Nortek PAH4VMX User manual

Installation Instructions
Indoor Air Handlers
These instructions are primarily intended to assist qualified individuals experienced in the proper
installation of heating and/or air conditioning appliances. Some local codes require licensed instal-
lation/service personnel for this type equipment. All installations must be in accordance with these
instructions and with all applicable national and local codes and standards.
Before beginning the installation, read these instructions thoroughly and follow all warnings and
cautions in the instructions and on the unit. When performing brazing operations have a fire extin-
guisher readily available and use a quenching cloth and brazing shield.
Improper installation, service, adjustment, or maintenance can cause fire, electrical shock or other
conditions which may result in personal injury or property damage. Unless otherwise noted in
these instructions, only factory authorized kits or accessories may be used when modifying this
product.

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Table of Contents
1. Air Handler Specifications................................................................................................... 4-5
Unit Dimensions .................................................................................................................... 4
2. Installation Requirements....................................................................................................... 5
Minimum Ampacity and Maximum Overcurrent Protection ................................................... 5
3. Air Ducts, Filters, Horizontal Applications ............................................................................ 6
4. Verify Pressurization ............................................................................................................... 9
5. Refrigerant Line Connections ................................................................................................9
6. Electrical Wiring..................................................................................................................... 11
7. Start-up and Adjustment....................................................................................................... 13
8. Optional Humidistat (Variable Speed Only) ......................................................................... 17
9. Care and Maintenance........................................................................................................... 18

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Figure 1. Unit Dimensions
1. AIR HANDLER SPECIFICATIONS
Indoor Air Handlers are designed and approved
for attic, basement, alcove, closet and crawl
space installations.
Factory ready horizontal Air Handlers may be
applied in upflow or horizontal-left and -right
discharge applications. These units may also
be applied in downflow discharge when applied
with the appropriate field kit (See Technical
Specifications).
Vertical only Air Handlers are factory ready for
upflow applications.These units may be applied
in downflow or horizontal left and right discharge
applications when applied with the appropriate
field kit (See Technical Specifications).
Dimensional drawing for the unit is shown in
Figure 1.
Field-installed electric heater kits are available.
Available heater kits for these units are listed
in the Technical Specifications. Instructions for
installing the electric heaters are included with
the heaters.
All units equipped with standard blowers may be
upgraded to variable speed with the addition of
a variable speed conversion kit. See Technical
Specifications for details.
3/4”
3/4”
3/4”
13”
1 7/8" K.O.
11/8” K.O.
(typ.)
11/4”
15/8”
17/8” 11/4”
3 1/4”
2 5/8”
11/8” K.O.
(typ.)
13/4” K.O.
(typ.)
1 7/8”
3 5/8”
5 5/8”
DETAIL “D”
3 1/4”
2 1/4”
15 1/4”
13”
SUCTION
LIQUID
“W”
1 1/8”
1 7/8”
7/8" K.O.
“H”
22"
“A”
Cabinet
Size H W A
Detail
D
A 43-5/16 14-3/16 12-3/4 No
B 43-5/16 19-11/16 18-1/4 No
Tall B 49-5/16 19-11/16 18-1/4 No
C 55-15/16 22-7/16 21 Yes

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Table 1. Minimum Ampacity and Maximum Overcurrent Protection
These wiring requirements are for units with optional heater kits.They can not be used
with 115 volt units.
Air handlers set up with 15 kw or more of electric
heat will normally be configured for multiple-
circuit power supply. They may, however, be
connected to a single-circuit power supply with
the addition of a single circuit accessory kit (See
Technical Specifications). Select the wire size
and over-current protection in accordance with
the minimum circuit ampacity and maximum
over-current protection shown in Table 1.
2. INSTALLATION REQUIREMENTS
Check Equipment — All installations shall
be made as described in these installation
instructions and in accordance with all ap-
plicable national and local codes including the
requirements of local utilities.
Requirements and Codes — Electrical power
wiring must be made in accordance with all ap-
plicable local codes and ordinances, and with
the current revision of the National Electric Code
(ANSI/NFPA 70). Air ducts must be installed in
accordance with the standards of the National
Fire Protection Association “Standard for In-
stallation of Air Conditioning and Ventilation
Systems” (NFPA 90A), “Standard for Installa-
tion of Residence Type Warm Air Heating and
Air Conditioning Systems” (NFPA 90B), these
instructions, and all applicable local codes.
National Fire Protection Association, Inc.
Batterymarch Park
Quincy, Maine 02269
www.nfpa.org
[phone]
Location — To insure proper condensate
drainage, the unit must be installed in a level
position within 1/4 inch over the height, width,
and depth of the unit. The best system perfor-
mance will be obtained if the unit is located in
a centralized position with respect to the air
distribution system.
When an air handler is installed in or above a
living space, the installation of an auxiliary drain
pan under the entire unit is required to reduce
the possibility of property damage.
240 VAC, 50 & 60Hz Single Phase 208 VAC, 60Hz Single Phase
Aux. Heat Installed
(Nom. KW) NONE 005H 008H 010H 015H 020H 025H 030H NONE 005H 008H 010H 015H 020H 025H 030H
Single Circuit
***Min. Circuit Amp. 7.5 32.5 46.6 57.5 82.5 107.5 132.5 157.5 7.5 29.1 41.2 50.8 72.4 94.0 115.7 137.3
*Wire AWG 75oC14 8 8(6**) 6 4(3**) 2 0 00 14 10(8**) 8 6 4 3 1 0
Maximum
Over-current
Rating
15 40 50 60 90 125 150 175 15 30 50 60 80 100 125 150
Multiple Circuit
Circuit A
***Min. Circuit Amp. 7.5 32.5 46.6 57.5 57.5 57.5 57.5 57.5 7.5 29.1 41.2 50.8 50.8 50.8 50.8 50.8
*Wire AWG 60oC14 8 6 4 4 4 4 4 14 10(8**) 6 6 6 6 6 6
*Wire AWG 75oC14 8 8(6**) 6 6 6 6 6 14 10(8**) 8 6 6 6 6 6
Maximum
Over-current
Rating
15 40 50 60 60 60 60 60 15 30 50 60 60 60 60 60
Circuit B
***Min. Circuit Amp. - - - - 25.0 50.0 50.0 50.0 - - - - 21.6 43.3 43.3 43.3
*Wire AWG 60oC- - - -10666 - - - -10666
*Wire AWG 75oC- - - -10888 - - - -10888
Maximum
Over-current
Rating
- - - - 30 60 60 60 - - - - 25 50 50 50
Circuit C
***Min. Circuit Amp. - - - - - - 25.0 50.0 - - - - - - 21.6 43.3
*Wire AWG 60oC- - - ---106 - - ----106
*Wire AWG 75oC- - - ---108 - - ----108
Maximum
Over-current
Rating
- - - - - - 30 60 - - - - - - 25 50
*All wire sizes for copper conductors only, based on NEC Table 310-16.
**Required for C-cabinet variable speed.
***Circuit ampacity slightly higher for variable speed. See label on blower.

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All servicing and cleaning of the air handler can
be done from the front. Adequate horizontal
clearances should be provided to allow for
service and care of the unit. A minimum 24 inch
clearance at the front of the unit is recommended.
These units are suitable for attic, closet, crawl
space or alcove installation at zero clearance
from combustibles.
Condensate Drain — The condensate pan
has primary and secondary drain connections.
The connections have 3/4 inch female pipe
threads.
All condensate drains should be a minimum
of 3/4 inch PVC pipe or equivalent. The drain
should maintain a minimum horizontal slope in
the direction of discharge of not less than 1 inch
vertical for every 10 feet of horizontal.
If the air handler is located in or above a living
space where damage may result from conden-
sate overflow, an auxiliary drain pan shall be
installed under the unit. A separate drain line
should extend from the pan to a conspicuous
point and serve as an alarm indicating that the
primary drain is restricted. As an alternative to
a separate drain line, an approved water level
indicator or float switch device should be used to
shut down the unit in the event water is detected
in the auxiliary pan.
Install a 5 inch trap in the condensate drain
line as close to the coil as possible. Make sure
that the top of the trap is below the bottom of
the drain pan to prevent the condensate from
overflowing the drain pan. Prime the trap with
water. Insulate the drain if it is located in an
unconditioned space, and test the condensate
line for leaks. Consult local codes for additional
restrictions or precautions.
NOTE: There must be only one trap in the drain
line. Using more than one trap may prevent
drainage.
IMPORTANT:
The plastic drain pan must be level
or slightly sloped toward the drain
lines.
3. AIR DUCTS, FILTERS,
HORIZONTAL APPLICATIONS
Air ducts should be installed in accordance with
the standards of the National Fire Protection
Association “Standard for Installation of Air
Conditioning and Ventilation Systems” (NFPA
90A), “Standard for Installation of Residence
Type Warm Air Heating and Air Conditioning
Systems” (NFPA 90B), these instructions, and
all applicable local codes.
Use transition fittings if the supply and/or return
air openings of the unit do not match the duct
openings. These transitions should be dimen-
sioned in accordance with standard practice as
specified in the ASHRAE recommendations for
duct transitions.
Flexible connectors should be used between the
unit and the ductwork to prevent transmission of
vibration from the unit to the structure.If electric
heater kits are installed, heat resistant material
must be used for the flexible connector at the
supply air end of the unit.
Air Filter Installation — The filter may be lo-
cated in the return air duct system or installed
into the air handler filter track located in the
bottom of the unit.
To install the filter, remove the filter door. The
filter sizes for the air handler cabinets are:
Cabinet Filter
A 12 x 20 x 1
B 18 x 20 x 1
C 20 x 20 x 1
WARNING:
Never operate the unit without a fil-
ter or with the doors removed. Dust
and lint in the return air can build up
on internal components, resulting
in a loss of efficiency, equipment
damage, and possible fire risk.
Upflow Applications — All air handlers are
factory shipped, ready for upflow configuration,
all return air must enter from the bottom of the
unit. A typical installation of the unit in a ducted
return air mode is shown in Figure 2.
Downflow Applications — The downflow
accessory kit (See Technical Specifications) is
required for downflow applications.Instructions
for installing the downflow accessory kit are
included with the kit. It is recommended that
the accessory be installed prior to installing
the unit. All return air in downflow applications

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must enter through the top of the unit. A typical
installation of the unit in a downflow application
is shown in Figure 3.
Horizontal Left And Horizontal Right — Air
handlers may or may not be shipped from the
factory with all the parts required for horizontal
left applications and horizontal right applications
(see Figure 4). If your unit does not have parts
for a horizontal application, a kit is available
(see Technical Specifications).
To Configure Unit for Horizontal LEFT
Installations:
1) Remove the coil access door.
2) IMPORTANT: Remove the plug from one
of the threaded holes in the horizontal drain
pan. Completely remove the webbing lo-
cated in the threaded holes of the horizontal
drain pan. If webbing is not removed, the
drain will not function properly and ceiling
damage may occur.
3) Insert a plug (from the horizontal drain pan)
into the open and unused drain hole in the
drain pan at the bottom of the unit to block
bypass air.
4) Remove the corresponding drain line
knockout from the coil access door to allow
access to the horizontal drain.
5) Replace the door and attach the drain
line.
To Configure Unit for Horizontal RIGHT
Installations:
1) Remove the coil access door. Unscrew the
line-set tube close-off plate from the front
left cabinet rail.
2) Slide the coil and drain pan assembly out
of the unit.
3) Remove the sheet metal hairpin covers
(if supplied) from the back of the coil and
discard.
4) Place the horizontal drain pan on the
opposite side of the coil. On units with 2
sets of knockouts, remove the other set of
knockouts in the coil spacing plates and
insert support rod.
5) Slide the coil and the horizontal drain pan
assembly back into the unit. Reattach the
tube close off plate.
6) IMPORTANT: Remove the plug from one
of the threaded holes in the horizontal
drain pan. Completely remove the web-
bing located in the threaded holes of the
drain pan. If webbing is not removed, the
drain will not function properly and ceiling
damage may occur. Insert the plug (from
the horizontal drain pan) into the open and
unused drain hole in the drain pan at the
bottom of the unit to block bypass air.
7) Remove the corresponding drain line
knockout from the coil access door to allow
access to the horizontal drain.
8) Replace the door and attach the drain
line.
Figure 3. Downflow Installation
Figure 2. Upflow Installation

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The unit may also be installed in a horizontal
application with the unit suspended from the
ceiling. A typical installation of the unit in a
suspended horizontal application is shown in
Figure 4.
NOTE: In all horizontal applications in which
the unit is installed above a finished ceiling
and/or living space, a secondary drain pan
must be installed under the entire unit to
avoid damage to the ceiling in the event of
condensate overflow.
Supply Air Ducts — Bend up the flanges on the
top of the unit and connect the supply air duct
over them. Secure the duct to the flange, using
appropriate fasteners for the type of duct used.
Seal the joint between the duct and the unit to
avoid air leakage and sweating. The supply air
ductwork must be of noncombustible material
for the first 24 inches from the unit.
Some installations with a short, straight run
from the unit to the first branch takeoff may
require acoustical lining inside the supply air
ductwork. Acoustical insulation must be in ac-
cordance with the current revision of the Sheet
Metal and Air Conditioning Contractors National
Association (SMACNA) application standard
for duct liners.
Duct lining material must be UL classified batts
or blankets with a fire hazard classification of
FHC-25/50 or less. Fiber ductwork may be
used in place of internal duct liners if the fiber
ductwork is in accordance with the current revi-
sion of the SMACNA construction standard on
fibrous glass ducts.
Fibrous ductwork and internal acoustical lining
must be NFPA Class I air ducts when tested per
UL Standard 181 for Class 1 ducts.
Through-the-Floor Installations —Whenever
the supply or return air ducts pass through
the floor, a 1/4” thick noncombustible resilient
gasket must be used between the duct, unit
and floor.
Ductwork in Unconditioned Spaces — All
ductwork located in unconditioned space must
be adequately insulated to prevent excess duct
loss and condensation. All externally insulated
ductwork must have an adequate vapor seal.
Figure 4. Typical Horizontal Installation Using Threaded Rod and
Supporting Members (Shown in Horizontal Left Position)
THREADED ROD
LOCATION OF
THE BLOWER DECK
SUPPORT MEMBER

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Consult your Distributor for the recommended
type and thickness of insulation for your area
as required by local codes.
4. VERIFY PRESSURIZATION
WARNING:
This coil is pressurized with Nitro-
gen. Pressure must be relieved in
order to prevent the potential of an
injury or fatality from the cap during
the removal process. Avoid direct
face exposure or contact with valve
when gas is escaping. Always ensure
adequate ventilation is present during
the depressurization process. Any
uncertainties should be addressed
before proceeding.
VERIFY PRESSURIZATION:
- Test by depressing Schrader valve and listen
for escaping gas
- If no pressure is found, test coil for leak
- If no leak is found, install coil
- If leak is found, clearly mark leak
location and return coil to your dis-
tributor for processing
5. REFRIGERANT LINE
CONNECTIONS
Note: Do not remove seals from the coil until
tubing connections are ready to be made.
Note: The air handler coil does not contain
a refrigerant charge. Reference installation
instructions included with outdoor unit for
information regarding the refrigerant charge
included in the outdoor unit.
Note: The following instructions are for air
handler models employing an orifice for the
refrigerant metering device.
The orifice employed in the air handlers has
been sized for use with the most popularly
matched outdoor unit.The orifice size in the coil
as shipped from the factory is listed on the air
handler rating plate. Check that the orifice size
provided with the air handler is correct for the
outdoor unit being applied. If the orifice size is
incorrect it should be replaced as follows:
WARNING:
This coil is pressurized with Nitro-
gen. Pressure must be relieved in
order to prevent the potential of an
injury or fatality from the cap during
the removal process. Avoid direct
face exposure or contact with valve
when gas is escaping.Always ensure
adequate ventilation is present dur-
ing the depressurization process.
Any uncertainties should be ad-
dressed before proceeding.
1. Remove cap from Schrader valve on liquid
line. Relieve all pressure from the coil by
depressing the valve on the end of the liq-
uid line. Remove the valve core. Properly
dispose of all removed parts.
2. Loosen the distributor body halves by ap-
plying two wrenches and squeezing them
together as shown in Figure 5, to turn the
assembly nut counterclockwise.
Figure 5. Wrenches on
Distributor Body and Assembly Nut
NITROGEN
HEALTH
FLAMMABILITY
REACTIVITY
0 Minimal Hazard 1 Slight Hazard
1
0
0NITROGEN
HEALTH
FLAMMABILITY
REACTIVITY
0 Minimal Hazard 1 Slight Hazard
1
0
0

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3. Continue to unscrew the assembly nut to
separate it from the distributor body.
4. Insert a light-gauge wire hook between
the distributor body and the orifice to lift
the orifice out of the body (See Figure 6).
Carefully remove the orifice being careful
not to scratch either part.
5. Check the actual size of the new orifice (the
size is stamped on the side of the orifice).
6. Insert the new orifice in the distributor body
as shown in Figure 7.
7. After installing the orifice in the distributor
body, re-attach the assembly nut to the dis-
tributor body and tighten it to 10-12 ft/lbs of
torque.If no torque wrench is available, mark
a line along both the nut and body after hand
tightening and then tighten an additional 1/4
turn. The misalignment of the two lines will
show how much the nut is tightened.
Line Connections:
8. If not already done so, release pressure from
the coil by removing the valve cap and then
depressing the valve on the end of the liquid
line. Remove the valve core and dispose of
properly.
9. Making note of orientation, remove the hole
grommets and tube close-off insulation from
around the coil and refrigerant line set.
Note: On models which use a TXV, it is recom-
mended to wrap a wet rag around the suction
line between the sensing bulb and the line set
braze joint before applying any heat.
10.Unbraze and remove the cap on the suction
line. Unbraze and remove the valve core
holder on the liquid line.
11. Cut the line set tubing to the proper length.
Be sure that the tubing has been sized in
accordance with the outdoor unit speci-
fications.
12. Inspect both refrigerant lines. The ends of
the lines must be round, clean, and free
of any burrs.
13. Place grommets in proper orientation onto
line set with sufficient distance to braze joint
as to not damage the grommets.
14. Insert the line set tubes into the coil tube
stubs until they bottom out.
Note: On models which use a TXV, it is recom-
mended to wrap a wet rag around the suction
line between the sensing bulb and the line set
braze joint before applying any heat.
15. Braze the individual connections with dry
nitrogen flowing through the joints to elimi-
nate internal oxidation and scaling.
16. Replace grommets and insulation. Check
the assembly for leaks.
17. Properly dispose of all removed parts.
Note: On horizontal or downflow applications of
models with the TXVs, to ensure proper perfor-
mance, the sensing bulb must be re-positioned
so it is in the 4 o’clock or 8 o’clock position on
the suction tube after final orientation of the
air handler.
WARNING:
To avoid the risk of electric shock,
personal injury or death, disconnect
all electrical power to the unit before
performing any maintenance or ser-
vice. The unit may have more than
one electrical power supply.
Figure 7. Orifice
Insertion in Distributor Body
Figure 6. Removal of Orifice