Carrier 50RTG User Manual

Page 15

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10. System Controls: To ensure that no catastrophic system

failures occur, verify that system controls are functioning
and that the sequencing is correct.

11. Freeze Protection for Water System: Verify that freeze

protection is provided for the building loop water system
when outdoor design conditions require it. Inadequate
freeze protection can lead to expensive tower and system
piping repairs.

12. System Water Loop: Verify that all air is bled from the

system. Air in the system impedes unit operation and
causes corrosion in the system piping.

13. Unit Filters: To avoid system damage, check that the unit

filter is clean.

14. Unit Fans: Manually rotate fans to assure free rotation.

Ensure that fans are properly secured to the fan shaft. Do
not oil fan motors on start-up since they are lubricated at
the factory.

15. System Control Center: Examine the system control

and alarm panel for proper installation and operation to
ensure control of the temperature set-points for operation
of the system’s heat rejector and boiler (when used).

16. Miscellaneous: Note any questionable aspects of the

installation.

17. Air Coil: To obtain maximum performance, the air coil

should be cleaned before starting the unit. A ten percent
solution of dishwasher detergent and water is recom-
mended for both sides of the coil. Rinse thoroughly with
water.

FIELD SELECTABLE INPUTS

Jumpers and DIP (dual in-line package) switches on the

control board are used to customize unit operation and can be
configured in the field.

C Control Jumper Settings (See Fig. 4)

C Control DIP Switches —

The C Control has 1 DIP

switch block with two switches. See Fig. 4.
PERFORMANCE MONITOR (PM) — DIP switch 1 will
enable or disable this feature. To enable the PM, set the switch
to ON. To disable the PM, set the switch to OFF.
STAGE 2 — DIP switch 2 will enable or disable compressor
delay. Set DIP switch to OFF for stage 2 in which the compres-
sor will have a 3-second delay before energizing.
NOTE: The alarm relay will not cycle during Test mode if
switch is set to OFF, stage 2.

D Control Jumper Settings

WATER COIL FREEZE PROTECTION (FP1) LIMIT
SETTING — Select jumper 3, (JW3-FP1 Low Temp) to
choose FP1 limit of 10 F or 30 F. To select 30 F as the limit, DO
NOT clip the jumper. To select 10 F as the limit, clip the jumper.
AIR COIL FREEZE PROTECTION (FP2) LIMIT SET-
TING — Select jumper 2 (JW2-FP2 Low Temp) to choose
FP2 limit of 10 F or 30 F. To select 30 F as the limit, DO NOT
clip the jumper. To select 10 F as the limit (for anti-freeze sys-
tems), clip the jumper.
ALARM RELAY SETTING — Select jumper 4 (JW4-AL2
Dry) for connecting alarm relay terminal (AL2) to 24 vac (R)
or to remain as a dry contact (no connection). To connect AL2
to R, do not clip the jumper. To set as dry contact, clip the
jumper.
LOW PRESSURE SETTING — The D Control can be con-
figured for Low Pressure Setting (LP). Select jumper 1 (JW1-
LP Norm Open) for choosing between low pressure input
normally opened or closed. To configure for normally closed
operation, do not clip the jumper. To configure for normally
open operation, clip the jumper.

D Control DIP Switches —

The D Control has 2 DIP

switch blocks. Each DIP switch block has 8 switches and is
labeled either S1 or S2 on the circuit board.
DIP SWITCH BLOCK 1 (S1) — This set of switches offers
the following options for D Control configuration:
Performance Monitor (PM) — Set switch 1 to enable or dis-
able performance monitor. To enable the PM, set the switch to
ON. To disable the PM, set the switch to OFF.
Compressor Relay Staging Operation — Switch 2 will en-
able or disable compressor relay staging operation. The com-
pressor relay can be set to turn on with stage 1 or stage 2 call
from the thermostat. This setting is used with dual stage units
(units with 2 compressors and 2 D controls) or in master/slave
applications. In master/slave applications, each compressor and
fan will stage according to its switch 2 setting. If switch is set to
stage 2, the compressor will have a 3-second delay before ener-
gizing during stage 2 demand.
NOTE: If DIP switch is set for stage 2, the alarm relay will not
cycle during Test mode.
Heating/Cooling Thermostat Type — Switch 3 provides selec-
tion of thermostat type. Heat pump or heat/cool thermostats
can be selected. Select OFF for heat/cool thermostats. When in
heat/cool mode, Y1 is used for cooling stage 1, Y2 is used for
cooling stage 2, W1 is used for heating stage 1 and O/W2 is
used for heating stage 2. Select ON for heat pump applications.
In heat pump mode, Y1 used is for compressor stage 1, Y2 is
used for compressor stage 2, W1 is used for heating stage 3 or
emergency heat, and O/W2 is used for RV (heating or cooling)
depending upon switch 4 setting.
O/B Thermostat Type — Switch 4 provides selection for heat
pump O/B thermostats. O is cooling output. B is heating out-
put. Select ON for heat pumps with O output. Select OFF for
heat pumps with B output.
Dehumidification Fan Mode (Not used on 50RTG) — Switch
5 provides selection of normal or dehumidification fan mode.
Select OFF for dehumidification mode. The fan speed relay
will remain OFF during cooling stage 2. Select ON for normal
mode. The fan speed relay will turn on during cooling stage 2
in normal mode.
Switch 6 — Not used.
Boilerless Operation — Switch 7 provides selection of boiler-
less operation and works in conjunction with switch 8. In
boilerless operation mode, only the compressor is used for
heating when FP1 is above the boilerless changeover tempera-
ture set by switch 8 below. Select ON for normal operation or
select OFF for boilerless operation.

IMPORTANT: Jumpers and DIP switches should only
be clipped when power to control board has been turned
off.

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