Nordic AHW Series User manual

5-Jul-2022 Page 1 002596MAN-01
AHW / AH4P-
Series
Hydronic
Air
Handlers
Model Size 65
Maritime Geothermal Ltd.
P.O. Box 2555, 170 Plantation Road
Petitcodiac, NB E4Z 6H4
[phone]
[email protected]
www.nordicghp.com
002596MAN-01
5-Jul-2022
Application, Installation, & Service Manual
AHW-65
(horizontal)
AHW-65
(vertical)
AH4P-65
(horizontal) AH4P-65
(vertical)

5-Jul-2022 Page 2 002596MAN-01
AHW—65—VSP—1—SDETV—xx
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 system, ensure all power sources
are DISCONNECTED. Electrical shock can cause serious personal injury or death.
CAUTION: Safety glasses and work gloves should be worn at all times whenever a unit is serviced.
A fire extinguisher and proper ventilation should be present whenever brazing is performed.
APPLICATION TABLE
MODEL CONTROL
METHOD VOLTAGE ORIENTATION REVISIONS
AHW-65 - 0
1
T V
S H 02
AHW-65 VSP 0
1
T V
S H 02
AH4P-65 - 0
1
T V
S H 02
AH4P-65 VSP 0
1
T V
S H 02
This manual applies only to the models and revisions listed in this table.
AIR COIL /
BLOWER
S D E
S D E
S D E
S D E
SAFETY PRECAUTIONS
Model Nomenclature
Series:
AHW = 2-pipe hydronic air handler
AH4P = 4-pipe hydronic air handler
Nominal Size:
65 = 5 Ton
Voltage Code:
0 = 115-1-60
1 = 208/230-1-60
Air Coil:
S = standard (non-coated)
K = e-coated Blower Type:
D = Direct Drive
Blower Motor:
E = ECM (constant airflow)
Air Outlet Orientation
T = Top
S = Side
Cabinet Orientation
V = Vertical
H = Horizontal
Revision:
01, 02 etc.
Control Method:
(identifier not present) = 24VAC signals
VSP = 0-10VDC from external controller

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Tables & Documents ........................................................ 3
AHW/AH4P-Series Description ....................................... 4
General Overview .................................................................... 4
Factory Options ...................................................................... 4
Installation Basics .............................................................. 5
Sample Bill of Materials ........................................................... 5
Unpacking the unit ................................................................... 5
Unit Placement ........................................................................ 5
AHW: Air Return & Outlet Orientation ..................................... 5
AH4P: Air Return & Outlet Orientation .................................... 5
AH4P Horizontal - Switching the Air Outlet Orientation............ 6
Plenum Heater Installation ....................................................... 6
Wiring ................................................................................... 7
Power Supply Connections ...................................................... 7
Control Transformer ................................................................ 7
Thermostat Requirements (non-VSP models) ......................... 7
Thermostat Requirements (-VSP models) ............................... 8
Water Valve Control with AH4P-Series .................................... 8
Piping ................................................................................... 9
Condensate Drain ................................................................... 9
Hydronic Loop(s) .................................................................... 9
002601PDG - Typical Duct & Piping Connections - AHW ...... 10
Ductwork ........................................................................... 11
Zoning .................................................................................... 11
Commercial/Industrial Installations ....................................... 11
Duct Systems - General ........................................................ 11
Table of Contents
Duct Systems - Grill Layout .................................................. 11
Thermostat Location ............................................................. 11
Plenum Heater ...................................................................... 11
Duct Sizing Guide ................................................................. 12
Startup Procedure ........................................................... 13
Pre-start Inspection ............................................................... 13
Unit Startup ........................................................................... 14
Startup Record ...................................................................... 15
Routine Maintenance ...................................................... 16
Maintenance Schedule ......................................................... 16
Troubleshooting Guide .................................................. 17
Model Specific Information ........................................... 20
Shipping Information ............................................................. 20
Electrical Specifications ......................................................... 20
Plenum Heater Electrical Specifications ................................ 20
Airflow .................................................................................... 21
Performance Tables: Horizontal Models (Heating) ................ 22
Performance Tables: Horizontal Models (Cooling) ................ 23
Performance Tables: Vertical Models (Heating) .................... 24
Performance Tables: Vertical Models (Cooling) ..................... 25
Wiring Diagram (24VAC Airflow Control) .............................. 26
Wiring Diagram (-VSP Models, 0-10VDC Airflow Control) .... 27
Dimensions: AHW ................................................................. 28
Dimensions: AH4P ................................................................ 29
Warranty ............................................................................ 30
Tables & Documents
Table 1 - Power Supply Connections ...................................................................................................... 7
Table 2 - Power Supply Connections (Plenum Heater) ........................................................................... 7
Table 3 - Control Signal Description (Single Airflow) ............................................................................... 7
Table 4 - Control Signal Description (Multiple Airflows) ........................................................................... 7
Table 5 - Control Signal Description (-VSP Models, 0-10VDC Operation) ............................................... 8
Table 6 - Airflow vs. Hot Air Grills .......................................................................................................... 11
Table 7 - Duct Sizing Guide ................................................................................................................... 12
Table 8 - Shipping Information .............................................................................................................. 20
Table 9 - Electrical Specifications .......................................................................................................... 20
Table 10 - Plenum Heater Electrical Specifications ............................................................................... 20
Table 11 - Airflow (24VAC Control) ........................................................................................................ 21
Table 12 - Airflow (-VSP Models, 0-10VDC Control) .............................................................................. 21
002601PDG - Typical Duct & Piping Connections - AHW ...................................................................... 10
002590SCH - AHW/AH4P Schematic Diagram, 24VAC Airflow Control ................................................ 26
002591SCH - AHW/AH4P Schematic Diagram, -VSP Models 0-10VDC Airflow Control ....................... 27
Tables
Documents

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AHW/AH4P-Series Description
General Overview
The Nordic AHW-series and AH4P-series are ducted hy-
dronic air handlers (fan coils) that can transfer the heating or
cooling effect from heated or chilled water into air in a forced air
duct system. The duct system of the air handler can be zoned,
or more commonly comprises one zone of a larger zoned heat-
ing/cooling/dehumidification system.
Being an air handler without its own heated or chilled
source, the 2-pipe AHW-series does require one indoor water
loop. This loop can be seasonally switched between heated
and chilled to perform heating or cooling duty.
Similarly, the AH4P-series is a 4-pipe version that requires
both heated and chilled indoor hydronic loops, for installations
where both are always available. In this way, both heating and
cooling are always instantly available, and also dehumidifica-
tion can be performed.
Both the AHW and AH4P are available in one model size
(65), which can be modulated over a very large capacity range
by varying the airflow and water flow. Both vertical and hori-
zontal versions are available, in 115-1-60 or 208/230-1-60 elec-
trical service.
The AHW-series has provision for an internal electric ple-
num heater, which can be ordered as an accessory. If a ple-
num heater is required with the AH4P-series, it is placed outside
the unit in the discharge ductwork.
The room thermostat or zone controller calls for either one
selectable airflow, or one of five airflows, from 900-2300 cfm. If
the –VSP option is ordered, it is also possible for the thermostat
or controller to use a 0-10VDC signal to request any airflow from
0-2500 cfm (see next section).
The blower motor is a premium constant-airflow ECM,
which delivers the selected air flow regardless of back pressure
from the duct system or air filter. The cabinet is constructed
from powder coated galvanized sheet metal and is fully insulat-
ed with fiberglass insulation.
Factory Options
The handler can be ordered in a vertical or horizontal
configuration from the factory.
The 2-pipe AHW or 4-pipe AH4P should also be correctly
specified at time of order.
Each model can be ordered with 24VAC control, in which
case 5 discreet airflows are available for activation by the ther-
mostat or control system; or continuously variable airflow (AHW-
65-VSP) in which the external thermostat or controller sends a 0
-10VDC signal to select any airflow from 0 to 2500 cfm.
See Model Nomenclature and Application Table on
page 2 for complete model numbers.
* See Piping chapter for annotated
copies of these diagrams

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Installation Basics
Sample Bill of Materials
FROM MARITIME GEOTHERMAL
• AHW/AH4P SERIES AIR HANDLER
• PLENUM HEATER __kW
• P/T PORTS AND HOSE ADAPTERS (2)
DUCTWORK
• OUTLET PLENUM ADAPTER W/ FLEXIBLE COLLAR
• RETURN AIR ADAPTER W/ FLEXIBLE COLLAR
• TRUNK DUCT W/ JOINERS
• 6” ROUND DUCT W/ADAPTERS
• ALUMINUM TAPE
• SHEET METAL SCREWS
PIPING
• PIPE (HYDRONIC LOOP & CONDENSATE DRAIN)
• PIPE FITTINGS
• ZONE VALVE or ZONE PUMP
• ANTIFREEZE (IF USED)
ELECTRICAL
• THERMOSTAT OR CONTROLLER
• SERVICE WIRE: 14-2 OR 12-2
• PLENUM HEATER SERVICE WIRE
• BREAKER
• PLENUM HEATER BREAKER
• THERMOSTAT WIRE 18-4 (OR 18-8 FOR MULTISPEED)
• THERMOSTAT WIRE 18-2 (PLENUM HEATER)
• FORK TERMINALS FOR TSTAT WIRE (10)
• CONDENSATE PUMP & HOSE (IF REQUIRED)
Unpacking the Unit
When the air handler reaches the site 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.
The unit is well constructed and every effort has been
made to ensure that it arrives intact; but it is in the customer's
best interest to check the unit thoroughly when it arrives.
Unit Placement
Ducted air units should be centrally located in the building
with respect to the conditioned space. A heating, cooling, or
dehumidification system cannot be expected to produce have an
even effect throughout the building when it is located at one end
of the structure and the air is transmitted a long distance with
uninsulated metal ductwork.
The front (piping side) access panel should remain clear of
obstruction for a distance of 2 ft (0.7 m) to facilitate servicing
and maintenance. Ensure the unit is level to eliminate any pos-
sible condensate draining issues.
Horizontal models come equipped with an air filter rack on
which all four sides are removable for changing air filter, while
vertical models come with an air filter rack which can be in-
stalled with the removable end on either side. Be careful not to
run piping in front of the filter rack access cover.
Note that since AHW units require an external condensate
trap (see Piping chapter), they can not easily be floor mounted.
They will instead need to be hung or placed on a low stand at
least 5.5” (14 cm) higher than the floor.
Horizontal units may be hung using threaded rod and an-
gle or channel iron bars underneath. Be sure the hanging sys-
tem is suitable for 2X the weight of the unit.
AHW: Air Return & Outlet Orientation
On all 2-pipe air handler models, the air return and outlet
are in a fixed orientation in relation to to ‘front’ of the unit (the
side where water pipes are located).
For horizontal 2-pipe models, the air returns to the back
side and is discharged to the right.
For vertical 2-pipe models, the air returns to the back side
and is discharged upwards.
See Dimensions section at the end of this manual.
AH4P: Air Return & Outlet Orientation
On all 4-pipe air handler models, the air return and outlet
are in a fixed orientation in relation to to ‘front’ of the unit (the
side where water pipes are located).
For horizontal 4-pipe models, the air returns on the left.
The blower position is field convertible in order to discharge air
to either the right side (default position) or back.
For vertical 4-pipe models, the air returns on the left side
and is discharged upwards.
See Dimensions section at the end of this manual.

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AH4P Horizontal -
Switching the Air Outlet Orientation
The AH4P horizontal model only has a field configurable
blower position, resulting in straight through (side) or back air
discharge. Its default location from the factory is in the straight
through (side) position. It can easily be placed in the end of the
unit to provide a 90° turn in the air flow.
To switch the location of the fan outlet:
1. Be sure power supply to unit is turned off.
2. Remove the screws that hold the access panel adja-
cent to the blower in place and remove it by pulling up
on the handle and then outward from the bottom.
3. Disconnect the two wiring harnesses and ground wire
from the fan motor.
4. Remove the screws that hold the cabinet roof in place,
so that the roof can be lifted slightly at the blower loca-
tion during the following step.
5. Remove the screws that hold the blower panel in
place and remove the blower in its panel by pulling up
and then outward from the bottom, lifting the roof
slightly as required.
6. Install the blower in the new location. Be sure to flip
the blower over so that the motor faces out the adja-
cent access panel, so that wiring harness may be re-
connected and that service access to the motor is
maintained even with ductwork connected. Secure
blower panel and cabinet roof with screws.
7. Reconnect both motor harnesses and ground wire.
8. Install the remaining access panel and secure with
remaining screws.
BLOWER IN SIDE DISCHARGE
POSITION (DEFAULT)
BLOWER IN BACK DISCHARGE
POSITION
Plenum Heater Installation
When ordering the plenum heater (which is ordered as
an accessory), be sure to specify the type of installation
anticipated, since the plenum heater models are different
for internal or external (duct) installation.
1. AHW-series (horizontal):
Plenum heater is mounted internally in air handler cabinet.
Remove the cabinet door; then remove screws from the
plenum heater cover plate, remove the cover plate, and
place the plenum heater in the cutout. Secure both flanges
of the plenum heater to the blower with six screws through
pre-punched holes. Use the knockouts on the cabinet for
electrical connections.
3. AH4P-series:
Plenum heater should be installed externally in the air dis-
charge duct outside the air handler 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 heat-
er is mounted in an approved position as per its instruc-
tions.
2. AHW-series (vertical):
Plenum heater is mounted internally at top of air handler
cabinet, from the outside. Remove the top right cover by
removing 3 screws, and place the plenum heater in the cut-
out. Slide it in and then down so that the bottom flange is
held in the cabinet groove. Secure the top flange of the
plenum heater using the 3 screws removed earlier, through
pre-punched holes. Use the knockout on the plenum heater
itself for electrical connections, since the plenum heater’s
electrical box remains exposed.

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TABLE 1 - Power Supply Connections (AHW/AH4P)
Line Description Voltages
L1/N Line 1 L1 for 230-1-60, N for 115-1-60
L2 Line 2 All
GND Ground All
TABLE 2 - Power Supply Connections
(Plenum Heater)
Line Description Voltages
L1 Line 1 All
L2 Line 2 All
GND Ground All (connect to ground lug)
Wiring
NOTE: A properly qualified electrician
should be retained for all connections to the
unit and associated controls. The connec-
tions to the unit MUST CONFORM TO LOCAL
CODES.
Power Supply Connections
The air handler 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 plastic grommet(s) for con-
nections to plenum heater power supply, thermostat, and water
valve.
NOTE: Two separate power supplies are required, one for
the air handler and a second one for the plenum heater.
Each must have its own supply wires and breaker.
A schematic (wiring) diagram 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 Specifica-
tions table in the Model Specific Information section contains
information about the wire and breaker size.
Control Transformer
The low voltage controls are powered by a class II trans-
former with impedance protection. If the transformer is acci-
dentally shorted out by directly connecting the R and C termi-
nals, it will need to be replaced.
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.
that a simultaneous G call is required, and that especially for
externally installed plenum heaters (as for AH4P-series), an
airflow setting resulting in an air velocity of at least 400 ft/min at
the elements is needed to prevent plenum heater high tempera-
ture safety trips.
Also, a 24VAC water valve maybe connected between V
and C.
TABLE 3 - Control Signal Description
(Single Airflow)
Signal Description
C 24VAC Common (Ground)
R 24VAC Hot
W2 Auxiliary heat
G Blower ON
V 24VAC water valve (connect between V & C)
CP 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)
For installations that require the controller to call for multi-
ple airflows, the grey wire jumper from G to an airflow terminal
should be disconnected (and well insulated to prevent acci-
dental shorting). The controller may then make a dry contact
between R and one of the five airflow terminals to activate those
airflows. A call for higher airflow will override a call for a lower
airflow value; for example, if R is connected to both the
1200cfm and 1500cfm terminals, the airflow will be 1500 cfm.
Note that if a 24VAC water valve connected between V
and C is to be opened, a G call must be made at the same time.
Auxiliary heat may be called for by making a dry contact
from R to W2, which will activate the plenum heater relay and
turn on the plenum heater through terminals CP and 1. Note
that a simultaneous airflow call is required, and that especially
for externally installed plenum heaters (as for AH4P-series), an
airflow setting resulting in an air velocity of at least 400 ft/min at
the elements is needed to prevent plenum heater high tempera-
ture safety trips.
TABLE 4 - Control Signal Description
(Multiple Airflows)
Signal Description
C 24VAC Common (Ground)
R 24VAC Hot
W2 Auxiliary heat
G Water valve open
900cfm
1200cfm
1500cfm
1900cfm
2300cfm
V 24VAC water valve (connect between V & C)
CP 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)
Activate airflow at this airflow value
(disconnect grey wire jumper to G and insulate
its fork terminal)
Thermostat Requirements
(non-VSP models)
In the most usual and simplest installation, the required
room thermostat is one which makes a dry contact between the
air handler’s R and G terminals in heating or cooling mode when
it wants the air handler blower to run. This is the only require-
ment for the thermostat.
In this case, the provided grey wire jumper from G should
be connected to the terminal corresponding to the desired air-
flow (900, 1200, 1500, 1900, or 2300 cfm).
Auxiliary heat may be called for by making a dry contact
from R to W2, which will activate the plenum heater relay and
turn on the plenum heater through terminals CP and 1. Note

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Thermostat Requirements
(-VSP models)
For –VSP models (e.g. AHW-65-VSP-...), the thermostat
or controller does not call for one discreet airflow value, but in-
stead uses a 0-10VDC signal to call for any airflow between 0
and 2500 cfm.
The airflow will be proportional to the DC input signal. For
example, a 5VDC input will result in an airflow of 1250 cfm re-
gardless of backpressure from the ductwork and air filter; and a
10VDC input signal will result in an airflow of 2500 cfm. (In
practice, airflows above 2300 cfm will likely be limited by the
maximum torque output of the blower motor, so will be less
than their nominal value.) Refer to airflow tables in the Model
Specific Information chapter for airflows with the various input
signals.
Note that if a 24VAC water valve connected between V
and V1 is to be opened, a dry contact between R and G must be
made at the same time as the DC airflow signal. This G call is
not required for airflow.
Auxiliary heat may be called for by making a dry contact
from R to W2, which will activate the plenum heater relay and
turn on the plenum heater through terminals CP and 1. Note
that for internally installed plenum heaters, at least 500 cfm
airflow must be called for at the same time by the 0-10VDC sig-
nal to run the blower and prevent plenum heater high tempera-
ture safety trips. More airflow will be required for externally in-
stalled heaters (as installed for AH4P-series) since the duct area
will be larger and airflow distribution over the duct cross section
will be more uneven; an airflow resulting in an air velocity of at
least 400 ft/min at the elements is required.
A motor speed output on the terminal RPMOUT is available.
This is a pulse output with 36 pulses per revolution. For exam-
ple, there will be:
 120 pulses per second at a motor speed of 200 rpm
 240 pulses per second at a motor speed of 400 rpm
 360 pulses per second at a motor speed of 600 rpm
 480 pulses per second at a motor speed of 800 rpm
Note that because of the constant airflow functionality, motor
speed will vary with duct and air filter backpressure at any given
airflow.
TABLE 5 - Control Signal Description
(-VSP Models, 0-10VDC Operation)
Signal Description
C 24VAC Common (Ground)
R 24VAC Hot
W2 Auxiliary heat
G Water valve open
0-10VDC+ Airflow demand signal 0-10VDC
GND Ground for airflow demand signal
RPMOUT Motor speed output (36 pulses/revolution)
V 24VAC water valve
V1
CP 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)
Water Valve Control with AH4P-Series
It should be noted that if an AH4P-series air handler is to
be used for heating or cooling duty (rather than dehumidifica-
tion), the two water valves will have to be controlled by the ther-
mostat or controller directly. This is because there is only one
water valve connection point in the air handler.
For dehumidification duty, both water valves may be con-
nected to the same terminals in the air handler to provide simul-
taneous operation.

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Piping
Condensate Drain
The unit comes equipped with one 3/4” female PVC socket
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;
an example is shown on the following page. During high humid-
ity conditions, there could be as much as 25 gallons of water
formed per day.
The condensate drain is not internally trapped, and an
external trap and vent must be installed. To have room for a
trap, the unit should be mounted at least 5.5” (14 cm) above
floor level, on a stand or using a hanger.
An external condensate pump may be installed if there is
not sufficient slope to drain condensate under gravity to a drain.
The unit should be mounted at a sufficient height to have room
for the condensate drain pump’s tank under the unit.
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.
See following page for a diagram showing the condensate
drain connection.
Hydronic Loop(s)
AHW-Series: The connections for the single hydronic loop are
1” brass female NPT. They are labelled ZONE IN and ZONE
OUT.
AH4P-Series: The connections for the heated and chilled loops
are 3/4” brass female NPT. They are labelled HOT ZONE IN,
HOT ZONE OUT, COLD ZONE IN, and COLD ZONE OUT.
Flexible piping may be used to avoid transmitting fan vibra-
tions through the piping system. Be sure to use piping that has
a temperature rating suitable for the maximum water tempera-
ture produced by the connected heating device.
All chilled water piping should be insulated with closed cell
pipe insulation to prevent condensation and dripping on walls
and floors. Similarly, all heated water piping should be insulated
to prevent heat loss.
A water valve may be connected on the OUT connection
port as shown on the following page, and controlled from the air
handler’s terminal strip.

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