OPERATING AND INSTALLATION MANUAL
STATIONARY WATER HEATERS
OKCE 100 NTR/2,2kW
OKCE 125 NTR/2,2kW
Družstevní závody Dražice-strojírna s.r.o.
(Works Cooperative - Dražice – Machine Plant, Ltd.)
Dražice 69
294 71 Benátky nad Jizerou
Tel.: 326 370 911, Fax: 326 370 980
www.dzd.cz
dzd@dzd.cz
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OKCE 100 NTR/2,2 kW
100 2,7 6
OKCE 125 NTR/2,2 kW
125 3,5 7,5
Heat losses
((Wh/24hr)/l)
Nominal
capacity (l)
Time of
content
heating
(hours)
Electricity
consumption for
heating of volume
from 15°C to 65°C
(in kWh)
Heat losses
((kWh/24hr)
Heater types
Energy
efficiency
class
Read carefully the below instructions prior to the installation of the heater!
Data sheet pursuant to Directive No 442/2004 Coll. and Annex No 7
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 indirect
water heaters. Product’s reliability and safety is proven by tests implemented by the Engineering Test Institute in
Brno.
The manufacturer reserves the right for engineering modification of the product.
The product is designed for permanent contact with drinkable water.
Guide Contents
1. USE ................................................................................................................................................................................ 2
2. PRODUCT DESCRIPTION ......................................................................................................................................... 3
3. IMPORTANT NOTICES ............................................................................................................................................. 3
4. OPERATING ACTIVITY ............................................................................................................................................... 3
5. PUTTING THE HEATER INTO OPERATION ......................................................................................................... 4
5. SERVICING .................................................................................................................................................................. 4
7. TECHNICAL PARAMETERS .................................................................................................................................... 6
8. PLUMBING FIXTURE ................................................................................................................................................ 7
9. ELECTRIC INSTALLATION ..................................................................................................................................... 7
10. TECHNICAL DATA CHART...................................................................................................................................... 8
11. PRESSURE LOSSES .................................................................................................................................................... 8
12. EXAMPLES OF HEATERS CONNECTION ............................................................................................................. 9
13. SPARE PARTS ........................................................................................................................................................... 10
14. HEATER CLEANING AND ANODE ROD EXCHANGE ....................................................................................... 10
15. INSTALLATION REGULATIONS ........................................................................................................................... 11
1. USE
Thanks to their construction and number of variants, the OKCE 100, 125 NTR series water heaters enable
economic preparation of hot service water (HSW) by means of various power sources. Their nominal performance
provides sufficient amount of hot water for flat units, premises, restaurants, and similar establishments. For HSW
reheat, electricity, various types of central heating boilers, recoverable energy sources (heat pumps, solar
collectors) and combination of those can be chosen.
Service water heating via thermal energy through heat exchanger
Closing valves of the heat exchanger must be opened which ensures heating water flow from the hot water heating
system. Together with a 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.
The time of heating using the heat exchanger depends on the temperature and flow of water in the hot water heating
system.
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2. PRODUCT DESCRIPTION
The heater tank is welded from a steel sheet; the exchangers from a steel tube and, as a unit, it is entirely coated
with hot water resistant enamel. A flange is welded onto the upper bottom of the receptacle with a flange lid
screwed to it. A sealing ring is inserted between the flange lid and the flange.
Thermowells for placing a heating element and sensors of regulation thermostat and safety fuse are located
in the flange lid. Electric wiring is placed underneath the plastic removable cover. The temperature of water can be
set using the thermostat.
For additional corrosion protection a magnesium anode is mounted in the upper part of the heater to adjust the
electric potential inside the tank, reducing the risk of corrosion. The heaters have outlets of hot and cold water and
a circulation opening welded to them. The tank is insulated with polyurethane foam of 40 - 65 mm thickness. The
heater shell consists of a steel, powder-paint coated, sheet; the connecting parts are metal coated. The entire heater
stands on three rectification screws with a possibility of levelling floor unevenness within the range of 10 mm. The
heater is to be placed on the ground. The tank is tested with pressure of 0.9 MPa, heat exchangers with 1.5 MPa.
The NTR version has a heat exchanger located in the bottom part of the heater, and one heating water source is
used for heating.
Placement and environment type
The heater is placed on the ground, next to the heating water source, or in its vicinity. All connecting distributions
must be properly insulated from heat. It is recommended to use the product in an indoor environment with air
temperatures from +2 to 45°C and a maximum relative humidity of 80%.
3. IMPORTANT NOTICES
- Without a proof issued by a professional company about performed electrical and plumbing fixture the
warranty shall be void.
- The Mg anode has to be checked regularly and exchanged, if needed.
- No stop valves can be put between the heater and the safety valve.
- All outlets of hot water must be equipped with a combination faucet.
- Before the first filling of water heater it is recommended to tighten the nuts of the flange joint of the tank.
- It is not allowed to handle the thermostat, aside from temperature resetting with a control button.
- All electric installation handling, setting, and regulation feature exchange, may only be implemented by a service
company.
- The thermal fuse must not be turned off! In case of a thermostat defect, the thermal fuse interrupts electric
power supply to the heating element if the water temperature in the heater exceeds 95°C.
- As an exception, the thermal fuse may also switch off due to water overheating caused by overheating the hot
water heating system boiler (in case of a combined heater).
- We recommend you operate the heater with one type of energy. In case a solar system is connected to the
bottom exchanger, it is necessary to connect a TJ 6/4" line element in the coupling above the heater for potential
additional heating.
4. OPERATING ACTIVITY
a) Water heating by electric energy
After the heater is connected to electric network, the heating element starts heating water. The element is turned on
and off by a thermostat. After reaching the temperature set, the thermostat switches off the electric circuit and thus
discontinues water heating. The control light signals if the element is in operation (light is on) or if it is off (the light goes out).
In case of longer operation without using the heated volume, the thermostat has to be set to position 5°C to 8°C (set the
“snowflake” symbol on the thermostat selector) to avoid its freezing, or electricity supply to the heater has to be switched off.
In combined versions, the stop valve on the inlet to the exchanger has to be closed, which prevents heating water in
the hot water heating system.
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b) Service water heating via thermal energy through heat exchanger
Closing valves of the heat exchanger must be opened which ensures heating water flow from the hot water heating
system. Together with a 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 (Fig. 2) as needed, in particular before the beginning of the heating season. The time of
heating using the heat exchanger depends on the temperature and flow of water in the hot water heating system. A combined
heater is made in universal design – depending on the need of connecting the closing valves to the heating element either from
the right, or from the left (Fig.2).
5. PUTTING THE HEATER INTO OPERATION
After connecting a heater to the water main, the hot water heating system, the electric network, and after testing its
safety valve (based on the valve manual attached), the heater may be put into operation.
Procedure:
a) Check both water and electric installation; for combined heaters, check the installation to a hot water heating
system. Check proper placement of operating and safety thermostat sensors. The sensors must be inserted all
the way in; first the thermostat and then the safety fuse.
b) Open the hot water valve on the combination faucet;
c) open the cold water inlet valve to the heater;
d) when the water starts flowing through the hot water valve, the filling of the heater is finished and the valve
needs to be closed;
e) Should a leak (of the flange lid) occur, we recommend tightening the screws of the flange lid;
f) Fasten the electric installation cover;
g) When heating service water heating by electric energy, turn on the electricity (for combined heaters, the
heating water inlet to the heating insert must be closed);
h) When heating the water with thermal energy from a hot water heating system, turn off the electricity and open
the valves at the inlet and outlet of heating water or bleed the exchanger. When commencing operation, flush
the heater until the cloudiness in the water is gone.
i) Make sure to fill in properly the warranty certificate.
5. SERVICING
Service devices of heaters of 80 to 200 l capacity are located under the transparent guard of the control panel.
Thermostat knob Indicator - Boost heating Lamp switching circuit Thermostat knob
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Lower temperature range
limit (about 5°C)
Fixed point on the control
panel
Anti-freezing temperature
(about 8°C)
Upper temperature range
limit (about 74°C)
”Ideal” temperature (about
60°C)
Regulation limited
Setting blocked
Temperature setting
Water temperature is set by turning the thermostat knob. The desired symbol is adjusted against the fixed point on
the control panel.
Notice: Adjusting the thermostat selector at the left backstop does not mean permanent shutoff of the heating
element.
When the heater is in use without blocking the daily rate, we do not recommend the temperature to be set above
60°C.
The maximum value to select is “60“.
Limiting the regulation range; locked settings.
For various safety reasons (unintentional scalding, preventing children or unauthorised person from handling), the
regulation range can be limited, or the setting on the thermostat blocked.
Regulation limited - pull off the thermostat knob (it will be tough at first) and you will find two cylindrical
pins 2,15mm on the back side of the knob
- pull off one pin and insert it to the corresponding hole of the selected maximum
temperature.
- put the knob back on (to the stop)
Setting blocked – set the selected temperature
pull off the thermostat knob without changing the setting and you will find two pins on the back
side of the knob; pull both of them and fit them into the holes corresponding with the selected
temperature so that the gap between the pins was without a hole, and the position was opposite
the set temperature.
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A 881 1046
B 621 751
C 521 621
Typ
OKCE 100 NTR/2,2 kW
OKCE 125 NTR/2,2 kW
7. TECHNICAL PARAMETERS
Cold water inlet
Hot utility water outlet
OKCE 100 NTR/2,2 kW, OKCE 125 NTR/2,2 kW
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8. PLUMBING FIXTURE
Safety valve
starting pressure
(MPa)
Admissible operating
water heater
pressure (MPa)
Max. pressure in
the cold water pipe
(MPa)
0.6
0.6
up to 0.48
0.7
0.7
up to 0.56
1 1 up to 0.8
Connection of heaters to plumbing fixtures is illustrated on Figures 1 and 2. For potential disconnection of
the heater, the service water inlets and outlets must be provided with screw coupling Js 3/4“. Safety valve is
mounted on the cold water inlet identified with a blue ring.
Each hot service water pressure heater must have a membrane spring loaded with a safety valve. Nominal clearance
of safety valves is defined in the ČSN 0 60830 standard. The heaters are not equipped with a safety valve. The
safety valve must be easily accessible, as close 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 a branch pipe. This allows easier exchange without having
to 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 to 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. 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 to the right. 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 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 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.
We recommend that the hot water distribution from the heater was as short as possible to minimise heat losses.
Heaters must be provided with a discharge valve mounted on the cold service water inlet to the heater (Fig. 2)
for potential disassembly or repair.
When assembling the security equipment, follow ČSN 06 0830.
9. ELECTRIC INSTALLATION
The electric wiring scheme is attached to the water heater on the side of the electric installation guard (see also
Fig.).
Connection, repairs, and wiring inspections may only be implemented by a company (person) authorised to such
activity.
Expert connection must be confirmed on the warranty certificate.
The heater is connected to the 400 V/50 Hz electric network using a fixed moving conductor with a switch that
turns off all network poles and the circuit breaker (protector).
Installations in bathrooms, laundromats, rest rooms, and showers, 33 2000-7-701 must be obeyed.
The degree of protection of electric parts of the heater is IP 45.
Respect the rules of protection against electrical injuries in accordance with ČSN 33 2000–4-41.
Wiring scheme:
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Type
1 2 3 4 5
Exchanger 1m2 7 24 51 86 130
Exchanger 1,45m2 9 32 68 115 174
Pressure loss mba r
tHV = 60 °C
Amount of heating wa ter in m3/h
1
1,5
2
3
5
10
20
50
100
200
Výměník s teplosměnou
plochou 1 m2
Výměník s teplosměnou
plochou 1,45 m2
Průtok topné vody m3/h
Odpor topné vody
mbar
4
Typ
OKCE 100 NTR/2,2 kW
OKCE 125 NTR/2,2 kW
Capacity l 96
115
Maximum weight of the heater
kg
59
71
Maximum operating pressure in the tank
MPa
0,6
0,6
Maximum operating overpressure in the exchanger
MPa 1 1
Maximum rating water temperature
°C
110
110
Maximum temperature of HSW*
°C
80
80
Lower exchanger heat delivery surface
m2 1 1,45
Bottom/top exchnger output at rating water temperature
of 80°C and flow 720 l/h
kW
24
32
Permanent HSW *
l/h
610
990
Time of heating by exchanger from 10°C to 60°C
min
14
14
Time of rating with electricity from 10°C to 60°C
hod 3 3,5
Power input
kW
2,2
Electric connection of kontrol elements
1 PE-N 230 V / 50 Hz
IP Protection
IP 44
Heat losos/Energy efficiency class
kWh/24 h
HSW – Hot service water 45°C
Exchanger with heat transfer
surface 1,45 m2
Exchanger with heat transfer
surface 1 m2
Heating water flow m3/h
Heating
water
resistance
mbar
10. TECHNICAL DATA CHART
11. PRESSURE LOSSES
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12. EXAMPLES OF HEATERS CONNECTION
Connecting a heater to a heating circuit
The heater is placed on the ground, next to the heating source, or in its vicinity. The heating circuit is connected to
marked inputs and outputs of the heater exchanger; the deaerating valve is mounted in the highest place. It is
necessary to install a filter into the circuit in order to protect the pumps, the three-way valve, and 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 HSW using a three-way valve, always follow the installation
instructions of the three-way valve’s manufacturer.
Connecting a Heater to a Hot Water Distribution
Cold water shall be connected to an inlet marked with a blue ring and writing “HSW INLET”. Hot water shall be
connected to an outlet marked with a red ring or writing “HSW OUTLET”. If the hot service water (HSW)
distribution is equipped with circulation circuit, it shall be connected to the outlet marked with “CIRCULATION”.
For potential drain of heater, the HSW inlet has to be provided with a “T” fixture with a drain valve. Each
individually lockable heater must be at the cold water inlet provided with a stop gate, test cock, safety valve with a
reverse flap and a pressure gauge.
An example of a group heater connection for steady hot water consumption from all tanks using
Tichelmann’s method
OV – Heating water TUV - Hot service water
SV - Cold water 1 - Return valve
C - circulation 2 - pump
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13. SPARE PARTS
- Flange lid - flange lid seal - insulation flange lid
- thermostat and thermal fuse - Magnesium anode - control button for the thermostat
- control lights with wires - capillary thermometer - set of M12 (or M10) bolts
When ordering spare parts, give part name, type, and type number from the heater label.
14. HEATER CLEANING AND ANODE ROD EXCHANGE
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 tank from scale and eventual replacement of the 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 the company in charge of service affairs clean and exchange the
anode. When discharging water from the heater, the mixing valve of the hot water tap must be open in order to
avoid creating underpressure that would prevent water discharge.
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15. INSTALLATION REGULATIONS
Regulations and instructions that must be obeyed during heater assembly:
a) to the heating system
ČSN 06 0310 – Thermal systems in buildings – Designing and Installation
ČSN 06 0830 – Thermal systems in buildings – Protecting devices
b) to the electrical network
ČSN 33 2180 - Connecting of electric devices and appliances
ČSN 33 2000-4-41 - Low voltage electric installations Protective measures to ensure safety – Protection against
electric shock
ČSN 33 2000-7-701 - Low voltage electric installations Single-purpose devices and devices in special premises Premises with tub or shower to hot service water heating system
c) to the hot service water heating system
ČSN 06 0320 - Thermal systems in buildings - Hot water preparation – Design and Project Engineering
ČSN 06 0830 – Thermal systems in buildings – Protecting devices
ČSN 73 6660 – Internal water mains
ČSN 07 7401 - Water and steam for thermal energy equipments with working steam pressure up to 8 MPa
ČSN 06 1010 - Tank water heaters with water and steam heating; and combined with electric heating
Technical requirements. Testing.
ČSN EN 12897 – Water supply – Indirectly heated closed tank-type water heaters
Both the electric and water installation must follow and meet the requirements and regulations relevant in the
country of use.
Disposal of packaging material and functionless product
A service fee for providing return and recovery of packaging material has been paid for
the packaging in which the water heater 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
boiler packages to a waste disposal place determined by the town. When the
operation terminates, disassemble and transport the discarded and unserviceable
heater to a waste recycling centre (collecting yard), or contact the manufacturer.
2-2014
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