Maritime Geothermal ATW-55 Manual

12-Feb-2019 Page 1 001970MAN-03
Maritime Geothermal Ltd.
P.O. Box 2555, 170 Plantation Road
Petitcodiac, NB E4Z 6H4
[phone]
ATW-Series
Reversing Air to Water Heat Pump
Two-Stage R410a
Model Sizes 25-75
[email protected]
www.nordicghp.com
001970MAN-03
ECO 000270 12-Feb-2019
Installation and Service Manual

Page 2 001970MAN-03 12-Feb-2019
Series:
ATW = Air To Water heat pump
Nominal Size:
25 = 020 compressor
45 = 030 compressor
55 = 040 compressor
65 = 051 compressor
75 = 060 compressor
80 = 067/070 compressor
Functions:
H = Heating
AC = Active Cooling
W = Domestic Hot Water
Refrigerant:
P = R410a
Voltage Code:
1 = 230-1-60 VAC
2 = 208-3-60 VAC
4 = 460-3-60 VAC
6 = 220-1-50 VAC
7 = 380-3-50 VAC
Indoor Loop Exchanger:
C = Copper
Y = CuNi coil & piping
Z = CuNi coil only
Revision:
01, 02 etc.
ATW—65—HACW—P—1T—C—xx
Compressor:
S = 1 Stage Scroll
T = 2 Stage Scroll
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
ACE—65—P—1/6—KDE—xx
Series:
ACE = All weather Condenser / Evaporator
(air source outdoor unit)
Nominal Size:
25 = for AT_-25
45 = for AT_-45
55 = for AT_-55
65 = for AT_-65
75 = for AT_-75
Voltage Code:
1/6 = 220~277-1-50/60
Air Coil:
S = Standard
K = Coated
Fan Type:
D = Direct Drive
Fan Motor:
E = ECM (Variable Speed)
Revision:
01, 02 etc.

12-Feb-2019 Page 3 001970MAN-03
APPLICATION TABLE - INDOOR UNIT
SIZE FUNCTION REFRIGERANT VOLTAGE COMPRESSOR
STAGES*
INDOOR
COIL
REVISIONS
ATW-25 H A C W P
1
2
4
6
7
T
C
Y
Z
03
ATW-45 HACW P
1
2
4
6
7
T
C
Y
Z
03
ATW-55 HACW P
1
2
4
6
7
T
C
Y
Z
03
ATW-65 HACW P
1
2
4
6
7
T
C
Y
Z
03
ATW-75 HACW P
1
2
4
7
C
Y
Z
03
6 S
This manual applies only to the models and revisions listed in this table.
T
Maritime Geothermal Ltd. has a continuous improvement policy and reserves the right to modify specification
data at any time without prior notice .
APPLICATION TABLE - FIRMWARE AND PC APP
Firmware Version* Associated PC APP Version
MGT GEN2 Bootload Firmware V2.90+ MGT GEN2 PC APP V1.52+
APPLICATION TABLE - OUTDOOR UNIT
MODEL REFRIGERANT VOLTAGE AIR COIL BLOWER TYPE BLOWER MOTOR REVISIONS
ACE-45 P 1/6 S
K D E 03
ACE-55 P 1/6 S
K D E 03
ACE-65 P 1/6 S
K D E 03 05
ACE-75 P 1/6 S
K D E 04 05 06
This manual applies only to the models and revisions listed in this table.

Page 4 001970MAN-03 12-Feb-2019
Table of Contents
Tables & Documents ................................................ 5
ATW System Description ....................................... 6
General Overview ................................................................... 6
1. Heating Mode ..................................................................... 6
Defrost Operation................................................................. 6
2. Cooling Mode ...................................................................... 6
ATW Sizing ..................................................................... 7
Air Source Heat Pumps .......................................................... 7
Heat Pump Sizing ................................................................... 7
Auxiliary Heat Sizing ............................................................... 7
Installation Basics ...................................................... 8
Sample Bill of Materials .......................................................... 8
Unpacking the unit .................................................................. 8
Indoor Unit Placement ............................................................ 8
Outdoor Unit Placement .......................................................... 9
Outdoor Fan Speed Reduction ............................................... 9
Outdoor Unit Mounting Height ................................................ 9
Average Max. Snow Depth Map - Canada ............................ 10
Wiring ............................................................................... 11
Indoor Unit Power Supply Connections ................................ 11
Outdoor Unit: Power Connections ........................................ 11
Indoor Loop Circulator Pump Wiring ..................................... 11
Control Transformer .............................................................. 11
BACnet Connections ............................................................ 11
Outdoor Unit: Signal Connections ......................................... 12
Setpoint Control Connections ................................................ 12
Setpoint Control: Aux. Connections ....................................... 12
Aquastat Connections (Optional) .......................................... 12
Disable Switch (field installed) ............................................... 12
002019CDG - Typ. ATW Series Wiring ................................. 13
002375QSS - Eco Ultra Tanks: Getting Started .................... 14
002067CDG - Typ. Heating Only Zone Wiring (Setpoint) ...... 15
002068CDG - Typ. Htg/Cooling Zone Wiring (Setpoint) ........ 16
002069CDG - Typ. Heating Only Zone Wiring (Signals) ........ 17
002070CDG - Typ. Htg/Cooling Zone Wiring (Signals) .......... 18
Piping ............................................................................... 19
Number of Tanks .................................................................. 19
Indoor Loop Water Lines ........................................................ 19
Domestic Hot Water (Desuperheater) Connections .............. 19
002239PDG - Typical Piping Connections - ATW Series ....... 20
002366PDG - Recommended Buffer Tank Piping ................. 21
002252PDG - Two Tank Piping with a Rev. Heat Pump ........ 22
002367PDG - Auxiliary Boiler Piping ..................................... 23
000530PDG - Typical Zone Types ......................................... 24
001055PDG - Connection to On-Demand DHW Tank ........... 25
000970PDG - Desup. Conn. to DHW Pre-Heat Tank ............ 26
Outdoor Unit Line Set ............................................ 27
Line Set Interconnect Tubing ................................................ 27
Oil Traps ............................................................................... 27
Pipe Insulation ...................................................................... 27
Silver Soldering Line Sets ..................................................... 27
Pressure Testing ................................................................... 27
Vacuuming the System .......................................................... 27
Charging the System ............................................................. 28
001983CDG - Typical ATW Line Set Connections ................ 29
Operation ....................................................................... 30
1. BACnet Control ................................................................. 30
2. Signals / Hardwired Control .............................................. 30
3. Setpoint Control ................................................................ 30
Setpoint Control Method 1 - Indoor Loop (ICR), One Tank .... 30
Typical Temperature Settings ............................................. 31
Top Up S1 Function ........................................................... 31
Summer Setback ................................................................ 31
Hydronic Auxiliary in Defrost .............................................. 31
Outdoor Reset .................................................................... 32
Setpoint Control Method 2 - Indoor Loop (ICR), 2 Tanks ....... 32
Setpoint Control Method 3 - External HTS/CTS, One Tank .. 33
Setpoint Control Method 4 - External HTS/CTS, 2 Tanks ..... 34
PC Application (PC App) ...................................... 35
PC Application Menus............................................................ 35
LCD Interface & Menus ......................................... 47
BACnet Interface ........................................................ 49
Startup Procedure .................................................... 53
Pre-start Inspection ............................................................... 53
Unit Startup ........................................................................... 54
Startup Record ...................................................................... 55
General Maintenance ............................................. 56
Troubleshooting Guide ......................................... 57
Troubleshooting Tools .......................................................... 65
Repair Procedures ................................................... 66
Model Specific Information ................................ 67
Shipping Information (Indoor Unit) ........................................ 67
Shipping Information (Outdoor Unit) ...................................... 67
Refrigerant Charge ............................................................... 67
Indoor Loop Flow Rates ........................................................ 67
Operating Temperature Limits .............................................. 67
Outdoor Unit Sound Levels (dBA) ......................................... 67
Indoor Unit Sound Levels (dBA) ........................................... 67
Pressure Drop Data ............................................................... 68
Standard Capacity Ratings ................................................... 70
Performance Tables: ATW-25 ............................................... 71
Performance Tables: ATW-45 ............................................... 72
Performance Tables: ATW-55 ............................................... 73
Performance Tables: ATW-65 ............................................... 74
Performance Tables: ATW-75 ............................................... 75
Electrical Specifications ........................................................ 76
Wiring Diagram (208/230-1-60) ............................................ 77
Electrical Box Layout (208/230-1-60) .................................... 78
Wiring Diagram (208-3-60) ................................................... 79
Electrical Box Layout (208-3-60) ........................................... 80
Wiring Diagram (460-3-60) .................................................... 81
Electrical Box Layout (460-3-60) ........................................... 82
ACE-45/55 Wiring Diagram .................................................... 83
ACE-65/75 Wiring Diagram .................................................... 83
ATW-Series Refrigeration Circuit - Heating Mode ................. 84
ATW-Series Refrigeration Circuit - Cooling/Defrost Mode ..... 85
Dimensions: ATW-25/45 ........................................................ 86
Dimensions: ATW-55 ............................................................. 88
Dimensions: ATW-65/75 ........................................................ 90
Appendix A: Control Board Description ...... 92
Appendix B: USB Driver Installation .............. 96
Appendix C: PC App Installation .................... 97
Appendix D: Updating Firmware ...................... 98
Updating Firmware via PC App ............................................. 98
Updating Firmware via Jumper Pins .................................... 100
Warranty ....................................................................... 101

12-Feb-2019 Page 5 001970MAN-03
Tables & Documents
Tables
Documents
Table 1 - Heat Pump Size vs. Heated Area .............................................................................................. 7
Table 2 - Auxiliary Heat Sizing ................................................................................................................ 7
Table 3 - Power Supply Connections .................................................................................................... 11
Table 4 - Outdoor Unit Power Supply Connections ............................................................................... 11
Table 5 - Indoor Loop Circulator Connections ....................................................................................... 11
Table 6 - Control Transformer ............................................................................................................... 11
Table 7 - BACnet Connections .............................................................................................................. 11
Table 8 - Outdoor Unit Signal Connections ........................................................................................... 12
Table 9 - Setpoint Control Connections ................................................................................................. 12
Table 10 - Setpoint Control: Aux. Connections ...................................................................................... 12
Table 11 - Aquastat (Signals Control) Connections ............................................................................... 12
Table 12 - Buffer Tank Size ................................................................................................................... 19
Table 13 - Interconnect Line Set Sizing ................................................................................................. 27
Table 14 - Extra Charge Required ......................................................................................................... 28
Table 15 - Extra Charge (Sizes 25-45) .................................................................................................. 28
Table 16 - Extra Charge (Sizes 55-75) .................................................................................................. 28
Table 17 - Typical Temperature Setpoints ............................................................................................. 31
Table 18 - Maximum Output Temperature ............................................................................................. 31
Table 19 - BACnet Objects - Control Signals (Read/Write) .................................................................... 49
Table 20 - BACnet Objects - Operation Mode Description (Read Only) ................................................. 49
Table 21 - BACnet Objects - Data (Read Only) ...................................................................................... 50
Table 22 - BACnet Objects - Alarm Descriptions (Read Only) ............................................................... 51
Table 23 - BACnet Objects - Fault Descriptions (Read Only) ................................................................. 52
Table 24 - Shipping Information (Indoor Unit) ........................................................................................ 67
Table 25 - Shipping Information (Outdoor Unit) ..................................................................................... 67
Table 26 - Refrigerant Charge ............................................................................................................... 67
Table 27 - Indoor Loop Flow Rates ....................................................................................................... 67
Table 28 - Operating Temperature Limits .............................................................................................. 67
Table 29 - Outdoor Unit Sound Levels (dBA) ........................................................................................ 67
Table 30 - Indoor Unit Sound Levels (dBA) ........................................................................................... 67
Table 31 - Loop Pressure Drop Data ..................................................................................................... 68
Table 32 - Standard Capacity Ratings - Heating ................................................................................... 70
Table 33 - Standard Capacity Ratings - Cooling ................................................................................... 70
Table 34 - ATW-Series Electrical Data .................................................................................................. 76
Table A1 - Control Board Connector Descriptions (Top) ........................................................................ 9 3
Table A2 - Control Board Connector Descriptions (Left Side) .............................................................. 93
Table A3 - Control Board Connector Descriptions (Bottom) .................................................................. 94
Table A4 - Control Board Connector Descriptions (Right Side) ............................................................. 95
002019CDG - Typical ATW Outdoor Unit, Aux. Heat, & Indoor Circulator Wiring ................................ 13
002375QSS - Eco Ultra Tanks: Getting Started .................................................................................... 14
002067CDG - Typical Zone and Auxiliary Wiring with GEN2 Setpoint Control (Heating Only) .............. 15
002068CDG - Typical Zone and Auxiliary Wiring with GEN2 Setpoint Control (Heating & Cooling) ..... 16
002069CDG - Typical Zone and Auxiliary Wiring with GEN2 Hardwired Option (Heating Only) ........... 17
002070CDG - Typical Zone and Auxiliary Wiring with GEN2 Hardwired Option (Heating & Cooling) ... 18
002239PDG - Typical Piping Connections - ATW Series ...................................................................... 20
002366PDG - Recommended Hydronic Buffer Tank Piping .................................................................. 21
002252PDG - Two Tank Piping with a Reversing Heat Pump ............................................................... 22
002367PDG - Auxiliary Boiler Piping ..................................................................................................... 23
000530PDG - Typical Zone Types for Hydronic Applications ................................................................. 24
001055PDG - Single Unit Connection to On-Demand Domestic Hot Water Pre-Heat Tank .................. 25
000970PDG - Desuperheater Connection to DHW Pre-Heat Tank ....................................................... 26
001983CDG - Typical ATW to Outdoor Unit Line Set Connections ....................................................... 29
001799SCH-01 - ATW-**-HACW-P-1*-* Schematic Diagram ................................................................. 77
001800ELB-01 - ATW-**-HACW-P-1*-* Electrical Box Diagram ............................................................ 78
002190SCH-01 - ATW-**-HACW-P-2*-* Schematic Diagram ................................................................. 79
002189ELB-01 - ATW-**-HACW-P-2*-* Electrical Box Diagram ............................................................ 80
002192SCH-01 - ATW-**-HACW-P-4*-* Schematic Diagram ................................................................. 81
002191ELB-01 - ATW-**-HACW-P-4*-* Electrical Box Diagram ............................................................ 82
001951SCH-01 - ACE Outdoor Unit Schematic Diagram ...................................................................... 83
002014SCH-01 - ACE 4-Fan Outdoor Unit Schematic Diagram ........................................................... 83
001840RCD-03 - ATW-Series Refrigeration Circuit Diagram - Heating Mode ........................................ 84
001841RCD-03 - ATW-Series Refrigeration Circuit Diagram - Cooling Mode ........................................ 85

Page 6 001970MAN-03 12-Feb-2019
General Overview
The ATW-Series heat pump is an air source heat pump
that can heat water for a hydronic heating system, or heat and
cool water for a hydronic heating/cooling system. Applications
include in-floor heating, heating through low-temperature radia-
tors, pre-heating domestic hot water through the use of an indi-
rect tank with hydronic coil, and heating and cooling through
hydronic air handlers.
Being an air source heat pump, it does not require a
ground loop, instead using an outdoor evaporator / condenser to
exchange heat with the outdoor air. Unlike most air source out-
door units on the market, this outdoor unit contains only an air
coil, ECM hub motor fan, heating mode electronic expansion
valve (EEV), and an outdoor temperature sensor.
The remaining components, including the compressor and
all electronics, are contained in the indoor unit. This has several
advantages: minimal installation and service work must be per-
formed outdoors, important components are in the conditioned
space for longevity, and heating domestic hot water is possible
(through a desuperheater circuit) since the fresh water lines are
inside and will never freeze.
The heat pump will be set up to heat or cool water in a
closed loop buffer tank to a user-selectable setpoint tempera-
ture; when a zone thermostat requires heat or cooling, it will
receive water flow by opening a zone valve or starting a zone
pump. Two tanks, heated and chilled, maybe used instead
where heating and cooling demands may occur simultaneously
or close together. Water temperature control will usually be
performed by a built-in routine that maintains the buffer tank
temperature without external sensors (’Setpoint Control’). Op-
tionally, BACnet, external tank sensors, or an external aquastat
can be used.
In additional to the main hydronic water heating/cooling
functions, 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 desuperheater circuit is built in, along
with a temperature control to turn the pump off when the DHW
temperature reaches 140°F/60°C.
Two-stage scroll compressors are standard. The outdoor
air coil is e-coated for corrosion protection, and the coaxial hy-
dronic heat exchanger is copper / steel with optional CuNi inner
tube available for applications where water quality may be an
issue. The cabinets are powder coated galvanized sheet metal.
Control is overseen by the Nordic GEN2 programmable control
board, which has many advanced features like laptop connectiv-
ity via the free PC App software, data logging & graphing, and
real time readout from electronic temperature & pressure sen-
sors.
1. Heating Mode
In hydronic heating mode, the heat pump heats water in
the buffer tank. Superheat is controlled by the heating EEV
located in the outdoor unit while the EEV in the indoor unit is set
to full open. As the unit operates, heat is extracted from the
outdoor air, which causes the air coil to eventually frost up to the
point that a defrost cycle is required. The time between defrost
cycles varies depending on the outdoor conditions; refer to the
Defrost Operation section below.
If the outdoor temperature is above 34°F(1°C), the outdoor
unit fan starts and stops when the heat pump starts and stops.
If the temperature is below 34°F(1°C), the outdoor fan will re-
main on at a very slow speed when the heat pump is off in order
ATW System Description
minimize the chance of a fan freeze up, and to prevent snow
from entering the unit through the fan opening during a snow
storm. The outdoor fan is controlled based on the suction pres-
sure and will slowly ramp up to the required speed when the
system starts. The heat pump will turn off and only the auxiliary
heating system will operate if the outdoor temperature gets too
cold. Refer to the Model Specific Information section for the
limits of operation.
Any air source heat pump will need auxiliary heat; see
Sizing section. This may almost any heating device, but
the most convenient is electric elements in the buffer tank, con-
trolled by the heat pump’s stage 3 temperature control (stages 1
& 2 being the two compressor stages).
Defrost Operation
The heat pump has an advanced defrost control algorithm
intended to provide a minimal number of defrosts and minimal
defrost cycle time, while achieving complete defrost. The out-
door unit’s unique design also has excellent resistance to coil
freeze-ups and potential future air coil damage as a result of
repeated freeze-ups.
The system uses the outdoor temperature and suction
pressure to determine when a defrost cycle should occur as well
as how long it should be. PID fan control allows the discharge
pressure to rise quickly and then be maintained at a desired
setpoint for quick defrosting. A “defrost disabled” period occurs
after a defrost cycle which allows a potential problem with the
unit to be identified as an alarm to prevent repetitive defrost
cycles.
The outdoor unit has a unique design for combatting ice
build up, which is a common problem with air source heat
pumps. The coil sits on a 15° angle and the area below the coil
is completely open (no drip tray). The angle causes the melting
frost/snow to run down the back of the coil, which creates a sin-
gle line of runoff along the back bottom edge of the coil rather
than along the entire bottom side of the coil. Runoff occurs
more quickly and at a higher velocity, minimizing the amount
that remains trapped at the bottom of the coil due to surface
tension between the coil fins. This arrangement means it is
virtually impossible for runoff to remain between coil pipes and
re-freeze between them, a common cause of air coil failure in air
source heat pumps.
2. Cooling Mode
In air cooling mode, the heat pump cools water in the buff-
er tank. Superheat is controlled by the cooling EEV located in
the indoor unit while the EEV in the outdoor unit is set to full
open. As the unit operates, heat is extracted from the buffer
tank and rejected to the outdoor air. There is no defrost cycle in
air cooling mode.
The outdoor fan is controlled based on the discharge pres-
sure and will slowly ramp up to the required speed when the
system starts. During operation, the fan speed will automatical-
ly adjust up or down to in order to maintain the discharge pres-
sure setpoint value. The discharge pressure will begin to rise
above the setpoint when the outdoor temperature exceeds the
point at which the outdoor fan speed reaches its maximum val-
ue. Two stage units will drop down to the first stage to reduce
the discharge pressure at very high outdoor temperatures. Re-
fer to the Model Specific Information section for the limits of
operation.

12-Feb-2019 Page 7 001970MAN-03
ATW Sizing
Auxiliary Heat Sizing
The easiest way to provide backup heat for new installa-
tions is by installing a buffer tank that has electric elements.
Buffer tanks with elements that are certified for space heating
use are available as accessories from Maritime Geothermal
Ltd., or others may be used.
An element size should be chosen that covers 100% of the
coldest day heat load, according to the heat loss analysis men-
tioned in the last section. This is because the elements will take
over heating duty if the outdoor temperature falls below the mini-
mum for heat pump operation (-7°F/-22°C), or if the heat pump
experiences a problem. If a heat loss analysis is not available,
the following table may be used as a guide.
This is an estimate of which unit size is required for a typi-
cal two-level home (main level and below grade basement) with
R-20 walls, R-40 ceiling and average size and number of win-
dows. The Heated Area is the area of the main level. The table
accounts for a basement the same size as the heated area.
It is highly recommended that a heat loss/gain analy-
sis be performed by a qualified person with software using
the CSA F-280 or Manual J methods before selecting a heat
pump size. The analysis will result in a heat load for the cold-
est day, which is influenced by, for example, the number of lev-
els, the size of the windows, the orientation of the home, at-
tached garage, bonus rooms, walk-out basement, and coldest
outdoor temperature for the region.
In northern climates, a heat pump model size can be se-
lected by matching the calculated heat load to the heat pump’s
heating capacity at an outdoor temperature of 35°F (1.7°C) and
an indoor water temperature of 105°F (40.5°C) for concrete in-
floor heating or 120°F (49°C) for other heating types. These
numbers can be found in the detailed performance tables in the
Model Specific Information section later in this manual.
This sizing will result in a good compromise between covering
as much of the cold weather heat load as possible without utiliz-
ing backup heat, while minimizing excessive cycling (turning on
and off frequently) during moderate outdoor temperatures.
It should be noted that sizing an air source heat pump is
always a compromise between covering coldest-day heat load
and minimizing cycling due to over-capacity in warm weather.
In cooling dominant climates, the heat pump should be
similarly sized, by matching the calculated cooling load to the
standard capacity rating at an outdoor temperature that matches
the local maximum outdoor temperature. The difference here is
that it is necessary to cover all of the cooling load, since there is
no backup cooling.
Even in northern heating dominant climates, it should
be ensured that 100% of the cooling load will be covered
when sizing the heat pump.
Air Source Heat Pumps
Since it is harder to extract heat from colder outdoor air,
any air source heat pump will have its lowest heating capacity
on cold days when building heat load is the highest. It is not
generally possible to oversize an air source heat pump to cover
100% of the coldest day heat load, since this would mean ex-
cessive compressor short-cycling during moderate outdoor
weather when heat pump capacity is much higher and heat load
is much lower.
For these reasons, it should be expected that any air
source heat pump will need auxiliary heat on the coldest
days.
Heat Pump Sizing
TABLE 1 shows the size of home each air source heat
pump model size is generally suitable for, in northern climates.
TABLE 1 - Heat Pump Size vs. Heated Area
Model sq.ft. m2
25 800 75
55 2,000 185
65 2,600 240
75 3,100 290
45 1,400 130
TABLE 2 - Auxiliary Heat Sizing
Model
Tank Element Size
Recommended EcoUltra Tank Available
25 7 kW 12 kW (50 gal)
55 12 kW 15 kW (70 gal)
65 15 kW 15 kW (70 gal)
75 20 kW 20 kW (70 gal)
45 10 kW 12 kW (50 gal)
For retrofits, the existing heating device (e.g. an electric or
gas boiler) may be used for auxiliary heat. It should be set up to
be activated as heating stage 3 by the heat pump as described
in the Wiring section, and piped in a parallel arrangement as per
the diagram in the Piping section.

Page 8 001970MAN-03 12-Feb-2019
Installation Basics
Sample Bill of Materials -
ATW Series
FROM MARITIME GEOTHERMAL
• ATW SERIES HEAT PUMP W/ACE OUTDOOR UNIT
• SHIELDED 18-8 WIRE
• BUFFER TANK W/ELEMENTS 12/15/20 kW
OPTIONAL FROM MARITIME GEOTHERMAL
• ANTI-VIBRATION PAD
• SOUND JACKET
• SECURE START
• AHW-65 AIR HANDLER(S)
DHW:
• PREHEAT TANK, 40 OR 60 GAL
• ½” COPPER PIPE
• ½” FITTINGS, BALL VALVES, BOILER DRAINS, CV
ELECTRICAL
• HEAT PUMP SERVICE WIRE: 6-3, 8-3, OR 10-3
• BUFFER TANK ELEMENT SERVICE WIRE
• 14-2 OUTDOOR RATED WIRE W/ DISCONNECT
SWITCH FOR OUTDOOR UNIT
• HEAT PUMP BREAKER
• BUFFER TANK ELEMENT BREAKER
• ELEMENT CONTACTOR & ELEC. BOX
(IF NOT USING TANK W/ DRY CONTACTS)
• THERMOSTAT WIRE 18-4
• THERMOSTAT WIRE 18-2
• FORK TERMINALS FOR TSTAT WIRE (6)
REFRIGERATION
• 1/2” & 7/8” (OR 3/8” & 3/4”) ACR TUBING
• PIPE INSULATION
• EXTRA R410A REFRIGERANT FOR LINESETS >20 FT
ZONES
• CIRCULATOR: HEAT PUMP TO TANK
• 1” PIPE & FITTINGS: HEAT PUMP TO TANK
• ZONES CIRCULATOR(S)
• ZONE TRANSFORMER & CIRC CONTACTOR
• ZONE VALVES (IF NOT INDIVIDUAL PUMPS)
• IN-FLOOR PIPING
• OTHER AIR HANDLERS, DUCTING
• ZONE THERMOSTATS
• RELAYS OR ZONE CONTROLLER
• ZONE SUPPLY & RETURN HEADERS:
1” COPPER PIPE & FITTINGS
• PIPE & FITTINGS TO ZONES
• EXPANSION TANK
• 2” STYROFOAM INSUL. (IF PAD NOT PURCHASED)
Unpacking the Unit
When the 2-piece 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.
Indoor Unit Placement
For air to water models, the placement of the unit has neg-
ligible effect on the operation and efficiency of the system. It is
recommended that the unit be placed near where the intercon-
nect piping to the outdoor unit will be to keep the piping distance
to a minimum. See the 3D diagram in the Piping section for a
detailed typical component layout.
The front and right side access panels should remain clear
of obstruction for a distance of two feet to facilitate servicing
and general maintenance. Left side access is optional (since
the compressor may be accessed by swinging out the front-side
electrical box), and no access is required on the back side.
An anti-vibration pad, available as an accessory, or a
piece of 2” styrofoam should be placed under the unit. This will
deaden vibrations and protect the cabinet from rusting.

12-Feb-2019 Page 9 001970MAN-03
Outdoor Unit Placement
The ACE unit must be placed outdoors, with the fan point-
ing away from the building. It should be at least 12 inches (30
cm) away from the building or other obstructions on the
back and sides for unimpeded return airflow. There should be
little or no obstruction in the fan (front) direction for at least 30
feet (9 m), otherwise airflow and therefore overall perfor-
mance will be reduced.
In addition, there should be at least two feet (0.6 m) of
clearance on the electrical box and refrigeration piping side of
the unit to facilitate servicing and general maintenance.
The outdoor unit must be bolted down to prevent a tipping
hazard. See next section.
Note that no field installed filter-dryer is required, since
one is included in the indoor unit.
Leg Kit Installation
Outdoor Unit Mounting Height
The outdoor unit must remain clear of snow and ice at all
times. Good performance depends on good airflow, which of
course cannot be achieved if the unit is buried in snow and re-
frozen defrost condensate.
There are several ways to accomplish this. First, look up
how much snowfall is expected in your area, either from local
knowledge or weather data. The snowfall map included on next
page can be used as a rough guide for Canada.
1. If the local climate has less than ~4” / 10 cm of snow
accumulation, the unit may be mounted directly on a
concrete pad. This is not recommended, since in this
case constant and ongoing care must be taken to
ensure re-frozen condensate does not build up under
unit.
2. The unit can be mounted on angle brackets attached
to the side of a building. Be sure to adhere to the
minimum clearance requirement of 12” (30 cm), and
use brackets designed for twice the unit weight.
3. Two different leg kits which add either 15” (38 cm) or
30” (76 cm) of additional height are available as an
accessory from Maritime Geothermal Ltd.
To attach the legs, first remove the three bolts with flat
washers that hold each foot plate in place. Leaving the foot
plate in place on the inside of the cabinet panel, slide the leg
over the outside of the panel and re-install the three bolts and
flat washers.
Whether or not a foot kit is used, be sure to mount the unit
using the 4 rubber grommets included with the unit, to dampen
any vibration. The unit must be fastened to its mounting surface
with four min. 5/16” bolts through these grommets to pre-
vent a tipping hazard due to impact or high wind.
IMPORTANT NOTE: The line set between the
indoor and outdoor units must not exceed 70
ft (21 m) in length.
Outdoor Unit
Fan Orientation
Outdoor Fan Speed Reduction
Should fan noise be a concern, for example if the outdoor
unit is mounted near a frequently open window, the outdoor fan
speed can be reduced (up to a maximum of 25%). This should
only be done if necessary, since a small loss in efficiency will
result.
The fan speed can be reduced via the LCD (see LCD In-
terface & Menus section) or PC App (see PC Application
section).

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Average Maximum Snow Depth - Canada (1979-1997)
Source: Natural Resources Canada

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Wiring
IMPORTANT NOTE: A properly qualified
electrician should be retained for all
connections to the heat pump and associat-
ed controls. The connections to the unit
MUST CONFORM TO LOCAL CODES.
TABLE 3 - Power Supply Connections
Line Description Voltages
L1 Line 1 All
L2 Line 2 All
L3 Line 3 3-phase only
GND Ground All (connect to ground lug)
* Only required if connecting 115VAC circulators.
N Neutral 208/230-1-60*, 208-3-60*,
460-3-60, 380-3-50
Indoor Unit Power Supply Connections
Power supply for the heat pump from the breaker panel is
supplied to the indoor unit. The unit has a concentric 1.093” /
0.875” knockout for main power supply connection to the electri-
cal box. There are also five 7/8” knockouts and a 1/2” opening
with plastic grommet (grommet hole is 3/8”) for connections to
circulation pumps, controls, optional aquastat, and power and
signal connections to the outdoor unit.
A schematic diagram (SCH) and electrical box layout
diagram (ELB) can be found on the electrical box cover of the
unit as well as in the Model Specific Information section of this
manual.
The Electrical Tables in the Model Specific Information
section contain information about the wire and breaker size.
Indoor Loop Circulator Pump Wiring
The indoor unit has provisions for connecting the indoor
circulator pump (between the heat pump and buffer tank) so that
it will be turned on whenever the compressor operates. Con-
TABLE 5 - Indoor Loop Circulator Connections
Signal Description
115V Connection for 115V circulator
(requires Nneutral connection to heat pump)
115V
230V
230V
Use a 2-conductor 14ga cable.
Connection for 230V circulator
TABLE 4 - Outdoor Unit Power Supply Connections
Line Description
L1 Supply line
L2 Supply line
GND Ground
Use a 2-conductor outdoor rated 14ga cable.
IMPORTANT NOTE: Most codes require a
disconnect switch visible and/or reachable
from the outdoor unit to be installed in the
power supply cable. If the switch has fuses
or breakers they must be no more than 10A.
Outdoor Unit: Power Connections
The ACE outdoor unit is powered from the indoor unit.
The power supply for the ACE unit is 208 to 277VAC, 50/60Hz.
The ATW and ACE units have matching terminal strips for these
connections. Use a two conductor, minimum 14ga outdoor rat-
ed cable for this connection. Refer to diagram.
Control Transformer
The low voltage controls, including the control board, are
powered by a 100VA class II transformer. 208/230-1-60 and
208-3-60 models have a resettable breaker on the secondary
side for circuit protection. Should the breaker trip, locate and
correct the problem and then reset the breaker by pressing in on
it.
All other voltage models have primary and secondary fus-
es for circuit protection.
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.
TABLE 6 - Control Transformer
Voltage Low Voltage Circuit Protection
(1) 208/230-1-60 Resettable breaker on transformer
(2) 208-3-60 Resettable breaker on transformer
(4) 460-3-60 Primary / Secondary fuses
(6) 220-1-50 Primary / Secondary fuses
(7) 380-3-50 Primary / Secondary fuses
BACnet Connections
If using BACnet for external control of heating/cooling de-
mand and/or monitoring of status, use a shielded twisted pair to
the connector at the bottom left of control board. There is an
optional termination jumper located above the connector.
See the BACnet Interface section for object names.
TABLE 7 - BACnet Connections
Line Description
A Communication +
B Communication -
GND Ground
Use a shielded twisted pair cable.
nect the circulator pump module to the appropriate terminal pair
(115V or 230V) on the terminal strip marked Indoor Circulator
Pumps, as per the voltage of the circulator pump. Ground
wires should be connected to the ground lug in the electrical
box. Ensure that the total current draw does not exceed the
value indicated on the label in the heat pump electrical box.
For 460VAC models, only 277VAC circulators may be
powered directly from the heat pump. If other voltage circulators
are used, they must be powered using an external contactor
actuated by the ICR terminal on the left side of the control board
and the C (24V ground) terminal.
OUTDOOR DISCONNECT SWITCH IS A
SAFETY DEVICE ONLY. Turn off breaker to
indoor unit before servicing to avoid costly
damage to electronic control board.

Page 12 001970MAN-03 12-Feb-2019
Outdoor Unit: Signal Connections
The speed of the fan and the heating mode expansion
valve (EEV) in the outdoor unit are controlled by the control
board in the ATW indoor unit, and a temperature sensor is read.
Therefore, communication wiring is required.
Connect an 8 conductor shielded outdoor rated cable
(supplied) between the terminal strips in the indoor and outdoor
units. The shield ground wire is connected only to the indoor
unit; do not connect the shield ground to the outdoor unit
(there is no terminal for it). Cut the shield ground wire
short at the cable sheath in the outdoor unit.
TABLE 8 - Outdoor Unit Signal Connections
Signal Description
EEVR Electronic Expansion Valve (Red)
EEVG Electronic Expansion Valve (Green)
EEVW Electronic Expansion Valve (White)
EEVB Electronic Expansion Valve (Black)
TR Outdoor Temperature Sensor (Power)
TG Outdoor Temperature Sensor (Signal)
TB Outdoor Temperature Sensor (Ground)
PWM+ Outdoor Fan Control
Shield GND Cable shield: see note above
Use provided 8 conductor shielded outdoor rated cable.
Aquastat Connections (Optional)
Most installations will use the internal Setpoint Control
routine to control buffer tank temperature, in which case no aq-
uastat is required. However, an aquastat or aquastats can be
used if required, for example if heating two loops with different
setpoint temperatures. This is Signals or Hardwired Control.
The CA, RA, Y1A, and Y2A connections are located on
the right side towards the top of the control board. The O termi-
nal is found on the terminal strip (along with an alternate R and
C connection). This is shown on the wiring (SCH) diagram
in the Model Specific Information section. The external device
needs to send the 24VAC signal from RA back to the Y1A and
Y2A terminals to call for the two stages of hydronic heating,
and RA back to O to activate cooling mode. C is the common or
ground terminal for use in powering the external device.
TABLE 11 - Aquastat (Signals Control) Connections
Signal Description
O Cooling Mode (Reversing Valve)
CA 24VAC common (ground)
RA 24VAC hot
Y1A Compressor ON (Part Load)
Y2A Compressor bump up to Stage 2 (Full Load)
Use an 18ga cable.
Setpoint Control Connections
If using the on-board Setpoint Control routine with sam-
pling to control buffer tank temperature, no external temperature
probe or aquastat is required. In this case, only one control
connection is required, a dry contact from R to O on terminal
strip to switch the heat pump into cooling mode. C may be used
in powering relays as shown in diagrams on following pages.
Note that in a one tank heating/cooling system, the O
signal must be continuously provided during cooling sea-
son. If it toggles with demand, the tank will be repeatedly
heated and cooled, resulting in high power usage.
TABLE 10 - Setpoint Control: Aux. Connections
Signal Description
CA 24VAC common (ground)
1A Hydronic Auxiliary (hot)
D1 Hydronic Auxiliary dry contacts
D2
H1 Hydronic Auxiliary ONLY dry contacts
(for high temperature auxiliary heat)
H2
Use a 2-conductor 18ga cable.
TABLE 9 - Setpoint Control Connections
Signal Description
C 24VAC common (ground)
R 24VAC hot
O Cooling Mode (Reversing Valve)
Use a 3-conductor 18ga cable.
An external temperature probe may be used with the on-
board Setpoint Control routine, or two probes (one for hot tank
and one for cold tank) may be used. This is called HTS/CTS
Setpoint Control; see Piping and Operation sections for details.
Setpoint Control: Aux. Connections
When using Setpoint Control, there are 3 methods for acti-
vating hydronic auxiliary heat. See diagram on following page.
First, a 24VAC signal on terminal 1A (with CA as ground/
common) is available to power the coil of an external contactor
to operate hydronic auxiliary heat. Choose this method if using
a heating device that doesn’t have its own electronic controller
or control transformer, e.g. a bare heating element in the buffer
tank. This signal can provide a maximum of 500mA at 24VAC.
1A defaults to OFF when heat pump is powered off.
Second, a dry contact on terminals D1 and D2 is available,
to actuate a heating device that has its own controller and trans-
former. In general, these types of devices will have their own
electronic temperature controller. Connection will be made to
that device’s E-E terminals or similar. D1-D2 defaults to ON
when heat pump is powered off. Therefore, it is necessary to
set the temperature control on the external heating device to a
limiting value, e.g. 125°F, and adjust its settings so it is only
activated by the heat pump’s controller. This method should be
used for the Thermo2000 EcoUltra tank that is available
from Maritime Geothermal as an accessory; see the setup
instruction sheet that comes with tank and on following page.
Third, a dry contact is available on terminals H1 and H2. It
operates similarly to D1-D2 above, but is only activated when
auxiliary heat is requested AND the compressor is off (i.e. when
the outdoor temperature has dropped below the minimum oper-
ating temperature). This should be used to actuate high temper-
ature heating devices that would interfere with heat pump opera-
tion if run simultaneously. H1-H2 defaults to ON when heat
pump is powered off.
D1-D2 and H1-H2 default to ON and so must be
used with an auxiliary heating device that has a
HIGH TEMPERATURE LIMITER to avoid a seri-
ous safety hazard.
Disable Switch (field installed)
A switch to disable demand from the control system may
be installed. On control board, jumper COM_IN to GND, and
toggle 12VDC to IN_SPARE to disable. See the main wiring
diagram in the Model Specific Information section.

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Piping
Indoor Loop Water Lines
The connections for the Indoor Loop circuit are 1”
brass FNPT. They are labelled as INDOOR IN and INDOOR
OUT. The ports are located on the front of the unit.
Recommended buffer tank piping is shown in diagrams on
following pages. They show all of the recommended compo-
nents as well as where they should be placed. If other types of
components are used or connected differently, this is done at
user’s discretion with the caution that heat pump may or may
not work properly.
NOTE: It is recommended that the water lines between the
heat pump and the buffer tank be copper or other high tempera-
ture piping.
NOTE: Care should be taken when routing the water lines to
ensure that adequate access to the heat pump is maintained so
as to not compromise ease of serviceability.
The minimum buffer tank size should follow the rule of 8
US gallons per ton of heat pump capacity. The following table
shows the minimum buffer tank size for each heat pump along
with the recommended size. The recommended size will mini-
mize the number of starts per hour and provide longer runtimes
for improved efficiency.
Domestic Hot Water
(Desuperheater) Connections
The connections for the DHW circuit are 1/2” brass
FPT fittings. They are marked as DHW IN and DHW OUT.
A typical piping diagram for a pre-heat tank configuration
can be found in document 000970PDG at the end of this sec-
tion. Be sure to note the position of the check valve and the
direction of water flow. Other configurations are possible, and
there may be multiple units tied together in larger buildings.
Ensure the tank is filled with water and under pressure
before activating the built-in DHW circulator as described below.
First, slightly loosen the boiler drain on the DHW Out pipe to
allow air to escape from the system. This step will make certain
that the domestic hot water circulator in the unit is flooded with
water when it is started.
Activate the built-in DHW circulator by connecting the
brown wire with the blue insulated terminal to L1 of the com-
pressor contactor. Ensure the power is off when connecting the
wire. Once connected the DHW switch on the front of the
unit may be used to enable/disable the domestic hot water circu-
lator.
The DHW loop may have to be purged of air several times
before good circulation is obtained. A temperature difference
between the DHW In and DHW Out can be felt by hand when
the circulator pump is operating properly.
For the pre-heat tank setup, the final tank should be set to
140°F (60°C), which is required by most codes. The pre-
heat tank does not require electric elements. This setup takes
full advantage of the desuperheater as it is the sole heat provid-
er to the pre-heat tank. The desuperheater remains active dur-
ing the compressor runtime until the pre-heat tank has been
completely heated by the desuperheater alone. This setup is
more energy efficient than a single tank setup, and eliminates
the possibility of reverse heating of the refrigerant gas under low
condensing temperature operating conditions.
WARNING: USE ONLY COPPER LINES TO
CONNECT THE DESUPERHEATER. TEMPERA-
TURES COULD REACH 200°F SHOULD THE
DHW CUTOUT SWITCH FAIL, POTENTIALLY
MELTING & RUPTURING PLASTIC PIPING.
CAUTION: the domestic hot water pump is
water lubricated; damage will occur to the pump
if it is run dry for even a short period of time.
CAUTION: If two (2) shut-off valves are located
on the domestic hot water ines as shown in the
diagram, a pressure relief valve must be in-
stalled to prevent possible damage to the do-
mestic hot water circulator pump should both
valves be closed.
TABLE 12 - Buffer Tank Size
Heat Pump Size Minimum Size
gal (L)
Recommended Size
gal (L)
25 16 (61) 50 (190)
45 24 (91) 50 (190)
65 40 (151) 70 (265)
75 48 (182) 70 (265)
If a tank size is not available, use the next size larger tank.
55 32 (121) 70 (265)
Number of Tanks
All systems will require at least one buffer tank. If there is
one buffer tank, it will contain the heated or chilled water. The
water in the tank will be chilled when the “O” signal is activated.
This buffer tank may have electric elements for auxiliary heat, or
an existing boiler may be used. See piping diagrams on follow-
ing pages.
If there is need for heating and cooling simultaneously or
in close proximity, or if need for a seasonal switchover is to be
avoided, two buffer tanks maybe installed. One will be always
be heated, and one will be always be chilled, controlled using
the on-board Setpoint Control routine. This routine has two op-
tions: the “O” signal from an external controller maybe be used
to tell the heat pump to switch to cooling mode and cool the cold
tank, or the “Auto Maintain” function may be used to automati-
cally maintain both the hot and cold tanks without external input.
See Operation section, and piping diagrams on following pages.
In addition to buffer tanks, domestic hot water preheat and
final heating tanks are recommended, for use with the desu-
perheater. These are part of the building’s domestic water sys-
tem, which is totally separate from the closed loop hydronic
heating/cooling system. See diagram at end of this section.
Note that connection of the desuperheater is not mandatory.

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