Bryant 452W - Manual (Page 8)

type antifreeze to use. Step ll.gives procedure for
adding Ucar-17 antifreeze. Step 12 covers
procedure for adding methanol antifreeze.
11. Adding Ucar-17 - Calculate capacity of chilled-
water circuit by using information given in Table
III. Refer to Table V and determine amount of
antifreeze required. Drain out amount of water
equal to amount of antifreeze to be added. Add
antifreeze, then check operating level and correct.
Omit Steps 12, 13, and 14.
NOTE: Do not use any chilled-water additive when
Ucar -17 is used in the recommended concentration.
12. Adding methanol antifreeze - Calculate capacity
of the chilled-water circuit by using information
given in Table III. Refer to Table V and deter­
mine amount of antifreeze required. Drain out
amount of water equal to amount of antifreeze to
be added. Add antifreeze, then check operating
level and correct.
NOTE: Methanol antifreeze does not contain an
inhibitor; therefore, add the required amount of
Chilled-Water Additive P/N 62875D1 as described in
Step 13.
13. Remove hand hole cover and add contents of
Chilled-Water Additive Package P/N 62875D1 to
chiller tank. Package supplied is sufficient for
systems up to 15 gallons. For systems larger than
15-gallon capacity, add one package for each ad­
ditional 15 gallons or fraction thereof.
14. Replace hand hole cover. Turn on pump. Pump
should operate a minimum of 10 minutes to
dissolve all chilled-water additive.
15. Turn off electrical power at disconnect switch.
Reconnect condenser fans motor leads in control
box. Turn on power at disconnect switch.
16. Replace access panel. Chiller is now ready for
operation.
Figure 8 - Chiller Tank
VI. CHECKING THE UNIT OPERATION
1. Be sure manual gas valve is off. Light pilots as
described on Instruction Plate.
2. Turn on manual gas valve with thermostat sub­
base switch levers on “cool” and “auto.” Set ther­
mostat below room temperature. To check
correct operation of electrical circuit, observe
operation of gas valve, condenser fan motors,
hydraulic pump, and indoor fan. Set thermostat
above room temperature and observe that unit
shuts off properly.
3. Check indoor fan operation by setting thermostat
subbase fan switch lever to “on.” Indoor fan
should operate continually with thermostat set
above or below room temperature.
4. To place system in operation, open main manual
gas valve, replace all panels, and set thermostat
at desired temperature.
Control Circuit Description
Refer to Figiire 9. Note that 24 volts (transformer
secondary voltage) is applied to chiller terminals R
and F whenever power is supplied to unit. When ther­
mostat calls for cooling, chiller terminal R is con­
nected to chiller terminal Y through thermostat.
Automatic Pilot Reignition
The automatic pilot reignition circuit consists of the
1-ohm resistor (llAl), pilot pressure switch (7P), and
the pilot and ignition coil assembly (6B). The pilot
pressure switch (7P) contacts close when gas is turned
on to the unit and current flows from chiller terminal
R, through the 1-ohm resistor (llAl), pilot pressure
switch (7P), the glow coil of the pilot assembly (6B)
via the pilot’s normally closed contacts to chiller ter­
minal F, and lights the pilot.
Approximately one minute after the pilot is ignited,
heat from pilot will cause normally open contacts of
the pilot to close and the normally closed contacts to
open.
If the pilot should go out, the normally open pilot
contacts (which were closed when the pilot was
ignited) will reopen, deenergizing the power relay
(2D) and the magnetic gas valve (5B). This will cause
all motors (3A1, 3A2, 3Cl & 3C2) to stop and the gas
valve to close. The normally closed pilot contacts
(which were opened by heat from the pilot) will close
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 pilots are ignited as described above.
Current flows from chiller terminal Y, through the
power relay winding (2D) and through the closed con­
tacts of the pilot (6B) to chiller terminal F. The
energized power relay winding (2D) causes the power
relay contacts (2D) to close and starts the two fan
motors (3Cl & 3C2), the hydraulic pump motor (3A1),
and the water pump motor (3A2).