Slant/Fin VGH-299-CH, Installation And Service Manual

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E93.1601EN032.C VGH installation manual 31
8.4.1 D
ELTA TEMPERATURE MODULATION
When the modulating circulator mode 1 Delta temperature modulation is selected the circulator modulates to
create a delta of T_Delta between the T_Supply and T_Return sensors. This modulation is only done when the
control is in burn.
When the boiler starts the duty cycle is kept at the Default Duty cycle setting for the time set by Burn Stabilize
Time. After this time, the PID calculated duty cycle is used.
During modulation, the duty cycle output changes according to the following logic:
• Actual delta temperature is greater than the selected T_Delta
• The circulator speed increases so there is less time to cool down the heated water. This results in the T_Return
temperature increasing.
• Actual delta temperature is smaller than the selected T_Delta
• The circulator speed decreases so there is more time to cool down the heated water. This results in the T_Return
temperature decreasing.
8.4.2 PID
CALCULATION SCALING
For a better burner modulation, the modulating circulator PID calculation interval is slower when the T_Supply
sensor is close to the actual CH supply setpoint.
The temperature range in which this is limited is set by the PID Scaling Range parameter. When the T_Supply
sensor is outside this range the PID calculation is performed every 100 ms. When the T_Supply sensor
temperature is at its setpoint the PID calculation is performed every 1000 ms.
In the range set by the PID Scaling Range parameter the PID calculation speed is scaled in a linear way.
Circulator: maximum electrical power
General
- The inrush current of a conventional circulator is approximately 2½ x its nominal current.
- The maximum switch current of the PCB is 4 A.
- The total current of pcb and gas valve is approx. 0.5 A. All field supplied circulators and valves for the boiler
loop, DHW, and the system that are connected to the boiler may not exceed 3.5 amps. Use separate relays if
higher currents are needed. The fan is separately connected to the main supply and has a fuse of 3.15 Amps.
Circulator P1 - boiler circulator.
This circulator is NOT part of the appliance. The maximum combined current for the boiler loop pump and any
additional pumps and valves may not exceed 2 amps.
Circulator P2 - calorifier circulator.
Circulator P2 is a DHW indirect tank circulator, meaning it’s not part of the appliance. The maximum combined
current for the indirect tank pump and any additional pumps and valves may not exceed 2 amps.
3-way valve.
The combined nominal current of circulator P1 and the 3-way valve may not exceed 2 amps
.
Circulator P3 - system circulator.
The maximum combined current of circulator P3 and the other connected circulators may not exceed 2 amps.
Warning (ECM circulators):
When using an ECM circulator, it cannot be powered directly by the boiler. Use a relay to isolate the boiler from
the circulator.
To all outputs following applies: maximum current 2 A each output.
Total output of all currents combined maximum 3.5 A.
The inrush current of the 3-way valve and/or circulators is maximum 8 A.
WARNING : Use an external relay if nominal circulator currents exceeds 2 Amp.
NOTICE