Drazice OKC 250 NTR/HP User manual

OPERATING AND
INSTALLATION MANUAL
Indirect water tank
OKC 250 NTR/HP
OKC 300 NTR/HP
OKC 400 NTR/HP
OKC 500 NTR/HP
OKC 750 NTR/HP
OKC 1000 NTR/HP
Družstevní závody Dražice - strojírna s.r.o.
Dražice 69, 294 71 Benátky nad Jizerou
Phone.: [phone]
Fax: +420 / 326 370 980
E-mail: expor[email protected]z

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CONTENTS
1PRODUCT TECHNICAL SPECIFICATION....................................................................................................... 4
1.1 FUNCTION DESCRIPTION ................................................................................................................... 4
1.2 DESIGN AND BASIC DIMENSIONS OF TANK....................................................................................... 4
1.2.1 PRODUCT DESCRIPTION............................................................................................................. 4
1.2.2 TECHNICAL DATA ....................................................................................................................... 5
1.2.3 PRESSURE LOSSES.................................................................................................................... 10
2OPERATION AND FITTING INSTRUCTIONS............................................................................................... 11
2.1 PUTTING THE TANK INTO OPERATION ............................................................................................ 11
2.2 CONNECTING A TANK TO HOT WATER SYSTEM.............................................................................. 12
2.3 PLUMBING FIXTURE......................................................................................................................... 13
2.4 CONNECTION OF TANK TO HOT WATER DISTRIBUTION SYSTEM.................................................... 14
2.5 CLEANING OF TANK AND EXCHANGE OF ANODE ROD.................................................................... 15
2.6 SPARE PARTS.................................................................................................................................... 16
3IMPORTANT NOTICES .............................................................................................................................. 16
3.1 IMPORTANT NOTICES ...................................................................................................................... 16
3.2 INSTALLATION REGULATIONS.......................................................................................................... 16
3.3 DISPOSAL OF PACKAGING MATERIAL AND NON-FUNCTIONING PRODUCT.................................... 16

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PRIOR TO THE INSTALLATION OF THE TANK, READ CAREFULLY THIS MANUAL!
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.
The present instructions will introduce you to the use, construction,
maintenance and other information regarding electrical water
tanks.
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 tank 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
The OKC 250 (300, 400, 500, 750, 1000) NTR/HP stationary tank is designed for the preparation of hot sanitary
water in combination with heat pump. Reheat can be carried out by the electric heater TJ 6/4".
1.2 DESIGN AND BASIC DIMENSIONS OF TANK
1.2.1 PRODUCT DESCRIPTION
The tank receptacle is welded of steel plate and, as a unit, protected with enamel that resists to hot water.
For additional corrosion protection two magnesium anodes are mounted in the upper part of the receptacle
and in the side flange to adjust the electric potential inside the receptacle, thus reducing effects of corrosion.
Inside the vessel there is a welded heat exchanger made of steel pipe with enamelled outer coating,
and connections of hot and cold water, circulation and thermostat tank.
The pipe heat exchanger is only intended for the heating circuit.
There is a cleaning and revision aperture on the side of the tank, ended with a flange of 110 mm clearance;
the spacing of eight M8 screws is 150 mm. The heater is equipped with a G 1 1/2" aperture for screwing
an additional heater in. This variant is used - if the tank is connected in a system with heat pump - to finish
heating water in the upper part of the tank to the desired temperature. Insulation of the receptacle is 50
or 60 mm Freon - free polyurethane foam; the shell of the tank is plastic.

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1.2.2 TECHNICAL DATA
Table 1
TYPE OKC 250
NTR/HP
OKC 300
NTR/HP
OKC 400
NTR/HP
OKC 500
NTR/HP
OKC 750
NTR/HP
OKC 1000
NTR/HP
CAPACITY l234 286 352 469 710 930
HEIGHT mm 1537 1558 1644 1914 2039 2053
DIAMETER mm 584 670 700 700 950 1050
MAXIMUM WEIGHT
WITHOUT WATER kg 119 133190 223 259 324
MAXIMUM OPERATING
PRESSURE IN THE TANK MPa 111111
MAXIMUM OPERATING
OVERPRESSURE IN THE
EXCHANGER
MPa 111111
MAXIMUM HEATING
WATER TEMPERATURE °C 110 110 110 110 110 110
MAXIMUM HOT WATER
TEMPERATURE °C 90 90 90 90 90 90
EXCHANGER HEAT SURFACE m22.5 3.2 5.2 6.4 7.0 9.0
EXCHANGER VOLUME L 17 21 32 39 47 63
ENERGY EFFICIENCY CLASS C C C C C C
STATIC LOSS W87 72 90 105 130 142

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OKC 250 NTR/HP
Figure 1
OKC 250 NTR/HP
A 1537
B 660
D 584
E 80
F 1460
G 1060
I 928
J 259
L 209
M 1330
P 355
R 1100

3/4" outer

1"outer

3/4" inner

1/2" inner

6/4" inner

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OKC 300 NTR/HP
Figure 2
OKC 300 NTR/HP
A 1558
B 750
D 670
E 77
F 1579
G 760
I 895
J 325
L 219
M 1309
P 438
R 1148

1"outer

3/4" inner

1/2" inner

6/4" inner

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OKC 400-500 NTR/HP
Figure 3
OKC 400 NTR/HP OKC 500 NTR/HP
A 1644 1914
B 812 812
C 852 852
D 700 700
E 55 55
F 1521 1790
G 843 1023
I 1138 1310
J 288 288
L 228 228
M 1081 1253
P 592 592
R 1237 1409

1"outer

3/4" inner

5/4" inner

1/2" inner

6/4" inner

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OKC 750 – 1000 NTR/HP
Figure 4
OKC 750 NTR/HP OKC 1000 NTR/HP
A 2039 2053
B 1017 1117
D 950 1050
D3 225 225
E 105 105
F 1891 1905
G 1123 1173
I 1491 1547
J 383 391
K 727 780
L 294 301
M 1433 1483

5/4"outer

6/4" inner

3/4" inner

5/4" inner

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1.2.3 PRESSURE LOSSES
Table 2
0
50
100
150
200
250
300
350
400
450
00,5 11,5 22,5 33,5 44,5 5
mbar
m3/h
OKC 250-500 NTR/HP
OKC 250 NTR/HP
OKC 300 NTR/HP
OKC 400 NTR/HP
OKC 500 NTR/HP

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2OPERATION AND FITTING INSTRUCTIONS
2.1 PUTTING THE TANK INTO OPERATION
To connect the tank to water supply system, hot water heating system or power supply and, after testing the
safety valve (accordingly with the manual attached to the valve), the tank can be put in operation.
Procedure:
a) Check the plumbing and electrical installation, including the connection to hot-water heating system.
Check proper placement of operating and safety thermostat sensors. The sensors must be inserted all
the way in; first the operating and then the safety thermostat.
b) open the hot water valve on the combination faucet;
c) open the cold water inlet valve to the tank
d) once water starts draining through the hot water valve, filling of the tank is completed and the valve
must be closed
e) should a leak (of the flange lid) occur, we recommend tightening the screws of the flange lid.
f) when sanitary water is heated with electric energy from hot water heating system, turn off electricity
an open the valves on the heating water inlet and outlet, possibly de-aerate the exchanger. Once
the operation restarts, keep flushing the tank until the cloud disappears
g) Make sure to fill in properly the warranty certificate.

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2.2 CONNECTING A TANK TO HOT WATER SYSTEM
Figure 5
The output hot water pipe on heaters with a volume of more than 200 litres is fitted with another DN 20
safety valve and opening pressure identical to the maximum operating pressure of the heater tank. This
safety valve does not replace the safety valve on the cold water inlet. No shut-off valve, non-return valve or
filter may be placed between the safety valve and the heater.
T fixtures with discharge valve for potential drain of water from the tank have to be mounted
on the cold water inlet of the tank.
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. Each
independently closing tank must be further provided on the hot water inlet with a test valve,
backflow valve, safety valve and manometer.

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2.3 PLUMBING FIXTURE
Power water connects to pipes with 3/4" thread in the bottom part of the tank. Blue - cold water
inlet; red - hot water outlet. For potential disconnection of the tank, the sanitary water inlets
and outlets must be provided with screw coupling Js 3/4". The safety valve is mounted
on the cold water inlet identified with a blue ring.
Every hot sanitary water pressure tank shall be equipped with membrane spring loaded
with safety valve. Nominal clearance of safety valves is defined by standard. Tanks are not
equipped with a 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 the maximum pressure in the water
main (Table 3). 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 the 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 below Table. Backflow valve must be fitted on the inlet pipe to ensure
the right operation of safety valve that prevents spontaneous heater draining of the tank and hot water
penetration back into the water main. We recommend that the hot water distribution from the tank
is as short as possible in order to reduce heat losses. At least one demountable joint must be mounted
between the tank and every supply pipe. Adequate piping and fittings with sufficiently dimensioned
maximum temperature and pressure values must be used.
Tanks must be provided with discharge valve mounted on the cold sanitary water inlet to the tank
for potential disassembly or repair. When assembling the security equipment, follow the standard.

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Table 3
2.4 CONNECTION OF TANK TO HOT WATER DISTRIBUTION SYSTEM
The tank is placed on the floor next to the heating source or in its proximity. The heating circuit shall be
connected to marked tank exchanger inputs and outputs, and bleeder valve installed at the highest point.
It is necessary to install a filter into the circuit in order to protect pumps, three-way valve, backflow flaps
and the exchanger from sedimentation. It is recommended to flush the heating circuit before the assembly.
All wiring connections must be properly insulated from heat. If the system works with priority heating of HUW
using a three-way valve, always follow the installation instructions of the three-way valve’s manufacturer.
Example of group connection of tanks by Tichellman method for equal HSW withdrawal of from all tanks
Figure 6
SAFETY VALVE
START-UP
PRESSURE
[MPa]
ACCEPTABLE
OPERATING
OVER-
PRESSURE OF
WATER TANK
[MPa]
MAXIMUM
PRESSURE IN
COLD WATER
PIPES [MPa]
0.6 0.6 up to 0.48
0.7 0.7 up to 0.56
11up to 0.8
OV - Heating water TUV - Hot sanitary water
SV - Cold water 1 - Back pressure valve
C - Circulation 2 - Pump

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2.5 CLEANING OF TANK AND EXCHANGE OF ANODE ROD
Repetitive water heating causes limestone sediment on both the enamelled tank walls and chiefly the flange
lid. The sedimentation depends on the hardness of water heated, its temperature, and amount of hot water
consumed.
We recommend checking and cleaning the vessel from scale and eventual replacement anode
rod after two years of operation
The anode life is theoretically calculated for two years of operation; however, it changes with water hardness
and chemical composition in the place of use. Based on such an inspection, the next term of anode rod
exchange may be determined. Have a company in charge of service affairs deal with the cleaning
and exchanging of the anode. When draining water from the tank, the combination faucet valve for hot water
must be open, preventing the occurrence of under-pressure in the tank receptacle which would stop water
from draining.
To prevent the occurrence of bacteria (e.g. Legionella pneumophila) within stack heating
it is recommended, if absolutely necessary, to increase the temperature of hot sanitary water
(HSW) periodically for a transitional period of time to at least 70℃. It is also possible to make
use of another way of disinfecting HSW.
PROCEDURE OF EXCHANGING ANODE ROD IN UPPER PART OF THE TANK
1. Turn off control voltage to the tank
2. Drain water from 1/5 tank.
PROCEDURE: Close water inlet in the tank
Open the hot water valve on the combination faucet.
Open the drain tap of the tank
3. Anode is screwed in under the plastic cover in the upper lid of the tank
4. Unscrew the anode using adequate wrench
5. Pull the anode out and follow reversed steps to install a new one
6. During the fitting, make sure the grounding cable (300 l) is connected properly; this is the condition
of the anode's proper functioning
7. Fill the tank with water
PROCEDURE OF EXCHANGING ANODE ROD IN SIDE FLANGE
1. Turn off control voltage to the tank
2. Drain water from the tank.
PROCEDURE: Close water inlet in the tank
Open the hot water valve on the combination faucet.
Open the drain tap of the tank
3. One anode is screwed in under the plastic cover in the upper lid of the tank, and the other one
is screwed in on the side flange
4. Unscrew the anode using adequate wrench
5. Pull the anode out and follow reversed steps to install a new one
6. Fill the tank with water

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2.6 SPARE PARTS
- magnesium anode
- contact thermometer
When ordering spare parts always state the name of the part, the type and type number from the tank's
plate.
3IMPORTANT NOTICES
3.1 IMPORTANT NOTICES
Without a proof issued by a professional company about performed electrical and plumbing
fixture the warranty shall be void.
Protective magnesium anode must be checked regularly and replaced, if necessary.
No closing armature may be mounted between the tank and the safety valve.
All outlets of hot water must be equipped with combination faucets.
Prior to the first filling the tank with water we recommend that the receptacle's flange
connection nuts are tightened.
3.2 INSTALLATION REGULATIONS
Both the electric and water installation must follow and meet the requirements
and regulations relevant in the country of use!
3.3 DISPOSAL OF PACKAGING MATERIAL AND NON-
FUNCTIONING PRODUCT
A service fee for providing return and recovery of packaging material has been
paid for the packaging in which the product was delivered. The service fee was
paid pursuant to Act No 477/2001 Coll., as amended, at EKO-KOM a.s. The client
number of the company is F06020274. Take the water tank packages to a waste
disposal place determined by the municipality. When the operation terminates,
disassemble and transport the discarded and unserviceable heater to a waste
recycling centre (collecting yard), or contact the manufacturer.
22-11-2017