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5 Application guidelines
Installer reference guide
18
ERHQ+ERLQ011~016 + 16CBV
Daikin Altherma – Low temperature split
4P449970-1 – 2016.06
5.4
Setting up the domestic hot water
tank
The DHW tank can be installed standalone as option. It contains a
2.4 kW anti-legionella heater.
5.4.1
System layout – Standalone DHW tank
FHL1
FHL2
FHL3
M
a
b c
e
d
g
e
f
h
j
i
a
Outdoor unit
b
Indoor unit
c
Heat exchanger
d
Pump
e
Shut-off valve
f
Motorised 3‑way valve
g
Collector (field supply)
h
DHW tank
i
Anti-legionella heater
j
Heat exchanger coil
FHL1...3
Under floor heating
5.4.2
Selecting the volume and desired
temperature for the DHW tank
People experience water as hot when its temperature is 40°C.
Therefore, the DHW consumption is always expressed as equivalent
hot water volume at 40°C. However, you can set the DHW tank
temperature at a higher temperature (example: 53°C), which is then
mixed with cold water (example: 15°C).
Selecting the volume and desired temperature for the DHW tank
consists of:
1
Determining the DHW consumption (equivalent hot water
volume at 40°C).
2
Determining the volume and desired temperature for the DHW
tank.
Possible DHW tank volumes
Type
Possible volumes
Standalone DHW tank
▪ 150 l
▪ 200 l
▪ 300 l
▪ 500 l
Energy saving tips
▪ If the DHW consumption differs from day to day, you can program
a weekly schedule with different desired DHW tank temperatures
for each day.
▪ The lower the desired DHW tank temperature, the more cost
effective. By selecting a larger DHW tank, you can lower the
desired DHW tank temperature.
▪ The heat pump itself can produce domestic hot water of maximum
55°C (50°C if outdoor temperature is low). The electrical
resistance integrated in the DHW tank (anti-legionella heater) can
increase this temperature. However, this consumes more energy.
Daikin recommends to set the desired DHW tank temperature
below 55°C to avoid using the electrical resistance.
The anti-legionella heater:
▪ Is used as emergency heater.
▪ Is used when the disinfection function for the DHW tank is
active.
▪ Can assist during defrost operation for the outdoor unit.
▪ The higher the outdoor temperature, the better the performance of
the heat pump.
▪ If energy prices are the same during the day and the night,
Daikin recommends to heat up the DHW tank during the day.
▪ If energy prices are lower during the night, Daikin recommends
to heat up the DHW tank during the night.
▪ When the heat pump produces domestic hot water, it cannot heat
up a space. When you need domestic hot water and space
heating at the same, Daikin recommends to produce the domestic
hot water during the night when there is lower space heating
demand.
Determining the DHW consumption
Answer the following questions and calculate the DHW consumption
(equivalent hot water volume at 40°C) using the typical water
volumes:
Question
Typical water volume
How many showers are needed
per day?
1 shower = 10 min×10 l/min =
100 l
How many baths are needed per
day?
1 bath = 150 l
How much water is needed at the
kitchen sink per day?
1 sink = 2 min×5 l/min = 10 l
Are there any other domestic hot
water needs?
—
Example: If the DHW consumption of a family (4 persons) per day is
as follows:
▪ 3 showers
▪ 1 bath
▪ 3 sink volumes
Then the DHW consumption = (3×100 l)+(1×150 l)+(3×10 l)=480 l
Determining the volume and desired temperature for the DHW
tank
Formula
Example
V
1
=V
2
+V
2
×(T
2
−40)/(40−T
1
)
If:
▪ V
2
=180 l
▪ T
2
=54°C
▪ T
1
=15°C
Then V
1
=280 l
V
2
=V
1
×(40−T
1
)/(T
2
−T
1
)
If:
▪ V
1
=480 l
▪ T
2
=54°C
▪ T
1
=15°C
Then V
2
=307 l
V
1
DHW consumption (equivalent hot water volume at 40°C)
V
2
Required DHW tank volume if only heated once
T
2
DHW tank temperature
T
1
Cold water temperature