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 200 NTR/Z
OKC 200 NTRR
OKC 250 NTRR
Družstevní závody Dražice-strojírna s.r.o.
(Works Cooperative - Dražice - Machine Plant, Ltd.)
Dražice 69, 294 71 Benátky nad Jizerou
tel.: +420 / 326 370 911
fax: +420 / 326 370 980
e-mail: expo[email protected]

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CONTENTS
1PRODUCT TECHNICAL SPECIFICATION....................................................................................................... 4
1.1 FUNCTION DESCRIPTION ................................................................................................................... 4
1.2 ADVICE FOR CUSTOMERS .................................................................................................................. 4
1.2.1HOT WATER CONSUMPTION ..................................................................................................... 4
1.2.2 ENERGY SAVING......................................................................................................................... 4
1.2.3 EMERGENCY POWER CONSUMPTION ....................................................................................... 5
1.3 DESIGN AND GENERAL HEATER DIMENSIONS................................................................................... 5
2OPERATION AND FITTING INSTRUCTIONS............................................................................................... 16
2.1 OPERATING CONDITIONS ................................................................................................................ 16
2.2 WALL MOUNTING............................................................................................................................ 16
2.3 PLUMBING FIXTURE......................................................................................................................... 18
2.4 CONNECTION OF INDIRECT TANK TO HOT WATER SYSTEM............................................................ 24
2.5 ELECTRICAL INSTALLATION.............................................................................................................. 25
2.5.1 GENERAL INFORMATION FOR ELECTRICAL INSTALLATION ..................................................... 25
2.5.2 ELECTRONIC THERMOSTAT WIRING METHODS ...................................................................... 25
2.6 FIRST COMMISSIONING................................................................................................................... 26
2.7 PUTTING OUT OF SERVICE, DISCHARGE .......................................................................................... 27
2.8 INSPECTION, MAINTENANCE & CARE FOR THE APPLIANCE............................................................ 28
2.9 MOST FREQUENT FUNCTION FAILURES AND THEIR CAUSES .......................................................... 29
3OPERATION OF THERMOSTAT................................................................................................................. 29
3.1 SERVICING........................................................................................................................................ 29
3.1.1 OPERATING DEVICES OF THE TANK ......................................................................................... 29
3.1.2 TEMPERATURE SETTING .......................................................................................................... 31
4IMPORTANT NOTICES .............................................................................................................................. 32
4.1 INSTALLATION REGULATIONS.......................................................................................................... 32
4.2 TRANSPORT & STORAGE INSTRUCTIONS ........................................................................................ 33
4.3 DISPOSAL OF PACKAGING MATERIAL AND NON-FUNCTIONING PRODUCT.................................... 33
5 PRODUCT ACCESSORIES .......................................................................................................................... 33

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CAREFULLY READ THIS MANUAL BEFORE INSTALLING THE WATER HEATER!
Dear Customer,
The Works Cooperative of Dražice - Machine Plant, Ltd., 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
1.1 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.
1.2 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
-enamelled 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 74°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
1.3 DESIGN AND GENERAL HEATER DIMENSIONS
The tank receptacle is made of steel plate and tested at 0.9 MPa of overpressure. The inside of the receptacle
is enamelled. 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 7, 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
Figure 2

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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 1400 1400 1580 1580
B 603 603 603 603
D 584 584 584 584
E 80 80 80 80
F 1280 1280 1460 1460
G 950 950 1060 1060
L 209 209 209 209
M 779 649 779 649
N - 709 - 889
O - 1149 - 1329

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 87 112 148 208 200 242 234
MAX OPERATING
OVERPRESSURE
IN THE TANK
MPa 0.6
MAX OPERATING
OVERPRESSURE
IN THE EXCHANGER
MPa 1
ELECTRICAL CONNECTION
OF CONTROL ELEMENTS 1 PE-N ~ 230V/50Hz
EL. PROTECTION IP 42
MAX TEMPERATURE HSW °C 80
RECOMMENDED HSW
TEMPERATURE °C 60
MAX WEIGHT OF THE
HEATER WITHOUT
WATER
kg 53 66 73 93 102 95 104
EXCHANGER HEAT
TRANSFER SURFACE m21.08 1.45 1.45 1.45 2 x 1 1.45 2x 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
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 1092
D 524 524 584
E 892 1057 1079
H 145 145 146
T 119 119 119
U 165 165 165
V 182 182 182

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Table 6
OKC 80 NTR/Z, OKC 100 NTR/Z, OKC 125 NTR/Z
Figure 7
TYPE
OKC 100
NTR/HV
OKC 125
NTR/HV
OKC 160
NTR/HV
VOLUME L 87 113 144
MAX OPERATING OVERPRESSURE IN THE TANK MPa 0.6
MAX OPERATING OVERPRESSURE IN THE
EXCHANGER MPa 1
ELECTRICAL CONNECTION OF CONTROL
ELEMENTS 1 PE-N ~ 230 V/50Hz
EL. PROTECTION IP 42
MAX TEMPERATURE HSW °C 80
RECOMMENDED HUW TEMPERATURE °C 60
MAX WEIGHT OF THE HEATER WITHOUT WATER kg 53 64 77
EXCHANGER HEAT TRANSFER SURFACE m21.08 1.45 1.45
RATED THERMAL OUTPUT AT HEATING WATER
TEMPERATURE 80°C AND FLOW 720 l/h W 24000 32000 32000
TIME OF HEATING BY EXCHANGER FROM 10°C
TO 60°C min 13 12 16
STATIC LOSS W 42 65 65

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OKC 160 NTR/Z
Figure 8
* in OKC 80 NTR/Z - 3/4" outer
Table 7

3/4" outer

1" outer

3/4" inner
OKC 80 NTR/Z OKC 100 NTR/Z OKC 125 NTR/Z OKC 160 NTR/Z
A 757 902 1067 1255
B 612 612 612 612
C 70 70 70 70
D 524 524 524 524
E 605 622 789 991
F 460 478 645 815
G - 550 550 830
H 142 270 268 254
I 211 263 263 263
J 501 703 703 703
K 172 172 172 172
R 450 450 450 450

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OKC 200 NTR/Z
Figure 9
Table 8
TYP OKC 200 NTR/Z
A 1290
B 655
C 70
D 584
E 784
F 600
G 889
H 496
I 239
J 679
K 172
R 450

3/4" outer

1" outer

3/4" inner

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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 MPa 0.6
MAX OPERATING
OVERPRESSURE IN THE
EXCHANGER
MPa 1
ELECTRICAL CONNECTION
OF CONTROL ELEMENTS 1 PE-N ~ 230V/50Hz
EL. PROTECTION IP 44
MAX TEMPERATURE HSW °C 80
RECOMMENDED HSW
TEMPERATURE °C 60
HEIGHT OF THE HEATER mm 757 902 1067 1255 1290
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 m20.41 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
STATIC LOSS W 40 47 57 67 72

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2OPERATION AND FITTING INSTRUCTIONS
2.1 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
litres 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 60°C (setting to position „ECO“ or „OPTIMUM“) - Figure 24, Figure 25. 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.
2.2 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 authorised 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 7, 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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2.3 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 minimise 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 equipped with 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
0.7 0.7 up to 0.56
11up to 0.8

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OKC 200 NTR, OKC 250 NTR
Figure 13