Head Pressure/Fan Cycling Control (Motormaster® Head Pressure Control) - Carrier 48FP Controls Operation And Troubleshooting

DESCRIPTION
Select Heat Type
Opt: Enable Occupied Heating
Select Heating Set Points:
Occupied Heating Set Point
Unoccupied Heating Set Point
Select Heat Coil Fan Off Set Point
*If value changed, enable Data Reset before leaving.
NOTE: Occupied Heating Set point serves as ''Morning Warm-Up Set Point.''
Sequence of Operation
1. Freezestat signal contacts close on temperature drop.
2. A 24-v signal applied to Channel 41.
3. After 2 to 10 second delay, the control will turn the
supply fan off, direct the heating control valve to fully
open, and return the economizer to the Minimum
Damper Position.
4. An alarm is initiated (alarm 88).
5. Alarm status maintained until control is manually
reset.
Configuration — To configure, configure the unit for Hydron-
ic Heating. See Hydronic Heat section for more information.
Connect switch contacts (NO) and 24-vac power supply to
Channel 41.
LEAD/LAG OPERATION — Lead/lag operation will dis-
tribute starts between the two refrigeration circuits in an effort
to equalize the running time on the two circuits. Lead/lag is
factory-enabled except when the Hot Gas Bypass (HGBP) op-
tion is ordered. The HGBP function is available on designated
lead circuit (circuit A) only, so lead/lag function is disabled.
To disable lead/lag, press
Press to disable.
ENTER
To enable lead/lag, press
Press to enable.
ENTER
HEAD PRESSURE/FAN CYCLING CONTROL (Motor-
master® Head Pressure Control) — The control will cycle
condenser-fan motors on each refrigeration circuit at low ambi-
ent temperatures in order to maintain proper head pressure and
liquid temperature for refrigeration system operation. See
Table 40.
Table 40 — Head Pressure Control Definitions
ITEM
HPSP Head Pressure Set Point
MMAS Motormaster Function Configuration
SCT Saturated Condensing Temperature
Sequence of Operation — Motormaster head pressure control
option enabled (default):
Sizes 034-078: On standard unit (without transducers), the first
stage of Outdoor Fan(s) operation (on each circuit) will turn on
when the Saturated Condensing Temperature on either circuit
is greater than (HPSP – 15 F).
NOTE: The default for HPSP is 113 F.
On units with transducer accessory, first stage of Outdoor
Fan operation (on each circuit) will turn on when Saturated
Condenser Temperature is greater than 138 F.
Table 39 — Configuring Hydronic Heating
HOW TO CONFIGURE AT HSIO
(Use ComfortWORKS® software)
. Scroll down to LLAG.
. Scroll down to LLAG.
DEFINITIONS
SET POINT
HEAT
OHEN
OHSP
UHSP
HCFO
The first stage of outdoor fan operation will turn off when
Saturated Condensing Temperatures on both circuits are less
than (HPSP – 37 F) for 90 seconds.
Sizes 088-104: On standard unit (without transducers), the first
stage of Outdoor Fan(s) operation (on each circuit) will turn on
when the Saturated Condensing Temperature on that circuit is
greater than (HPSP – 15 F).
NOTE: The default for HPSP is 113 F.
On units with transducer accessory, first stage of Outdoor
Fan operation (on each circuit) will turn on when Saturated
Condenser Temperature is greater than 138 F.
The first stage of outdoor fan operation will turn off when
Saturated Condensing Temperature is less than (HPSP – 37 F)
for 90 seconds and is off.
All Units: The second stage of outdoor fan operation will be
off whenever compressors on its circuit are off. The second
stage of outdoor fan operation will be delayed for 60 seconds
after start of compressor (or until SCT is greater than 143 F,
when the second stage of outdoor fan operation will start
immediately). The control will energize the second stage of
outdoor fan operation whenever the SCT exceeds the HPSP.
The control will deenergize the second stage of outdoor fan
operation when the SCT has been less than (HPSP – 35 F) for
period of 2 minutes.
NOTE: The second stage of outdoor fan operation on a circuit
may be added as rapidly as 2 seconds but may not be removed
during two minutes of minimum ON time.
Motormaster option disabled: The first stage of outdoor fan
operation for a refrigerant circuit will be on whenever mechan-
ical cooling is on for that circuit. Outdoor fan motor no. 1 is off
when mechanical cooling is OFF.
The second stage of outdoor fan operation will be off when-
ever compressors on its circuit are off. The control will ener-
gize the second stage of outdoor fan operation whenever the
SCT exceeds the HPSP. The control will deenergize the second
stage of outdoor fan operation when the SCT has been less than
(HPSP – 35 F) for period of 2 minutes.
NOTE: The second stage of outdoor fan operation on a circuit
may be added as rapidly as 2 seconds but may not be removed
during 2 minutes of minimum ON time.
Configuration — See Table 41. To disable the Motormaster
function, press
down to MMAS. Press
enabled.
To enable the Motormaster function, press
the subfunction. Scroll down to MMAS. Press
to enable.
To adjust the default Head Pressure Set Point, press
. Scroll down to HPSP. Enter the new value. Default is
113 F. Range is 80 to 150 F. Enable Data Reset.
32
RANGE
Hot water/Steam = 1*, None = 0
Enable = 1; Disable = 0
55 to 80 F (13 to 27 C)
40 to 80 F (4 to 27 C)
35 to 65 F (2 to 18 C)
to enter the subfunction. Scroll
to disable. The default is
ENTER
to enter
ENTER