Daikin Altherma 3 GEO - Domestic Hot Water Control Strategies; Reheat Mode Operation Details; Scheduled Mode Operation Guide

4 Operation
User reference guide
18
EGSAH/X06+10(U)DA9W(G)
Daikin Altherma 3 GEO
4P569819-1A – 2019.10
4.7 Domestic hot water control
4.7.1 About domestic hot water control
Depending on the DHW tank mode (installer setting), you use a
different domestic hot water control:
▪ Reheat only
▪ Schedule + reheat
▪ Schedule only
INFORMATION
In case of error code AH and no interruption of the
disinfection function occurred due to domestic hot water
tapping, following actions are recommended:
▪ When the Reheat only or Schedule + reheat mode
is selected, it is recommended to program the start-up
of the disinfection function at least 4 hours later than
the last expected large hot water tapping. This start-up
can be set by installer settings (disinfection function).
▪ When the Schedule only mode is selected, it is
recommended to program an Eco action 3hours before
the scheduled start-up of the disinfection function to
preheat the tank.
When weather-dependent operation is used for the tank, the tank
temperature is determined automatically by the outdoor temperature.
For more information, see "4.9Weather-dependent curve"[424].
To determine which domestic hot water mode you are using
(method 1)
Check the installer settings table filled in by the installer.
To determine which domestic hot water mode you are using
(method 2)
1 Go to [5]: Tank.
2 Check which items are displayed:
[5.1]
[5.2]
[5.3]
[5.4]
[5.5]
Eco setpoint
Schedule
Reheat setpoint
Comfort setpoint
Powerful operation
If… is displayed Then the DHWtank mode =…
Only [5.1] Powerful
operation
Reheat only
All items except [5.4]
Reheat setpoint are
displayed
Schedule only
All items including [5.4]
Reheat setpoint are
displayed
Schedule + reheat
4.7.2 Reheat mode
In reheat mode the DHW tank continuously heats up to the
temperature shown on the home screen (example: 50°C) when the
temperature drops below a certain value.
t
60°C
00:00 07:00
50°C
15°C
40°C
14:00 21:00
1
2
3
4
T
t
T
t
DHWtank temperature
t Time
INFORMATION
When the DHW tank mode is reheat, the risk for capacity
shortage and comfort problem is significant. In case of
frequent reheat operation, space heating/cooling function
is regularly interrupted.
4.7.3 Scheduled mode
In scheduled mode the DHWtank produces hot water corresponding
to a schedule. The best time to allow the tank to produce hot water is
at night, because the space heating demand is lower.
Example:
t
60°C
00:00 07:00
50°C
15°C
40°C
14:00 21:00
1
2
3
4
5
T
t
T
t
DHWtank temperature
t Time
▪ Initially, the DHW tank temperature is the same as the
temperature of the domestic water entering the DHW tank
(example: 15°C).
▪ At 00:00 the DHWtank is programmed to heat up the water to a
preset value (example: Comfort = 60°C).
▪ During the morning, you consume hot water and the DHW tank
temperature decreases.
▪ At 14:00 the DHWtank is programmed to heat up the water to a
preset value (example: Eco = 50°C). Hot water is available again.
▪ During the afternoon and evening, you consume hot water again
and the DHWtank temperature decreases again.
▪ At 00:00 the next day, the cycle repeats.
4.7.4 Scheduled + reheat mode
In scheduled + reheat mode, the domestic hot water control is the
same as in scheduled mode. However, when the DHW tank
temperature drops below a preset value (=reheat tank temperature –
hysteresis value; example: 35°C), the DHW tank heats up until it
reaches the reheat set point (example: 45°C). This ensures that a
minimum amount of hot water is available at all times.
Example: