the transformer to the 208 terminal
of the transformer.
Thermostat Requirements
A 2-stage heating and 1-stage cooling heat pump configu-
rable thermostat is required. The first thermostat heating stage
activates the compressor by sending a Y signal, and the second
activates the electric auxiliary (accessory plenum heater) by
sending a W2 signal. The electrical diagram on the electrical
box cover provides a description of the signal connections, as
does the below table. Refer to diagram on a following page for
connections between the thermostat and the heat pump.
Cooling mode is activated by the thermostat by sending an
O signal, along with a Y signal to activate the compressor.
TABLE 6 - Control Signal Description
Signal Description
C 24VAC common (ground)
G Fan lowest speed (for air recirculation)
R 24VAC hot
L Fault (24VAC when fault condition)
O Cooling mode (reversing valve)
Y Compressor ON
W2 Auxiliary / Emergency Heat
C(I) Plenum heater dry contact
(Connect to C or I in plenum heater)
1 Plenum heater dry contact
(Connect to 1 and 2 in plenum heater)
Blower Motor
The blower is equipped with a 5-speed (actually 5 constant
torque) direct drive ECM. The motor features a soft start which
provides a smooth, quiet ramp up to operating speed .
The lowest speed is activated by a G signal from the ther-
mostat, used for air recirculation or fan only mode. There are 4
speeds associated with compressor operation, one of which
should be selected during heat pump commissioning.
Move the fork terminal with the yellow and purple wire to
one of the terminals SP1 / SP2 / SP3 / SP4. Measure the airflow
in the discharge ductwork and select a speed that most closely
matches the required airflow for the model size according to the
following table. Proper airflow can be verified by observing the
air delta T, which should be 25-32°F. Assuming a room tem-
perature of 68°F, high pressure at proper airflow should be 320-
400 psi as measured with a refrigeration gauge set.
If too low an airflow is selected, heat pump efficiency will
be lower and nuisance high or low safety control trips may oc-
TABLE 7 - Airflow
Model Required
Airflow
R/RH-09 325
R/RH-12 400
R/RH-18 650
R/RH-24 800
cur. Too high an airflow will
result in excessive noise
and a cooler discharge air
temperature. If the target
airflow cannot be achieved
even on SP4, the ductwork
is likely undersized and
ductwork design should be
reviewed as per following
chapter.

11-May-2021 Page 11 002512MAN-01
TABLE 8 - Control Board Fault Codes
Fault LED Flashes
High Pressure 1
Low Pressure 2
Condensate Overflow 4
Brownout 5
Safety Controls
The heat pump has two important built in safety controls
which are designed to protect the unit from situations which
could damage it should the operation of the refrigeration circuit
fall outside the allowable operating range.
1. High Pressure Control
The high pressure safety control monitors the compressor
discharge pressure and will shut the compressor down if the
condensing pressure becomes too high.
There are (3) main reasons this control would activate in
response to the operating conditions of the unit while operating
in heating mode:
1. Low or no indoor loop flow.
2. High indoor loop entering liquid temperature.
3. Dirty or fouled indoor loop heat exchanger.
4. High refrigerant charge after service, or mechanical
malfunction (see Troubleshooting section).
2. Low Pressure Control
The low pressure control monitors the compressor suction
pressure and will shut the compressor down if the refrigerant
evaporating pressure becomes too low, risking the danger of
freezing conditions in the evaporator.
There are (3) main reasons this control would activate in
response to the operating conditions of the unit while operating
in heating mode:
1. Low or no outdoor loop flow.
2. Low outdoor loop entering liquid temperature.
3. Dirty or fouled outdoor loop heat exchanger.
4. Low refrigerant charge due to leak, or mechanical mal-
function (see Troubleshooting section).
The unit contains a control board that monitors the safety
controls and operates the compressor accordingly. The low
pressure control and high pressure controls are connected to
the control board as shown on the wiring diagram later in this
manual.
The compressor will not be allowed to start if a ‘fault’ con-
dition exists. A ‘fault’ occurs if either one of the pressure con-
trols exhibits an open circuit. In addition, the board monitors a
condensate overflow sensor, located in the drip tray, and the
voltage of the 24vac transformer. A fault will occur if a conden-
sate overflow is detected, or a low voltage condition (electricity
grid brownout) is detected.
The control board has an on-board LED and an ALR pin
with a 24VAC output, which is routed to the L terminal of the
thermostat terminal strip. An external indicator or relay can be
connected across L and C on the terminal strip if external signal-
ing is desired. Should a fault condition occur, the LED will flash
the code of the fault condition. The codes are shown in the fol-
lowing table. The control board will lock out the compressor for
five minutes when a fault occurs. The control board will then
restart the compressor if the fault has been cleared. Should a
second fault condition occur within a 60 minute period the con-
trol board will go into permanent lockout mode and energize the
ALR pin. The LED will flash the fault code until the control
board is reset by powering down the unit.
The board has a TEST jumper, which defeats the 5 minute
anti-short cycle timer for test purposes. If left in the TEST posi-
tion, it will time out and return to normal operation after a set
time period. This is to prevent compressor short cycling and
possible damage or shortened lifespan if the jumper is acci-
dentally left in the TEST position.
There are also FREEZE TEMP and WATER TEMP jump-
ers on the control board. Under standard heat pump configura-
tions, these are not used and have no effect on heat pump oper-
ation.
Open/Closed Loop LPC Selection
There are two low pressure controls (LPC’s) in the heat
pump: 75 psi for building loop or open loop (fresh water), and 55
psi for closed loop (antifreeze). As shipped, the open loop LPC
will be active, since there will be no jumper between LP1 and
LP2 on the heat pump’s terminal strip.
If a closed ground loop with antifreeze is used, a wire jump-
er should be installed between LP1 and LP2 on the heat pump’s
terminal strip. This will cause the lower 55 psi low pressure con-
trol to be selected, to allow a lower loop temperature than would
be appropriate for fresh water before tripping.
WARNING: WHEN LP1 AND LP2 ARE CON-
NECTED, A PROPER LOOP ANTIFREEEZE
SOLUTION IS REQUIRED TO PREVENT
FREEZING AND RUPTURING OF THE HEAT
EXCHANGER, VOIDING THE WARRANTY.

11-May-2021 Page 12 002512MAN-01
Piping
Condensate Drain
The unit comes equipped with one 3/4” female PVC socket
or 3/4” PVC female NPT drain connection. This drain allows the
condensate which forms during the air conditioning cycle to be
removed from the unit. The drain should be connected and
vented as per local codes. During high humidity weather, there
could be as much as 25 gallons of water formed per day.
For vertical R units, the condensate drain is internally
trapped and does not require an external trap. For horizontal
RH units, the condensate drain is not internally trapped,
and an external trap and vent must be installed.
An external condensate pump may be installed if there is
not sufficient drain piping slope possible to drain condensate
under gravity to its destination.
To avoid overflow of the condensate pan, the drain line
and trap should be inspected periodically to ensure they are not
plugged with accumulated debris.
There is an alarm for condensate overflow, which will disa-
ble unit operation.
See following pages for diagrams showing the condensate
drain connection.
Outdoor Loop
The connections for the Outdoor Loop are 1/2” or 3/4”
brass female NPT. They are labelled OUTDOOR IN and
OUTDOOR OUT.
See the following page for an illustration of a building loop
installation, and also the following chapters for details on ground
loop and open loop installations.

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11-May-2021 Page 14 002512MAN-01
Ductwork
Blower Motor
The indoor unit is equipped with a direct drive 5-speed
ECM blower. See Wiring chapter for description and airflow
adjustment.
Duct Systems - General
Ductwork layout for a heat pump will differ from traditional
hot air furnace design in the number of leads and size of main
trunks required. Air temperature leaving the heat pump is
normally 95º -105ºF (35-40ºC), much cooler than that of a
conventional fossil fuel furnace. To compensate for this, larger
volumes of lower temperature air must be moved and
consequently duct sizing must be able to accommodate the
greater airflow without creating a high static pressure or high
velocity at the floor diffusers.
A duct system capable of supplying the required airflow is
of utmost importance. Maritime Geothermal Ltd. recommends
that the external static pressure from the duct system be kept
below 0.2 inches of water total. In some instances the number
of floor diffusers will actually double when compared to the
number that would be used for a hot air oil-fired furnace. Refer
to following tables.
1. Generally allow 100 cfm for each floor grill.
2. All leads to the grills should be 6'' in diameter (28sq.in. each).
3. The main hot air trunks should be at least 75% of the square
surface area of leads being fed at any given point.
4. Return air grills should have a minimum of the same total
square surface area as the total of the supply grills.
5. The square surface area of the return trunks should equal
the square surface area of the grills being handled at any
given point along the trunk.
It is VERY IMPORTANT that all turns in both the supply
trunks and the return trunks be made with TURNING RADII. Air
act like a fluid and, just like water, pressure drop is increased
when air is forced to change direction rapidly around a sharp or
irregular corner.
It is recommended that flexible collars be used to connect
the main trunks to the heat pump. This helps prevent any vibra-
tions from travelling down the ductwork. If a plenum heater is
installed, the collar should be at least 12” away from the heater
elements.
If desired, the first 5-10 feet of the main supply trunks can
be insulated internally with acoustical duct insulation to further
inhibit any noise from the unit from travelling down the ductwork.
If a plenum heater is installed, insulation should not be placed
within 12” of the heater elements.
Duct Systems - Grill Layout
Most forced air heating systems have the floor grills placed
around the perimeter of the room. Supply grills should be
placed under a window when possible to help prevent conden-
sation on the window. As mentioned in the previous sub-
section, supply grill leads should be 6'' in diameter (28 square
inches each) to allow 100 cfm of airflow.
In a typical new construction, there should be one supply
grill for every 100 square feet of area in the room. When rooms
require more than one grill, they should be placed in a manner
that promotes even heat distribution, such as one at each end of
the room. It is always a good idea to place a damper in each
grill supply or place adjustable grills so that any imbalances in
the heat distribution can be corrected.
The total number of supply grills available is based on the
heat pump nominal airflow. The table shows the number of
grills recommended per heat pump size.
Return grills should be mounted on the floor. At minimum
they should be the same size as the supply grill, it is highly rec-
ommended that they be 25% to 50% larger than the total
supply. They should be placed opposite the supply grills
when possible to ensure distribution across the room. For
rooms requiring more than one supply grill, it may be possible to
use one larger return grill if it can be centrally positioned oppo-
site of the supply grills, however it is preferred to have one re-
turn for each supply to optimize heat distribution across the
room.
Thermostat Location
Most small installations are a single ducted air zone with
one thermostat. The thermostat should be centrally located
within the space, typically on the main floor. It should be placed
away from any supply grills, and should not be positioned direct-
ly above a return grill. The thermostat can be located in a hall-
way, or on the inner wall of a room. It should be noted that most
buildings not have any supply ducts in the hallway. This can
lead to a temperature lag at the thermostat if there is very little
air movement in the hallway, causing the space to be warmer
than indicated by the thermostat.
Plenum Heater
As described in the Installation Basics section, the plenum
heater will be installed in the discharge ductwork outside the
unit, at least 12” away from any flexible duct collars. There is an
accessory plenum heater with a wider cage profile available that
is more suitable for duct installation than the model with the nar-
rower cage which is meant for internal installation in larger heat
pumps.
TABLE 9 - Heat Pump Size vs. Hot Air Grills
Model Size (tons) # of Grills (@100 cfm)
09 0.75 3
12 1 4
18 1.5 6
24 2 8

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11-May-2021 Page 16 002512MAN-01
Airflow
(CFM)
Diameter
(in) Rectangular Equivalents (in)
Return Air
Diameter
(in)
Airflow
(L/s)
37 5 2.25 x 10 3 x 8 3.5 x 6 4 x 5.5 5 x 5 ` 5 17
63 5 2.25 x 10 3 x 8 3.5 x 6 4 x 5.5 5 x 5 6 30
100 6 3.25 x 10 4 x 8 5 x 6 5.5 x 5.5 6 x 6 7 47
152 7 3.25 x 14 4 x 11 5 x 8.5 6 x 7 6.5 x 6.5 8 72
212 8 4 x 15 5 x 12 6 x 10 7 x 8 8 x 8 9 100
226 8 4 x 15 5 x 12 6 x 10 7 x 8 8 x 8 10 107
277 9 5 x 15 6 x 12 7 x 10 8 x 9 8.5 x 8.5 10 131
304 9 5 x 15 6 x 12 7 x 10 8 x 9 8.5 x 8.5 12 143
393 10 6 x 15 7 x 13 8 x 11 9 x 10 9.5 x 9.5 12 185
411 12 7 x 18 8 x 16 9 x 14 10 x 12 11 x 11 12 194
655 12 7 x 18 8 x 16 9 x 14 10 x 12 11 x 11 14 309
680 14 8 x 22 9 x 19 10 x 17 11 x 15 12 x 14 13 x 13 14 321
995 14 8 x 22 9 x 19 10 x 17 11 x 15 12 x 14 13 x 13 16 470
1325 16 8 x 30 10 x 22 12 x 18 14 x 16 15 x 15 18 625
1450 16 8 x 30 10 x 22 12 x 18 14 x 16 15 x 15 20 684
1750 18 8 x 40 10 x 30 12 x 24 14 x 20 16 x 17 16.5 x 16.5 20 826
2000 18 8 x 40 10 x 30 12 x 24 14 x 20 16 x 17 16.5 x 16.5 22 944
2250 20 10 x 38 12 x 30 14 x 26 16 x 22 18 x 19 18.5 x 18.5 22 1062
2600 20 10 x 38 12 x 30 14 x 26 16 x 22 18 x 19 18.5 x 18.5 24 1227
2900 22 12 x 36 14 x 30 16 x 26 18 x 23 20 x 20 24 1369
3400 22 12 x 36 14 x 30 16 x 26 18 x 23 20 x 20 26 1605
3600 24 14 x 38 16 x 32 18 x 28 20 x 25 22 x 22 26 1699
4300 24 14 x 38 16 x 32 18 x 28 20 x 25 22 x 22 28 2029
5250 26 16 x 38 18 x 32 20 x 30 22 x 24 24 x 24 30 2478
6125 28 18 x 38 20 x 34 22 x 30 24 x 28 26 x 26 32 2891
6500 28 18 x 38 20 x 34 22 x 30 24 x 28 26 x 26 34 3068
7250 30 20 x 40 22 x 38 24 x 32 26 x 30 28 x 28 34 3422
7800 30 20 x 40 22 x 38 24 x 32 26 x 30 28 x 28 36 3681
8500 32 22 x 40 24 x 38 26 x 34 28 x 32 30 x 30 36 4012
9200 32 22 x 40 24 x 38 26 x 34 28 x 32 30 x 30 38 4342
9800 34 24 x 42 25 x 40 26 x 38 28 x 34 30 x 32 31 x 31 38 4625
10900 34 24 x 42 25 x 40 26 x 38 28 x 34 30 x 32 31 x 31 40 5144
28 x 40 30 x 36 32 x 34 33 x 33
30 x 42 32 x 38 34 x 36 35 x 35
30 x 45 34 x 40 36 x 38 37 x 37
TABLE 10 - Duct Sizing Guide (external static of 0.20” H2O)
Minimum
Duct Area
(sq.in)
20
20
28
38
50
50
64
64
79
113
113
154
154
201
201
254
254
314
314
380
380
452
452
531
616
616
707
707
804
804
908
908

11-May-2021 Page 17 002512MAN-01
Figure 1: Ground Loop Accessories & Tools
Ground Loop Installations
Once the lines have been filled and no more air bubbles are
appearing in the line, adjust the circulator pump module valves
to circulate water through the heat pump using the same
technique as described above. When all air is removed reverse
the flow of water through the lines by interchanging the flush
cart lines and purge again. You will be able to visibly tell when
all air is removed.
Refer to diagrams 000608INF & 000609INF at the end of
this section for typical ground loop configurations. They are for
reference only, and should not be used to replace formal train-
ing and computerized loop design.
Once the ground loop has been pressure tested and the
header pipes have been connected to the circulator pump mod-
ule, the heat pump can be connected to the circulator pump
module.
Circulator Pump Module
Maritime Geothermal Ltd. offers compact pump modules
with built in three way valves to facilitate filling and purging the
ground loop. Refer to drawing 000906CDG at the end of this
section. Alternatively, Grundfoss Model UPS 26-99 or Taco
Model 0011 pumps or other brands with similar pumping capa-
bility may be used. The single pump module will typically han-
dle systems up to 3 tons. This is based on a typical parallel
system with one circuit per ton.
Calculate the total pressure drop of the ground loop
(including headers, indoor piping and heat pump exchanger
drop) based on the antifreeze type and concentration at the de-
sired minimum loop temperature. A pump module that can de-
liver the flow required for the unit at the calculated total pressure
drop should be selected. Refer to the Model Specific Infor-
mation section for unit flow requirements. Loop pressure
drops can be calculated using software such as those men-
tioned in the Horizontal Ground loops section, or can be calcu-
lated in a spreadsheet using the pipe manufacturer’s pressure
drop tables for pipe diameter and fittings.
The circulator pump module must be connected to the heat
pump Outdoor Loop ports with a lineset suitable for the flow
required with minimum pressure drop. 1” rubber or plastic lines
should be used.
The installation of P/T plugs/ports (pressure / temperature,
pronounced “Pete’s plugs” ) is recommended on both the
entering and leaving lines at the heat pump. This will allow the
installer or homeowner to check water flow through the loop by
measuring the pressure difference through the heat exchanger
and comparing it to that listed in the Model Specific Information
section. P/T ports, adapters, and gauge adapters and are avail-
able as accessories from Maritime Geothermal Ltd..
Flushing & Purging
Once the groundloop has been installed and all connections
are completed between the heat pump, circulator pump module
and ground loop, the entire ground loop system should be
pressure tested with air to 100 PSIG to make sure there are
no leaks on any of the inside fittings. Soap all joints and observe
that the pressure remains constant for 1 hour.
When satisfied that all connections are leak free, release
the air pressure and connect a purge cart (see Figure 1) to the
flushing access ports at the pump module (refer to drawing
000906CDG). A temporary flushing system can alternately be
constructed using a 45 gal. barrel and a pump with sufficient
volume and head capability to circulate fluid at a velocity of at
least 2 ft/min through all parts of the loop.
Adjust the circulator pump module valves to connect the
purge cart to the ground loop. Begin pumping water through the
ground loop, ensuring that the intake of the pump stays
submerged at all times by continuously adding water. Water
flowing back from the return line should be directed below the
water level in the barrel or flush tank to prevent air being mixed
with the outgoing water.
Purge Cart
2-pump module
Barbed Adapters
PE Adapters
Gauge adapter
for P/T port
P/T port
P/T adapters for
heat pump
(1” NPT to barb)

11-May-2021 Page 18 002512MAN-01
TABLE 12 - Volume of fluid per 100 ft. of pipe
Volume /100ft.
Type of Pipe Diameter I.gal gal L
Copper 1” 3.4 4.1 15.5
1-1/4” 5.3 6.4 24.2
1-1/2” 7.7 9.2 34.8
Rubber Hose 1” 3.2 3.9 14.8
Polyethylene 3/4” IPS SDR11 2.3 2.8 10.6
1” IPS SDR11 3.7 4.5 17.0
1-1/4” IPS SDR11 6.7 8.0 30.3
1-1/2” IPS SDR11 9.1 10.9 41.3
2” IPS SDR11 15.0 18.0 68.1
Other Item Volumes
Heat Exchanger Average 1.2 1.5 5.7
Purge Cart Tank See cart manual TBD
TABLE 11 - Antifreeze Percentages
BY VOLUME
Protection to: 10°F 15°F 20°F 25°F
Methanol 25% 21% 16% 10%
Propylene Glycol 38% 30% 22% 15%
Protection to: 10°F 15°F 20°F 25°F
Methanol 16.8% 13.6% 10% 6.3%
Propylene Glycol 30% 23.5% 18.3% 12.9%
BY WEIGHT
pressure before actual water pressure is put on the system .
Systems without an expansion tank will experience greater fluc-
tuations in pressure between the heating and cooling seasons,
causing pressure gauges to have different values as the loop
temperature changes. This fluctuation is normal since
expansion and contraction of the loop fluid must be handled by
the elasticity of the plastic loop.
Pressurize the loop to a static pressure of 45 psig. when
installing a system in the fall going into the heating season.
Pressurize the loop to a static pressure of 25 psig. when
installing a system in the spring or summer going into the
cooling season.
After operating the heat pump for a period of time, any
residual air in the system should be bled off and the static pres-
sure should be verified and adjusted if necessary. Add
additional water / antifreeze mix with the purge cart to bring the
pressure back to the original setting if required.
Pipe Insulation
All ground loop piping inside the structure (between the
structure entry point and the heat pump) should be insulated
with 3/8” thick closed cell pipe insulation to prevent condensa-
tion and dripping onto floors or walls.
Low Pressure Control Selection
The purpose of the low pressure control is prevent heat
exchanger freezing in the case of a flow problem.
Unlike other NORDIC model series, low pressure control
selection for open loop for the R/RH 09-24 is done manually,
with a wire jumper. For closed loops with antifreeze, make sure
a jumper is connected between LP1 and LP2 on the heat
pump’s terminal strip. This will cause the lower 55 psi low pres-
sure control to be selected, to allow a lower loop temperature
than would be appropriate for fresh water before tripping.
Although many different antifreeze solutions have been
employed in geothermal systems, the alcohols such as
methanol or ethanol have the most desirable characteristics for
groundloop applications. The overall heat transfer
characteristics of these fluids remain high although care must be
taken when handling pure alcohols since they are extremely
flammable. Once mixed in a typical 25% by volume ratio with
water the solution is not flammable. In situations where alcohols
are not allowed as a loop fluid due to local regulations then
propylene glycol is a non-toxic alternative which can be
substituted . Propylene glycol should only be used in cases
where alcohols are not permitted since the heat transfer
characteristics are less desirable and it becomes more viscous
at low temperatures, increasing pumping power.
The volume of fluid that your loop system holds can be
closely estimated by totaling the number of ft. of each size pipe
in the system and referencing the following table for
approximate volume per 100 ft.
When the volume of the loop has been calculated and the
appropriate amount of antifreeze is ready for addition by
referencing the table, drain the equivalent amount of water from
the flush cart or mixing barrel and replace it with the antifreeze.
When using alcohols, be sure to inject below the water
line to reduce initial volatility of the pure antifreeze. If the
loop is large it may be necessary to refill the tank with antifreeze
several times to get all the antifreeze into the loop. Pump the
loop for 5 to 10 minutes longer to ensure the remaining fluid has
been well mixed.
Initial Pressurization
At this point open all valves in the flow circuit and slowly
close off the supply and return flush cart valves in a manner that
leaves about 20-30 psig. on the system. If an air bladder
expansion tank is used it should be charged to the above
Adding Antifreeze Solution
In most mid and northern areas of the US and in all of
Canada it is necessary to condition the loop fluid by the addition
of some type of antifreeze solution so that it will not freeze
during operation in the winter months. This antifreeze is required
because the loop fluid will normally reach a low entering
temperature of 28°F to 32°F (-2°C to 0°C) and refrigerant
temperatures inside the heat pump’s heat exchanger may be as
low as 20°F (11°C) cooler. See following table for details of
freeze protection provided by different concentrations.
WARNING: Add enough antifreeze to allow
for a temperature 20°F (11°C) lower than the
expected lowest loop fluid temperature
entering the heat pump. Insufficient anti-
freeze concentration could cause the heat
exchanger to freeze and rupture, voiding the
warranty.

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