Dhw Storage With Thermostat; Dhw Mode 2 - Slant/Fin VHG-100-CH Installation And Service Manual

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
0 → Time
1 → OFF
2 → ON
Default DHW_Priority is set to 2 (ON).
Table 11.16
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
DHW_Mode
DHW__Store_Setpoint
sets the desired DHW temperature
DHW_Store_Hyst_Down
Point where boiler starts for heat
demand = setpoint – hysteresis
DHW_Supp_Hyst_Up
Boiler stops firing when setpoint +
hysteresis up is reached
DHW_Store_Supply_Extra
increases the supply temperature to the
storage until DHW-Store_Setpoint plus
DHW_Store_Supply_Extra
Table 11.17
Status Variables
DHW control state
Central Heating controller state
Table 11.18
DHW S
TORAGE WITH THERMOSTAT
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.
104
Description
DHW has priority to CH during DHW_Max_Priority_Time
CH always has priority to DHW
DHW always has priority to CH
Display
menu #
PB 01
PB 115
PB 36
PB 37
PB 38
; DHW
E93.1901EN032 Installation and Service Manual SlantFin VGH-CH / CO
Level
Installer
User
Installer
Installer
Installer
Value
0  Idle
1  Request
2  Demand
3  Post circulation
4  Off
2
MODE
(Default) Range
Value
0 0, 1, 2, 3, 4, 5, 6, 7, 8
104 ... 160 °F
122ºF
(50 ºC) (40....71 °C)
0 ... 36 °F
7.2ºF
4 ºC) (0....20 °C)
0 ... 36 °F
5.4ºF
3 ºC) (0....20 °C)
27 °F 0... 54 °F
(15 °C) (0...30 °C)