Installation Instructions
453
Size 48
Series D
GAS-FIRED AIR CONDITIONER
Important - Read Before Installing
1. Check all local or other applicable codes for informa
tion concerning proximity to property lines, height
above roof, obstructions, etc.
2. Be sure the power supply available (voltage, fre
quency, and phase) corresponds to that specified on
the unit (230-60-1).
3. Check the electrical service provided by the utility
for the building to be sure that the service capacity
is sufficient to handle the load imposed by this unit.
4. Refer to the regulations of the service gas supplier
and the local building, heating, plumbing or other codes
in effect in the area in which installation is to be made.
5. Refer to the dimensional drawing on page 2 for
location of electrical, gas and chilled water connections
prior to setting the unit in place.
6. Model 453 chillers are not designed for operation
at outdoor ambients below 40°F.
7. When this chiller is used in conjunction with a
boiler, a 4-pipe system must be used. A common piping
system cannot be used. Use separate coils and piping.
GENERAL
Model 48-453 is a gas-fired air-cooled absorption
system which supplies chilled water to the cooling coil
and is suitable for residential and small commercial
air conditioning systems.
This unit is used for cooling only with indoor or outdoor
coil assemblies. The 48-453, can also be used in con
junction with a Bryant gas-fired furnace to provide
“all-seasons” air conditioning for warm air or cool
air as outside temperature dictates.
Multiple Chillers and Cooling Coiis
When it is planned to connect two or more chillers or
coils, additional piping and electrical information is
required and should be obtained from your Bryant
distributor.
Operation at Atmospheric Pressure
The chilled water tank on this unit is vented to the
atmosphere; consequently, the chilled water circuit
operates at atmospheric pressure. Therefore, conven
tional piping practices for a closed, pressurized system
do not apply for this unit.
briiant
Cancels; 39453D67
I
39453D86
8/15/71
F i L & s
I
■
¡DO NOTi ^REMOVE
w
B71285
Figure 1 - Model 453 Gas Air Conditioner
NOTE: When the water chiller is piped to a boiler as
described below, the indoor coil operates at or near
atmospheric pressure when used for cooling; it may be
pressurized when it is used with the boiler for heating.
When the chiller is piped with a boiler to form a com
bination heating and cooling system, provisions must
be made for a positive shutoff between the chiller tank
and the boiler.
When the boiler is in operation, the chiller tank must
be by-passed. A sediment strainer must be installed at
the chiller tank inlet when a common pipe connects
the chiller tank and boiler.
When the chiller is in operation, the boiler, of course,
should be by-passed.
Installation
Installation of Model 48-453, Series D Gas Chiller
consists of the following steps:
I. Locating and Mounting the Unit
II. Connecting Chilled Water Line
III. Making Electrical Connections
IV. .Making Gas Connections
V. Charging System with Water
VI. Checking the Unit Operation
VII. Adjusting Gas Input
VIII. Balancing the System
Each of the above steps is discussed in detail in this
instruction. Read the entire Installation Instructions
before starting the installation.
-1-
note; panel on front side
PROVIDES additional SERVICE
ACCESS.
-GAS CONNECTION
r 1"
l^HOLE-^PIPE 3!
Figure 2 - Unit Dimensional Drawing
A7C
RATINGS, CAPACITIES and COMPONENT INFORMATION
Gas Input BTUH 112,000
Power Supply (Voltage - Frequency - Phase) 230-60-1
Electrical Input
Condenser Air Flow
Refrigerant
Amount Lbs 1 1.0
Total Solution Lbs 30
Factory Test Pressure (Refrigerant Cycle)
Relief Valve Set (Refrigerant Cycle)
Operating Chiller Water Volume Gal. 3.8
Operating Chiller Water Level Above Base Inches
Internal Chilled Water Pressure Loss
Pressure in Chilled Water Tank
Nominal Chilled Water Flow Rate
Water-Solution Pump Motor
HP & Service Factor
Speed
Frame
Pulley Pitch Dia & Bore
Water Pump Pulley Pitch Dia & Bore Inches
Solution Pump Pulley Pitch Dia & Bore Inches
Belt Length & Width
Fan Motor
HP 1/3
Speed
Frame
Fan Diameter
Unit Weight
* Atmospheric
-2-
KW 1.45
CFM 4,200
Type R-717
PSIG
PSIG
Ft Water
PSIG *0
GPM
RPM
Inches
Inches
RPM
Inches
Lbs 740
450
450
9-5/8
2.5
10
1/2-1.6
3450
48
3.09-0.50
2.74-0.628
7.03-0.626
36.5x5/16
825
48
26
LIQUID SUCTION
HEAT EXCHANGER
CONTROL BO.
\
SERVICE
VALVE D
SERVICE VALVE C
RECTIFIER
CHILLER TANK
FAN
PUMP
INLETTANK
SERVICE
VALVE E I
PUMP ^
DISCHARGE
TANK
SUCTION DISCHARGE HYDRAULIC PUMP/
VALVE VALVE WATER PUMP MOTOR
Figure 3 - Partially Disassembled Unit (Front View)
FAN MOTOR
NONCONDENS
ABLE CUSHION
HYDRAULIC
PUMP
B71299
SAIL SWITCH
/
SERVICE
VALVE A'
ABSORBER/
CONDENSERASSY.
SOLUTION
COOLED ABSORBER
GAS INLET
CONNECTION
A643
GAS VALVE/
REGULATOR
'A-'t-T....' . . RESISTOR
- ' I _ ■. PARJ load
i ■ • - 1>C0NT SW.
BURNER PILOT PRESSURE
CAPACITOR
821 RELAY
T -»f-TRANSFORMER
LOW-VOLTAGE
TERMINAL BLOCK
MANUAL
RESET
BUTTON
POWER SUPPLY
CONNECTIONS
GENERATOR
PILOT
ADJUSTING
SCREW
PILOT
ASSEMBLY SWITCH
Figure 4A - Partially Disassembled Unit (Left Side View)
■
GAS INLET^
CONNECTION
REGULATOR
639 GAS PILOT
VALVE ADJUSTING
SCREW
Figure 4B - Partial View of Unit Equipped
with the A639 Gas Valve (Left Side View)
PILOT
ASSY.
BURNER
A70026
-3-
I. LOCATING AND MOUNTING THE UNIT
The construction of Model 48-453 is such that the unit
can be mounted on any NONCOMBUSTIBLE base.
However, there are several conditions, or circum
stances, that result in the requirement of field supplied
supports. Some of these circumstances are:
1. When state and/or local building codes prohibit
mounting the unit directly on a base.
2. When the unit is to be placed in an area where there
is danger of standing water.
Mounting Base
The unit is supported on 3 rails attached to the bottom
of the base. These rails extend the full length of the
unit as shown in the dimensional drawing on page 2.
The recommended types of mounting bases for all
installations are:
a. Precast concrete lintels.
Use three lintels run the depth of the unit; one each
under the right and left end and one at the center of
the unit.
b. Concrete blocks.
Use a block under each corner plus a block under each
of the two long sides midway between the corner
blocks. Arrange the blocks so that the center rail as
well as the front and back rail is supported.
c. Concrete slab.
Minimum thickness 4 inches.
CAUTION: ALWAYS USE NONCOMBUSTIBLE
MATERIAL FOR THE BASE.
Rooftop Installations
1; Place the unit above a load-bearing wall whenever
possible.
2. Roof areas are susceptible to standing water; there
fore, field-supplied supports should be placed under
the unit. Allow a minimum of 6 inches clearance
between bottom of unit and roof.
Clearances
The condenser coil is located at the back of the unit
with the condenser air inlet through the rear of the unit
and the discharge through the louvered top panel.
The minimum clearance between the back of the unit
and a wall is 15 inches. If the overhang is less than 7
feet above the unit, the unit must be mounted outside
a plumb line from the eaves of the overhang. The clear
ance on the right and left ends should be a minimum of
2 feet to provide access for servicing. See Figure 5.
II. CONNECTING CHILLED WATER LINES
Refer to the following information: “Multiple Chillers
and Cooling Coils,” page 1; “Operation at Atmospheric
TABLE I
Allowable Distances between Coil Model 405, 406, 407, 414 and Chiller (Note 1)
Pipe Size Bryant Quick-Connect Polyethylene
(Inches) Tubing (Note 2)
3/4" 42' 40' 45' 6Г
1" 90' 176' 189' 200'
Note 1: Values shown are for one direction only, and
using Bryant water coils. Total length of pipe (from
chiller to coil and return) would be double the values
shown. All distances shown are shown on the predica
tion that only long elbows are used. Galvanized well
head elbows are used with the polyethylene pipe. When
using Bryant Quick-Connect Tubing, avoid any sharp
bends that would tend to restrict or stop the flow
of water.
Note 2: If Quick-Connect Tubing is used and coil is
above chiller water level, refer to PAM 400.2.6.
Simplified Guidelines When
Using Quick-Connect Tubing
1. Do not exceed 12 feet elevation with 3/4" Quick-
Connect.
Pressure,” page 1; and “Freezing Weather Protection,”
page 8.
Copper Galvanized
Pipe Pipe Pipe
2. Do not exceed 10 feet elevation with 1" QuickConnect.
3. Do not exceed 15 feet of horizontal tubing at those
elevations.
4. Exercise good practice to avoid kinking, sagging
and stretching.
5. Any excess lengths should be coiled up at the lowest
elevation.
6. Polyethylene or hard pipe should be used at higher
installation.
-4-
□
Avoid
Open
Windows
Sleeping
Qu Öfters
Living
Area
Figure 5 - Locating the Unit
Gorage
Avoid
“Ells"
□ %
Good
Location
Air
Flow
15"--
Minimum
A70022
Materials
1. Chilled Water Piping
a. Use Bryant Quick-Connect Tubing.
b. Polyethylene pipe—satisfactory substitute; use
medium density flexible pipe whose wall thick
ness approximates Schedule 40 pipe (Commercial
Standard CS 255-63). Pipe must be made from
virgin material. Do not use pipe manufactured
from reclaimed material.
c. Copper—satisfactory substitute.
d. Galvanized—satisfactory substitute.
2. Fittings
a. Galvanized—use when possible.
b. Brass —satisfactory substitute.
Pipe Length and Diameter
Table I shows the maximum length of pipe of different
diameters that can be used between the pump dis
charge and the coil inlet and still maintain minimum
allowable (design) water flow rate.
1. Multiply table values by two to obtain the total
length of pipe from chiller to coil and return.
2. Length is measured along the pipe path and there
fore includes vertical distance between the water coil
and the chiller.
3. Lengths shown in Table I are based on using a total
of eight elbows in the entire water line (chiller to coil
and return). Lengths are predicated on the use of a
Bryant matching water coil. For greater distances use
larger size pipe.
TABLE II
Water Flow Rate at Various External Pressures
Water Flow Rate - GPM
5
6
7
8
9
10
11
12
13
14
15
Pressure External to Unit
38.3
37.5
36.7
35.8
34.7
33.5
32.5
31.0
29.5
27.5
26.0
4. For calculating chilled water pipe size for coils
not listed, use friction loss method with allowance for
coil pressure loss. Refer to coil instructions for pressure
loss at design water flow rate. Refer to Table II show
ing available head with standard pump drive.
Insulation
1. Insulate both supply and return lines.
NOTE: Bryant Quick-Connect Tubing is preinsulated.
2. Material should be of good quality and be covered
with a good vapor barrier. Armaflex or equivalent is
recommended. Use 1/2 inch wall thickness. (Bryant
Quick-Connect Tubing is preinsulated.)
Height of Coil Above Unit
The maximum vertical distance from Model 48-453
Chiller to top of coil is 30 feet.
Water Coil Connections
1. If the cooling coil is used in connection with a
heating unit and the heating unit is not approved for
installation downstream from the cooling coil, install
the cooling coil in parallel with or downstream from
the heating unit. This will avoid condensation in the
heating unit. If the coil and heating unit are installed
in parallel, the dampers or other means used to control
flow of air should be adequate to prevent chilled air
from entering the heating unit; if manually operated,
the dampers shall be equipped with some means to
prevent operation of either unit unless the dampers are
in full heat or full cool position.
2. If the coil is located in a warm air stream, do not
connect polyethylene pipe directly to the coil. Connect
a minimum of 24 inches of copper or galvanized pipe
to both the coil inlet and outlet; then connect the
polyethylene pipe to these nipples.
NOTE: not required when using Bryant QuickConnect Tubing.
3. On installations where the water in the outside piping
freezes and the coil is in a heated air stream, precautions
must be taken to provide for water expansion. The
connecting polyethylen'e pipe acts as an expansion
vessel if there is sufScient footage in the heated space
(space not subject to freezing). Table III shows the
minimum lengths (total inlet and outlet) of polyethylene
piping of various diameters that are required to provide
adequate expansion volume.
TABLE III
Nominal
Pipe Size
Inches
3/4
1
Length of Polyethylene
Pipe in feet
32
20
If the total polyethylene chilled water line footage in
the heated space is not as long as the minimum values
shown in the table, tee a vertical pipe of sufficient
volume into either of the coil connections to provide
-5-
for expansion, or drain the lines during freezing
weather.
NOTE: No minimum run required when using Bryant
Quick-Connect Tubing.
III. MAKING ELECTRICAL CONNECTIONS
1. Make all electrical connections in accordance with
the National Electrical Code and any local ordinances
or codes that might apply.
2. Provide a separate power supply for the air
conditioner.
3. Provide a fused disconnect switch within sight of
and not more than 50 feet from the unit. A 15 amp
standard fuse or a 10 amp Fusetron is suggested.
Use minimum wire size of #14 copper wire or #12
aluminum wire. The 230V power supply connects to
a terminal block in the control box located inside the
service panel on the left side of the unit. The conduit
enters through a knockout located on the back of the
unit and attaches to the opening in the bottom of the
control box.
(a) Materials required for unit piping shown in Figure 6:
Quantity Description
1/2" X 3" nipple
1/2" X 90° elbow
112" \ 15" nipple
(b) Materials required for unit piping shown in Figure 7;
Quantity Description
1 1/2" X 1-1/8" close nipple
1 1/2" X 90° elbow
1 1/2" X 15" nipple
A knockout, adjacent to the line voltage knockout, is
also provided for the low voltage wires to the thermo
stat control. See Figure 2 for location of knockouts.
The thermostat wires connect to the low voltage
terminal board in the control box.
Low Voltage Power Supply
This unit is equipped with a 24V transformer. The
transformer secondary winding (control circuit voltage)
is connected to terminals R and F of the low voltage
terminal board.
IV. making gas connections
The following recommendations apply to the installa
tion, tests and operation of appliances and piping
systems for natural and propane gases:
1. Before making any gas connections, refer to the
regulations of the serving gas supplier and the local
building, heating, plumbing or other codes in effect
in the area in which the installation is made.
2. The gas supply pipe enters through a knockout
located in the rear of the unit near the right side. Refer
to Figure 2 on page 2 for gas inlet hole location. The
unit piping for 48-453 units equipped with the A643
combination regulator-gas valve is shown in Figure 6.
The unit piping for 48-453 units equipped with the
A639 gas valve and 1/2" regulator is shown in Figure 7.
Figure 6 - Unit Piping for Model 48-453 Equipped
with A643 Combination Gas Valve-Regulator
f-X 15
Y X 90^* ELBOW-
\ NIPPLE
II II
1-^ CLOSE
NIPPLE
MANUAL
SHUT-OFF
VALVE
REGULATOR
Figure 7 - Unit Piping for Model 48-453 Equipped
with Separate Regulator and the A639 Gas Valve
.PILOT
SHUT-OFF
VALVE
-6-
3. A wrench-type shut-ofF valve should be installed
in the gas line within sight of, and convenient to the
unit.
4. Joint compound (pipe dope) which is resistant to
the action of liquified petroleum gases should be applied
sparingly and only to the male threads of the joints.
5.. Install a drip leg trap in the gas supply riser leading
to the unit. After gas pipe connections have been made,
purge the lines, as described below, and check for
leakage. Use a soap and water or other recommended
solution.
6. Never use matches, candles, flame or other source
of ignition to check for leaks.
Pilot
Light the pilot, using the procedure outlined on the
lighting instructions on unit rating plate. However,
when lighting the pilot for the first time, perform the
following additional steps:
1. If the supply line was not purged prior to connecting
the unit, it will be full of air. Since it would take a long
time to vent this air through the small pilot port, it is
recommended that the pilot supply line be disconnected
at the gas valve. Set the gas valve knob to the PILOT
position and leave the pilot supply tube disconnected
until the odor of gas is detected. Never purge gas lines
into the combustion chamber. Allow five minutes to
elapse and light the pilot in accordance with the in
structions on the unit rating plate.
NOTE: On units equipped with the A639 gas valve
and separate regulator, disconnect the pilot supply tube
at the pilot shutoff valve when purging the gas supply
line.
2. The pilot flame should be soft blue in color.
a. For natural gas this flame should be of sufficient
length to provide good impingement on the
monometal of the Bryant pilot. The flame should
extend upward and above main burner ports.
3. If the pilot flame does not have the appearance
described above, it may be adjusted in the following
manner:
Units equipped with A643 valve - Refer to Figure 4A.
Turn the three-position manual A643 valve knob to the
PILOT position. Remove pilot sealing cap screw to
expose the pilot gas adjusting screw. Adjust the pilot
gas adjusting screw until the pilot flame has the desired
appearance as described in Step 2 above. Replace cap
screw.
Unit equipped with separate regulator and A639
gas valve —Refer to Figure 4B and Figure 7. Turn the
pilot shut-ofif valve to the full open position. Remove
the pilot sealing cap screw to gain access to the pilot
gas adjusting screw. Adjust the pilot gas adjusting
screw until the pilot flame has the desired appearance
as described in Step 2. Replace cap screw.
V. CHARGING THE SYSTEM WITH WATER
CAUTION;
1. Do not run the pump dry.
2. Freezing weather will not damage the pump; how
ever, do not attempt to operate the pump when the
chiller or chilled water lines are frozen.
Adjusting Chilled Water Level
1. Turn off main manual gas shutoff valve.
2. Remove unit top casing then remove cover from
top of chilled water tank. See Figure 8.
Figure 8 - Chiller Tank
3. Disconnect chilled water line at chiller inlet. (When
installing chilled water lines, it is advisable to leave
this connection open until lines have been flushed).
4. Fill tank with tap water until distributor pan is
covered with water. A garden hose is useful for filling
the tank with water.
NOTE: Tap water having less than 60 ppm chlorides
may be used in the chilled water circuit with proper
additive. In those areas where tap water contains more
than 60 ppm chlorides, use distilled or deionized water
with proper additive. Do not use “softened” water or
otherwise treated water.
5. Start pump. Continue adding water to the tank and
operate pump until all foreign matter has been flushed
from the lines. Remove hose.
6. Turn off pump. Reconnect water line at chiller inlet.
7. Add water to tank to raise water level above the
drain plug. The operating level drain plug is located at
the side of the chilled water tank. See Figure 8.
NOTE: The drain plug is accessible by removing the
front access panel.
8. Start pump. Adjust water level with the pump run
ning. This is accomplished by removing the drain plug.
The operating water level is properly adjusted when
water ceases to flow from the drain opening. Replace
drain plug and check for leaks.
-7-
Corrosion Protection
The components of the chilled water circuit must be
protected from corrosion by the addition of an inhibitor
to the chilled water circuit. Chilled water additive
P/N 6463 ID 1 must be added to the chilled water circuit
when water only, or water and methanol antifreeze
are used in the chilled water circuit.
The chilled water additive package P/N 6463 ID 1
contains sufficient corrosion protection for chilled water
systems containing up to 10 gallons of water. For
systems larger than 10 gallons, add 1/2 package for
each additional 5 gallons of water or fraction thereof.
To estimate the chilled water capacity of the chilled
water circuit, refer to Table IV.
TABLE IV
Water Capacity
in Gallons
48-453 Chiller Tank 3.8
Bryant 18,000 Btuh coil 0.6
Bryant 48,000 Btuh coil 1.3
Bryant 36,000 Btuh coil 1.0
1 ft. 3/4-inch pipe 0.03
1 ft. l-inch pipe
0.05
Add required amount of the chilled water additive by
spreading additive over the distributor pan while water
is circulating (pump running).
CAUTION: Do not add any type of chilled water
additive when Ucar-17 antifreeze is used for freeze
protection. Ucar-17 contains sufficient inhibitor when
used in the recommended concentration listed in Tables
V and VI. Refer to following section on Freezing
Weather Protection.
Freezing Weather Protection
Model 48-453 was not designed for operation at out
door ambients below 40°F.
Freeze protection is normally required only on those
systems which:
(a) Use hard piping (copper or galvanized).
(b) Use polyethylene piping without sufficient length
of piping in the conditioned space.
(c) Have the cooling coil in an unheated area where
freezing could occur, such as a rooftop unit.
Table V lists the type of antifreeze, minimum amount
of concentration, and the type of chilled water additive
to use in the chilled water system.
TABLE V
*Minimum Concentration
Antifreeze
Methanol
Ucar-17
*For protection required at various ambients, refer to Table VI.
(Percent of Volume)
20
33
Type of Chilled
Water Additive
Borax & Chromate
(P/N 6463 ID 1)
None-See Note 1
NOTE 1: Ucar-17 is the only approved permanent
(Glycol-base) antifreeze for use with galvanized
systems. Do not add any other chilled water additive
to systems containing Ucar-17. The system must be
thoroughly flushed before changing from another
chilled water additive or antifreeze to Ucar-17.
In any system containing both aluminum and galvanized
chillers, Ucar-17 must be used when freeze protection
is required and the minimum concentration must be
33% by volume. Do not use any other chilled water
additive.
TABLE VI
Percent of
Lowest Outdoor Winter
Temperature ( F)
20
15
10
5
0
-5
- 10
- 15
-20
-25
-30
Antifreeze Concentration
Menthanol
20
20
22
26
29
32
34 39
36
38
43
44
Ucar-17
33
33
33
33
33
36
42
45
47
49
VI. CHECKING THE UNIT OPERATION
1. Be sure main manual gas valve is oif. Light pilot
as described on the unit rating plate.
2. Set thermostat to “cool”; set thermostat fan switch
to “auto”; set thermostat below-room temperature.
3. Turn on power at main disconnect switch to unit.
4. Check indoor fan operation by turning thermostat
fan switch to “on” for continuous operation. Move
thermostat above room temperature and observe that
the indoor fan remains on.
5. To place the system in operation; open the main
manual gas valve, replace all panels, and set the ther
mostat at the desired temperature.
Control Circuit Operation
Refer to Figure 9. Note that 24 volts (transformer
secondary voltage) is applied to chiller terminals R and
F whenever 230V-60Hz-lc/) volt power is supplied to
the unit. When the thermostat calls for cooling, chiller
terminal R is connected to chiller terminal Y through
the thermostat.
Automatic Pilot Reignitlon
The automatic pilot reignition circuit consists of the
resistor (llA), pilot assembly (6B), and pilot pressure
switch (7P). The pilot pressure switch (7P) contacts
close when gas is turned on to the unit and current
flows through the resistor (11 A), glow coil of pilot
assembly (6B) via the pilot’s normally closed contacts.
-8-
through the pilot pressure switch to terminal F and
lights the pilot.
Approximately one minute after the pilot is ignited,
heat from the pilot will cause the pilot’s normally open
contacts to close and the normally closed contacts
to open.
If the pilot should go out, the normally open pilot con
tacts (which were closed when the pilot was ignited)
will reopen, de-energizing the power relay (2G) and
the heat motor of the gas valve (5A). This will cause
both motors (3A & 3C) to stop and the gas valve to
close. The normally closed pilot contacts will close
again and complete the current path to reignite the pilot.
Cooling Operation
Two current paths are provided from chiller terminal Y
to chiller terminal F when the thermostat calls for
cooling and the pilot is ignited as described above.
Current flows from chiller terminal Y through hi-temp
limit switch (7H), closed contacts of circuit breaker
(2J), resistance coil of power relay (2G), the normally
open contacts of pilot assembly (6B), and through the
pressure switch (7P) to chiller terminal F. The ener
gized power relay (2G) starts the fan motor (3C) and
the solution/water pump motor (3A).
Current also flows from chiller terminal Y through
hi-temp limit switch (7H), circuit breaker (2J) closed
contacts, sail switch (7D), part load control switch (7L),
the heat motor of gas valve (5A), normally open con
tacts of pilot assembly (6B), through the pressure switch
(7P) to chiller terminal Fi The current flow through
the heat motor of the gas valve, energizes the gas valve
(5A) causing it to open and supply gas to the genera
tor burner.
Part Load Control
This current flow through the heater causes the nor
mally closed contacts of the circuit breaker to open,
removing the 24-volts potential from the gas valve and
the power relay (2G).
The de-energized gas valve will turn off the gas supply
to the burner, and both the fan motor (3C) and
solution/water pump motor (3A) will stop running. The
circuit breaker is reset manually by pushing the red
reset button that protrudes through the bottom of the
control box. The reset button is accessible by removing
the left side access panel.
VII. adjusting gas input
The gas input must be checked and adjusted if neces
sary to agree with the input shown on the unit’s rating
plate.
The natural gas units are equipped with adjustable gas
pressure regulators.
The propane gas units are not equipped with a pressure
regulator.
Check natural gas units by the following method:
1. Measure gas at meter. Be sure all other gas ap
pliances are turned off. Increase or decrease input to
burner by adjusting the gas pressure regulator.
2. Set manifold pressure according to Table VII for
the Btu value and specific gravity of the gas to be
supplied to the unit. Connect manometer to 1/8-inch
pressure tap on gas valve and, with unit in operation,
set correct pressure by adjustment of the gas pressure
regulator.
Example: Natural Gas
1025 Btu
0.63 Specific Gravity
The part load control circuit utilizes a temperature
sensitive switch and a long capillary tube which is
inserted a minimum of six inches in the chilled water
supply line. The part load control switch (7L) contacts
open when the chilled water supply temperature drops
below 40±1°F. The opening of the switch contacts
de-energizes the gas valve which shuts off the gas
supply to the burners. The power relay (2G) remains
energized; therefore, the fan motor (3C) and the
solution/water pump motor (3A) will continue to run.
The part load control switch contacts will close again
when the chilled water temperature rises to 42±1°F.
The gas valve is re-energized and the gas supply to
the burner is turned on again.
High-Temperature Cutoff
The high temperature cutoff circuit includes a hi-temp
limit switch (7H) located on the front of the generator,
plus a circuit breaker (2J) which is located in the con
trol box.
If the generator becomes overheated, the hi-temp limit
switch will open causing all current in the Y leg to pass
through the heater element of circuit breaker (2J).
TABLE VII
BTU
Value
900 3.5
950 3.3 3.4 3.5
1000 2.85
1025 2.7
1050
1100
0.59
2.55 2.6 2.7 2.75 2.8
2.35 2.4 2.5 2.55
Specific Gravity
0.61 0.63 0.65
3.6
2.9
2.75 2.8 3.0
3.7
3.1 3.15
3.8 3.9
3.6
0.67
3.7
3.2
3.1
2.6
For manifold pressures exceeding 3.3 inches or less
than 2.7 inches, consult your local gas utility.
3. Refer to Table VII and note that the gas manifold
should be 2.8 inches wc for these values.
4. With manometer connected to the pressure tap, set
pressure to 2.8 inches by adjusting gas pressure
regulator.
Check propane gas units as follows:
The burner orifice is sized for the rated input with a
manifold pressure of 11.0 wc. Connect manometer to
1/8-inch pressure tap on the gas valve and adjust
regulator at the supply tank to provide a manifold
pressure of 11.0 inches wc.
CAUTION: The unit may be run for short periods with
panels removed. Prolonged operation with panels
removed should not be attempted.
VII. BALANCING THE SYSTEM
After the unit is in operation and the input has been
measured to agree with the rating plate requirements,
the system must be balanced.
Any approved method of checking the air flow over
the water coil may be utilized. Refer to Model 453
service instructions for a review of standard methods.
LEGEND
1A Transformer
2G Power Relay
(Heat Motor)
2J Lockout Relay
(Circuit Breaker)
3A Pump Motor
3C Fan Motor (PSC)
5A Gas Valve (Heat Motor)
6B Pilot (Reignition)*
7D Sail Switch
7H Hi-Temp Limit Control
7L Part Load Control
7P Pressure Switch
(Pilot Gas)
11A Resistor
230-60-1
Figure 9 - Model 48-453 Chiller Wiring Diagram
*Or thermocouple Pilot & Pilot Relay
(Reignition).
10-
FIELD , HIGH VOLTAGE WIRING — —
FIELD LOW VOLTAGE WIRING
--------------
FIELD HIGH VOLTAGE WIRING —
FIELD LOW VOLTAGE WIRING
-----------
*NOTE 1: A cooling relay must be installed on the belt drive Model
394 Series E and F Furnaces. See furnace wiring label.
*NOTE 2; When connecting to a 394 Furnace that has the cooling
relay factory installed, remove the green lead from terminal X. Run
this green lead through hole marked F and connect to chiller
terminal F.
Figure 10 - Connecting Modei 48-453 Chiller to
Model 394 Series E, F or G Direct Drive or *Belt
Drive Furnace
-11-
Remove the three leads (brown lead and two yellow leads) from ter
minal 4 of the cooling fan relay in the 48W-379A Furnace. Connect
these three leads together and tape. Connect a wire (size AWG 18)
from cooling relay terminal 4 to chiller terminal F.
Figure 11 - Connecting Model 48-453 Chiller
Model 48W-379A Series A or B Furnace
to
FIELD HIGH VOLTAGE WIRINGFIELD LOW VOLTAGE WIRING-
*Cooling relay not furnished. Use Bryant P/N 52643C02 and con
nect as shown.
Figure 12 - Connecting Modei 48-453 Chiiier to
Modei 48-405 Fan Coii Unit
12-
Loading...