Table of Contents
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ITEM
SG.CF
STAGED HEAT CONFIGS
HT.ST
Staged Heat Type
CAP.M
Max Cap Change per Cycle
M.R.DB
St.Ht DB min.dF/PID Rate
S.G.DB
St.Heat Temp. Dead Band
RISE
Heat Rise dF/sec Clamp
LAT.L
LAT Limit Config
LIM.M
Limit Switch Monitoring?
SW.H.T
Limit Switch High Temp
SW.L.T
Limit Switch Low Temp
HT.P
Heat Control Prop. Gain
HT.D
Heat Control Derv. Gain
HT.TM
Heat PID Rate Config
NOTE(S):
a. Some configurations are model number dependent.
Table 47 — Staged Gas Heat
NUMBER OF
HT.ST
STAGES
CONFIGURATION
2
0
5
1
9
2
Table 48 — Modulating Gas Heat
NUMBER OF
HT.ST
STAGES
CONFIGURATION
1
3
3
4
6
5
St.Ht DB Min.dF/PID Rate (M.R.DB)
This configuration is deadband minimum temperature per second
rate. See capacity calculation logic on this page for more details.
St.Heat Temp.Dead Band (S.G.DB)
This configuration is a deadband delta temperature. See capacity
calculation logic on this page for more details.
Heat Rise in dF/Sec Clamp (RISE)
This configuration clamps heat staging up when the leaving-air
temperature is rising too fast.
LAT Limit Config (LAT.L)
This configuration senses when leaving air temperature is outside
a delta temperature band around set point and allows staging to
react quicker.
Limit Switch Monitoring? (LIM.M)
This configuration allows the operation of the limit switch moni-
toring routine. This is always enabled for 48P Series as a limit
switch temperature sensor is always present for staged and modu-
lating gas operation. It is not used on SCR electric heat units.
Limit Switch High Temp (SW.H.T)
This configuration is the temperature limit above which stages of
heat will be shed.
Limit Switch Low Temp (SW.L.T)
This configuration is the temperature limit above which no addi-
tional stages of heat will be allowed.
Heat Control Prop. Gain (HT.P)
This configuration is the proportional term for the PID which runs
in the HVAC mode LOW HEAT.
Heat Control Derv. Gain (HT.D)
This configuration is the derivative term for the PID which runs in
the HVAC mode LOW HEAT.
Table 46 — Staged Heat Configuration
EXPANSION
UNIT SIZE
HEAT SIZE
48P
030-050
Low
030-050
High
055-100
Low
055-100
High
UNIT SIZE
HEAT SIZE
48P
030-050
Low
030-050
High
055-100
Low
055-100
High
RANGE
UNITS
0 to 8
HTSTGTYP
5 to 45
HTCAPMAX
0 to 5
HT_MR_DB
0 to 5
^F
HT_SG_DB
0.05 to 0.2
HTSGRISE
0 to 20
^F
HTLATLIM
Yes/No
HTLIMMON
80 to 210
dF
HT_LIMHI
80 to 210
dF
HT_LIMLO
0 to 1.5
HT_PGAIN
0 to 1.5
HT_DGAIN
30 to 300
sec
HTSGPIDR
Heat PID Rate Config (HT.TM)
This configuration is the PID run time rate.
Staged Heating Logic
If the HVAC mode is HIGH HEAT:
•
On 48P units, the supply fan for staged heating is controlled
by the integrated gas control (IGC) boards and, unless the
supply fan is on for a different reason, will be controlled by
the IFO. On 50P units, the fan is ON whenever heat is ON.
•
Command all stages of heat ON.
If the HVAC mode is LOW HEAT:
•
On 48P units, the supply fan for staged and modulating gas
heating is controlled by the integrated gas control (IGC)
boards and, unless the supply fan is on for a different rea-
son, will be controlled by the IGC IFO input. On 50P
units, the fan is ON whenever the heat is ON.
•
The unit will control stages of heat to the heating control
point (Run Status
point in a LOW HEAT HVAC mode for staged heat is the
heating supply air set point (Setpoints
Staged Heating PID Logic
The heat control loop is a PID design with exceptions, overrides,
and clamps. Capacity rises and falls based on set point and supply-
air temperature. When the ComfortLink control is in Low Heat or
Tempering Mode (HVAC mode), the algorithm calculates desired
heat capacity. Basic factors governing the control technique are:
•
How frequently the algorithm is run.
•
The amount of proportional and derivative gain applied.
•
The maximum allowed capacity change each time this algo-
rithm is run.
•
Deadband hold-off range when rate is low.
This routine is run once every "HT.TM" seconds. Every time the
routine is run, the calculated sum is added to the control output
value. In this manner, integral effect is achieved. Every time this
algorithm is run, the following calculation is performed:
Error = HT.C.P – LAT
Error_last = error calculated previous time
P = HT.P*(Error)
D = HT.D*(Error – Error_last)
The P and D terms are overridden to zero if:
Error < S.G.DB AND Error > – S.G.DB AND D < M.R.DB AND
D > – M.R.DB.
"P + D" are then clamped based on CAP.M. This sum can be no
larger or no smaller than +CAP.M or –CAP.M.
67
CCN POINT
DEFAULT
0
a
45
a
0.5
2
0.06
10
Yes
170
a
160
a
1
1
90
a
VIEW
HT.C.P). The heating control
SA.HT).
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