Table of Contents
Advertisement
Finally, the desired capacity is calculated:
Staged Heat Capacity Calculation = "P + D" + old Staged Heat
Capacity Calculation.
NOTE: The PID values should not be modified without approval
from Carrier.
IMPORTANT: When gas or electric heat is used in a VAV appli-
cation with third-party terminals, the HIR relay output must be
connected to the VAV terminals in the system in order to enforce
a minimum heating cfm. The installer is responsible to ensure
the total minimum heating cfm is not below limits set for the
equipment. Failure to do so will result in limit switch tripping
and may void warranty.
Staged Gas Heat Staging
Different unit sizes will control heat stages differently based on
the amount of heating capacity included. These staging patterns
are selected based on the unit model number. The selection of a set
of staging patterns is controlled via the heat stage type configura-
tion parameter Configuration
ting HT.ST to 0, 1, or 2 configures the unit for Staged Gas Heat.
The selection of HT.ST = 0, 1, or 2 is based on the unit size and
heat size. See Table 47.
As the heating capacity rises and falls based on demand, the
staged gas control logic will stage the heat relay patterns up and
down respectively. The Heat Stage Type configuration selects the
staging pattern that the staged gas control will use. In addition to
the staging patterns, the capacity for each stage is also determined
by the staged gas heating PID algorithm. Therefore, choosing the
heat relay outputs is a function of the capacity desired, the avail-
able heat staging patterns configured with heat stage type
(HT.ST), and the capacity presented by each staging pattern.
As the staged gas control desired capacity rises, it is continually
checked against the capacity of the next staging pattern. When the
desired capacity is greater than or equal to the capacity of the next
staging pattern, the next heat stage is selected (Run Status
VIEW
HT.ST = Run Status
Similarly, as the staged gas control desired capacity drops, it is
continually checked against the next lower stage. When the de-
sired capacity is less than or equal to the next lower staging pat-
tern, the next lower staging pattern is selected (Run Status
VIEW
HT.ST = Run Status
The first two staged gas heat outputs are located on the MBB. Out-
puts 3, 4, 5, and 6 are located on the SCB. These outputs are used
to yield from 2 to 9 stages as shown in Table 47. The heat stage se-
lected (Run Status
VIEW
the maximum number of stages possible (Run Sta-
tus
VIEW
H.MAX). See Tables 49-51.
Modulating Gas Heat Staging
Different unit sizes will control heat stages differently based on
the amount of heating capacity included. These staging patterns
are selected based on the unit model number. The selection of a set
of staging patterns is controlled via the heat stage type configura-
tion parameter Configuration→HEAT→ SG.CF→HT.ST. Set-
ting HT.ST to 3, 4, or 5 configures the unit for Modulating Gas
Heat. The selection of HT.ST = 3, 4, or 5 is based on the unit size
and heat size. See Table 48.
As the heating capacity rises and falls based on demand, the mod-
ulating gas control logic will stage the heat relay patterns up and
down respectively (Run Status→VIEW→HT.ST) and set the ca-
pacity of the Modulating Gas section (Outputs→ HEAT→
H1.CP). The Heat Stage Type configuration selects one of the
HEAT
SG.CF
HT.ST. Set-
VIEW
HT.ST +1).
VIEW
HT.ST –1).
HT.ST) is clamped between 0 and
staging patterns that the modulating gas control will use. In addi-
tion to the staging patterns, the capacity for each stage is also de-
termined by the modulating gas heating PID algorithm. Therefore,
choosing the heat relay outputs and setting the modulating gas sec-
tion capacity is a function of the capacity desired, the available
heat staging patterns configured with heat stage type (HT.ST), and
the capacity range presented by each staging pattern.
As the modulating gas control desired capacity rises, it is continu-
ally checked against the capacity ranges of the next higher staging
patterns. Since each stage has a range of capacities, and the capac-
ities of some stages overlap, the control selects the highest stage
with sufficient minimum capacity.
Similarly, as the modulating gas control desired capacity drops, it
is continually checked against the capacity ranges of the next low-
er stages. The control selects the lowest stage with sufficient max-
imum capacity.
The first two modulating gas heat outputs are located on the MBB.
Outputs 3, 4, 5, 6, and the analog output that sets the modulating
gas section capacity are located on the SCB. The heat stage select-
ed (Run Status→VIEW→HT.ST) is clamped between 0 and the
maximum number of stages possible (Run Status→ VIEW→
H.MAX). See Tables 52-54.
SCR Electric Heat Staging
Different unit sizes will control heat stages differently based on
the amount of heating capacity included. These staging patterns
are selected based on the unit model number. The selection of a set
of staging patterns is controlled via the heat stage type configura-
tion parameter Configuration→HEAT→SG.CF→HT.ST. Set-
ting HT.ST to 6, 7 or 8 configures the unit for SCR Electric Heat.
The selection of HT.ST = 6, 7 or 8 is based on the unit size and
heat size. See Table 55.
For HT.ST=6 there is only 1 heat stage. Whenever the heat is ener-
gized, all heaters will be active will be modulated through the
SCR control.
On 2 stage heat patterns (HT.ST=7 or 8), as the heating capacity
rises and falls based on demand, the SCR electric heat control log-
ic will stage the heat relay patterns up and down respectively (Run
Status→VIEW→HT.ST) and set the capacity of the SCR Electric
Heat section (Outputs→HEAT→H1.CP). The Heat Stage Type
configuration selects one of the staging patterns that the SCR elec-
tric heat control will use. In addition to the staging patterns, the ca-
pacity for each stage is also determined by the SCR electric heat-
ing PID algorithm.
Therefore, choosing the heat relay outputs and setting the SCR
electric heat section capacity is a function of the capacity desired,
the available heat staging patterns configured with heat stage type
(HT.ST), and the capacity range presented by each staging pattern.
As SCR electric heat control desired capacity rises, it is continual-
ly checked against the capacity ranges of the next higher staging
patterns. Since each stage has a range of capacities, and the capac-
ities of some stages overlap, the control selects the highest stage
with sufficient minimum capacity.
Similarly, as the SCR electric heat control desired capacity drops,
it is continually checked against the capacity ranges of the next
lower stages. The control selects the lowest stage with sufficient
maximum capacity.
The electric heat outputs are located on the MBB. The analog out-
put that sets the SCR electric heat section capacity is located on
the SCB. The heat stage selected (Run Status→ VIEW→HT.ST)
is clamped between 0 and the maximum number of stages possi-
ble (Run Status→VIEW→H.MAX). See Tables 56-58.
68
Advertisement
Table of Contents
Troubleshooting
