51
Table 49 — Heating Configuration
*Some defaults are model number dependent.
Fan-Off Delay, Gas Heat (G.FOD)
This configuration is the delay in seconds, after a gas heat
mode has ended (
HT.CF
=2,3
) that the control will continue to
energize the supply fan.
Fan-Off Delay, Elec Heat (E.FOD)
This configuration is the delay in seconds, after an electric heat
mode has ended (
HT.CF
=1
) that the control will continue to
energize the supply fan.
HEAT MODE SELECTION PROCESS
There are two possible heat modes that the control will call out
for heating control: HVAC Mode = LOW HEAT and HVAC
Mode = HIGH HEAT. These modes will be called out based on
control type (
C.TYP
).
VAV-RAT (C.TYP = 1) and VAV-SPT (C.TYP = 2)
There is no difference in the selection of a heating mode for either
VAV-RAT or VAV-SPT, except that for VAV-SPT, space tempera-
ture is used in the unoccupied period to turn on the supply fan for
10 minutes before checking return-air temperature. The actual se-
lection of a heat mode, LOW or HIGH for both control types, will
be based upon the controlling return-air temperature.
With sufficient heating demand, there are still conditions that
will prevent the unit from selecting a heat mode. First, the unit
must be configured for a heat type (
Configuration
HEAT
HT.CF
not equal to “NONE”). Second, the unit has a con-
figuration which can enable or disable heating in the occupied
period except for a standard morning warm-up cycle (
Configu-
ration
HEAT
OC.EN
). (Morning warm up is a Linkage
function.) See descriptions in the Setting Up the System sec-
tion for more information.
If the unit is allowed to select a heat mode, then the next step is an
evaluation of demand versus setpoint. At this point, the logic is the
same as for control types SPT Multi-Stage and SPT-2 Stage,
(
C.TYP
= 5,6) except for the actual temperature compared against
setpoint. See Temperature Driven Heat Mode Evaluation
section.
Tstat-Multi-Stage (C.TYP=3) and Tstat-Multi-Stage2 (C.TYP=4)
There is no difference in the selection of a heat mode between
the control types TSTAT multi-stage2 or TSTAT multi-stage.
These selections only refer to how cooling will be handled.
With thermostat control the W1 and W2 inputs determine
whether the HVAC Mode is LOW or HIGH HEAT.
With thermostat control the W1 and W2 inputs determine
whether the HVAC Mode is LOW or HIGH HEAT.
W1 = ON, W2 = OFF: HVAC MODE = LOW HEAT*
W2 = ON, W2 = ON: HVAC MODE = HIGH HEAT
* If W2 = ON and W1 is OFF, a “HIGH HEAT” HVAC Mode will be called
out but an alert (T422) will be generated. See Alarms and Alerts on
page 101.
SPT Multi-Stage (C.TYP = 5) and SPT Multi-Stage2
(C.TYP = 6)
There is no difference in the selection of a heat mode between the
control types SPT Multi-Stage2 or SPT multi-stage. For a valid
heating type selected (
HT.CF
not equal to zero) the unit is free to
select a heating mode based on space temperature (SPT).
If the unit is allowed to select a heat mode, then the next step is an
evaluation of demand versus setpoint. At this point, the logic is the
same as for control types VAV-RAT and VAV-SPT (
C.TYP
= 1,2),
except for the actual temperature compared against setpoint. See
Temperature Driven Heat Mode Evaluation
section.
TEMPERATURE DRIVEN HEAT MODE EVALUATION
This section discusses the control method for selecting a heating
mode based on temperature. Regardless of whether the unit is con-
figured for return air or space temperature, the logic is exactly the
same. For the rest of this discussion, the temperature in question
will be referred to as the “controlling temperature.”
First, the occupied and unoccupied heating setpoints under
Set-
points
must be configured.
Then, the heat/cool setpoint offsets under
Configuration
D.LV.T
should be set. See Table 50.
Related operating modes are under
Operating Modes
MODE
.
The first thing the control determines is whether the unit is in
the occupied mode (
OCC
) or in the temperature compensated
start mode (
T.C.ST
). If the unit is occupied or in temperature
compensated start mode, the occupied heating setpoint
(
OHSP
) is used. In all other cases, the unoccupied heating set-
point (
UHSP
) is used.
The control will call out a low or high heat mode by comparing
the controlling temperature to the heating setpoint and the heating
setpoint offset. The setpoint offsets are used as additional help in
customizing and tweaking comfort into the building space.
Demand Level Low Heat on Offset (L.H.ON)
This is the heating setpoint offset below the heating setpoint at
which point Low Heat starts.
ITEM
EXPANSION
RANGE
UNITS
CCN POINT
DEFAULT
HEAT
HEATING CONFIGURATION
HT.CF
Heating Control Type
0 to 3
HEATTYPE
0*
HT.SP
Heating Supply Air Setpt
80 to 120
dF
SASPHEAT
85
OC.EN
Occupied Heating Enabled
Yes/No
HTOCCENA
No
LAT.M
MBB Sensor Heat Relocate
Yes/No
HTLATMON
No
G.FOD
Fan Off Delay, Gas Heat
45 to 600
sec
GAS_FOD
45
E.FOD
Fan Off Delay, Elec Heat
10 to 600
sec
ELEC_FOD
30
SG.CF
STAGED GAS CONFIGS
HT.ST
Staged Gas Heat Type
0 to 4
HTSTGTYP
0*
CAP.M
Max Cap Change per Cycle
5 to 45
HTCAPMAX
45*
M.R.DB
S.Gas DB min.dF/PID Rate
0 to 5
HT_MR_DB
0.5
S.G.DB
St.Gas Temp. Dead Band
0 to 5
^F
HT_SG_DB
2
RISE
Heat Rise dF/sec Clamp
0.05 to 0.2
HTSGRISE
0.06
LAT.L
LAT Limit Config
0 to 20
^F
HTLATLIM
10
LIM.M
Limit Switch Monitoring?
Yes/No
HTLIMMON
Yes
SW.H.T
Limit Switch High Temp
110 to 180
dF
HT_LIMHI
170*
SW.L.T
Limit Switch Low Temp
100 to 170
dF
HT_LIMLO
160*
HT.P
Heat Control Prop. Gain
0 to 1.5
HT_PGAIN
1
HT.D
Heat Control Derv. Gain
0 to 1.5
HT_DGAIN
1
HT.TM
Heat PID Rate Config
60 to 300
sec
HTSGPIDR
90
ITEM
EXPANSION
RANGE UNITS
CCN
POINT
DEFAULT
OHSP
Occupied Heat Setpoint 55 to 80 dF
OHSP
68
UHSP
Unoccupied Heat Set-
point
40 to 80 dF
UHSP
55
ITEM
EXPANSION
RANGE
CCN POINT
MODE
MODES CONTROLLING UNIT
OCC
Currently Occupied
ON/OFF
MODEOCCP
T.C.ST
Temp.Compensated Start
ON/OFF
MODETCST
Summary of Contents for WEATHERMAKER 48A2020
Page 112: ...112 Fig 20 Typical Main Control Box Wiring Schematic 48 50A Units ...
Page 113: ...113 Fig 21 Typical Auxiliary Control Box Wiring Schematic ...
Page 114: ...114 Fig 22 Typical 2 Stage Gas Heat Wiring Schematic Size 060 Units Shown ...
Page 115: ...115 Fig 23 Typical Staged Gas Heat Wiring Schematic Size 060 Units Shown TO NEXT PAGE ...
Page 116: ...116 Fig 23 Typical Staged Gas Heat Wiring Schematic Size 060 Units Shown cont ...
Page 117: ...117 Fig 24 Typical Electric Heat Control Schematic 50 Series Size 060 Units Shown ...
Page 118: ...118 Fig 25 Typical Controls Option Wiring Schematic SW1 SW2 OR DEHUMIDIFY SWITCH ...
Page 119: ...119 Fig 26 Typical Power Schematic 48 50A2 A3 A4 A5 060 Unit Shown ...
Page 120: ...120 Fig 27 Typical Power Schematic of Greenspeed Low Ambient Option 48 50A 060 Unit Shown ...
Page 121: ...121 Fig 28 Typical Small Chassis Component Location Size 020 035 Units ...
Page 122: ...122 Fig 29 Typical Large Chassis Component Locations Size 040 060 Units ...
Page 185: ...185 APPENDIX C VFD INFORMATION cont Fig F Internal Enclosure Fan Replacement A48 7716 ...