Wolf BWL-1S-07 - Configuring the Dual Mode Point; Diagram for Calculating Dual Mode Point

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Conguringthedualmodepoint
32 Conguringthedualmodepoint
32.1 Congurationexample
Central heating demand (building heat load) to DIN 4701 or EN 12831 of 7.7 kW. A DHW demand for 4 people
(0.25 kW/person) and a standard outside temperature of -16 °C are assumed.
Thepowersupplyutilityspeciesablockingtimeof2x2hours.TheblockingtimefactorZis1.1.
Usingthesegures,therequiredheatpumpoutputiscalculatedasfollows:
Q
HP
= (Q
G
+ Q
DHW
)xZ = (7.7 kW + 1.0 kW) x 1.1 = 9.6 kW
Q
E-rod
= Q
HP
- Q
HP,Tn
= 9.6 kW - 4.7 kW = 4.9 kW
.
.
.
.
.
.
Q
HP
: Required peak output of the heat pump system
Q
G
: Building heat load (building heat demand, heating energy demand)
Q
DHW
: Output demand for DHW heating
Q
E-rod
: Immersion heater output
Q
HP,Tn
: Heating output of heat pump for standard design point
Z : Blocking time factor
.
.
.
.
.
32.2 Diagramforcalculatingthedualmodepointandtheoutputofthe
electricimmersionheater
0
5
10
15
20
25
30
-20 -15 -10 -5 0 5 10 15 20 25 30 35
0
5
10
15
20
25
30
-20 -15 -10 -5 0 5 10 15 20 25 30 35
0
5
10
15
20
25
30
-20 -15 -10 -5 0 5 10 15 20 25 30 35
0
1
2
3
4
5
6
-20 -15 -10 -5 0 5 10 15 20 25 30 35
0
1
2
3
4
5
6
-20 -15 -10 -5 0 5 10 15 20 25 30 35
0
1
2
3
4
5
6
-20 -15 -10 -5 0 5 10 15 20 25 30 35
0
2
4
6
8
10
-20 -15 -10 -5 0 5 10 15 20 25 30 35
0
2
4
6
8
10
-20 -15 -10 -5 0 5 10 15 20 25 30 35
0
2
4
6
8
10
-20 -15 -10 -5 0 5 10 15 20 25 30 35
Air intake temperature [°C]
Heating output [kW]
Max. compressor speed
Min. compressor speed
Heating limit temperature
Standard outside temperature
-16
2
1
5
4.9kW
Q
HP
.
Q
E-rod
.
Q
HP,Tn
.
4.7
9.6
6
Dual mode point
-6
4
3
1
Standard outside temperature
2
Required peak output of the heat pump system Q
HP
.
3
Heat demand of the building up to the heating limit pressure
4
Dual mode point (= point where the heat demand of the building intersects with the max. compressor speed)
5
Proportion of heat pump heating output at standard outside temperature
6
Proportion of electric immersion heater heating output at standard outside temperature