Drazice OKHE ONE20 Specification sheet

OPERATING AND
INSTALLATION MANUAL
FLAT WATER TANK-TYPE WATER HEATER FOR
VERTICAL MOUNTING
Electric water heaters
OKHE ONE20
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]z

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CONTENTS
1PRODUCT TECHNICAL SPECIFICATION....................................................................................................... 4
1.1 FUNCTION DESCRIPTION ................................................................................................................... 4
1.2 ADVICE FOR CUSTOMERS .................................................................................................................. 4
1.2.1 HOT WATER CONSUMPTION ..................................................................................................... 4
1.2.2 ENERGY SAVING......................................................................................................................... 4
1.2.3 EMERGENCY POWER CONSUMPTION ....................................................................................... 4
1.3 DESIGN AND GENERAL HEATER DIMENSIONS................................................................................... 6
2PERATION AND FITTING INSTRUCTIONS ................................................................................................... 7
2.1 OPERATING CONDITIONS .................................................................................................................. 7
2.2 WALL MOUNTING.............................................................................................................................. 7
2.3 PLUMBING FIXTURES......................................................................................................................... 8
2.4 ELECTRICAL INSTALLATION.............................................................................................................. 10
2.4.1 GENERAL INFORMATION FOR ELECTRICAL INSTALLATION ..................................................... 10
2.5 OPERATION...................................................................................................................................... 10
2.6 FIRST COMMISSIONING................................................................................................................... 11
2.7 PUTTING OUT OF SERVICE, EMPTYING............................................................................................ 11
2.8 INSPECTION, MAINTENANCE & CARE FOR THE APPLIANCE............................................................ 12
2.9 MOST FREQUENT FUNCTION FAILURES AND THEIR CAUSES .......................................................... 13
3OPERATION OF THERMOSTAT................................................................................................................. 14
3.1TEMPERATURE SETTING .................................................................................................................. 14
4IMPORTANT NOTICES .............................................................................................................................. 14
4.1 INSTALLATION REGULATIONS.......................................................................................................... 14
4.2 TRANSPORT & STORAGE INSTRUCTIONS ........................................................................................ 15
4.3 DISPOSAL OF PACKAGING MATERIAL AND NON-FUNCTIONING PRODUCT.................................... 15
5PRODUCT ACCESSORIES .......................................................................................................................... 15

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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
Tank type water heater (the heater hereinafter) is designed for the accumulation heating of service water
by electric energy. Water is heated by an electric element in an enamelled thermally insulated tank.
The element is at the time of heating controlled by a thermostat the temperature of which can be adjusted
continuously (within the range between 5°C and 74°C). Once the selected temperature is reached, heating
interrupts automatically. Water accumulated in the tank is then used for the consumption. The tank keeps
constant pressure of water from the water main. If the combination faucet hot water valve is opened, water
from the water supply conduit pressed out by cold water pressure flows out of the heater. How water drains
off the upper part, and incoming water stays in the bottom part of the heater. The pressure principle allows
hot water withdrawal at any place away from the heater.
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.
Find out in what time intervals your electricity supplier provides reduced tariff and, depending
on that information, select relevant volume and power input of the heater so that your hot
water consumption covered the needs of your household.
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.
1.2.3 EMERGENCY POWER CONSUMPTION
Even if no heated water is withdrawn from the heater, there is some minor leakage of heat.
That 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.

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TYPE OKHE ONE 20
VOLUME L 20
MAX OPERATING
OVERPRESSURE IN THE
TANK
MPa 0.6
ELECTRICAL CONNECTION V 1/N/PE ~ 230V/50Hz
RECOMMENDED BREAKER 10 A
INPUT W 2200
EL. PROTECTION IP 44
MAX OPERATING
TEMPERATURE OF HOT
WATER (HW)
°C 80
RECOMMENDED HOT
WATER (HW)
TEMPERATURE
°C 60
HEIGHT OF THE HEATER mm 591
SIZE OF THE HEATER
width x depth mm 523x301
MAX WEIGHT OF THE
HEATER WITHOUT WATER kg 17
TIME OF EL. HEATING FROM
10°C TO 60°C* hrs 0.5
LOAD PROFILE S
ANNUAL CONSUMPTION
OF ELECTRIC ENERGY kWh 485
MIXED WATER V40 l14.24
ENERGY EFFICIENCY CLASS A
Table 1

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1.3 DESIGN AND GENERAL HEATER DIMENSIONS
The receptacles of the heater tank are made of steel plate and tested by 1.5 MPa multiple of operation
pressure value. The inside of the receptacle is enamelled. In the bottom part of the tank there are wells
for placing the heating, regulation and safety element of the water heater (heating element with right thread
G 5/4“, thermostat sensor and thermal fuses). A thermometer is installed in the top part of the heater that
transmits information on heating the volume of service water. The receptacle of the heater is provided with
a quality polyurethane insulation that ensures minimum heat losses.
Wiring is installed in the bottom part of the heater. Water temperature may be set by a thermostat
in the range from 5 °C to 74 °C. Cold water inlet is marked with a blue circle, hot water is marked with a red
circle. All other steel parts are protected against corrosion by paint and galvanic coating. To ensure protection
against corrosion there is an anode rod installed in the head of the heating element that dissolves during the
operation of the heater and must be replaced after 2 to 3 years of service (depending on the chemical
composition of water).
Dimensions of heaters - Figure 1
Technical description: OKHEONE20
Figure 1
Table 2
OKHE ONE 20
A 591
B 301
D 523
E 345
H 246
K 120
R 180
1/2" outer

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¨
i
2PERATION AND FITTING INSTRUCTIONS
2.1 OPERATING CONDITIONS
The heater may only be used in accordance with the conditions specified on the nameplate
and the instructions contained in this manual. Besides the legally acknowledged national
regulations and standards, also conditions for the connection defined in local electric and water
works have to be adhered to, as well as the installation and operation manual.
The temperature at the place of heater installation must be higher than +2°C; and the room
must not freeze. The heater has to be mounted at such a place that can be counted
with as handy; it means that the appliance must be easily accessible for possibly necessary
maintenance, repair or replacement, as the case may be.
If water is strongly calcareous we recommend that any of the common decalcifying device
was installed with the appliance, or the thermostat to be set to the minimum operation
temperature of 60°C (Figure 6). For proper operation, drinkable water of adequate quality shall
be used.
2.2 WALL MOUNTING
Prior to the mounting check the bearing capacity of the wall and the material it is made of,
considering the weight of the heater filled with water. Depending on the wall material choose
adequate fixtures. Should you have any doubts regarding the wall bearing capacity, consult
the suspension with a building specialist.
Neither the control knob of the thermostat, nor another part of the control panel is a bearing
part which may be used for any handling of the heater!
If the hot water heater 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 heater has to be left available under the heater.
When mounted directly under the ceiling, the distance from the ceiling has to be 100 mm
at least.
If the water heater is mounted in enclosed areas, inter-ceilings, built-in structures and recesses,
ensure sufficient access to service fittings, electrical terminal boards, anodes and manholes.
Minimum spacing from manhole is 600 mm.
The heater is mounted in vertical position directly on the wall. Fastening screws must have
guaranteed spacing t = 180 mm.

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180mm
Figure 2
2.3 PLUMBING FIXTURES
The heater connects to water distribution tubes with G1/2“ thread in the bottom part of
the heater. Blue - cold water supply, red - hot water outlet. For potential disconnection of
the heater, the service water inlets and outlets must be provided with screw coupling Js 1/2“.
The safety valve is mounted on the cold water inlet identified with a blue ring.
The heater must be equipped with a membrane, spring-loaded safety valve. Safety valves with
fixed pressure settings from the manufacturer are used for the assembly. Each individually
lockable heater must be fitted with a cap on the cold water inlet, a test valve or a stopper
to check the operation of the check valve, with a check valve and a relief valve (Figure 3).
The safety valve with a check valve is supplied with the heater.
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 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.
Find necessary pressure values in the below.
Heaters must be provided with a discharge valve mounted on the cold service water inlet to the heater
for potential disassembly or repair. When assembling the security equipment, follow the standard.

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Table 3
Figure 3
Figure 4
SAFETY VALVE
START-UP
PRESSURE [MPa]
ALLOWABLE
OPERATING
OVERPRESSURE
OF WATER HEATER
[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

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2.4 ELECTRICAL INSTALLATION
2.4.1 GENERAL INFORMATION FOR ELECTRICAL INSTALLATION
Execute the connection as indicated in the wiring diagram. Factory connection must not be changed!
The degree of protection of electric parts of the heater is IP 44. Power input of electric element is 2200 W.
Figure 5
It is necessary to observe the below requirements during the electric wiring.
•Heater is connected to 230V/50Hz power supply via a fixed movable cable (depending
on the method of wiring)
•The circuit must contain a breaker disconnecting all poles of the network, and a circuit
breaker (protector).
•Installations in bathrooms, lavatories and showers must comply with the standards
that require that the heater is fitted with a safety terminal for connecting via protective
conductor of yellow-green colour of minimum cross section of 4 mm2.
•Access to the power section of the heater is only possible once the heater is disconnected
from the power supply and the cover of the heater unscrewed.
•Adhere to the protection against electric shock injury according to standard.
2.5 OPERATION
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. Setting the thermostat
to the 0 symbol doesn't mean that the appliance has been turned off.

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2.6 FIRST COMMISSIONING
Before connecting to the electricity, the heater must be filled with water. The process of first
heating must be executed by licensed professional who has to check it. Both the hot water outlet
pipe and safety armature parts may be hot.
During the heating up process the water that increases its volume during the heating must visibly
drip off the safety valve. When heating is finished, the set temperature and the actual
temperature of consumed water should be roughly equal. When the heater is connected
to a water piping, power grid and the safety valve has been tested, the heater can be put in
operation.
Before the first putting into service or after a longer shutdown, the appliance has to be rinsed
out and flushed yet before the heating is activated. Before the heating starts, the heater must
be completely filled with water and the system properly flushed and vented. First heating
of the heater has to be watched.
Procedure of putting the heater into operation:
1. Check the water main and wiring. Check proper placement of the operating and safety thermostat
(thermal fuse) sensors. The sensors must be inserted all the way in; first the operating and then the
safety thermostat.
2. Open the hot water valve on the mixing faucet.
3. Open the cold water inlet valve to the tank.
4. As soon as the water starts running through the hot water valve, the heater is filled and the valve
can be closed.
5. In case of leakage (of flange lid), we recommend that the flange lid bolts are fastened.
6. Screw down the electric installation guard.
7. Turn on the power supply.
8. When commencing operation, flush the heater until the cloudiness in the water is gone.
9. Make sure to fill in properly the warranty certificate.
2.7 PUTTING OUT OF SERVICE, EMPTYING
If the heater is put out of service for longer period, or is not going to be used for some time, we
recommend it is disconnected from the power grid on all poles. The switch for the power cord
or fuse machines must be shut down.
In locations that are permanently exposed to frost, hot water tank shall be emptied prior
to the beginning of the cold season, if the appliance is not used for several days, and if the power
supply is disconnected.

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Drainage of service water shall be performed after closing the shut-off valve in the cold water
supply piping (through the discharge valve for a combination of safety valves) and with
simultaneous opening of all hot water valves of connected fittings (water can be also drained
through the safety valve. Hot water may outflow during the drainage! If there is a risk of frost,
be aware that not only the water in the hot water tank and the water in the hot water piping
may freeze, but also the water in the entire cold water supply piping. It is therefore purposeful
to discharge all fixtures and pipes where water flows all the way to the section of the house
water meter (connection of the house to the water main) that is no longer threatened by frost.
When the heater is to be used again, it has to be filled with water and one needs to make sure
that the water flowing out at the hot water valves contains no bubbles.
2.8 INSPECTION, MAINTENANCE & CARE FOR THE APPLIANCE
During the heating process the water that increases its volume during the heating must visibly
drip off the safety valve drain. At full heating (about 74℃) the volumetric water gain is approx.
3.5% of the heater’s capacity. The function of the safety valve has to be checked regularly.
If the safety valve control knob is lifted or turned to the “Control” position, the water must flow
out easily, without any obstacles, from the safety valve element to the outfall line. 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.
Attention! The inlet cold water pipe and the connection fitting of the heater may heat up!
If the hot water heater does not work, or if hot water is not withdrawn, no water shall drip off
the safety valve. If water drips, then the water pressure in the supply piping is either too high
(if higher than 5.5 bar, a pressure control valve has to be fitted), or the safety valve in the inlet
piping is malfunction. Please call a specialised plumber immediately!
Repetitive water heating causes lime scale sediment on both the tank walls and mainly
on the heating body. Lime scale settling depends on hardness of heated water, its temperature
and on the volume of hot water used. If water contains a lot of minerals, after one to two years
of operation an expert must be called to remove scale forming inside the heater and the loose
sediments. Cleaning takes place through the hole in the flange - dismantle the heating element
and clean the heater. A new sealing has to be used for re-fitting. Since the inside of the heater
has special enamel which must not get in contact with the scale removing agent - do not work
with decalcification pump. Remove the calcerous buildup with a timber or plastic tool
and hoover it up or wipe off with a cloth. Then the appliance must be thoroughly flushed
and the heating process checked as on the first putting in operation. Do not use any abrasive
cleaning agents (such as liquid sand, chemicals - acid, alkaline) or paint thinners (such
as cellulose thinner, trichlor, and the like) to clean the outer shell of the heater. For cleaning
of the outer shell of the heater use a wet cloth and add a few drops of liquid detergent
commonly used in households.

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We recommend checking and cleaning the tank from lime 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. If the anode is only blocked with sediments clean its surface and, if used up, mount
a new one. Have a company in charge of service affairs deal with the cleaning and exchanging
of the anode.
2.9 MOST FREQUENT FUNCTION FAILURES AND THEIR CAUSES
FAILURE SYMPTOM INDICATOR SOLUTION
Water is cold •Light on
•The temperature set on the thermostat
is too low
•Heating element failure
Water is cold •Light off
•No supply voltage!
•Thermostat failure
•Safety thermostat shut off probably due
to failed operation thermostat
Water is not warm enough •Light on •heating element failure
Temperature of water is not
corresponding with the
temperature set on the
control
•Defective thermostat
Water is constantly dripping
off the safety valve •Light off •high input pressure
•defective safety valve
Table 4
Do not attempt to repair the failure yourselves. Seek either expert or service help. It does not
take much for an expert to remove the defect. When making a repair appointment, report
the type and serial number you find on the performance plate of your water heater.

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3OPERATION OF THERMOSTAT
3.1 TEMPERATURE SETTING
Water temperature can be set by turning the knob of the thermostat between 0 °C to 74 °C by the symbol
of the thermostat knob.
Figure 6
4IMPORTANT NOTICES
4.1 INSTALLATION REGULATIONS
-Without a confirmation of performed electrical installation issued by an authorised company,
the warranty certificate shall be void.
-Check and exchange the Mg anode regularly.
-Please make sure that for the connection of your heater you don't need an approval of the local
electricity supplier.
-No stop valves can be put between the heater and the safety valve.
-With overpressure in the water distribution system higher than 0.48 MPa, it is recommended
that a reduction valve is fitted before the safety valve.
-All hot water outputs must have a combination faucet.
-Before filling the heater with water for the first time, it is recommended to fasten the flange
connection nuts of the tank.
-It is not allowed to handle the thermostat, aside from temperature resetting with a control button.
-All electric installation handling, adjustment and replacement of the regulation elements shall only
be performed by an authorised service company.
-The thermal fuse must not be turned off! In case of thermostat defect, the thermal fuse interrupts
electric power input to the heating element if the water temperature in the heater exceeds 90 °C.
-If the heater or the facility with heater is without surveillance for longer period, shut off the cold
water inlet and power supply to the heater. Empty the heater if there is a risk of frost.
-The tank may only be used in accordance with the conditions specified on the nameplate and with
the instructions contained in this manual.

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-The recommended operating pressure in the hot water circuit is 0.48 MPa. At the hot water discharge
we recommend that a reverse flap and an expansion tank are installed (at least 4% of hot water
volume in the manifold) to eliminate reverse pressure shocks.
Both the electric and water installation must follow and meet the requirements
and regulations relevant in the country of use!
4.2 TRANSPORT & STORAGE INSTRUCTIONS
The device shall be transported and stored in dry place and protected from weather effects with temperature
range from -15 to +50°C. During loading and unloading the instructions stated on the packaging shall be
observed.
4.3 DISPOSAL OF PACKAGING MATERIAL AND NON-
FUNCTIONING PRODUCT
The packaging that the product was delivered in has been paid for in form of
a service fee for the provision of the return and recovery. The packaging that
the product was delivered in has been paid for in form of a service fee for
the provision of the return and recovery. Take the water heater packaging
to a waste disposal place determined by the municipality. Disassemble
the discarded and unserviceable product after the operation terminates,
and transport it to a waste recycling centre (collecting yard), or contact
the manufacturer.
5PRODUCT ACCESSORIES
The product is supplied together with a safety valve. Safety valve is packed and placed in the upper section
of the heater’s packaging.
It is in your own interest to check the completeness of the accessories.
2-10-2018