Slant/Fin VHG-100-CH, Installation And Service Manual

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104
E93.1901EN032 Installation and Service Manual SlantFin VGH-CH / CO
DHW Priority
Standard DHW demand has priority ( PB: 43 ) over CH demand but the priority period is limited up to
DHW_Max_Priority_Time ( PB43 ). The priority timer starts when both CH and DHW demand are present. After
the DHW_Max_Priority_Time is achieved, the control will switch from DHW to CH operation. CH has priority now
for a maximum period of DHW_Max_Priority_Time.
DHW priority Description
0
→
Time DHW has priority to CH during DHW_Max_Priority_Time
1
→
OFF CH always has priority to DHW
2
→
ON DHW always has priority to CH
Default DHW_Priority is set to 2 (ON).
Store warm hold function
Because of the presence of the indirect tank sensor ( T_Store ) the control can detect demand for holding the indirect
tank hot. If T_Store drops below DHW_Store_Setpoint minus DHW_Store_Hold_Warm the boiler starts at
minimum power. The boiler stops if T_Store is higher than DHW_Store_Setpoint plus DHW_Store_Hyst_Up .
Relevant variables
Specific Parameters Display
menu # Level (Default)
Value Range
DHW_Mode PB 01 Installer 0 0, 1, 2, 3, 4, 5, 6, 7, 8
DHW__Store_Setpoint
sets the desired DHW temperature
PB 115 User 122
º
F
(50
º
C)
104
…
160
°
F
(40
…
.71
°
C)
DHW_Store_Hyst_Down
Point where boiler starts for heat
demand = setpoint
–
hysteresis
PB 36 Installer 7.2
º
F
4
º
C)
0
…
36
°
F
(0
…
.20
°
C)
DHW_Supp_Hyst_Up
Boiler stops firing when se
hysteresis up is reached
PB 37 Installer 5.4
º
F
3
º
C)
0
…
36
°
F
(0
…
.20
°
C)
DHW_Store_Supply_Extra
increases the supply temperature to the
storage until DHW-Store_Setpoint plus
DHW_Store_Supply_Extra
PB 38
Installer 27
°
F
(15
°
C)
0
…
54
°
F
(0
…
30
°
C)
Status Variables Value
DHW control state
Central Heating controller state
0

Idle
1

Request
2

Demand
3

Post circulation
4

Off
DHW S
TORAGE WITH THERMOSTAT
; DHW
MODE
2
This mode is only available for Heating Only boilers (VGH-CH).
In this mode DHW is prepared by warming up an indirect tank.
There is a 3-way valve is already in a Heating Only boiler and will be activated when this mode is used, connect
an indirect tank directly to the connections under the boiler.
The temperature of the DHW in the indirect tank is regulated by a thermostat/aquastat (instead of a sensor), which
must provide only an open/closed signal to the control.
When the thermostat/aquastat closes, the control detects a demand from the DHW indirect tank and starts the
DHW circulator.
If the supply temperature T_Supply drops below DHW_Store_Setpoint minus DHW_Supp_Hyst_Down the boiler
starts. When the boiler is ON the power is PID-controlled based on T_Supply toward DHW_Store_Setpoint.
The boiler is stopped when the supply temperature rises above DHW_Store_Setpoint plus DHW_Supp_Hyst_Up.
The demand for DHW ends when the indirect tank thermostat/aquastat opens. The circulator continues
DHW_Post_Circulator_Period after the DHW demand has stopped.
For DHW priority, see paragraph 11.10.3.
Table 11.16
Table 11.17
Table 11.18