Hitachi 7E300020, Технический каталог, Страница: 74 / 158

4. Capacity and selection data
TCGB0075 rev.0 - 11/2012
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Step 3: Calculation for the heating capacity of the combination (case YUTAKI S80 with electric heater)
Once applied the applicable correction factors, the actual heating capacity provided by the RAS-4H(V)RNME-AF +
RWH-4.0FS(V)NFE system is 11.47 kW. This heating capacity does not cover the required heating load for the coldest
days (13.0 kW).
In these cases, the water electric heater supplied by HITACHI as accessory (WEH-6E) will provide the auxiliary capacity
required to cover temporary heating needs.
The auxiliary electric heater provides a maximum power of 6.0 kW which must be added to the heating
capacity provided by the pre-selected unit. The result is:
Q
H
= 11.47 kW + 6 kW =
17.47 kW
In this example, the heating capacity resulting is higher than the heating demand of 13.0 kW estimated for the coldest days
of the year, so that pre-selection of the RAS-4H(V)RNME-AF + RWH-4.0FS(V)NFE system can be taken as valid.
The energy system resulting will be the following:
17.47 kW, -10 ºC WB
Capacity of the YUTAKI S80
Heating
capacity
Outdoor ambient
temperature
11.43 kW, -5 ºC WB
Heating load
covered
11.47 kW, -10 ºC WB
13.0 kW, -10 ºC WB
9.0 kW, -5 ºC WB
Heating load
demanded
SP1
SP2
SP3
Three steps electric heater control
As it has been explained in chapter Features and benefits , the desired heating supplied by the electric heater can be more
exactly adjusted by means of the 3 steps electric heater control. When the electric heater is working in steps 1 or 2, the
power input will be reduced comparing with the total power input of the electric heater.
In this example, this option can be applied. The electric heater can work on 1 step (2.0 kW) and the re -
quired heating load for the coldest days will be covered with a reduction of power input. The result will be:
Q
H
= 11.47 kW + 2.0 kW = 13.47 kW
SP1
13.47 kW, -10 ºC WB
Capacity of the YUTAKI S80
Heating
capacity
Outdoor ambient
temperature
11.43 kW, -5 ºC WB
Heating load
covered
11.47 kW, -10 ºC WB
13.0 kW, -10 ºC WB
9.0 kW, -5 ºC WB
Heating load
demanded