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Minimum required circulator head.
The design flow of the boiler should be between a delta T of 20 °F and a delta T of 40°F at high fire depending
boiler model and near boiler piping. When utilizing properly designed primary secondary piping the internal boiler
circulator is sized to provide the required flow for the given model. To calculate the minimum required circulator
head and flow for a specific Delta T, take the resistance of the boiler and add the resistance of the boiler loop
piping to make a good design. The Slant/Fin plumbing kit has a minimal pressure drop equivalent to less than 1
foot of head. If a smaller delta T is desired than the built-in boiler circulator can provide an external circulator can
be added in the field external to the boiler in line with the boiler circulator on the return.
ΔT = 20 °F
VGH-80-CH / VGH-90-CO
VGH-100-CH
VGH-120-CH / VGH-150-CO
VGH-150-CH
VGH-180-CH / VGH-200-CO
ΔT = 40 °F
VGH-80-CH / VGH-90-CO
VGH-100-CH
VGH-120-CH / VGH-150-CO
VGH-150-CH
VGH-180-CH / VGH-200-CO
Modulating circulator for CH demand
The VGH boiler is provided with an internal circulator which can be switched on or off. The internal circulator is set
to speed settings 3 and this must never be changed. If the required flow is too low, an external circulator can be
installed by connecting the external circulator to the PWM circulator connection (see paragraph 10.3.1).
The control supports PWM modulation for the general circulator. Parameter 136 has to be set to modulating
(Factory set to on/off circulator) when using a modulating circulator. With this parameter the speed of the external
modulator must be set. The boiler circulator is modulated when there is a demand for CH.
During any other demand, the PWM circulator will run at a fixed speed set by the Default Duty cycle parameter.
How the circulator is modulated is controlled with the Modulating_Pump_Mode setting.
Modulating circulator modes
There are several modulating circulator modes implemented in the software. By selecting a different modulating
circulator mode, the circulator behavior can be changed. The following modulating circulator modes are available.
Modulating circulator mode
0
Disabled
1
Delta temperature
modulation
2
Fixed 20% speed
3
Fixed 30% speed
4
Fixed 40% speed
5
Fixed 50% speed
6
Fixed 60% speed
7
Fixed 70% speed
8
Fixed 80% speed
9
Fixed 90% speed
10
Fixed 100% speed
50
Minimum required flow
gal/min
7.60
9.50
11.40
14.25
17.10
Minimum required flow
gal/min
3.8
4.76
5.73
7.14
8.57
Details
No circulator modulation; the PWM duty cycle is always 0%
Calculated duty cycle to create a delta temperature between the
T_Supply and T_Return sensor
Fixed duty cycle of 20%
Fixed duty cycle of 30%
Fixed duty cycle of 40%
Fixed duty cycle of 50%
Fixed duty cycle of 60%
Fixed duty cycle of 70%
Fixed duty cycle of 80%
Fixed duty cycle of 90%
Fixed duty cycle of 100%
E93.1901EN032 Installation and Service Manual SlantFin VGH-CH / CO
Pressure drop boiler including
Slant/Fin plumbing kit
3
m
/h
ft.W.C.
1.73
27.3
2.16
36.6
2.59
26.2
3.24
48.6
3.88
69.4
Pressure drop boiler including
Slant/Fin plumbing kit
3
m
/h
ft.
0.86
6.83
1.08
10.00
1.30
7.89
1.62
12.16
1.95
17.42
Table 8.3
m.W.C.
8.3
11.2
8.0
14.8
21.2
Table 8.1
m.W.C.
2.1
3.0
2.4
3.8
5.3
Table 8.2
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