Drazice OKCE 300 NTR Manuale operativo e di installazione - Pagina 12
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Heating unit 3-6 kW
The 3-6 kW heating unit allows 4 universal types of connection based on either the required time of heating, or
possibilities of electric network in the place of use. To achieve the chosen performance of the heating unit, connect
the inlet conductor to the terminal board L1-L2-L3-N and interconnect the terminals on the terminal board 1 – 10
according to the below schemes:
R = 1 kW
R
R
3
PE
L1 L2 L3
N
1 2 3 4 5 6 7 8
11.
SECURITY EQUIPMENT
Each hot service water pressure heater must have a safety valve with a membrane spring. Nominal clearance of
safety valves is defined in the ČSN 0 60830 standard. The safety valve must be well accessible, as near to the
heater as possible. The input pipes must have at least the same clearance as the safety valve. The safety valve is
placed high enough to secure dripping water drain by gravity. We recommend mounting the safety valve onto the
branch led above the heater in order to simplify the exchange without the necessity of drain the water from the
heater. Safety valves with fixed pressure settings from the manufacturer are used for the assembly. Starting
pressure of a safety valve must be identical with the maximum allowed heater pressure, and at least 20% higher
than the maximum pressure in the water main. If the water main pressure exceeds such value, a reduction valve
must be added to the system. No stop valves can be put between the heater and the safety valve. During the
assembly, follow the guide provided by the safety equipment manufacturer.
Before putting the safety valve into operation it always needs to be checked by manual removal of the membrane
from the valve seat and turning the make-and-break device button always in the direction of the arrow. After being
turned, the button must click back into a notch. Proper function of the make-and-break device results in water
draining through the safety valve outlet pipe. In common operation, such a check needs to be implemented at least
once a month, and after each heater shutdown for more than 5 days.
Water may be dripping off the safety valve through a drain pipe. The pipe has to be therefore freely open to the
atmosphere, placed vertically and shall be in an environment free of temperatures below the freezing point.
When draining the heater, use a recommended drain valve. First, close water input into the heater.
Find necessary pressure values in the following table.
For proper safety valve operation, a backflow
valve must be mounted on the inlet pipes,
preventing spontaneous heater draining and hot
water penetrating back into the water main.
Notice: The 300 litre heaters are not equipped
with a safety valve.
When assembling the security equipment, follow ČSN 06 0830.
1
R
R
3
2
1
R
R
2
3
2
9 10
3
2
3 kW
1 PE - N AC 230 V / 50 Hz
L2 L3
N
3 kW
2 PE - N AC 400 V / 50 Hz
N
L1 L2 L3
4 kW
3 PE - N AC 400 V / 50 Hz
N
L1 L2 L3
6 kW
3 PE - N AC 400 V / 50 Hz
L2 L3
N
1
3
2
1
3
2
Safety valve
Admissible operating
starting pressure
water heater
(MPa)
pressure (MPa)
0.6
0.7
1
12
1 2 3 4 5 6 7 8
9 10
1
2 3
4
5
6 7
8
1
2 3
4
5
6 7
8
1 2 3 4 5 6 7 8
Max. pressure in
the cold water pipe
(MPa)
0.6
do 0.48
0.7
do 0.56
1
do 0.8
9 10
9 10
9 10