Suntherm MSVT Series User manual

MORTEX PRODUCTS INC. 501 TERMINAL RD FORT WORTH, TX 76106 Page 1
Multi-Position DX and Chilled Water-Cooling with Electric Heating
MODELS: MSVT Series With Single-Stage Cooling/Heat Pump Air-Flow
MSVE Series With Single or Two-Stage Cooling/Heat Pump Air-Flow
INSTALLATION MANUAL
SAVE THIS MANUAL FOR FUTURE REFERENCE
8 – Field Installed Electric Heater Kits .....................................................16
9 – Thermostat Wiring and Connections ..............................................17
10 – Blower Performance ..............................................................................21
11 – Motor Speed Selection and Air Handler Startup.........................22
12 – Final System Checkout..........................................................................23
13 – Wiring Diagrams......................................................................................24
19 – Low Voltage Connections: 1-Stage Heat & 1-Stage Cooling..........18
20 – Low Voltage Connections: 1-Stage Heat & 1-Stage HP ....................18
21 – Low Voltage Connections: 2-Stage Heat & 1-Stage Cooling..........19
22 – Low Voltage Connections: 2-Stage Heat & 1-Stage HP ....................19
23 – Constant Torque Motor Terminals ..............................................................22
24 – ECM Control Board Layout.............................................................................22
25 – ECM Motor Control Plug Pin Positions .....................................................22
26 – Wiring Diagram:MSVE 18-72; ECM Mtr; No Electric Htr ...................24
27 – Wiring Diagram:MSVE 18-72; ECM Mtr; 5 kW Electric Htr...............24
28 – Wiring Diagram:MSVE 25-72; ECM Mtr; 10 kW Electric Htr ............25
29 – Wiring Diagram:MSVE 37-72; ECM Mtr; 15 kW Electric Htr ............25
30 – Wiring Diagram:MSVE 42-72; ECM Mtr; 20 kW Electric Htr ............26
31 – Wiring Diagram:MSVT 18-72; C.T. Motor; No Electric Htr................26
32 – Wiring Diagram:MSVT 18-72; C.T. Motor; 5kW Electric Htr.............27
33 – Wiring Diagram:MSVT 18-72; C.T. Mtr; 10kW Electric Htr................27
34 – Wiring Diagram:MSVT 36-72; C.T. Mtr; 15kW Electric Htr ...............28
35 – Wiring Diagram:MSVT 37-72; C.T. Mtr; 20kW Electric Htr................28
11 – Electric Heater Kit Model Numbers .................................................. 16
12 – Accessory Heater Kit Model Number Nomenclature................. 17
13 – Low Voltage Wire Gauge and Maximum Lengths....................... 17
14 – Typ Heat/Cool T-stat Wire Colors & Low Voltage Connections.. 19
15 – Typ Heat PumpT-stat Wire Colors & Low Voltage Connections ..... 19
16 – Blower Performance – Constant Torque Motors.......................... 21
17 – Blower Performance – ECM Motors.................................................. 21
18 – Constant Torque Motor Terminal Connections............................ 22
19 – ECM Motor Control Connector Terminal Descriptions.............. 23
1 – General...........................................................................................................1
2 – Safety..............................................................................................................2
3 – Location, Clearances and Return Air Requirements......................7
4 – Air Handler Orientation, Supply Air Duct, & Return Air Filters...8
5 – Installing the Air Handler...................................................................... 10
6 – Refrigerant Piping, TXV, and Condensate Piping......................... 10
7 – Line Voltage Wiring.................................................................................12
1. Air handler is rated for 208/240 VAC at 60 Hertz.
2. Air handler size varies by model.
3. Air handler is designed for A/C or heat pump operation.
4. Air handler is designed for upow, downow and
horizontal applications.
5. Air handler must not be operated with the access
panels removed.
6. Air handler is listed by ETL in the United States and Canada.
1 – Dimensional Data DX Cool With & Without Electric Heat ............5
2 – Dimensional Data Chilled Water With & Without Electric Heat 6
3 – Clearance – Access for Service...............................................................7
4 – Closet Clearances .......................................................................................7
5 – Air Filter Base Accessory for 1”or 2” Air Filters .................................8
6 – Indoor Coil Disassembly When Converting to Downow...........9
7 – Indoor Coil Assembly When Converting to Downow.................9
8 – Combustible Floor Base Installation....................................................9
9 – Indoor Coil Below Outdoor Unit Piping.......................................... 10
10 – Typical TXV Connections...................................................................... 10
11 – TXV Sensing Bulb Location.................................................................. 11
12 – TXV Bulb Placement............................................................................... 11
13 – Typical Condensate Trap....................................................................... 12
14 – Component Locations – Electric Heat Control Box .................... 15
15 – Component Locations – No Heat Control Box ............................. 15
16 – Control Box Circuit Breaker Locations............................................. 15
17 – Circuit Breaker Location on Front Panel ......................................... 15
18 – Cabinet Wiring Entrances ...............................................................................17
1 – Air Handler Model Specications.........................................................3
2 – Air Handler Model Number Nomenclature.......................................4
3 – Dimensional Data DX Cooling With or Without Electric Heat ....5
4 – Dimensional Data Chilled Water With or Without Electric Heat 6
5 – Clearances to Combustibles...................................................................7
6 – Electrical Data: 18-36 kBTU–Single Branch Circuit...................... 13
7 – Electrical Data: 37-72 kBTU–Single Branch Circuit...................... 13
8 – Electrical Data: 25-36 kBTU–Dual Branch Circuit ......................... 14
9 – Electrical Data: 37-72 kBTU–Dual Branch Circuit ......................... 14
10 – Electric Heater Heating Capacities ................................................... 14
The following list includes important facts and information regarding the air handler models covered in this manual.
LIST OF SECTIONS
LIST OF FIGURES
LIST OF TABLES
SECTION 1: GENERAL

MORTEX PRODUCTS INC. 501 TERMINAL RD FORT WORTH, TX 76106 Page 2
This is a safety alert symbol. When this symbol is seen on
labels or in manuals, be alert to the potential for personal injury.
Understand and pay particular attention to the signal words
DANGER, WARNING, or CAUTION.
DANGER: Indicates an imminently hazardous situation, which if
not avoided, will result in death or serious injury.
WARNING: Indicates a potentially hazardous situation, which if
not avoided, could result in death or serious injury.
CAUTION: Indicates a potentially hazardous situation, which if
not avoided, may result in minor or moderate injury.It is also
used to alert against unsafe practices and hazards involving
property damage.
Improper installation may create a condition where the
operation of the product could cause personal injury or
property damage.
Improper installation, adjustment, alteration, service or
maintenance can cause injury or property damage. Refer
to this manual for assistance; or for additional information
consult a qualied contractor, installer, or service agency.
FIRE OR ELECTRICAL HAZARD
Failure to follow the safety warnings exactly could result in
serious injury, death, or property damage.
A re or electrical hazard may result causing property
damage, personal injury or loss of life.
This product must be installed in strict compliance with
the installation instructions and any applicable local, state,
and national codes including, but not limited to, building,
electrical, and mechanical codes.
The Clean Air Act of 1990 bans the intentional venting of
refrigerant (CFC’s and HFC’s) as of July 1, 1992. Approved
methods of reclaiming must be followed. Fines and/or
incarceration may be levied for non-compliance.
MS Series Multi-Position Air Handler
Safety Requirements
This appliance should be installed in accordance with all
national and local building/safety codes and requirements,
local plumbing or waste-water codes, and other applicable
codes. In the absence of local codes, install in accordance with
the following codes.
• Standard for the Installation of Air Conditioning and
Ventilating Systems (NFPA 90A)
• Standard for the Installation of Warm Air heating and
Air Conditioning Systems (NFPA 90B)
• National Electrical Code (NFPA 70)
• Canadian Electrical Code, Part I (CSA C22.2) or ANSI/NFPA
No. 70
• All local codes (State, City, and Township)
NOTE: All applicable codes take precedence over any
recommendation made in these instructions.
SunTherm assumes no responsibility for units installed in
violation of any code or regulation.
1. Refer to the unit rating plate for the air handler model
number, and then see the dimensions page of this
instruction for return air plenum dimensions in Figures 1
and 2. The plenum must be installed according to the above
listed codes or the instructions in this manual.
2. Refer to the dimensions page of this instruction and the duct
connector and combustible oor base dimensions shown in
Figure 9 for the proper duct connector or combustible oor
base for downow applications. The duct connector and
combustible oor base must be installed according to the
instructions in this manual.
3. These models are not ETL listed or approved for
installation into a Manufactured (Mobile) Home.
4. Provide clearances from combustible materials as listed
under Clearances to Combustibles.
5. Provide clearances for servicing ensuring service access is
allowed for the control box, electric elements, hot water
coil and the blower.
6. Check the rating plate and the power supply to be sure the
electrical characteristics match.
7. Failure to carefully read and follow all instructions in this
manual can result in malfunction of the air handler, death,
personal injury, and/or property damage.
8. Electric air handler shall be installed so the electrical
components are protected from water.
9. Installing and servicing heating/cooling equipment can be
hazardous due to electrical components.
10. Only trained and qualied personnel should install repair or
SECTION 2: SAFETY

Always shut o electricity at the disconnect switch or turn
o the circuit breakers in the main electrical panel before
performing any service on this air handler.
Models MS**18,24 MS**25,30,36 MS**37,42,48,60 MS**72
Available Electric Heat kW 5,10 5,10,15 5,10,15,20 5,10,15,20
Blower Size (D x W) 9 x 6 (MSVE)
10 x 7 (MSVT)
10 x 7 (MSVE)
10 x 8 (MSVT)
12 x 9
(MSVE & MSVT)
12 x 10
(MSVE & MSVT)
Unit Voltage 208/240V, 60 HZ, 1 PH
Max. External SP (Duct), In. W.C. 0.50
Thermostat Circuit 24 VAC,60 Hz, 40VA
Available Blower Motors
1. 5 SPD CONSTANT TORQUE MOTOR
2. VARIABLE SPEED ECM MOTOR
MORTEX PRODUCTS INC. 501 TERMINAL RD FORT WORTH, TX 76106 Page 3
service heating/cooling equipment. Untrained service
personnel can perform basic maintenance functions such as
cleaning of exterior surfaces and replacing the air lters.
Observe all precautions in the manuals and on the attached
labels when working on this appliance.
11. These instructions cover minimum requirements and
conform to existing national standards and safety codes. In
some instances, these instructions exceed certain local
codes and ordinances, especially those who have not
kept up with changing home and/ or HUD construction
practices. These instructions are to be followed and are the
minimum requirement for a safe installation.
12. The size of the unit should be based on an acceptable heat
loss calculation for the structure. ACCA, Manual J or other
approved methods may be used.
13. Check the rating plate and power supply to be sure that the
electrical characteristics match. This air handler must be
connected to a nominal 208/240 VAC, 1 Phase, 60-Hertz
power supply. DO NOT CONNECT THIS AIR HANDLER TO A
50 HZ POWER SUPPLY OR A VOLTAGE ABOVE 250 VOLTS.
14. Ground connections must be securely fastened to the
control box and ground wires must be secure.
GENERAL INFORMATION
This single piece air handler provides the exibility for
installation in any upow, downow, or horizontal application.
The versatile models may be used with or without electric heat
or hot water heat. The direct-drive variable speed ECM and
5-speed constant torque motors provide a selection of
air-ow volume to match any application. The air handler can
be positioned for bottom air return in the upow position, top
air return in the downow position, or air return through the
end of the air handler in the horizontal position.
NOTE: Refer to the instructions in this manual for the proper
downow conversion kit and instructions on the proper
conversion to downow.
Inspection
As soon as the air handler is received, it should be inspected for
possible damage during transit. If damage is evident, the extent
of the damage should be noted on the carrier’s freight bill. A
separate request for inspection by the carrier’s agent should be
made in writing. Before installing the air handler, you should
check the cabinet for screws or bolts which may have loosened
in transit. There are no shipping or spacer brackets which need
to be removed before startup.
See local distributor for more information. Mortex Products, Inc
assumes no liability for freight damage.
Also check to be sure all accessories such as heater kits, and
coils are available. Installation of these accessories should
be accomplished before the air handler is set in place or the
connecting of the wiring, electric heat, ducts or piping.
Table 1: Air Handler Model Specications

MORTEX PRODUCTS INC. 501 TERMINAL RD FORT WORTH, TX 76106 Page 4
MODEL NUMBER NOMENCLATURE
MS VT 36 15 B 862T AA
I II III IV V VI VII
ISeries
MS = Multi-Position Single-Piece
II
Motor Type
VT = Variable Constant Torque
VE = Variable Speed ECM
III
Unit Size (Capacity in MBTUH)
12 through 24 - Small Cabinet
25 through 36 - Medium Cabinet
37 through 72 - Large Cabinet
OS = No Cooling Small Cabinet
OM = No Cooling Medium Cabinet
OL = No Cooling Large Cabinet
IV
Heating Conguration
00 = Cooling Only
05 = 5 kW Electric Heating Capacity
10 = 10 kW Electric Heating Capacity
15 = 15 kW Electric Heating Capacity
20 = 20 kW Electric Heating Capacity
VAir Handler Voltage
B = 208/240
VI
SUMMIT Evaporator Coil Conguration
862T = DX Coil Geometry And Metering Device
8K2N = CW Coil Geometry, No Metering Device
VII Option Code
AA = Standard Factory Options
Table 2: Electric Heat Air Handler Model Number Nomenclature

DIMENSIONAL DATA MULTI-POSITION AIR HANDLER COOL ONLY OR ELECTRIC HEAT
Model A B C D E F G H J K L M N P R S T
MS**18, 24 17.50 43.00 21.00 15.63 12.50 13.50 11.00 6.75 16.75 14.00 11.00 10.75 2.00 1.50 5.00 16.10 20.20
MS**25, 30, 36, 38, 46 21.00 48.00 21.00 19.00 12.50 14.50 13.00 6.75 20.00 17.00 12.75 10.30 2.30 4.35 5.00 19.90 20.80
MS**37, 42, 48, 60, 72 24.50 58.88 21.75 22.25 14.25 19.75 17.25 6.75 26.00 23.00 16.75 14.35 2.30 4.35 4.50 23.50 20.70
MORTEX PRODUCTS INC. 501 TERMINAL RD FORT WORTH, TX 76106 Page 5
Figure 1: Dimensional Data DX Cooling With Or Without Electric Heat
Table 3: Dimension Data - DX Cooling With & Without Electric Heat

DIMENSIONAL DATA MULTI-POSITION AIR HANDLER COOL ONLY OR ELECTRIC HEAT
Model A B C D E F G H J K L M N P R S T
MS**18, 24 17.50 43.00 21.00 15.63 12.50 13.50 11.00 6.75 16.75 14.00 11.00 10.75 2.00 1.50 5.00 16.10 20.20
MS**25, 30, 36, 38, 46 21.00 48.00 21.00 19.00 12.50 14.50 13.00 6.75 20.00 17.00 12.75 10.30 2.30 4.35 5.00 19.90 20.80
MS**37, 42, 48, 60, 72 24.50 58.88 21.75 22.25 14.25 19.75 17.25 6.75 26.00 23.00 16.75 14.35 2.30 4.35 4.50 23.50 20.70
MORTEX PRODUCTS INC. 501 TERMINAL RD FORT WORTH, TX 76106 Page 6
Table 4: Dimensional Data - Chilled Water With And Without Electric Heat
Figure 2: Dimensional Data Chilled Water With And Without Electric Heat

MODEL TOP (in) BACK (in) SIDES (in) FRONT OF FURNACE DUCT (in)
ALCOVE (in) CLOSET (in)
ELECTRIC 0 0 0 30 6 1
MORTEX PRODUCTS INC. 501 TERMINAL RD FORT WORTH, TX 76106 Page 7
LOCATION
Access for servicing is an important factor in the location of
any air handler. Provide a minimum of 30 inches in front of the
appliance for access to the control box, heating elements, water
pump, blower and air lters. This access may be provided by a
closet door or by locating the appliance so that a wall or partition
is not less than 30 inches from the front access panel. As the
location is usually predetermined, check with owner’s or dealer’s
installation plans. If location has not been decided, consider the
following in choosing a suitable location.
1. Select a location with adequate structural support, space for
service access, clearance for return and supply duct connections.
2. Normal operating sound levels may be objectionable if the
air handler is placed directly over or under some rooms such as
bedrooms, study, etc.
3. It is best to locate the air handler so that supply air ducts are
about the same length and the return air ducts are about the
same length to provide even air distribution of supply and
return air to and from the living spaces.
4. Locate appliance where electrical supply wiring can be easily
routed to main electrical panel and where electrical wiring will
not be damaged.
5. Locate appliance where thermostat wiring can be easily routed
to the thermostat and where the wiring will not be damaged.
6. Locate appliance where refrigerant lines can be easily routed
from the indoor coil to the outdoor unit.
7. Locate the appliance where condensate lines can be easily
routed to an available drain or outside. Be sure to route
condensate drain piping so as not to obstruct access to the air
lter.
8. When the coil is installed in a draw-through conguration as in
this air handler, a negative pressure is created in the condensate
drain system. To assure proper condensate drainage and to
prevent condensate from being drawn into the blower, it is
recommended that a trap be installed in the primary (main) and
secondary (overow) drain lines. Refer to the CONDENSATE
DRAIN PIPING section and Figure 13 in this manual. If the
secondary drain is not used, it must be capped.
9. The draw-through design can also cause exterior surface
of cabinet to sweat when air handler is installed in a non
conditioned space such as an attic or garage. The installer must
provide protection such as full-size auxiliary drain pan under
all air handlers installed in a non-conditioned space to prevent
damage from condensation runo. Some states, cities and
counties require additional insulation to be installed on the
exterior casing of the air handler to prevent sweating. Refer to
the state, city, county or local code for insulation requirement
to be sure the installation is in compliance. In the absence of
a local code, it is recommended that air handlers installed in
non-conditioned spaces be insulated on the exterior of the
entire cabinet including the front access panel with one (1) inch
thick berglass that has a vapor barrier on the outside.
SECTION 3: LOCATION, CLEARANCES AND RETURN AIR
REQUIREMENTS
CLEARANCES
This air handler is approved for zero (0) inches clearance to
combustible material on any part of the air handler exterior
casing. Refer to Table 5 and Figures 3 and 4 for clearance to
combustibles and for service access clearances.
Table 5: Clearances to Combustibles
Figure 3: Clearance – Access for Service
Figure 4: Closet Clearances

MORTEX PRODUCTS INC. 501 TERMINAL RD FORT WORTH, TX 76106 Page 8
RETURN AIR REQUIREMENTS
Provisions shall be made to permit the air in all rooms in the
living space to return to the air handler. Failure to comply may
cause a reduction in the amount of return air available to the
blower, causing reduced air ow resulting in improper heating
of the living space. The reduced air ow may cause the air
handler to cycle on the electric heater’s over-temperature limit
causing premature heating element failure.
The return air opening can be located in the oor, on a closet
front door, or in a side wall above the air handler cabinet. If the
opening for the return air is located in the oor, side walls, or
closet door anywhere below the appliance cabinet, a 6-inch
minimum clearance between the air handler and the wall or
door must be provided on the side where the return is located
to provide for proper air ow. The 6-inch minimum clearance
is not required if there is a return grille installed above the air
handler casing providing the grille has a sucient return air
opening.
For the air handler to work properly, a closet or alcove must
have a certain total free area opening for the return air.
For A/C and HP Air Handlers 1/3 HP Blower Motor On
(MSVE, MSVT18 & 24)
• Minimum 200 in free area opening
• Use Return Grille or Coil Cabinet
For A/C and HP Air Handlers 1/2 HP Blower Motors On
(MSVE, MSVT25, 30, & 36)
• Minimum 250 in² free area opening
• Use Return Grille, A/C Coil Cabinet, or any return grille with a
minimum 250 in² free area opening.
For A/C and HP Air Handlers with Electric Heat use 3/4 HP
Blower Motor On (MSVE, MSVT 37, 42, 48, & 60)
• Minimum 390 in² free area opening
• Use Return Grille, or A/C Coil Cabinet, or any return grille with
a minimum 390 in² free area opening.
For A/C and HP Air Handlers use 1.0 HP Blower Motor On
(MSVE, MSVT72)
• Minimum 430 in² free area opening
• Use Return Grille, or A/C Coil Cabinet, or any return grille with
a minimum 430 in² free area opening.
SECTION 4: AIR HANDLER ORIENTATION, SUPPLY AIR
DUCT, AND RETURN AIR FILTERS
The air handler is shipped from the factory congured to be
installed in an upow or horizontal right- to-left air-ow position.
Horizontal right-to-left means when facing the front of the air
handler and when it is laid on its side, the supply air opening is on
the left and the return opening is on the right. This air handler is
eld convertible to a horizontal left-to-right air-ow position.
UPFLOW APPLICATIONS
In an upow installation the discharge outlet is at the top. Care
should be taken to ensure air handler is level to permit proper
condensate drainage. Normal upow installation will be in a
closet or basement. If installed in a closet, the closet should have
a platform framed in that measures at least 12 inches in height
with an opening cut in the top of the platform for the return air
to enter the bottom of the air handler. A lter frame and lter
can be used that covers the opening and is sealed to prevent air
by-passing the lter. A lter grille can be used that is located as
described in RETURN AIR REQUIREMENTS.
The minimum lter size is shown as follows:
Standard Throw Away Air Filter @ 300 ft/min or Less
800 CFM = 20 x 20 x 1
1000 CFM = 20 x 25 x 1
1200 CFM = 20 x 30 x 1
1400 CFM = 25 x 30 x 1
1600 CFM = 25 x 30 x 1
1800 CFM = 30 x 30 x 1
2000 CFM = 30 x 40 x 1 or two 30 x 20 x 1
2400 CFM = 30 x 40 x 1 or two 30 x 20 x 1
Pleated Air Filter @ 500 ft/min or Less
800 CFM = 16 x 16 x 1
1000 CFM = 18 x 20 x 1
1400 CFM = 20 x 20 x 1
1200 CFM = 20 x 20 x 1
1600 CFM = 20 x 25 x 1
1800 CFM = 20 x 30 x 1 or two 20 x 15 x 1
2000 CFM = 20 x 30 x 1 or two 20 x 15 x 1
2400 CFM = 25 x 30 x 1 or two 14 x 30 x 1
Another option is to use a SunTherm Air Filter Base Accessory Kit
which can be used on the return air end of the air handler when
congured in the upow position (See Figure 5). The lter base
is placed over the return plenum in the oor and sealed to the
plenum using sealant or caulking material and/or tape. The air
handler is placed on top of the return lter base and the return
opening sealed to prevent leaks.
FILTER BASE ASSEMBLY KIT – FIELD INSTALLED
86ET0002 – 16”X 20” X 2”Small Cabinet 86ET0001 and
20”X 20” X 2” Medium Cabinet
86ET0003 – 20” X 24”X 2”Large Cabinet
Figure 5: Air Filter Base Accessory for 1” or 2” Air Filters.
Notes for Air Filter Base Accessory
• The lter size adjustment knobs are located on both sides of
the base.
• Make sure the ow arrow on the air lter is pointing towards
the coil.
• The Air Filter Base Accessory can also be used on the return
air end of the air handler when congured in the downow
position in place of a wall, door or ceiling mounted return
lter grille.
After the air handler has been secured to the return platform,
connect the supply air outlet to a plenum to the top of the air
handler and secure it with screws. Use a non-tape sealant such
as mastic or an aerosol sealant to seal duct leakage. If the air
handler is installed in a basement, run the supply and return
duct work in accordance with local codes. Use a non-tape
sealant such as mastic or an aerosol sealant to seal duct leakage.

AIR HANDLER
COIL ACCESS DOOR
INDOOR COIL
COIL SUPPORT RAILS
AIR HANDLER
COIL ACCESS DOOR
INDOOR COIL
COIL SUPPORT RAILS
MORTEX PRODUCTS INC. 501 TERMINAL RD FORT WORTH, TX 76106 Page 9
HORIZONTAL APPLICATION
Horizontal applications will normally be used in an attic or crawl
space. This type of installation requires supply air plenum or duct
to be connected to the supply collar and a return air plenum or
duct be attached to the air handler inlet collar. The supply ducts
will be connected to the supply air plenum and routed through
the attic to a register in each room. Use a non-tape sealant such as
mastic or an aerosol sealant to prevent leaks in the ducts and the
plenum.
NOTE: The same return air ltration requirements apply to
horizontal applications as upow applications. Refer to the upow
orientation section for return air lter requirements on this page.
The opposite end of the return air duct is attached to a return
lter grille housing. The lter grille is usually located in a wall,
just below the ceiling or the ceiling in a hallway. Use a non-tape
sealant such as mastic or an aerosol sealant to prevent leaks in the
ducts and the plenum.
The air handler is shipped to be installed without modication in
a right-to-left conguration.
To convert the air handler for left-to-right applications:
1. Remove the air handler access panels.
2. Remove the cooling coil.
3. Move the condensate drain pan to the right side.
4. Reinstall the cooling coil.
5. Connect the condensate drains and refrigerant lines.
6. Reinstall air handler access panels.
DOWNFLOW APPLICATIONS
This air handler may be converted to a downow conguration
using a required downow conversion kit by following the
instructions below (See Figures 6 and 7).
NOTE: The same return air ltration requirements apply to
downow applications as upow applications. Refer to the upow
orientation section on page 8 of this manual for return air lter
requirements.
1. Remove the blower and control box access panel.
2. Remove indoor coil access panel and discard it. The indoor coil
access panel will not be re-used.
3. Remove indoor coil assembly with drain pan by sliding out the
front of the air handler as shown in the Figure
4. Remove 6 screws (3 on each side of air handler), securing
indoor coil support rails. Refer to Figure 6.
5. Flip the air handler so the discharge is on the bottom.
6. Re-install the indoor coil support rails in the holes provided in
the air handler casing as shown in Figure 7. Use the six (6)
screws that were removed in step 4 to secure the indoor coil
support rails to the air handler casing.
7. Re-install the cooling coil in the upright position as shown in
Figure 7.
8. Remove the new indoor coil access panel from the conversion
kit and install over the indoor coil section as shown in Figure 7.
9. Re-install the blower and control box access panel in the
upside-down position and secure with the screws that were
removed in step 1.
Figure 6: Indoor Coil Disassembly
When Converting to Downow
Figure 7: Indoor Coil Assembly
When Converting to Downow Operation.
Figure 8: Combustible Floor Base Installation

OUTDOOR UNIT
LIQUID LINE
SUCTION LINE
INDOOR COIL
MORTEX PRODUCTS INC. 501 TERMINAL RD FORT WORTH, TX 76106 Page 10
DX Refrigerant Piping:
Air handlers with DX type indoor coils require liquid and suction
piping sized in accordance with outdoor unit manufacturer’s
instructions. Indoor coils have sweat copper connections.
Refrigerant lines should be soldered with silver solder or high
temperature brazing alloy. Suction line must be insulated to
avoid condensate from forming and dropping o. Armaex
pipe insulation (or equivalent) with 3/8”(1 cm) minimum wall
thickness is recommended. In severe conditions such as hot or
high humidity areas require 1/2”(1.3 cm) minimum wall thickness
may be required. If outdoor unit is installed above indoor coil,
then oil traps are required at equal intervals along suction line
(see Figure 9). Horizontal suction lines should slope downward
Prior to installing the air handler, make sure the holes are cut into
the oor for the refrigerant tubing, the drain line, the electrical
wiring, the thermostat wiring and the outdoor unit control wiring.
1. Remove the top shipping cover and corner posts.
2. Remove the bottom shipping cover.
3. Remove the blower and control box access panel.
4. Remove the coil compartment access panel.
5. Place the air handler into position using one of the
following choices:
(a) If the Combustible Floor Base is used, slide the
air handler onto the combustible oor base until the
air handler touching the anges on the back of the
oor base.
(b) If the Combustible Floor Base is not used, slide the
air handler over the duct opening until the opening
in the air handler lines up with the duct opening in
the oor.
6. Secure the air handler by one of the two choices:
(a) If the Combustible Floor Base is used, secure the air
handler to the oor by drilling two holes through the air
handler base and the oor base at the right and left front
inside corners of the cabinet. Use two screws to secure
the air handler to the oor.
(b) If the Combustible Floor Base is not used, secure the air
handler to the oor by drilling two holes through the
air handler base at the left and right front inside corners
of the cabinet. Use two screws to secure the air handler
to the oor.
7. Use calking, sealers, and/or tape to seal between the
combustible oor base and the opening on the air handler
or between the opening on the air handler and the duct in
the oor.
8. Connect the electrical supply wires and the thermostat
control wires in the control box.
9. Connect the refrigerant lines to the coil.
10. Re-install the coil compartment access panel and secure
with the screws that were removed in step 3.
11. Re-install the blower and control box access panel and secure
with the screws that were removed in step 2.
12. Turn the power on to the air handler by following the
procedure in the Users Information Manual.
13. Set the thermostat to the desired temperature.
• Install 1 oil trap for a height dierence of 15 ft to 25 ft
(4.6 m to 7.6 m) between indoor and outdoor units.
• Install 2 oil traps for a height dierence of 26 ft to 50 ft
(7.9 m to 15.2 m) between indoor and outdoor units.
• Install 3 oil traps for a height dierence of 51 ft to 100 ft
(15.5 m to 30.5 m) between indoor and outdoor units.
• Install 4 oil traps for a height dierence of 101 ft to 150 ft
(30.8 m to 45.7 m) between indoor and outdoor units.
Thermal Expansion Valves (TXV)
SunTherm air handlers can have a factory installed thermal
expansion valve (TXV) or a TXV may be eld installed. The factory
and eld installed TXV’s for this air handler have an internal check
valve making them compatible for both cooling only and heat
pump applications. The TXV has an external pressure equalizer,
non-adjustable superheat, and a 15% bleed rate. A hard start
capacitor on the outdoor unit is normally not required when
a 15% bleed TXV is used, but may be necessary if compressor
starting issues are encountered.
Field Installed TXV Kit Information
R72DB0053HX: R-410A, 1.5 – 2.5 Ton, 15% Bleed,
Inlet: Male Rotolock, Outlet: Female Swivel Nut
R72DB0054HX: R-410A, 3.0 – 5.0 Ton, 15% Bleed,
Inlet: Male Rotolock, Outlet: Female Swivel Nut
Figure 10: Indoor Coil Below Outdoor Unit Piping
SECTION 5: INSTALLING THE AIR HANDLER
SECTION 6: REFRIGERANT PIPING, TXV,
AND CONDENSATE PIPING
1 inch for every 20 feet toward outdoor unit. The manufacturer
recommends that dry nitrogen be owed through refrigerant
lines during soldering operation.

MORTEX PRODUCTS INC. 501 TERMINAL RD FORT WORTH, TX 76106 Page 11
Coil is pressurized with nitrogen from the factory. Relieve
pressure before installing TXV by depressing the Shrader
valve on the coil manifold.
FIELD INSTALLED TXV INSTALLATION
The TXV assembly is to be installed between the owrator
distributor and the existing liquid line attached to the owrator
distributor as shown in Figure 10.
1. After the coil pressure has been relieved, turn the female swivel
nut counter-clockwise to remove.
2. Remove the piston from the owrator distributor tting using
a small diameter wire or paper clip. ALWAYS REMOVE PISTON
FROM DISTRIBUTOR BODY WHEN TXV IS INSTALLED).
3. Attach the TXV by connecting the female swivel nut on TXV
outlet to the owrator distributor (aligning Teon seal rst) and
torque swivel nut to 10-30 ft. lbs.
4. Attach liquid line with female swivel nut to male rotolock tting
on TXV inlet (Aligning Teon seal rst) and torque swivel nut to
10-30 ft. lbs.
5. Remove the cap from the male Schrader valve port on the coil
manifold. Attach equalizer tube with 1/4” female are nut.
FIELD INSTALLED AND FACTORY INSTALLED TXV
INSTRUCTIONS – SENSING BULB, LEAK CHECK, EVACUATION
1. Install the TXV bulb on the suction line just outside the air
handler cabinet using the two bulb clamps furnished with kit as
shown in Figure 11.
2. The bulb should be installed on the upper portion of a
horizontal section of the suction line between 10:00 o’clock and
2:00 o’clock as shown in Figure 12.
3. If the bulb must be installed on a vertical run, the bulb should
be located at least 6 inches from any bend, and on the tubing
side opposite the plane of the bend. On vertical bulb
installations, the bulb should be positioned with the bulb
capillary tube at the top.
4. The bulb must be insulated using thermal insulation to protect
it from the eect of the surrounding ambient temperature.
5. After completing the installation of the TXV (including equalizer
tube), leak check the coil and evacuate the coil through the
liquid and suction line valves on the outdoor unit.
Figure 10: Typical TXV Connections
Figure 11: TXV Sensing Bulb Location
Figure12: TXV Bulb Placement

Air handler must be located so that if any connections
should leak, water will not cause damage to the adjacent
area. When such locations can’t be avoided, a suitable
drain pan should be installed under the air handler, not
over 1 ½”deep, with minimum length and width at least
2” greater than the air handler dimensions and connected
to an adequate drain. Under no circumstances is the
manufacturer to be held liable for any water damage in
connection with this air handler.
MORTEX PRODUCTS INC. 501 TERMINAL RD FORT WORTH, TX 76106 Page 12
CONDENSATE DRAIN PIPING:
The air handler“A”coil drain pan has two ¾”NPT female primary
and two secondary connections (left or right hand). Piping
from each tting used is to have 2” minimum trap (See Figure
13) and each run in such a manner as to provide enough slope
for adequate drainage to a visible area. Do not pipe these two
ttings together into a common drain. if a secondary drain is not
installed, the secondary drain connection must be capped.
The unit internal wiring is complete except for the power supply
and the thermostat wires. See wiring diagram and/or Tables 6 - 9
for wire size, fuse/circuit breaker size, and ground wire sizes The
use of cable connectors on incoming power supply wires to
relieve any strain on wiring is recommended. Follow the steps
below to connect the power supply wires.
Single Circuit Line Voltage Wiring Connections
1. Remove the blower and control box access panel.
2. Remove the control box cover.
3. Install the cable connectors on the 7/8” diameter holes on the
right side of the control box.
4. Strip 1/2”of the insulation on the end of each wire.
5. Insert the wires through the holes in the air handler casing and
through the cable connectors.
6. Insert the BLACK wire into the L1 screw terminal on the rst
SECTION 7: LINE VOLTAGE WIRING
Figure 13: Typical Condensate Trap
circuit breaker from the top and tighten the set screw to clamp
down on the wire.
7. Insert the WHITE or RED wire into the L2 screw terminal on the
rst circuit breaker down from the top and tighten the set screw
to clamp down on the wire.
8. If a single circuit is being used for a 5 kW, 10kW, 15kW or 20kW
model, install a BLACK jumper wire from the L1 terminal on
circuit breaker #1 to the L1 terminal on circuit breaker #2 and a
WHITE or RED jumper wire from the L2 terminal on circuit
breaker #1 to the L2 terminal on circuit breaker #2. Refer to
Figures 14, 16, and 17 for circuit breaker locations.
9. Insert the GREEN wire into the ground lug and tighten the
set screw.
NOTE: The 100 amp 4-Pole Jumper Bar Assembly part number
68BAE001 can be used in place of the jumper wires.
Dual Circuit Line Voltage Wiring Connections: 15kW or 20kW
Models
1. Insert the BLACK wire from the second power supply into the L1
screw terminal on the second circuit breaker down from the top
and tighten the set screw to clamp down on the wire.
2. Insert the WHITE or RED wire from the second power supply
into the L2 screw terminal on the second circuit breaker down
from the top and tighten the set screw to clamp down on the
wire Insert both GREEN wires into the ground lug and tighten
the set screw.
3. Tighten the screws on the cable connectors until the power
supply wires are securely fastened to the connector.
NOTE: The air handler is equipped with either one or two
circuit breakers. These circuit breakers protect the wiring inside
of the air handler in the event of a short circuit. Additionally,
these breakers provide a means of disconnecting the power
to the air handler. The circuit breakers in the air handler are
not meant to protect the branch circuit wiring between the
air handler and the home’s breaker panel. General wire and
breaker sizes are shown in Tables 6 - 9. If sheathed cable is used,
refer to NEC National Electrical Code (NFPA 70) or the Canadian
Electrical Code, Part I (CSA C22.1) and local codes for additional
requirements concerning supply circuit wiring. Electrical data
can be found in Tables 6-9.
IMPORTANT - All installation on eld wiring must be rated at
60ºC or higher. Please refer to the wiring diagrams on the air
handler or the tables this manual for more information. The
15kW and 20kW models may be connected to a single or dual
branch circuit.
IMPORTANT - Refer to the NEC National Electrical Code (NFPA
70) or the Canadian Electrical Code, Part I (CSA C22.1) and local
codes for wiring material requirement.
The eld installed electric heat accessories are used on cooling
or heat pump models that were not purchased with electric
heat from the factory. Each air handler model is approved for
use with the eld installed accessory electric heat kit.

AIR HANDLER MODELS
MSVE 18, 24 MSVT 18, 24 MSVE 25, 30, 36 MSVT 25, 30, 36
5 kw Heater Amps - 208/240 VAC 18.0/20.8 18.0/20.8 18.0/20.8 18.0/20.8
10 kW Heater Amps - 208/240 VAC 36.1/41.7 36.1/41.7 36.1/41.7 36.1/41.7
15 kW Heater Amps - 208/240 VAC N/A N/A 54.1/62.5 54.1/62.5
Indoor Blower Motor Type ECM CONSTANT TORQUE ECM CONSTANT TORQUE
Indoor Blower Amps – 208/240 VAC 0.90/0.78 0.83/0.72 2.33/2.03 1.91/1.66
Heater - kW 0 5 10 0 5 10 0 5 10 15 0 5 10 15
Minimum Circuit Ampacity 1.1 27.0 53.1 1.0 26.9 53.0 2.9 28.6 54.6 80.7 2.4 28.1 54.2 80.2
Min. Wire Size (90°C) #14 #12 #8 #14 #12 #8 #14 #12 #8 #4 #14 #12 #8 #4
Minimum Wire Size (75°C) #14 #10 #6 #14 #10 #6 #14 #10 #6 #4 #14 #10 #6 #4
Minimum Wire Size (60°C) #14 #10 #6 #14 #10 #6 #14 #10 #6 #3 #14 #10 #6 #3
Ground Wire Size * * * * * * * * * * * * * *
Maximum Overcurrent
Protection Amps 15 30 60 15 30 60 15 30 60 90 15 30 60 90
AIR HANDLER MODELS
MSVE 37, 42, 48, 60 MSVT 37, 42, 48, 60 MSVE 72 MSVT 72
5 kw Heater Amps - 208/240 VAC 18.0/20.8 18.0/20.8 18.0/20.8 18.0/20.8
10 kW Heater Amps - 208/240 VAC 36.1/41.7 36.1/41.7 36.1/41.7 36.1/41.7
15 kW Heater Amps - 208/240 VAC 54.1/62.5 54.1/62.5 54.1/62.5 54.1/62.5
20 kW Heater Amps - 208/240 VAC 72.2/83.4 72.2/83.4 72.2/83.4 72.2/83.4
Indoor Blower Motor Type ECM CONSTANT TORQUE ECM CONSTANT TORQUE
Indoor Blower Amps – 208/240 VAC 2.88/2.50 2.40/2.09 4.31/3.75 6.58/5.72
Heater - kW 0 5 10 15 20 0 5 10 15 20 0 5 10 15 20 0 5 10 15 20
Minimum Circuit Ampacity 3.6 29.2 55.2 81.2 107.4 3.0 28.7 54.7 80.7 106.8 5.4 30.7 56.8 82.8 108.9 8.2 33.2 59.2 85.3 111.4
Min. Wire Size (90°C) #14 #12 #6 #4 #3 #14 #12 #8 #4 #3 #14 #10 #6 #4 #3 #14 #10 #6 #4 #2
Minimum Wire Size (75°C) #14 #10 #6 #4 #2 #14 #10 #6 #4 #2 #14 #10 #6 #4 #2 #14 #10 #6 #3 #2
Minimum Wire Size (60°C) #14 #10 #4 #3 #1 #14 #10 #6 #3 #1 #14 #8 #4 #3 #1 #14 #8 #4 #2 #1
Ground Wire Size * * * * * * * * * * * * * * * * * * * *
Maximum Overcurrent
Protection Amps 15 30 60 90 110 15 30 60 90 110 15 35 60 90 110 15 35 60 90 125
MORTEX PRODUCTS INC. 501 TERMINAL RD FORT WORTH, TX 76106 Page 13
Table 7: Electrical Data: 37-72 kBTU Models - Single Branch Circuit
15kW and 20kW models may have a dual or single power supply. Single power supply requires a jumper bar or a jumper wire.
+ Refer to the National Electrical Code Table 250-95 for Non-Sheathed Conductor Ground Wire.
* Ground conductor must be the same size and temperature rating as the other conductors listed in Table 7.
Table 6: Electrical Data: 18-36 kBTU Models - Single Branch Circuit
15kW and 20 kW models may have a dual or single power supply. Single power supply requires a jumper bar or a jumper wire.
+ Refer to the National Electrical Code Table 250-95 for Non-Sheathed Conductor Ground Wire.
* Ground conductor must be the same size and temperature rating as the other conductors listed in Table 6.

AIR HANDLER MODELS
MSVE 37, 42, 48, 60 MSVT 37, 42, 48, 60 MSVE 72 MSVT 72
Circuit Number 1 2 1 2 1 2 1 2
15 kW Heater Amps - 208/240 VAC 18.0/20.8 38.1/41.7 18.0/20.8 38.1/41.7 18.0/20.8 38.1/41.7 18.0/20.8 38.1/41.7
20 kW Heater Amps - 208/240 VAC 36.1/41.7 36.1/41.7 36.1/41.7 36.1/41.7 36.1/41.7 36.1/41.7 36.1/41.7 36.1/41.7
Indoor Blower Motor Type ECM CONSTANT TORQUE ECM CONSTANT TORQUE
Indoor Blower Amps 2.88/2.50 2.40/2.09 4.31/3.75 6.58/5.72
Heater - kW 15 20 15 20 15 20 15 20
Circuit Number 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2
Minimum Circuit Ampacity 29.1 52.1 55.3 52.1 28.6 52.1 54.7 52.1 30.7 52.1 56.8 52.1 33.2 52.1 59.3 52.1
Minimum Wire Size (90°C) #12 #8 #6 #8 #12 #8 #8 #8 #10 #8 #6 #8 #10 #8 #6 #8
Minimum Wire Size (75°C) #10 #6 #6 #6 #10 #6 #6 #6 #10 #6 #6 #6 #10 #6 #6 #6
Minimum Wire Size (60°C) #10 #6 #4 #6 #10 #6 #6 #6 #8 #6 #4 #6 #8 #6 #4 #6
Ground Wire Size * * * * * * * * * * * * * * * *
Maximum Overcurrent Protection Amps 30 60 60 60 30 60 60 60 35 60 60 60 35 60 60 60
ELECTRIC HEATER HEATING CAPACITIES
5 kW 10 kW 15kW 20kW
BRANCH
CIRCUIT 1 1 1 2 1 2
240 VAC BTU/HR 17,033 34,067 34,067 17,033 34,067 34,067
kW 4.99 10.00 10.00 4.99 10.00 10.00
230 VAC BTU/HR 15,876 33,686 33,686 15,876 33,686 33,686
kW 4.65 9.78 9.78 4.65 9.78 9.78
220 VAC BTU/HR 14,736 30,222 30,222 14,736 30,222 30,222
kW 4.32 8.86 8.86 4.32 8.86 8.86
TOTAL HEATING CAPACITY @ 240 VAC BTU/HR 17,033 34,067 51,149 68,134
kW 4.99 10.00 14.99 20.00
AIR HANDLER MODELS
MSVE 25, 30, 36 MSVT 25, 30, 36
Circuit Number 1 2 1 2
15 kW Heater Amps - 208/240 VAC 18.0/20.8 38.1/41.7 18.0/20.8 38.1/41.7
Indoor Blower Motor Type ECM CONSTANT TORQUE
Indoor Blower Amps 2.33/2.03 1.91/1.66
Heater - kW 15 15
Circuit Number 1212
Minimum Circuit Ampacity 28.6 52.1 28.1 52.1
Minimum Wire Size (90°C) #12 #8 #12 #8
Minimum Wire Size (75°C) #10 #6 #10 #6
Minimum Wire Size (60°C) #10 #6 #10 #6
Ground Wire Size * * * *
Maximum Overcurrent Protection Amps 30 60 30 60
MORTEX PRODUCTS INC. 501 TERMINAL RD FORT WORTH, TX 76106 Page 14
Table 9: Electrical Data: 37-72 kBTU Models – Dual Branch Circuit
+ Refer to the National Electrical Code Table 250-95 for Non-Sheathed Conductor Ground Wire.
* Ground conductor must be the same size and temperature rating as the other conductors listed in Table 9.
Table 10: Electric Heater Heating Capacities
Table 8: Electrical Data: 25-36 kBTU Models – Dual Branch Circuit
+ Refer to the National Electrical Code Table 250-95 for Non-Sheathed Conductor Ground Wire.
* Ground conductor must be the same size and temperature rating as the other conductors listed in Table 8.

For personal safety be sure to turn the electrical power
“OFF” at the main electrical panel and at the air handler
control box circuit breakers before attempting any service
or maintenance operations.
Homeowners should never attempt to perform any
maintenance which requires opening the air handler
control box cover. Refer to Figures 18 and 19.
This air handler is not equipped with a shield that
covers the line voltage electrical supply wires and the
circuit breaker connections. Take precautions to prevent
accidental electrical shock. Be sure to turn the electrical
power“OFF” at the main electrical panel and at the air
handler control box circuit breakers before removing
the front panel. Refer to Figure 16 for the circuit breaker
location on the front panel.
MORTEX PRODUCTS INC. 501 TERMINAL RD FORT WORTH, TX 76106 Page 15
Figure 14: Component Locations – Electric Heat Control Box
NOTE: Casing or cabinet must be permanently grounded in accordance with the National Electrical Code or other applicable codes.
Figure 15: Component Locations – No Heat Control Box Figure 16: Circuit Breaker Location on Front Panel
Figure 17: Control Box Circuit Breaker Location.

MORTEX PRODUCTS INC. 501 TERMINAL RD FORT WORTH, TX 76106 Page 16
SECTION 8: FIELD INSTALLED ELECTRIC HEATER KITS
Models Equipped With Circuit Breakers
Model No Cabinet
Size
Voltage Phase Hertz Heater
kW
Motor
BSXHK05B Small 208/240 1 60 5 C.T.
BSXHK10B Small 208/240 1 60 10 C.T.
BMXHK05B Medium 208/240 1 60 5 C.T.
BMXHK10B Medium 208/240 1 60 10 C.T.
BMXHK15B Medium 208/240 1 60 15 C.T.
BLXHK05B Large 208/240 1 60 5 C.T.
BLXHK10B Large 208/240 1 60 10 C.T.
BLXHK15B Large 208/240 1 60 15 C.T.
BLXHK20B Large 208/240 1 60 20 C.T.
BSEHK05B Small 208/240 1 60 5 ECM
BSEHK10B Small 208/240 1 60 10 ECM
BMEHK05B Medium 208/240 1 60 5 ECM
BMEHK10B Medium 208/240 1 60 10 ECM
BMEHK15B Medium 208/240 1 60 15 ECM
BLEHK05B Large 208/240 1 60 5 ECM
BLEHK10B Large 208/240 1 60 10 ECM
BLEHK15B Large 208/240 1 60 15 ECM
BLEHK20B Large 208/240 1 60 20 ECM
Table 11: Electric Heater Kit Model Numbers
The eld installed electric heat accessories are used on cooling
or heat pump models that were not purchased with electric heat
from the factory. Each air handler model is approved for use with
the eld installed accessory electric heat kit.
INSTALLING THE HEATERS
1. Follow the instructions in the USERS INFORMATION MANUAL
to properly shut down the air handler.
2. Remove the block o plate shown in Figure 15 and discard.
Retain the screws, they will be used to secure the electric heater
mount plate.
3. Insert electric heat kit into the opening where the block o
plate was removed. Secure the mounting plate with the screws
that were removed from the block o plate.
4. Connect the six-pin male plug on the electric heater assembly
to the six-pin female plug mounted on the side of the low
voltage control box divider panel.
5. Remove the wiring diagram from the kit, remove the paper
that covers the adhesive back and place the electric heat wiring
diagram over the wiring diagram located on the blower housing.
6. Follow the instructions in the USERS INFORMATION MANUAL to
properly start up the air handler.
NOTE: All models have factory installed circuit breakers and
electric heater kits have eld installed circuit breakers. The models
are MS, MM, US, UM are congured as follows:
Small cabinet MS**18, 24
Medium cabinet MS**25, 30, 36
Large cabinet MS**37, 42, 48, 60, 72
POWER SUPPLY CONNECTIONS
If the air handler has been installed prior to installing the electric
heaters or if an older air handler is being replaced, the supply
power wires must be checked to make sure the wires are the
proper sizes to handle the current load for the heaters. Refer to
Tables 6 - 9 for correct wire size. If the supply power wire
size is incorrect, new wires will need to be installed.
FOR CIRCUIT BREAKER MODELS ONLY: After the supply
wiring has been connected to the circuit breakers, remove the
transformer and indoor blower motor wires from the terminal
block (See Figure 15) and connect them to load side of circuit
breaker #1.
LOW VOLTAGE CONNECTIONS
If the air handler was previously installed, nothing will need to
change on the low voltage wiring. If this is a new installation refer
to SECTION 9 of these instructions.

To prevent damage, carefully insert the electric heating
assembly through the rectangular opening in the front
of the discharge opening so the heat element support
rod is seated into the hole on the back side of the
discharge opening.
After installing the electric heater, a one-inch clearance
must be maintained on all sides of the supply air duct and/
or plenum for a minimum of 36 inches from the air handler
discharge opening
LOW VOLTAGE
WIRE ENTRANCE
SUPPLY
WIRE ENTRANCE
MORTEX PRODUCTS INC. 501 TERMINAL RD FORT WORTH, TX 76106 Page 17
Table 12: Accessory Electric Heater Kit Model Number Nomenclature
SECTION 9: THERMOSTAT WIRING AND CONNECTIONS
Table 13: Low Voltage Wire Gauge and Max Lengths
Thermostat Wiring
Thermostat wires connect through side of air handler and should
be no smaller than 22 gauge. Refer to Table 13 for recommended
wire gauge, lengths and maximum current for each wire gauge.
Thermostat wires can enter through the side or top of the air
handler casing. When bringing wiring through the top or side of
the air handler casing, cable connectors must be installed to hold
wiring in place and to relieve any strain on the wiring.
Max. Thermostat
Wire Length
Thermostat Wire
Gauge
Thermostat Wire
Maximum Current
0 - 100 Feet 22 3.0 Amps
0 - 125 Feet 20 3.0 amps
0 - 250 Feet 18 3.0 amps
The use of an 8 conductor cable from the thermostat to the air
handler is recommended. The thermostat wire colors and the
typical heating / cooling connections are listed in Table 14. The
thermostat wire colors and the typical heat pump connections are
listed in Table 15.
Figure 18: Cabinet Wiring Entrances
Thermostat Installation
The thermostat should be located on an inside wall in an open
area to more closely regulate average room air, preferably where
there is air movement back to air handler. Locating height of ther-
mostat is important. If possible, the thermostat should be located
in a hallway upstream from the air handler return airow, not
within 3 feet of from any windows and 52 to 66 inches above the
oor. DO NOT place the thermostat within three feet of any of the
air-distribution supply air registers.
Maintenance, operating and/ or programming instructions are in
the envelope accompanying the thermostat. Give the envelope
to the homeowner.

CC C
YY
W/E
W/E
G
RH
RC R
O
O/B
EM
W2
W2
O/B
W2
Y2
Y1
W/1
G
R
AIR HANDLER
TRANSFORMER
24 VAC
24 VAC
COMMON
HEAT PUMP UNIT
OUTDOOR SECTION
FOLLOW MANUFACTURER'S
INSTRUCTIONS
AIR HANDLER
THERMOSTAT
JUMPER
MSVE
ONLY
MSVE
ONLY
CC C
Y
W/2
Y
W/E
G
RH
RC
O
EM
W2
Y2
Y1
W/1
G
R
AIR HANDLER
TRANSFORMER
24 VAC
24 VAC
COMMON
COOLING UNIT
OUTDOOR SECTION
AIR HANDLER
MSVE
ONLY
MSVE
ONLY
THERMOSTAT
JUMPER
MORTEX PRODUCTS INC. 501 TERMINAL RD FORT WORTH, TX 76106 Page 18
Do not locate thermostat within 3 feet of any of the
following items:
1. Air distribution supply air registers
2. Lights or heat lamps
3. Aquariums
4. Televisions, stereo, ampliers, surround sound systems
5. Stoves or any cooking appliance
6. Refrigerator
7. Washer and/or dryer
8. Water heater tank
9. Sink or near any hot water
10. Within 15 feet of any electric space heater
11. Within two feet of any sunlight
Air Handler and Outdoor Unit With Separate Transformers
If the air-hander and the outdoor unit have separate transformers,
it is important to use a thermostat with isolated heating and
cooling contacts“RC”and “RH” to prevent interconnection of
Class II 24 Volt Systems. Most modern thermostats have separate
heating and cooling contacts for use with homes that have an air
handler and outdoor unit that are completely separate and each
have a 24 VAC transformer for system control. These thermostats
have a“RC” terminal for cooling and a“RH”terminal for heating.
Connect the outdoor unit RED wire from the“R”terminal on the
outdoor unit to the“RC” terminal on the thermostat and the RED
air handler pigtail wire to the“RH”terminal on the thermostat.
If the air handler and outdoor unit using separate transformers
are both connected to the thermostat“R” terminal, a transformer
burnout can occur or either the air handler or outdoor unit
control system could go into lockout mode. If an air handler and
outdoor unit with separate transformers are being installed and
the thermostat does not have the“RC” and“RH”terminals, a new
thermostat with“RC”and “RH” terminals must be purchased and
installed.
IMPORTANT: Cycle the air handler and outdoor unit separately to
make sure both operate correctly.
Thermostat Heat Anticipator
Some thermostats have a heat anticipator setting that must be
set to the settings shown below in order to function correctly.
If the heat anticipator setting is too low, the system will short
cycle. If the heat anticipator setting is too high, the system will
run long heat cycles thus causing the temperature to overrun the
temperature setting. This will cause the homeowner or user to
feel too warm by the time the blower completes its cycle and too
cold by the time the system cycles on again. The heat anticipator
should be set to 0.4 for all heating kW’s.
The thermostat may be a“self-setting”type in which no heat
anticipator will be found on the thermostat, eliminating the need
for eld adjustment.
Figure 20: Typical Low Voltage Connections -
Single-Stage Heat and Single-Stage Heat Pump
Figure 19: Typical Low Voltage Connections -
Single-Stage Heat and Single-Stage Cooling

CC C
YY
W/E
G
RH
RC
O
EM
W2
Y2
Y1
W/1
G
R
AIR HANDLER
TRANSFORMER
24 VAC
24 VAC
COMMON
COOLING UNIT
OUTDOOR SECTION
AIR HANDLER
THERMOSTAT
JUMPER
MSVE
ONLY
MSVE
ONLY
CC C
YY
W/E
G
RH
RC
O
O/B
EM
W2
Y2
O/B
Y1
W/1
G
R
R
AIR HANDLER
TRANSFORMER
24 VAC
24 VAC
COMMON
HEAT PUMP UNIT
OUTDOOR SECTION
AIR HANDLER
THERMOSTAT
JUMPER
W/E
W2
FOLLOW MANUFACTURER'S
INSTRUCTIONS
MSVE
ONLY
MSVE
ONLY
THERMOSTAT
WIRE COLOR
DESCRIPTION LETTER CODE AIR HANDLER PIG TAIL
WIRE CONNECTION
THERMOSTAT AND
AIR HANDLER
TERMINAL BLOCK
CONNECTION
OUTDOOR UNIT
CONNECTIONS
RED 24 VAC R RED R N/A
WHITE 1st Stage Heat W1 WHITE W or W1 N/A
BLACK 2nd Stage Heat W2 BROWN W2 N/A
GREEN Indoor Fan G GREEN G N/A
YELLOW Cooling /1st Stage Cooling Y/Y1 YELLOW Y/Y1 Y/Y1
BLUE Optional 2nd Stage Cooling Y2 BLUE Y2 Y2
BROWN 24 VAC Common C GREY (ECM)
BLUE (Constant Torque) C C
THERMOSTAT
WIRE COLOR
DESCRIPTION LETTER CODE AIR HANDLER PIGTAIL
WIRE CONNECTION
THERMOSTAT AND
AIR HANDLER
TERMINAL BLOCK
CONNECTION
OUTDOOR UNIT
CONNECTIONS
RED 24 VAC R RED R R
WHITE 1st Stage Electric Heat W1 WHITE E (Thermostat)
W1 (Air Handler)
See Outdoor Unit
Instructions
BLACK 2nd Stage Electric Heat W2 BROWN W2 N/A
GREEN Indoor Fan G GREEN G N/A
YELLOW Cooling /1st Stage Cooling Y/Y1 YELLOW Y/Y1 Y/Y1
BLUE Optional 2nd Stage Cooling Y2 BLUE Y2 Y2
ORANGE Heat Pump Reversing Valve
(Most Brands) O N/A O See Outdoor Unit Instructions
ORANGE Heat Pump Reversing Valve
(Some Brands) B N/A B See Outdoor Unit Instructions
BROWN 24 VAC Common CGREY (ECM Mtr)
BLUE (Constant Torque) C C
MORTEX PRODUCTS INC. 501 TERMINAL RD FORT WORTH, TX 76106 Page 19
Figure 21: Typical Low Voltage Connections -
Two-Stage Heat / Single-Stage Cooling
Figure 22: Typical Low Voltage Connections -
Two-Stage Heat / Single-Stage Heat Pump
Table 14: Typical Heat / Cool Thermostat Wire Color Colors and Low Voltage Connections
Note: If a single-stage heat thermostat is used with an air handler with two-stage heat, install a jumper between W1 and W2
on the low voltage terminal block or connect the W1 and W2 pigtail wires together with the WHITE thermostat wire.
Table 15: Typical Heat Pump Thermostat Wire Color Colors and Low Voltage Connections

MORTEX PRODUCTS INC. 501 TERMINAL RD FORT WORTH, TX 76106 Page 20
Typical Heating/Cooling Thermostat Wiring Connections
1. Remove blower / control box access panel.
2. Remove the control box cover.
3. Insert the wire cables from the thermostat and outdoor unit
through the 9/16”diameter hole located in the top or side of
the air handler and into the control box. Place the thermostat
wire cable next to the air handler low voltage terminal block
(LVTB) or low voltage pigtails. Secure the thermostat and
outdoor unit wire cables in the 9/16”diameter hole with a strain
relief to prevent wire connections from being pulled apart.
4. Strip 1/2”of the insulation on the end of each wire.
5. Connect the RED (24 VAC) supply thermostat wire to the“R”
terminal on the LVTB or to the RED air handler pigtail wire and
secure with a wire nut.
6. Connect the WHITE (rst stage heating) thermostat wire to
the“W1”terminal on the LVTB or to the WHITE air handler
pigtail wire and secure with a wire nut.
7. Connect the GREEN wire from the thermostat“G”terminal
thermostat wire to the“G”terminal on the LVTB or to the
GREEN air handler pigtail wire and secure with a wire nut.
8. Connect the YELLOW wire from the thermostat “Y” terminal to
the wire from the outdoor unit compressor contactor
coil with a wire nut.
9. For MSVE models (ECM motor), also connect the YELLOW
wire from the thermostat to both the YELLOW “Y1” and BLUE
“Y2”air handler pigtails with a wire nut for single-stage cooling
applications to assure full nominal airow. For 2-stage cooling
applications, connect the wires from the thermostat“Y1”
terminal to the YELLOW “Y1”air handler pigtail and connect
the wire from the thermostat“Y2” terminal to the BLUE“Y2” air
handler pigtail.
10. Connect the BROWN 24 VAC common wire from the
thermostat“C” terminal to the“C”terminal on the LVTB or to
the air handler 24 VAC common pigtail wire (GRAY
for ECM motor, BLUE for constant torque motor) with a wire
nut. Also connect the 24 VAC common wire from the
outdoor unit compressor contactor coil to the“C”terminal on
the LVTB or to the thermostat and outdoor unit 24 VAC
common wires with a wire nut.
11. For 15kW and 20kW models, connect the BLUE wire from the
thermostat “W2” terminal (2nd stage heat) to the“W2” terminal
on the LVTB or to the BROWN air handler pigtail wire and secure
with a wire nut.
NOTE: If single-stage heat thermostat is used with a 15kW
or 20kW air handler, place a jumper between the“W1”and
“W2” terminals on the LVTB or connect the BROWN and the
WHITE air handler pigtail wires to the WHITE wire from the
thermostat“W”terminal with a wire nut.
Typical Heat Pump - Heating/Cooling Thermostat Wiring
Connections
1. Remove the blower / control box access panel.
2. Remove the control box cover.
3. Insert the wire cables from the thermostat and outdoor unit
through the 9/16”diameter hole located on the top or side
of the air handler and into the control box. Place the
thermostat and outdoor unit wire cables next to the air
handler low voltage terminal block (LVTB) or low voltage
pigtails. Secure the thermostat and outdoor unit wire cable
with a strain relief in the 9/16”diameter hole to prevent wire
connections from being pulled apart.
4. Strip 1/2”of the insulation on the end of each wire.
5. Connect the RED (24 VAC) wire from the thermostat “R”
terminal to the“R” terminal on the LVTB or to the RED air
handler pigtail wire and with the wire from the“R” terminal or
pigtail on the outdoor unit. Fasten the three wires together
securely with a wire nut.
6. Connect the WHITE (emergency heat) wire from the
thermostat“E” terminal to the “W1” terminal on the air handler
LVTB or to the WHITE air handler pigtail wire with a wire nut. If
applicable, also connect the wire from the outdoor control
board that calls for supplemental heat during the defrost cycle
to the“W1”terminal on the air handler LVTB or to the WHITE
air handler pigtail wire. Refer to the outdoor unit installation
instructions for additional information.
7. Connect the GREEN wire from the thermostat“G”terminal to
the“G”terminal on the LVTB or to the GREEN air handler
pigtail wire and securely fasten the two wires together with a
wire nut.
8. Connect the YELLOW wire from the thermostat “Y” terminal to
the wire from the outdoor unit“Y” terminal or pigtail with
a wire nut.
9. For MSVE models (ECM motor), also connect the YELLOW
wire from the thermostat to both the YELLOW “Y1” and BLUE
“Y2”air handler pigtails with a wire nut for single-stage cooling
applications to assure full nominal airow. For 2-stage cooling
applications, connect the wires from the thermostat“Y1”
terminal to the YELLOW “Y1”air handler pigtail and connect
the wire from the thermostat“Y2” terminal to the BLUE“Y2” air
handler pigtail.
10. Connect the BROWN 24 VAC common wire from the
thermostat“C” terminal to the“C”terminal on the LVTB or to
the air handler 24 VAC common air handler pigtail wire (GRAY
for ECM motor, BLUE for constant torque motor) with a wire
nut. Also connect the 24 VAC common wire from the outdoor
unit“C” terminal or pigtail to the“C”terminal on the LVTB or to
the thermostat and outdoor unit 24 VAC common wires with
a wire nut.
11. Connect the ORANGE wire from the thermostat“O”or“B”
terminal with the wire from the outdoor unit“O”or “B”
terminal or pigtail with a wire nut. Refer to the outdoor unit
installation instructions for additional information.
12. For 15kW and 20kW models, connect the BLACK wire from the
thermostat “W2” terminal (2nd stage heat) to the“W2” terminal
on the LVTB or to the BROWN air handler pigtail wire and secure
with a wire nut.
NOTE: If single-stage heat thermostat is used with a 15kW
or 20kW air handler, place a jumper between the“W1”and
“W2” terminals on the LVTB or connect the BROWN and the
WHITE air handler pigtail wires to the WHITE wire from the
thermostat“W”terminal with a wire nut.