Nibe Drazice OKC 100 NTR Specification sheet

OPERATING AND
INSTALLATION MANUAL
INDIRECT HOT WATER TANKS
OKC 100 NTR OKC 100 NTR/HV OKC 80 NTR/Z
OKC 125 NTR OKC 125 NTR/HV OKC 100 NTR/Z
OKC 160 NTR OKC 160 NTR/HV OKC 125 NTR/Z
OKC 200 NTR OKC 160 NTR/Z
OKC 250 NTR OKC 100.1 NTR/HV OKC 200 NTR/Z
OKC 200 NTRR OKC 125.1 NTR/HV
OKC 250 NTRR
Družstevní závody Dražice-strojírna s.r.o.
Dražice 69, 294 71 Benátky nad Jizerou
tel.: +420 / 326 370 911
fax: +420 / 326 370 980
e-mail: [email protected]

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CONTENTS
1 PRODUCT TECHNICAL SPECIFICATION....................................................................................................... 4
FUNCTION DESCRIPTION ................................................................................................................... 4
ADVICE FOR CUSTOMERS.................................................................................................................. 4
1.2.1 HOT WATER CONSUMPTION..................................................................................................... 4
1.2.2 ENERGY SAVING......................................................................................................................... 4
1.2.3 EMERGENCY POWER CONSUMPTION....................................................................................... 5
DESIGN AND GENERAL HEATER DIMENSIONS................................................................................... 5
2 OPERATION AND FITTING INSTRUCTIONS............................................................................................... 17
OPERATING CONDITIONS ................................................................................................................ 17
WALL MOUNTING............................................................................................................................ 17
PLUMBING FIXTURE......................................................................................................................... 19
CONNECTION OF INDIRECT TANK TO HOT WATER SYSTEM............................................................ 25
ELECTRICAL INSTALLATION.............................................................................................................. 26
2.5.1 GENERAL INFORMATION FOR ELECTRICAL INSTALLATION ..................................................... 26
FIRST COMMISSIONING................................................................................................................... 26
PUTTING OUT OF SERVICE, DISCHARGE .......................................................................................... 27
INSPECTION, MAINTENANCE & CARE FOR THE APPLIANCE............................................................ 27
MOST FREQUENT FUNCTION FAILURES AND THEIR CAUSES.......................................................... 28
3 OPERATION OF THERMOSTAT................................................................................................................. 29
OPERATING DEVICES OF THE TANK................................................................................................. 29
3.1.1 TEMPERATURE SETTING.......................................................................................................... 30
4 IMPORTANT NOTICES.............................................................................................................................. 30
INSTALLATION REGULATIONS.......................................................................................................... 30
TRANSPORT & STORAGE INSTRUCTIONS ........................................................................................ 31
DISPOSAL OF PACKAGING MATERIAL AND NON-FUNCTIONING PRODUCT.................................... 31
5 PRODUCT ACCESSORIES .......................................................................................................................... 31

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CAREFULLY READ THIS MANUAL BEFORE INSTALLING THE WATER HEATER!
Dear Customer,
Družstevní závody Dražice - strojírna s.r.o., would like to thank you
for your decision to use a product of our brand. With this guide, we
will introduce you to the use, construction, maintenance and other
information on electrical water heaters.
The product is not intended to be controlled by
a) people (including children) with reduced physical, sensual or mental capacities, or
b) people with insufficient knowledge and experiences unless supervised by responsible person,
or unless properly instructed by such responsible person.
The manufacturer reserves the right for engineering modification of the product. The product is designed
for permanent contact with drinkable water.
It is recommended to use the product in indoor environment with air temperatures from +2 °C to +45 °C
and a relative humidity up to 80 %.
Product’s reliability and safety is proven by tests implemented by the Engineering Test Institute in Brno.
Made in the Czech Republic.
Meaning of pictograms used in the Manual
Important information for heater users.
Abiding by the recommendations of the manufacturer serves to ensure trouble-free operation
and the long service life of the product.
Caution!
Important notice to be observed.

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1PRODUCT TECHNICAL SPECIFICATION
FUNCTION DESCRIPTION
Indirect stationary NTR and NTRR series TANKS are used to prepare HSW in combination with another hot
water supply, mostly gas boiler; in NTRR types in combination of two hot water sources (gas boiler + solar
system, heat pump). Their nominal performance provides sufficient amount of hot service water (HSW) even
for large flat units - premises, restaurants and similar establishments. In case of increased hot water
consumption, these tanks heat water continuously, operating similarly to flow heaters.
Closing valves of the heat exchanger must be opened which ensures heating water flow from the hot water
heating system. Together with closing valve, it is recommended to install an air outlet valve at the inlet to
the heat exchanger in order to bleed the heat exchanger as needed, in particular before the beginning of the
heating season (Figure 12, Figure 13, Figure 14, Figure 15, Figure 16, Figure 17 - by the type). The time it takes
to heat up using the heat exchanger depends on the temperature and flow of water in the hot water heating
system. A suspended tank is made in a universal design –depending on the need of connecting the closing
valves to the heating element either from the right, or from the left.
ADVICE FOR CUSTOMERS
1.2.1 HOT WATER CONSUMPTION
Consumption of hot water in households depends on the number of people, amount of sanitary
equipment, length, diameter and insulation of piping in the flat, or on individual habits of users.
The cheapest option of water heating comes at the time when the electricity rate is reduced.
1.2.2 ENERGY SAVING
The heater is insulated with quality polyurethane Freon free foam. Set the temperature of the
heater's thermostat to that level only that you need to run your home. Thus, you will reduce
electricity consumption, as well as the amount of lime sediments on the walls of the receptacle
and on the electric body.
Benefits of using indirect heater:
-installation and connection to hot water supply
-very fast hot utility water heating
-enameled steel tank ensures compliance with all hygienic requirements for the quality of HUW
-integrated protective magnesium anode increases corrosion resistance
-quality polyurethane insulation ensures minimum heat losses
-smoothly settable HUW temperature up to 75 °C
-multiple supply points,
-light indication of the heater's run,
-HSW temperature control,
-possibility of connecting HUW circulation.

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1.2.3 EMERGENCY POWER CONSUMPTION
If no heated water is taken from the tank, a small amount of heat leaks. This loss is measured
for a period of 24 hours at the temperature of 65 °C in the heater, and at 20 °C in its ambient
area. The resulting value is expressed in units [kWh/24h] and indicates the amount of power
needed to maintain the set temperature.
Table 1
DESIGN AND GENERAL HEATER DIMENSIONS
The tank receptacle is made of steel plate and tested by 1.5 MPa multiple of operation pressure value.
The inside of the receptacle is enameled. A flange is welded onto the lower bottom of the receptacle with
a flange lid screwed onto it. A sealing ring is inserted between the flange lid and the flange. Thermowells
for thermostat sensors and thermometer installation are placed in the flange lid. An anode rod is mounted
onto the M8 nut. The water reservoir is insulated by means of polyurethane foam. Electric wiring is placed
underneath the plastic removable cover. The temperature of water can be set using the thermostat. Heat
exchanger(s) is/are welded onto the pressure tank.
Description of basic parts of the tank - by individual types (Figure 1, Figure 2, Figure 3)
Heater dimensions - (Figure 4, Figure 5, Figure 6, Figure 7, Figure 8, Figure 9) and (Table 2, Table 3, Table 5,
Table 6, Table 8).
TYPE
HEATING WATER
FLOW [l/h]
PRESSURE LOSS [mbar]
HEAT LOSS [kW/24H]
OKC 100 NTR
720
33
0.9
OKC 125 NTR
46
1.05
OKC 160 NTR
46
1.4
OKC 200 NTR
46
1.8
OKC 250 NTR
46
2.1
OKC 200 NTRR
2 x 33
1.8
OKC 250 NTRR
2 x 33
2.1

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Technical description: OKC 100 NTR, OKC 125 NTR, OKC 160 NTR, OKC 200 NTR, OKC 250 NTR,
OKC 200 NTRR, OKC 250 NTRR
Figure 1
Technical description: OKC 100 NTR/HV, OKC 125 NTR/HV, OKC 160 NTR/HV
OKC 100.1 NTR/HV, OKC 125.1 NTR/HV
Figure 2
The thermometer is only for OKC 100 - 160 NTR/HV. Types OKC 100.1 - 125.1 NTR/HV
are without thermometer.

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Technical description: OKC 80 NTR/Z, OKC 100 NTR/Z, OKC 125 NTR/Z, OKC 160 NTR/Z, OKC 200 NTR/Z
Figure 3

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OKC 100 NTR, OKC 125 NTR, OKC 160 NTR
Figure 4
Table 2
OKC 100 NTR
OKC 125 NTR
OKC 160 NTR
A
902
1067
1255
B
565
565
565
D
524
524
524
E
893
1058
1246
G
535
635
897
H
145
145
145
L
195
195
195
M
635
765
765

3/4" outer

1" outer

3/4" inner

1/2" inner

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OKC 200 NTR, OKC 250 NTR, OKC 200 NTRR, OKC 250 NTRR
Figure 5
Table 3
OKC 200 NTR
OKC 200 NTRR
OKC 250 NTR
OKC 250 NTRR
A
1412
1412
1595
1595
B
620
620
620
620
D
584
584
584
584
E
75
75
75
75
F
1275
1275
1455
1455
G
945
945
1055
1055
L
205
205
205
205
M
775
645
775
645
N
-
705
-
885
O
-
1145
-
1325

3/4" outer

1" outer

3/4" inner

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Table 4
TYPE
OKC 100
NTR
OKC 125
NTR
OKC 160
NTR
OKC 200
NTR
OKC 200
NTRR
OKC 250
NTR
OKC 250
NTRR
VOLUME
L
87
113
148
208
200
242
234
MAX OPERATING
OVERPRESSURE
IN THE TANK
bar
6
MAX OPERATING
OVERPRESSURE
IN THE EXCHANGER
bar
10
ELECTRICAL CONNECTION
OF CONTROL ELEMENTS
1 PE-N ~ 230V/50Hz
EL. PROTECTION
IP 42
MAX OPERATING
TEMPERATURE IN THE
TANK
°C
80
MAX OPERATING
TEMPERATURE IN THE
EXCHANGER
°C
110
RECOMMENDED HSW
TEMPERATURE
°C
60
MAX WEIGHT OF THE
HEATER WITHOUT
WATER
kg
53
66
73
88
102
92
104
EXCHANGER HEAT
TRANSFER SURFACE
m2
1.08
1.45
1.45
1.45
2 x 1
1.45
2 x 1
RATED THERMAL OUTPUT
AT HEATING WATER
TEMPERATURE OF 80°C
AND FLOW 720 L/H
W
24000
32000
32000
32000
2 x
24000
32000
2 x
24000
TIME OF HEATING BY
EXCHANGER FROM 10°C
TO 60°C
min
13
12
16
23
13 / 25
26
14 / 28
ENERGY EFFICIENCY
CLASS
B
C
C
C
C
C
C
STATIC LOSS
W
42
54
75
82
82
87
87

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OKC 100 NTR/HV, OKC 125 NTR/HV, OKC 160 NTR/HV
Figure 6
Table 5

3/4" outer

3/4" outer

3/4" outer

3/4" outer

3/4" outer

1/2" inner
OKC 100 NTR/HV
OKC 125 NTR/HV
OKC 160 NTR/HV
A
902
1067
1090
D
524
524
584
E
892
1057
1080
H
145
145
143
T
119
119
119
U
165
165
165
V
182
182
182

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OKC 100.1 NTR/HV, OKC 125.1 NTR/HV
Figure 7 Table 6

3/4" outer

3/4" outer

3/4" outer

3/4" outer

3/4" outer

1/2" inner
OKC 100 NTR/HV
OKC 125 NTR/HV
A
895
1060
d
440
440
D
584
584
E
885
1050
H
130
130
T
119
119
U
165
165
V
182
182

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Table 7
TYPE
OKC 100
NTR/HV
OKC 125
NTR/HV
OKC 160
NTR/HV
OKC 100.1
NTR/HV
OKC 125.1
NTR/HV
VOLUME
L
87
113
144
85
111
MAX OPERATING
OVERPRESSURE IN THE
TANK
bar
6
MAX OPERATING
OVERPRESSURE IN THE
EXCHANGER
bar
10
ELECTRICAL CONNECTION
OF CONTROL ELEMENTS
1 PE-N ~ 230 V/50Hz
EL. PROTECTION
IP 42
MAX OPERATING
TEMPERATURE IN THE TANK
°C
80
MAX OPERATING
TEMPERATURE IN THE
EXCHANGER
°C
110
RECOMMENDED HSW
TEMPERATURE
°C
60
MAX WEIGHT OF THE
HEATER WITHOUT WATER
kg
53
64
77
56
73
EXCHANGER HEAT
TRANSFER SURFACE
m2
1.08
1.45
1.45
1.08
1.45
RATED THERMAL OUTPUT
AT HEATING WATER
TEMPERATURE 80°C AND
FLOW 720 l/h
W
24000
32000
32000
24000
32000
TIME OF HEATING BY
EXCHANGER FROM 10°C
TO 60°C
min
13
12
16
13
12
ENERGY EFFICIENCY CLASS
B
C
C
A
A
STATIC LOSS
W
42
65
65
29
33

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OKC 80 NTR/Z, OKC 100 NTR/Z, OKC 125 NTR/Z
Figure 8
OKC 160 NTR/Z, OKC 200 NTR/Z
Figure 9
* in OKC 80 NTR/Z - 3/4" outer

3/4" outer

1" outer

3/4" inner

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Table 8
OKC 80 NTR/Z
OKC 100 NTR/Z
OKC 125 NTR/Z
OKC 160 NTR/Z
OKC 200 NTR/Z
A
757
902
1067
1255
1300
B
612
612
612
612
672
C
70
70
70
70
70
D
524
524
524
524
584
E
605
622
789
991
804
F
460
478
645
815
600
G
-
550
550
830
902
H
142
270
268
254
490
I
211
263
263
263
252
J
501
703
703
703
692
K
172
172
172
172
172
R
450
450
450
450
450

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Table 9
TYPE
OKC 80
NTR/Z
OKC 100
NTR/Z
OKC 125
NTR/Z
OKC 160
NTR/Z
OKC 200
NTR/Z
VOLUME
L
76
95
120
148
196
MAX OPERATING
OVERPRESSURE IN THE TANK
bar
6
MAX OPERATING
OVERPRESSURE IN THE
EXCHANGER
bar
10
ELECTRICAL CONNECTION
OF CONTROL ELEMENTS
1 PE-N ~ 230V/50Hz
EL. PROTECTION
IP 44
MAX OPERATING
TEMPERATURE IN THE TANK
°C
80
MAX OPERATING
TEMPERATURE IN THE
EXCHANGER
°C
110
RECOMMENDED HSW
TEMPERATURE
°C
60
HEIGHT OF THE HEATER
mm
757
902
1067
1255
1300
DIAMETER OF THE HEATER
mm
524
524
524
524
584
MAX WEIGHT OF THE HEATER
WITHOUT WATER
kg
38
56
61
70
84
EXCHANGER HEAT TRANSFER
SURFACE
m2
0.41
1.08
1.08
1.08
1.08
RATED THERMAL OUTPUT
AT HEATING WATER
TEMPERATURE 80°C
AND FLOW 720 l/h
W
9000
24000
24000
24000
24000
TIME OF HEATING
BY EXCHANGER FROM 10°C
TO 60°C
min
29
14
17
22
28
ENERGY EFFICIENCY CLASS
B
B
C
C
C
STATIC LOSS
W
40
47
57
67
72

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2OPERATION AND FITTING INSTRUCTIONS
OPERATING CONDITIONS
The tank shall only be used in accordance with the conditions specified on the power plate
and in instructions for electric wiring. Besides the legally acknowledged national regulations
and standards, also conditions for connection defined in the local electric and water works have
to be adhered to, as well as the installation and operation manual. The cold water inlet of each
individually closable heater must be fitted with a seal, test tap or plug to check the non-return
valve, as well as a non-return valve and safety valve. Heaters with a volume of more than 200
liters must also be fitted with a pressure gauge.
The room, in which the appliance will be operated, must be frost-free. The appliance has to be
mounted at a convenient place; it means that the appliance must be easily available for potential
necessary maintenance, repair or replacement, as the case may be.
We emphasize that the tank shall not be connected to power supply if flammable liquids
(gasoline, stain cleaner) or gases, etc., are handled in its proximity.
If water is strongly calcareous we recommend that any of the common decalcifying devices was
installed with the appliance, or that the thermostat was set to the minimum operating
temperature of 55 °C (setting to position „OPTIMUM“) - Figure 21. For proper operation,
drinkable water of adequate quality shall be used. To avoid potential sediments, we recommend
that the device was installed together with a water filter.
WALL MOUNTING
Prior to mounting, check the loading capacity of the wall and depending on the type of masonry,
choose a suitable anchorage material, or reinforce the wall, if needed. The NTR/Z water heater
shall only be mounted in vertical position so that the lower edge of the tank was placed at least
600 mm above the floor. In combined tanks, elbows have to be attached to the heating water
inlet and outlet and, by turning them, the mounting either from the right or from the left has to
be determined (Figure 17). With regard to various types of bearing masonry and wide range of
special anchorage material available at the market, we do not provide the tanks with that
material. The anchorage system has to be selected individually, depending on the conditions.
We recommend an authorized company perform mounting on the wall and anchorage or discuss
the anchorage with a professional.
If hot water tank is mounted in a tight, smaller space, or in an intermediate ceiling, etc., you
have to make sure that the connecting side of the appliance (connections to water supply, area
for electric plugging) remained accessible and no heat accumulation occurs. Free space of up to
600 mm from the bottom edge of the tank has to be available under the tank.

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Mount the anchors by the dimensional drawing (Figure 8, Figure 9) in a 450 mm spacing. Double check
the torque of the suspension bolts on the heater and suspend the heater. Using the detent support in the
bottom part of the heater make sure it runs in parallel with the wall (Figure 10) in 80-125 L heaters .
Figure 10
Figure 11

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PLUMBING FIXTURE
Connecting tanks to plumbing fixtures is shown in (Figure 12, Figure 13, Figure 14, Figure 15,
Figure 16, Figure 17). For potential disconnection of the tank, utility water inlets and outlets
must be provided with Js 3/4" screw coupling. If the hot utility water (HUW) distribution
is equipped with circulation circuit, the reverse pipe is connected to the inlet identified
as CIRCULATION. Types 100, 125, 160 NTR and 100, 125, 160 NTR / HV are equipped with a drain
outlet. A “T” plumbing with a drain valve has to be mounted in type 200 and 250 NTR(R) on the
HSW inlet. The tank shall be equipped with a safety valve to ensure the operation. The safety
valve is mounted on the cold water inlet identified with a blue ring. We recommend that the hot
water distribution from the heater was as short as possible to minimize heat losses. Tanks must
be provided with a discharge valve mounted on the cold service water inlet into the heater
for potential disassembly or repair.
Every hot utility water pressure tank shall be equippedwith membrane spring loaded with safety
valve. Safety valve shall be easily accessible, fitted as close as possible to the tank. The inlet pipes
must have at least the same clearance as the safety valve. Safety valve is placed high enough to
secure dripping water drain by gravity. We recommend mounting the safety valve onto a branch
pipe. Easier exchange without the necessity of draining water from the tank. Safety valves with
fixed pressure settings from the manufacturer are used for the assembly. The starting pressure
of the safety valve must be identical to the maximum allowed pressure of the tank, and at least
20 % higher than is the maximum pressure in the water main (Table 10). If the water main
pressure exceeds such value, a reduction valve must be added to the system. No closing
armature may be mounted between the tank and the safety valve. During assembly, follow the
guide provided by the safety equipment manufacturer.
It is necessary to check the safety valve each time before putting it into operation. It is checked
by manual moving of the membrane from the seat, 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 regular operation, such a check needs to be carried out at least once a month,
and after each shutdown of the tank longer than 5 days. Water may be dripping off the drain
pipe of the safety valve; the pipe must be open into the air, pointed down; environment
temperatures must not drop below zero. When draining the tank, use the recommended drain
valve. First of all, close water inlet in the tank. Find necessary pressure values in the following
table. For proper safety valve operation, a backflow valve shall be mounted on the inlet pipes,
preventing spontaneous heater draining of the tank and hot water penetration back into
the water main.

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Table 10
CONNECTING A TANK TO A WATER AND HEATING SYSTEM
OKC 100 NTR, OKC 125 NTR, OKC 160 NTR
Figure 12
SAFETY VALVE STARTING
PRESSURE [MPa]
ACCEPTABLE OPERATING OVER-
PRESSURE OF THE WATER
HEATER [MPa]
MAX COLD WATER PRESSURE
IN PIPING [MPa]
0,6
0,6
up to 0,48