Controls, Start-Up, Operation, Service and ... - Climayoreo
Controls, Start-Up, Operation, Service and ... - Climayoreo
Controls, Start-Up, Operation, Service and ... - Climayoreo
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Limit Switch Low Temp (SW.L.T) — This configuration is<br />
the temperature limit above which no additional stages of heat<br />
will be allowed.<br />
Heat Control Prop. Gain (HT.P) — This configuration is the<br />
proportional term for the PID which runs in the HVAC mode<br />
LOW HEAT.<br />
Heat Control Derv. Gain (HT.D) — This configuration is the<br />
derivative term for the PID which runs in the HVAC mode<br />
LOW HEAT.<br />
Heat PID Rate Config (HT.TM) — This configuration is the<br />
PID run time rate.<br />
Staged Gas Heating Logic<br />
If the HVAC mode is HIGH HEAT:<br />
• The supply fan for staged gas heating is controlled by the<br />
48P integrated gas control (IGC) boards <strong>and</strong> unless the<br />
supply fan is on for a different reason, will be controlled<br />
by the IGC IFO input.<br />
• Comm<strong>and</strong> all stages of heat ON<br />
If the HVAC mode is LOW HEAT:<br />
• The supply fan for staged gas heating is controlled by the<br />
integrated gas control (IGC) boards <strong>and</strong> unless the<br />
supply fan is on for a different reason, will be controlled<br />
by the IGC IFO input.<br />
• The unit will control stages of heat to the heating control<br />
point (Run StatusVIEWHT.C.P). The heating control<br />
point in a LOW HEAT HVAC mode for staged gas is<br />
the heating supply air set point (SetpointsSA.HT).<br />
Staged Gas Heating PID Logic — The heat control loop is a<br />
PID design with exceptions, overrides <strong>and</strong> clamps. Capacity<br />
rises <strong>and</strong> falls based on set point <strong>and</strong> supply-air temperature.<br />
When the staged gas control is in Low Heat or Tempering<br />
Mode (HVAC mode), the algorithm calculates the desired heat<br />
capacity. The basic factors that govern the controlling technique<br />
are:<br />
• how frequently the algorithm is run.<br />
• the amount of proportional <strong>and</strong> derivative gain applied.<br />
• the maximum allowed capacity change each time this<br />
algorithm is run.<br />
• deadb<strong>and</strong> hold-off range when rate is low.<br />
This routine is run once every “HT.TM” seconds. Every<br />
time the routine is run, the calculated sum is added to the control<br />
output value. In this manner, integral effect is achieved.<br />
Every time this algorithm is run, the following calculation is<br />
performed:<br />
Error = HT.C.P – LAT<br />
Error_last = error calculated previous time<br />
P = HT.P*(Error)<br />
D = HT.D*(Error – Error_last)<br />
The P <strong>and</strong> D terms are overridden to zero if:<br />
Error < S.G.DB AND Error > – S.G.DB AND D < M.R.DB<br />
AND D > – M.R.DB.<br />
Table 44 — Staged Gas Configuration<br />
61<br />
“P + D” are then clamped based on CAP.M. This sum can be<br />
no larger or no smaller than +CAP.M or –CAP.M.<br />
Finally, the desired capacity is calculated:<br />
Staged Gas Capacity Calculation = “P + D” + old Staged Gas<br />
Capacity Calculation.<br />
NOTE: The PID values should not be modified without<br />
approval from Carrier.<br />
IMPORTANT: When gas or electric heat is used in a VAV<br />
application with third party terminals, the HIR relay output<br />
must be connected to the VAV terminals in the system in<br />
order to enforce a minimum heating cfm. The installer is<br />
responsible to ensure the total minimum heating cfm is not<br />
below limits set for the equipment. Failure to do so will<br />
result in limit switch tripping <strong>and</strong> may void warranty.<br />
Staged Gas Heat Staging — Different unit sizes will control<br />
heat stages differently based on the amount of heating capacity<br />
included. These staging patterns are selected based on the<br />
model number. The selection of a set of staging patterns is controlled<br />
via the heat stage type configuration parameter (HT.ST).<br />
As the heating capacity rises <strong>and</strong> falls based on dem<strong>and</strong>, the<br />
staged gas control logic will stage the heat relay patterns up <strong>and</strong><br />
down, respectively. The Heat Stage Type configuration selects<br />
one of the staging patterns that the stage gas control will use. In<br />
addition to the staging patterns, the capacity for each stage<br />
is also determined by the staged gas heating PID control.<br />
Therefore, choosing the heat relay outputs is a function of the<br />
capacity desired, the heat staging patterns based on the heat<br />
stage type (HT.ST) <strong>and</strong> the capacity presented by each staging<br />
pattern. As the staged gas control desired capacity rises, it is<br />
continually checked against the capacity of the next staging<br />
pattern.<br />
When the desired capacity is greater than or equal to the<br />
capacity of the next staging pattern, the next heat stage is selected<br />
(Run StatusVIEWHT.ST = Run StatusVIEW<br />
HT.ST + 1). Similarly, as the capacity of the control drops, the<br />
desired capacity is continually checked against the next lower<br />
stage. When the desired capacity is less than or equal to the<br />
next lower staging pattern, the next lower heat stage pattern<br />
is selected (Run StatusVIEWHT.ST = Run Status<br />
VIEW HT.ST – 1). The first two staged gas heat outputs<br />
are located on the MBB board <strong>and</strong> outputs 3, 4, 5, <strong>and</strong> 6 are<br />
located on the SCB board. These outputs are used to yield from<br />
2 to 9 stages as shown in Table 45. The heat stage selected<br />
(Run StatusVIEWHT.ST) is clamped between 0 <strong>and</strong> the<br />
maximum number of stages possible (Run StatusVIEW<br />
H.MAX) for the chosen set of staging patterns. See<br />
Tables 46-48.<br />
ITEM EXPANSION RANGE UNITS CCN POINT DEFAULT<br />
SG.CF STAGED GAS CONFIGS<br />
HT.ST Staged Gas Heat Type 0 - 4 HTSTGTYP 0*<br />
CAP.M Max Cap Change per Cycle 5 - 45 HTCAPMAX 45*<br />
M.R.DB S.Gas DB min.dF/PID Rate 0 - 5 HT_MR_DB 0.5<br />
S.G.DB St.Gas Temp. Dead B<strong>and</strong> 0 - 5 ^F HT_SG_DB 2<br />
RISE Heat Rise dF/sec Clamp 0.05 - 0.2 HTSGRISE 0.06<br />
LAT.L LAT Limit Config 0 - 20 ^F HTLATLIM 10<br />
LIM.M Limit Switch Monitoring? Yes/No HTLIMMON Yes<br />
SW.H.T Limit Switch High Temp 110 - 180 dF HT_LIMHI 170*<br />
SW.L.T Limit Switch Low Temp 100 - 170 dF HT_LIMLO 160*<br />
HT.P Heat Control Prop. Gain 0 - 1.5 HT_PGAIN 1<br />
HT.D Heat Control Derv. Gain 0 - 1.5 HT_DGAIN 1<br />
HT.TM Heat PID Rate Config 60 - 300 sec HTSGPIDR 90<br />
*Some configurations are model number dependent.