Morning Warm Up; Tempering Mode - United Technologies Carrier Weathermaker 48A2 Controls, Start-Up, Operation, Service, And Troubleshooting

Table 59 — IGC LED Indicators
LED INDICATION
On Normal Operation
Off Hardware Failure
1 Flash Fan On/Off Delay Modified
2 Flashes Limit Switch Fault
3 Flashes Fame Sense Fault
4 Flashes Five Consecutive Limit Switch Faults
5 Flashes Ignition Lockout Fault
6 Flashes Ignition Switch Fault
7 Flashes Rollout Switch Fault
8 Flashes Internal Control Fault
9 Flashes Software Lockout
NOTES:
1. There is a 3-second pause between error code displays.
2. If more than one error code exists, all applicable error codes
will be displayed in numerical sequence.
3. Error codes on the IGC will be lost if power to the unit is
interrupted.
RELOCATE SAT (Supply Air Temperature) SENSOR FOR
HEATING IN LINKAGE APPLICATIONS — On CCN in-
stallations employing ComfortID™ terminals, the factory SAT
location must be changed to a new location downstream of the
unit's heating system. The ComfortID terminal controls read
the SAT value for their "proof-of-heat" sequence before termi-
nals open to Minimum Heating positions during unit heating
sequence.
Determine a location in the supply duct that will provide a
fairly uniform airflow. Typically this would be a minimum of
5 equivalent duct diameters downstream of the unit. Also, care
should be taken to avoid placing the thermistor within a direct
line-of-sight of the heating element to avoid radiant effects.
Run a new two-wire conductor cable from the control box
through the low voltage conduit into the space inside the build-
ing and route the cable to the new sensor location.
Installing a New Sensor — A field-provided duct-mount tem-
perature sensor (Carrier P/N 33ZCSENPAT or equivalent
10,000 ohms at 25 C NTC [negative temperature coefficient]
sensor) is required. Install the sensor through the side wall of
the duct and secure.
Re-Using the Factory SAT Sensor — The factory sensor is
attached to one of the supply fan housings. Disconnect the sen-
sor from the factory harness. Drill a hole insert the sensor
through the duct wall and secure in place.
Attach the new conductor cable to the sensor leads and ter-
minate in an appropriate junction box. Connect the opposite
end inside the unit control box at the factory leads from MBB
J8 terminals 11 and 12 (PNK) leads. Secure the unattached
PNK leads from the factory harness to ensure no accidental
contact with other terminals inside the control box.
MORNING WARM UP — Morning Warm Up is a period of
time that assists CCN linkage in opening up downstream zone
dampers for the first heating cycle of a day.
The Morning Warm Up Period is CCN linkage mode "2"
and is relayed in the following conditions:
• Temperature Compensated Start Mode is active AND Heat
Mode in effect AND LAT is warm enough or is to be
ignored due to placement.
• The unit just went into occupied mode and there has been
no cooling mode yet and a heat cycle occurs or was in prog-
ress when the unit went occupied.
In both cases, if and when the heat mode terminates, a heat
cycle has occurred and any subsequent heat cycles will not be
treated as a morning warm up period.
TEMPERING MODE — In a vent or cooling mode, the roof-
top may encounter a situation where the economizer at mini-
mum position is sending cold outside air down the ductwork of
ERROR CODE
the building. Therefore, it may be necessary to bring heat on to
counter-effect this low supply-air temperature. This is referred
to as the tempering mode.
Setting up the System — The relevant setpoints for Temper-
ing are located at the local display under Setpoints:
ITEM EXPANSION
Tempering
T.PRG
Purge SASP
Tempering in
T.CL
Cool SASP
Tempering Vent
T.V.OC
Occ SASP
Tempering Vent
T.V.UN
Unocc. SASP
Operation — First, the unit must be in a vent mode, a low cool
mode, or a high cool HVAC mode to be considered for a tem-
pering mode. Secondly, the tempering mode is only allowed
when the rooftop is configured for staged gas (Configuration
 
HEAT HT.CF=3).
If the control is configured for staged gas, the control is in a
vent, low cool, or high cool HVAC mode, and the rooftop con-
trol is in a situation where the economizer must maintain a
minimum position, then the evaporator discharge temperature
(EDT) will be monitored. If the EDT falls below a particular
trip point then the tempering mode may be called out:
HVAC mode = "Tempering Vent"
HVAC mode = "Tempering LoCool"
HVAC mode = "Tempering HiCool"
The decision making/selection process for the tempering
trip setpoint is as follows:
• If an HVAC cool mode is in effect, then the vent trip point is
T.CL.
• If in a pre-occupied purge mode (Operating Modes

MODE IAQ.P=ON), then the trip point is T.PRG.
• If in an occupied mode (Operating Modes

IAQ.P=ON), then the trip point is T.V.OC.
• For all other cases, the trip point is T.V.UN.
NOTE: The unoccupied economizer free cooling mode does
not qualify as a HVAC cool mode as it is an energy saving
feature and has its own OAT lockout already. The unoccupied
free cooling mode (HVAC mode = Unocc. Free Cool) will
override any unoccupied vent mode from triggering a temper-
ing mode.
If OAT is above the chosen tempering setpoint, tempering
will not be allowed. Additionally, tempering mode is locked
out if any stages of mechanical cooling are present.
A minimum amount of time must pass before calling out
any tempering mode. In effect, the EDT must fall below
the trip point value –1° F continuously for a minimum of
2 minutes. Also, at the end of a mechanical cooling cycle, there
must be a minimum 10 minutes of delay allowed before con-
sidering tempering during vent mode in order to allow any
residual cooling to dissipate from the evaporator coil.
If the above conditions are met, the algorithm is free to
select the tempering mode (MODETEMP). If a tempering
mode becomes active, the modulating heat source (staged gas)
will attempt to maintain leaving-air temperature (LAT) at the
tempering setpoint used to trigger the tempering mode. The
technique for modulation of setpoint for staged gas and
hydronic heat is the same as in a heat mode. More information
regarding the operation of heating can be referenced in the
Heating Control section.
Recovery from a tempering mode (MODETEMP) will
occur when the EDT rises above the trip point. On any change
in HVACMODE, the tempering routine will re-assess the
tempering setpoint which may cause the control to continue or
exit tempering mode.
53
CCN
RANGE UNITS DEFAULT
POINT
–20-80 dF TEMPPURG 50
5-75 dF TEMPCOOL 5
–20-80 dF TEMPVOCC 65
–20-80 dF TEMPVUNC 50


MODE