Demand For Domestic Hot Water; No Domestic Hot Water; Dhw Mode 0; Dhw Storage With Sensor; Dhw Mode 1 - Slant/Fin VGH-299-CH Installation And Service Manual

Demand for Domestic Hot Water

12.9.1 N D H
O OMESTIC OT
No domestic hot water is available. The T_DHW_Out sensor does not need to be connected.
12.9.2 DHW S
TORAGE WITH SENSOR
Mode 1: DHW is prepared by warming up a store. Either a DHW circulator or 3-way valve can be used to switch
to DHW mode.
The DHW temperature in the tank is measured with sensor T_Store and set with parameter DHW_Store_Setpoint.
When this sensor drops below DHW_Store_Setpoint
demand for the store and starts the general and DHW circulator.
If the supply temperature T_Supply is below
DHW_Store_Setpoint plus
When the boiler is ON, the power is PID-modulated so T_Supply is regulated towards
DHW_Setpoint plus DHW_Store_Supply_Extra.
The boiler is stopped when the supply temperature rises above
DHW_Store_Setpoint plus
The demand for the tank is ended when the tank-sensor rises above
DHW_Store_Setpoint plus
DHW Priority
Standard DHW demand has priority over CH demand but the priority period is limited up to
DHW_Max_Priority_Time. 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.
Different DHW Priority types can be chosen:
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.
Table 12. 18
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
The boiler stops if T_Store is higher than DHW_Store_Setpoint
Relevant variables
Specific Parameters
DHW_Mode
DHW_Store_Setpoint Sets the desired DHW temperature.
DHW_Store_Supply_Extra
Increases the supply temperature to the store until
DHW_Store_Setpoint + DHW_Store_Supply_Extra.
Table 12. 19
Status Variables
DHW control state
Central Heating controller state
Table 12. 20
W ; DHW 0
ATER MODE
; DHW 1
MODE
DHW_Store_Supply_Extra
DHW_Store_Supply_Extra
DHW_Store_Hyst_Up. The circulator continues DHW_Post_Pump_Period.
minus DHW_Store_Hold_Warm the boiler starts at minimum power.
Level
2: Installer
1: User
2: Installer
E93.1601EN032.C VGH installation manual
minus DHW_Store_Hyst_Down the control detects a
minus DHW_Supp_Hyst_Down the boiler is started as well.
plus DHW_Supp_Hyst_Up.
plus DHW_Store_Hyst_Up.
(Default) Value Range
5 ??? 0, 1, 2, 3, 5, 6, 7, 8
149 ºF (65 ºC) 104...160 ºF (40...71 ºC)
27 ºF (15 ºC) 0...54 ºF (0...30 ºC)
Value
0  Idle
1  Request
2  Demand
3  Post circulation
4  Off
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