Selecting The Volume And Desired Temperature For The Dhw Tank - Daikin R32 Split Series Installer's Reference Manual

6 | Application guidelines

6.2.2 Selecting the volume and desired temperature for the DHW tank

Installer reference guide
24
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.
Determining the DHW consumption
Answer the following questions and calculate the DHW consumption (equivalent
hot water volume at 40°C) using typical water volumes:
Question
How many showers are needed per
day?
How many baths are needed per day?
How much water is needed at the
kitchen sink per day?
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
V =V +V ×(T −40)/(40−T
1 2 2 2
V =V ×(40−T )/(T −T )
2 1 1 2 1
V DHW consumption (equivalent hot water volume at 40°C)
1
V Required DHW tank volume if only heated once
2
T DHW tank temperature
2
T Cold water temperature
1
1 shower = 10 min×10 l/min = 100 l
1 bath = 150 l
1 sink = 2 min×5 l/min = 10 l
—
)
1
Typical water volume
Example
If:
▪ V =120 l
2
▪ T =54°C
2
▪ T =15°C
1
Then V =187 l
1
If:
▪ V =480 l
1
▪ T =54°C
2
▪ T =15°C
1
Then V =307 l
2
EKHWET90~120BAV3
R32 Split series – Domestic hot water tank
4P680077-1 – 2021.11