2TWA2-IN-1A
18-BC51D3-2
Installer’s Guide
Heat Pumps
2TWA0, 2TWA2
ALL phases of this installation must comply with NATIONAL, STATE AND LOCAL CODES
IMPORTANT — This Document is customer property and is to remain with this unit. Please return to service information
pack upon completion of work.
These instructions do not cover all variations in
systems nor provide for every possible contingency to
be met in connection with installation. All phases of
this installation must comply with NATIONAL, STATE
AND LOCAL CODES. Should further information be
desired or should particular problems arise which are not
covered sufficiently for the purchaser’s purposes, the matter
should be referred to your installing dealer or local distributor.
5 FT. ABOVE UNIT-UNRESTRICTED
1
A. GENERAL
The following instructions cover 2TWA Heat Pump Units.
NOTICE:
These outdoor units may be used with indoor units
equipped with Thermostatic Expansion Valve or Accutron™
Flow Control Check Valve (F.C.C.V.) assembly for refrigerant
flow control only.
Check for transportation damage after unit is uncrated.
Report promptly, to the carrier, any damage found to the unit.
To determine the electrical power requirements of the unit,
refer to the nameplate of the unit. The electrical power
available must agree with that listed on the nameplate.
3. Avoid locating the unit where condensation and freezing
of defrost vapor may annoy the customer. For instance,
installing the unit under a bedroom, kitchen, or picture
window may be annoying to the customer since conden-
sate and fog will occur during the defrost cycle.
The Weathertron® Heat Pump has been designed and
manufactured to withstand and operate in severe winter
conditions. However, there are precautionary steps which
should be taken at the time of installation which will help
assure the efficient operation of the unit. It is recom-
mended that these precautions be taken for units
being installed in areas where snow accumulation and
prolonged below freezing temperatures occur.
4. Avoid locating the unit under the eaves or other over-
head structures as sizeable icicles may form and the unit
may be damaged by these falling icicles.
B. LOCATION AND PREPARATION
1. Units should be elevated 3 to 12 inches above the pad or
rooftop, depending on local weather. This additional
height will allow better drainage of snow and ice (melted
during defrost cycle) prior to its refreezing. This should
prevent a build-up of ice around the unit which occurs
when unit is not elevated. Insure that drain holes in
unit base pan are not obstructed preventing
draining of defrost water.
OFTHE UNIT
1. When removing unit from the pallet, notice the tabs on
the basepan. Remove tabs by cutting with a sharp tool as
shown on page 2, Figure 2, and slide unit off of pallet.
2. The unit should be set on a level support pad at least as
large as the unit base pan, such as a concrete slab. If this
is not the application used please refer to application
bulletin “Trane APB2001-02”.
2. If possible, avoid locations that are likely to accumulate
snow drifts. If not possible, a snow drift barrier should be
installed around the unit to prevent a build-up of snow
on the sides of the unit and should be of sufficient
distance from the unit to prevent restriction of airflow to
and from the unit. Also allow for proper maintenance
space. The barrier should be constructed of materials
which will blend in with the building design.
3. The support pad must NOT be in direct contact with any
structure. Unit must be positioned a minimum of 12"
from any wall or surrounding shrubbery to insure
adequate airflow. Clearance must be provided in front of
control box (access panels) and any other side requiring
service access to meet National Electrical Code. Also, the
unit location must be far enough away from any struc-
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GAS LINE SERVICE VALVE
GAS LINE BALL SERVICE VALVE
5
6
CAP
1/4 TURN ONLY
COUNTERCLOCKWISE
FOR FULL OPEN
POSITION
VALVE STEM
UNIT SIDE
OF VALVE
PRESSURE TAP PORT
GAS LINE CONNECTION
CAP
6. Precautions should be taken to avoid heat damage
to the pressure tap valve core during brazing. It is
recommended that the pressure tap port valve
core be removed and a wet rag wrapped around
the valve body.
BODY
COOLING
HEATING
NOTICE:
Use care to make sure that no moisture enters pressure tap
port, while wet rag is being used.
CORE
NOTICE:
b. Isolation hangers should also be used when refriger-
ant lines are run in stud spaces or enclosed ceilings.
Precautions should be taken to avoid heat damage to
basepan during brazing. It is recommended to keep the
flame directly off of the basepan.
c. Where the refrigerant lines run through a wall or sill,
they should be insulated and isolated.
7. Use a Dry Nitrogen Purge and Brazing Alloy without
flux when brazing the field line to the copper factory
connection. Flow dry nitrogen into either valve pressure
tap port, thru the tubing and out the other port while
brazing.
d. Isolate the lines from all ductwork.
E. SERVICE VALVE OPERATION
BRASS LIQUID AND GAS LINE SERVICE VALVES
The Brass Liquid and Gas Line Service Valves are factory
shipped in the seated position to hold factory charge. The
pressure tap service port (when depressed) opens only to the
field brazing side of the valve when the valve is in the seated
position. The liquid line valve is not a back seating valve (see
WARNING below).
8. Braze using accepted good brazing techniques.
LEAK CHECK
IMPORTANT:
Replace pressure tap port valve core before attaching hoses for
evacuation.
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WARNING
After the brazing operation of refrigerant lines to both the
outdoor and indoor unit is completed, the field brazed
connections must be checked for leaks. Pressurize through
the service valve ports, the indoor unit and field refrigerant
lines with dry nitrogen to 350-400 psi. Use soap bubbles or
other leak-checking methods to see that all field joints are
leak-free! If not, release pressure; then repair!
Extreme caution should be exercised when opening the
Liquid and Gas Line Service Valves.Turn valve stem
counterclockwise only until the stem contacts the rolled
edge. (See Figures 4 and 6) No torque is required.
BRASS GAS LINE BALL SERVICE VALVE
The Brass Gas Line Service Valve is shipped in the closed
position to hold the factory refrigerant charge. The pressure
tap service port (when depressed) opens only to the field
brazing side when the valve is in the closed position.
SYSTEM EVACUATION
NOTE:
Since the outdoor unit has a refrigerant charge, the gas and
liquid line valves must remain closed.
The Gas Line Service Valve is full open with a 1/4 turn. See
Figure 5.
1. Upon completion of leak check, evacuate the refrigerant
lines and indoor coil before opening the gas and liquid
line valves.
BRAZING REFRIGERANT LINES
1. Remove lower access cover to access service valves.
2. Before brazing, remove plugs from external copper stub
tubes. Clean internal and external surfaces of stub tubes
prior to brazing.
2. Attach appropriate hoses from manifold gauge to gas
and liquid line pressure taps.
NOTE:
3. Cut and fit tubing, minimizing the use of sharp 90° bends.
4. Insulate the entire gas line and its fittings.
Unnecessary switching of hoses can be avoided and com-
plete evacuation of all lines leading to sealed system can
be accomplished with manifold center hose and connecting
branch hose to a cylinder of HCFC-22 and vacuum pump.
5. Do NOT allow uninsulated liquid line to come in direct
contact with bare gas line.
18-BC51D3-2
3
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3. Attach center hose of manifold gauges to vacuum pump.
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WARNING
4. Evacuate until the micron gauge reads no higher than
350 microns.
When installing or servicing this equipment, ALWAYS
exercise basic safety precautions to avoid the possibility
of electric shock.
5. Close off valve to vacuum pump and observe the micron
gauge. If gauge pressure rises above 500 microns in one
(1) minute, then evacuation is incomplete or system has
a leak.
1. Power wiring and grounding of equipment must comply
with local codes.
6. If vacuum gauge does not rise above 500 microns in one
(1) minute, the evacuation should be complete.
2. Power supply must agree with equipment nameplate.
3. Install a separate disconnect switch at the outdoor unit.
4. Ground the outdoor unit per local code requirements.
7. With vacuum pump and micron gauge blanked off, open
valve on HCFC-22 cylinder and charge refrigerant lines
and indoor coil with vapor to tank pressure of HCFC-22
supply.
5. Provide flexible electrical conduit whenever vibration
transmission may create a noise problem within the
structure.
NOTE:
6. The use of color coded low voltage wire is recommended
to simplify connections between the outdoor unit, the
thermostat and the indoor unit.
DO NOT VENT REFRIGERANT INTO THE ATMOSPHERE.
8. Close valve on HCFC-22 supply cylinder. Close valves on
manifold gauge set and remove refrigerant charging
hoses from liquid and gas pressure tap ports.
Table 1 --- NEC Class II Control Wiring
24 VOLTS
NOTE:
A 3/16" Allen wrench is required to open liquid line service
valve. A 1/4" Open End or Adjustable wrench is required to
open gas line valve. A 3/4" Open End wrench is required to
take off the valve stem cap.
WIRE SIZE
18 AWG
16 AWG
14 AWG
MAX. WIRE LENGTH
150 FT
225 FT.
9. The liquid line shut-off valve can now be opened.
Remove shut-off valve cap. Fully insert hex wrench into
the stem and backout counterclockwise until valve stem
just touches rolled edge (approximately five [5] turns)
observing WARNING statement on page 3. See Figure 4.
300 FT.
7. Table 1 defines maximum total length of low voltage
wiring from outdoor unit, to indoor unit, and to
thermostat.
10. Replace liquid service pressure tap port cap and valve
stem cap. These caps MUST BE REPLACED to
prevent leaks. Replace valve stem and pressure tap cap
finger tight, then tighten an additional 1/6 turn.
8. Mount the indoor thermostat in accordance with instruc-
tion included with the thermostat. Wire per appropriate
hook-up diagram (included in these instructions).
11. The gas valve can now be opened. For a ball type gas
valve, open the gas valve by removing the shut-off valve
cap and turning the valve stem 1/4 turn counterclock-
wise, using 1/4" Open End or Adjustable wrench. See
Figure 5. For brass gas line service valve opening, follow
9 and 10 above. See Figure 6.
G. DEFROST CONTROL
The demand defrost control measures heat pump outdoor
ambient temperature with a sensor located outside the
outdoor coil. A second sensor located on the outdoor coil is
used to measure the coil temperature. The difference be-
tween the ambient and the colder coil temperature is the
difference or delta-T measurement. This delta-T measure-
ment is representative of the operating state and relative
capacity of the heat pump system. By measuring the change
in delta-T, we can determine the need for defrost. The coil
sensor also serves to sense outdoor coil temperature for
termination of the defrost cycle.
12. The gas valve is now open for refrigerant flow. Replace
valve stem cap to prevent leaks. Again, these caps
MUST BE REPLACED to prevent leaks. Replace valve
stem and pressure tap cap finger tight, then tighten an
additional 1/6 turn. See Figure 4.
If refrigerant lines are longer than 15 feet and/or a different
size than recommended, it will be necessary to adjust system
refrigerant charge upon completion of installation. See unit
Service Facts.
FAULT IDENTIFICATION
A fault condition is indicated by the flashing light on the
defrost control inside the heat pump control box.
F. ELECTRICAL CONNECTIONS
PIN IDENTIFICATION
7
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CAUTION
Three phase scroll compressors will run in reverse if
powered up with improper phasing. If the compressor is
running backwards there will be little or no difference in
suction and discharge pressure and it will make a distinct
louder sound. Reversing any two of the field installed
power leads will correct the compressor rotation. Failure to
change the power leads to correct compressor rotation
may result in compressor damage during operation.
4
18-BC51D3-2
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In normal operation, the defrost control light will flash once
each second. If the light is flashing more than once per
second or not at all, refer to the service manual for that unit.
H. COMPRESSOR START UP
After all electrical wiring is complete, SET THE THERMO-
STAT SYSTEM SWITCH IN THE OFF POSITION SO
COMPRESSOR WILL NOT RUN, and apply power by closing
the system main disconnect switch. This will activate the
compressor sump heat (where used). Do not change the
Thermostat System Switch until power has been applied for
one (1) hour. Following this procedure will prevent potential
compressor overload trip at the initial start-up.
PIN IDENTIFICATION (See Figure 7.)
1. TEST_COMMON (Shorting any of the other pins to this
pin causes the function of the other pin to be executed.
Leaving this pin open results in the normal mode of
operation.)
2. TST = Test (Shorting TEST_COMMON to this pin
speeds up all defrost board timings.)
I. OPERATIONAL AND CHECKOUT
PROCEDURES
3. FRC_DFT = Forced Defrost (Short TEST_COMMON to
this pin for two (2) seconds to initiate a forced defrost.
Remove the short after defrost initiates.)
Final phases of this installation are the unit Operational and
Checkout Procedures which are found in this instruction on
page 8. To obtain proper performance, all units must be
operated and charge adjustments made in accordance with
procedures found in the Service Facts.
DEFROST CONTROL CHECKOUT
Normal operation requires:
a. LED on board flashing 1 time/second.
b. 24V AC between R & B
J. ELECTRIC HEATERS
Electric heaters, if used, are to be installed in the air han-
dling device according to the instructions accompanying the
air handler and the heaters.
c. 24V AC between Y & B with unit operating
d. Defrost initiation when FRC_DFT pin is shorted to
TEST_COMMON pin.
K. OUTDOORTHERMOSTAT
If a defrost control problem is suspected, refer to the service
information in control box.
An outdoor thermostat TAYSTAT250B may be field installed.
For data, see wiring diagram attached to unit and instruction
sheet packaged with outdoor thermostat.
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WARNING
Do NOT connect 24 VAC toT1 (ODS-A) terminal. ODS-A
thermistor WILL BE BLOWN.
L. SEACOAST SALT SHIELD
BAYSEAC001 (Seacoast Kit) is available for application on
units installed within one mile of salt water including
seacoasts and inland waterways.
TYPICAL FIELD HOOK-UP DIAGRAMS
Notes:
1. Be sure power supply agrees with equipment nameplate.
2. Power wiring and grounding of equipment must comply with local codes.
3. Low voltage wiring to be No. 18 AWG minimum conductor.
4. ODT-B must be set lower than ODT-A.
5. If outdoor thermostats (ODT) are not used, connect W1 to W2 and W3.
6. N/A to programmable thermostat.
LEGEND
FACTORY WIRING
FIELD WIRING
18-BC51D3-2
5
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2TWA OUTLINE DRAWING
Note: All dimensions are in MM (Inches).
MODELS
BASE FIG.
A
B
C
D
E
F
G
H
J
K
2TWA0030A
2TWA0036A
2TWA0042A
2TWA0048A
2TWA0060A
2TWA0072A
2TWA2030A
2TWA2036A
2TWA2042A
2TWA2048A
2TWA2060A
2
2
3
3
4
4
2
3
3
3
4
2
2
2
2
1
1
2
1
1
1
1
730 (28-3/4) 724 (28-1/2) 651(25-5/8) 3/4 5/16 137 (5-3/8) 65 (2-5/8) 210 (8-1/4) 57 (2-1/4) 457 (18)
730 (28-3/4) 724 (28-1/2) 651(25-5/8) 7/8 3/8 137 (5-3/8) 65 (2-5/8) 210 (8-1/4) 57 (2-1/4) 457 (18)
832 (32-3/4) 829 (32-5/8) 756 (29-3/4) 7/8 3/8 137 (5-3/8) 86 (3-3/8) 210 (8-1/4) 79 (3-1/8) 508 (20)
832 (32-3/4) 829 (32-5/8) 756 (29-3/4) 1-1/8 3/8 137 (5-3/8) 86 (3-3/8) 210 (8-1/4) 79 (3-1/8) 508 (20)
841 (33-1/8) 946 (37-1/4) 870 (34-1/4) 1-1/8 3/8
1045 (41-1/8) 946 (37-1/4) 870 (34-1/4) 1-1/8 3/8
152 (6)
152 (6)
98 (3-7/8) 219 (8-5/8) 86 (3-3/8) 508 (20)
98 (3-7/8) 219 (8-5/8) 86 (3-3/8) 508 (20)
730 (28-3/4) 724 (28-1/2) 651 (25-5/8) 3/4 5/16 137 (5-3/8) 65 (2-5/8) 210 (8-1/4) 57 (2-1/4) 457 (18)
832 (32-3/4) 829 (32-5/8) 756 (29-3/4) 1-1/8 3/8 143 (5-5/8) 92 (3-5/8) 210 (8-1/4) 79 (3-1/8) 508 (20)
832 (32-3/4) 829 (32-5/8) 756 (29-3/4) 1-1/8 3/8 143 (5-5/8) 92 (3-5/8) 210 (8-1/4) 79 (3-1/8) 508 (20)
933 (36-3/4) 829 (32-5/8) 756 (29-3/4) 1-1/8 3/8 143 (5-5/8) 92 (3-5/8) 210 (8-1/4) 79 (3-1/8) 508 (20)
1045 (41-1/8) 946 (37-1/4) 870 (34-1/4) 1-1/8 3/8
152 (6)
98 (3-7/8) 219 (8-5/8) 86 (3-3/8) 508 (20)
From Dwg. 21D153074 Rev. 5
6
18-BC51D3-2
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MOUNTING HOLE LOCATION
Note: All dimensions are in MM (Inches).
NOTE: For model base size,
see table on page 6.
From Dwg. 21D152989 Rev. 0
18-BC51D3-2
7
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Installer’s Guide
CHECKOUT PROCEDURE
After installation has been completed, it is recommended that the entire system be checked against the following list:
1. Refrigerant Line, Leak checked .................................. [
2. Suction Lines and Fittings properly insulated ........... [
]
]
8. Supply registers and return grilles open and
unobstructed ............................................................... [
]
]
9. Return air filter installed............................................ [
3. Have all Refrigerant Lines been secured and
isolated properly? ........................................................ [
]
10. Thermostat thermometer is accurate. Check
against a reliable thermometer. Adjust per
4. Have passages through masonry been sealed?
If mortar is used, prevent mortar from coming
into direct contact with copper tubing ........................ [
instructions with thermostat ...................................... [
]
]
]
]
]
11. Is correct speed tap being used?
(Indoor blower motor) ................................................. [
5. Verify tightness of all electrical connects ................... [
12. Operate complete system in each mode to
6. Observe outdoor fan during on cycle for clearance
and smooth operation ................................................. [
insure safe operation................................................... [
]
]
7. Indoor coil drain line drains freely. Pour water
into drain pan.............................................................. [
TROUBLESHOOTING CHART — WHAT TO CHECK
SYSTEM FAULTS
REFRIGERANT CIRCUIT
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
P
P
P
P
S
S
P
S
S
S
S
S
Head Pressure Too High
Head Pressure Too Low
P
S
S
S
S
P
P
S
S
S
S
S
S
S
S
S
S
P
P
S
S
P
P
P
P
P
Suction Pressure Too High
Suction Pressure Too Low
Liquid Refrig. Floodback (TXV)
P
P
P
P
S
S
S
S
P
P
P
P
P
P
S
S
S
S
S
S
S
S
Liquid Refrig. Floodback
(Cap. Tube)
S
S
P
I.D. Coil Frosting
S
S
P
P
S
S
S
S
S
P
P
S
S
S
S
S
S
Compressor Runs
Inadequate or No Cooling/Htg
ELECTRICAL
C
H
C
H
C
H
C
H
C
H
C
H
P
P
P
P
P
P
P
P
S
S
P
P
S
S
P
P
P
P
Compressor
Won’t Start
&
O.D. Fan
S
S
P
P
P
P
P
P
P
P
S
S
S
S
S
S
S
S
S
S
S
S
P
P
Compressor Will Not Start
But O.D. Fan Runs
O.D. Fan Won’t Start
S
S
S
S
S
S
S
S
P
P
P
P
Compressor Hums But Won’t Start
Compressor Cycles on IOL
P
P
P
P
S
S
S
S
P
P
P
P
S
S
S
S
S
S
S
S
S
P
P
P
S
S
P
P
S
S
S
S
I.D. Blower Won’t Start
DEFROST
C
H
C
H
C
H
Unit Won’t Initiate Defrost
P
P
P
P
P
P
Defrost Terminates on Time
Unit Icing Up
P
P
S
S
S
C
-
Cooling
H
-
Heating
P
-
Primary Causes
S
-
Secondary Causes
-
3
Phase Only
*
Literature Order Number
File Number
P.I.
2TWA2-IN-1A
SV-UN-S/S-2TWA2-IN-1A 9/02
2TWA2-IN-1 4/02
Supersedes
Stocking Location
PI Louisville & Webb/Mason - Houston
Trane
A business of
American Standard Companies
Trane has a policy of continuous product and product data improvement and it reserves the right to change
design and specifications without notice.
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