Thermona THERM EL 8, THERM EL 15, THERM EL 30, THERM EL 23, THERM EL 38 Operating Instructions Manual

Operation and
Maintenance
Manual for
Electric Boilers

(user manual)

version: February, 2008

THERM EL 8

THERM EL 15

THERM EL 23

THERM EL 30

THERM EL 38

THERM EL 45

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1. CONTENTS

1. CONTENTS ................................................................................................................................................ 2

2. GENERAL USE ......................................................................................................................................... 3

3. GENERAL CHARACTERISTICS OF THERM – EL ELECTRIC BOILERS .................................. 3

4. TECHNICAL DATA ................................................................................................................................. 7

5. BASIC INSTRUCTIONS FOR BOILER INSTALLATION ................................................................. 8

6. BOILER OPERATION ........................................................................................................................... 13

7. BOILER CONTROL AND DISPLAY OF BASIC OPERATIONAL INFORMATION .................. 16

8. USER MENU ............................................................................................................................................ 19

9. PUTTING THE BOILER INTO OPERATION.................................................................................... 21

10.

DIAGRAM FOR SERVICEABLE CONNECTING CHARGE PRESSURES OF HEATING WATER

....... 23

11. THERM EL BOILERS CONNECTION TO THE POWER SUPPLY............................................... 24

12. WARRANTY AND RESPONSIBILITY FOR DEFECTS................................................................... 31

13. DOMESTIC HOT WATER STORAGE TANK HEATING MODE .................................................. 31

14. THERM EL 8, 15, 23 BOILER ASSEMBLY (KW) ............................................................................. 33

15. THERM EL 30, 38, 45 BOILER ASSEMBLY (KW) ........................................................................... 34

16. WALL-MOUNTING OF THE BOILER ............................................................................................... 35

17. BOILER DIMENSIONS AND CONNECTION.................................................................................... 35

18. RECORD OF REPAIRS AND ANNUAL INSPECTIONS .................................................................. 36

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2. General use

The construction of THERM-EL electric boilers is designed for hot-water heating systems with induced
water circulation. They can be installed in central or individual-storey heating with induced circulation sealed or
open systems and they are characterized by an environmentally friendly operation without requirements for
venting of the combustion product. Service-free operation enables the installation of an external regulator, other
external regulating or controlling components (not included in the boiler delivery package!), simple equitherm
regulator or room thermostat integrated directly in the automatic controlling system which maintains the pre-set
room temperature. The electric boiler can be used as a universal source of heat for heating flats, small family
houses, resort houses and also as an alternative source to another main heat source of heating and hot water
preparation (also for transitional periods) – for heat pumps, accumulation systems or in previously installed
central or single-storey heating systems etc. To attain higher output levels, boilers can be connected into a
cascade format.

3. General characteristics of THERM – EL electric boilers

Therm-EL electric boilers are wall-mounted appliances designed for water heating in a heating system and
potentially for domestic hot water heating (hereinafter referred to as “DHW”) in an indirect heating storage
tank.

THERM-EL electric boilers are manufactured in three performance versions in the lower output category:
8, 15 and 23 kW. The higher output series offers the following three types: 30, 38 and 45 kW. Structural
design as well as controlling system of these boilers are almost identical to the lower output series.

The electric boiler is formed by a steel vessel with inbuilt heating bars, heating temperature probe and safety
thermostat (these components are all located under one cover in the upper part of the vessel). The vessel is made
from a varnished steel sheet and it is fitted with thermal insulation. Heating water inlet, on which a circular
pump is mounted, is welded at the bottom part of the boiler. A lug located in the upper part of the vessel is
adjusted to the cup for the boiler temperature sensor and emergency thermostat. Heating water outlet and
threaded sleeve pieces are also located in the upper part of the vessel. Heating bars (up to 6) are screwed in the
sleeve pieces. Total output of each heating bar is 7.5 kW (there are three separate heating bodies with the output
of 2.5 kW in each heat bar). An automatic vent valve is placed at the highest point of the water heating circuit.

The boiler control box enables connection of an external room thermostat, addition of interface for the boiler
cascade connection type, programmable (time) switch and MRC (mass remote control) tariff switch.

Switching and electric line protection of the boiler and output inlets for the heating bars are not
located in the boiler but they always form part of the electric distributor of the flat or house. Terminals of the

main wiring are concentrated in the right part of the boiler. A sufficiently rated output line contactor or switch
(correctly marked!) which are used for disconnecting the electric boiler from the power network must be
connected right next to the boiler during its installation.

♦ Boiler operation characteristics:

Operational stage of the boiler is launched when heating system temperature drops below the temperature
set on the boiler control panel or on the room thermostat. Control circuit of the heating bars becomes activated
and heating water inside the boiler body becomes heated gradually. After the required temperature has been
reached in the room (if a room thermostat is applied), the control microprocessor unit starts switching off the
heating bodies one by one and the heating of the water stops. At this moment the function of an adjustable
limited pump deceleration (in terms of time or temperature) becomes activated.

As standard, Therm-EL boilers are also fitted with emergency thermostat which delivers maximum safety.
It is connected to the control circuit of the integrated output contactor. The disconnection of the emergency

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thermostat (disjunction of the controlling circuit relay and heating bars) and thus the boiler shut-down occur
when the temperature reaches 105°C. Shall the emergency thermostat become disconnected, the boiler can be
only put back into operation by an authorized service engineer. Another protection of the boiler is assured by a
pressure switch which disengages the control circuit when the heating system water pressure decreases (when
there is not enough water in the heating system). When the system becomes replenished with water, the boiler
automatically relaunches operation. Proper deaeration of the heating system must be assured prior to launching
and also during boiler operation. The heating system bleeding is partially ensured by the automatic vent valve
which is placed at the outlet of heating water from the boiler body.

♦ Selected important characteristics and merits of THERM- EL electric boilers:

• top microprocessor control

• very quiet operation (switch power relay of the heating bodies)

• state-of-the-art design

• ergonomic, interactive control

• smooth regulation – 2.5 kW regulation step (5 kW with the higher performance series)

• service-adjustable pump deceleration

• protection of the pump against particulate build-up

• PID regulation

• anti-freeze protection

• DHW heating option (terminals for an external three-way valve, NTC temperature sensor or a storage tank thermostat)

• optional connection of an external NTC sensor (integrated equitherm regulation)

• connection of an NTC temperature room sensor (automatic controlling system as a room regulator)

• integrated safety switch contactor for all output phases

• possibility of an intelligent cascade boiler connection format (up to 32 boilers – with smooth output modulation)

• optional external control by means of GSM (external modem necessary)

• optional connection of an external regulator with OpenTherm communication

• balanced loading of the heating bars and bodies

• power relays do not form part of the processor board printed circuits (easy servicing and replacement). Special relays with
integrated fastons were used, i.e. high currents do not flow through printed circuits.

• boiler start system functioning on the basis of a mass remote control (MRC)

• external control of energy input (relief relay)

• soft start

• integrated Grundfos UPS 15/60 pump

• integrated 7 l expansion vessel (with the lower performance series)

• integrated safety valve

• automatic bleeding

• digital heating water pressure sensor (fitted with all types)

• auto-diagnostics, unequivocal service notification of defects

• optional boiler parameter adjustment (rich service menu)

• three-digit display (displays selected temperatures, pressure, output, error messages etc.)

• further 7 LEDs for unequivocal signalling of the operational conditions

• option of a default setting (immediate change of operation into the factory settings mode)

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♦ Brief characteristics of the main merits of THERM-EL electric boilers:

Simple and intuitive operation

The control is designed in a simple, understandable and unambiguous way. Simple operation is also enabled by way of a
three-digit LED 7-seg display complemented by an unambiguous signalling system of a series of LEDs.

Pump protection against clogging

Regular spinning of the pump (once every 24 hours) prevents potential clogging of the pump during an extended boiler
down time.

Optional DHW heating

It is possible to additionally connect an external indirect DHW heating storage tank to the THERM-EL boiler. Heating of
the storage tank water is ensured by means of changing the position of the three-way valve. The boiler electronics can
communicate with the temperature sensor (continuous DHW temperature regulation) as well as with the traditional storage
tank thermostat (can be set in the service menu).

External regulatory elements

Boiler control by way of room thermostat or equitherm sensor is commonplace. Connection of the boiler to the room
thermostat or equitherm probe leads to further savings for electricity. The THERM-EL boiler is moreover able to cooperate
with regulators communicating via the OpenTherm communication protocol. Additional communication interface is not
necessary.
If the NTC temperature sensor is connected only in a room of reference according to which the whole heated space is
regulated, automatic control system can be used as a simple room regulator! (This can be set in the user menu.)

Safety switch contactor

Safety three-phase contactor is inserted in the power branch circuit at the boiler inlet which can cut the power from the
heating bars in case of emergencies and detected incorrect conditions (for further details see auto-diagnostics of the
automatic control system) and prevent a potentially dangerous situation from occurring.

Boiler cascade connection format option

The boiler electronics enable connection of up to 32 boilers into a single intelligent cascade which modulates the
performance ranging from minimum output of the first boiler to the total of maximum outputs of all boilers combined. The
interconnection of the master and slave boilers is possible only through a system of intelligent modules – i.e. the same
interface must be used for master as well as slave boilers.

GSM operated boiler

The boiler can be switched on and off by means of a mobile phone (it is however necessary that an external modem is
used; the modem is not an item of the boiler delivery package!). The boiler operation can be remotely launched by calling
on a GSM modem connected to the boiler, for example prior to returning from holiday, so that the house has a pleasant
temperature at the time of arrival.

Balanced service load of heating bars

Principle of a balanced service load on the heat bars extends their life-time. The heating bar which was connected first will
be also disconnected first within the framework of the regulation cycle which leads to an increase in overall reliability and
prolonged durability of the appliance. The processor assess the operational time of individual heating bars and actuates
them in a manner which ensures a thermally balanced loading of the boiler (the boiler body) and even service load of the
bars.

MRC system for launching the boiler operation

THERM-EL boilers signal and respond to commands from the MRC receiver of the external distributor. The output signal
of this receiver must be connected to the reset conductor which is attached to the MRC/R terminal. This method of remote

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control enables the boiler to operate in a low tariff rate and thus significantly reduce energy costs. Maximum boiler output
can be limited in the service menu if the operation must proceed also outside the so-called “low tariff”.

!!! Shall other ways of installing the MRC receiver be applied the output of which is one of the phases (MRC/L1

-L3), it is necessary to assure transmission to the R level (reset conductor) by means of e.g. installing an
auxiliary relay in the external distributor.

Soft start

The soft start function rests in a gradual heat-up of the heating system which is therefore protected against abrupt upward
temperature gradient. When the boiler is switched on or a new regulation period is initiated and the resulting quick change
in temperature caused by induction of heat into the system could also bring about noise due to the dilatation of pipes, the
boiler is actuated in the so-called “soft start” and limits the output after it is launched.

Auto-diagnostics, unambiguous signalling and service messages

THERM-EL electric boilers are equipped with a very useful system of auto-diagnostics chiefly with respect to service.
This function facilitates speedy and efficient removal of a potential boiler defect. Apart from the commonly displayed user
values – heating water temperature (the TOP circuit), DHW temperature, outdoor or room temperature sensor, TOP circuit
pressure – the display can show other service information if the service menu is set up correspondingly: E.g. disconnection
or short circuit of all sensors, boiler output, MRC condition and other error messages.

Wide choice of parameter settings

Service and user menus of THERM-EL boilers provide a wide range of boiler settings according to specific conditions of
operation or based on customer requirements:

- The option of setting various outputs for the heating water and heating of DHW undoubtedly offers positive financial
effects.

- The possibility of setting different outputs with the MRC signal switched on or off provides the user with a pleasant heat
comfort.

External energy input control

If there are several concurrently operating electrical apparatuses and the household has increased requirements for power
take-off, the THERM-EL boiler user will certainly appreciate the external energy input control function. A relief relay can
be connected to the distributor with a pre-set value of the electric current. If the current reaches e.g. 30 A, the boiler
disconnects a specified number of heating bars and relieves the whole system.

SLEEP standby mode

Another function the advantage of which will be namely appreciated by those users who stay outside home for longer
periods of time is the SLEEP mode. This mode is used in situations when the house will not be inhabited for an extended
period and the user wants to have the heating system reliably safeguarded against solidification or freeze-up. Boiler in the
SLEEP mode consumes minimum amount of power but the protective boiler functions – spinning, unblocking and anti­freeze protections – are also active. If the boiler is connected to an equitherm sensor, the drop in outside temperature
activates an anti-freeze protection which can protect not only the actual boiler but the entire heating system.

If during the boiler's operation (i.e. not only in the SLEEP mode) none of the control panel buttons becomes
activated (when heating and DHW heating are switched off by the respective button), the display automatically
switches over to the saving mode (only the LED is turned on).

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4. Technical data

Lower performance series:

THERM EL 8 THERM EL 15 THERM EL 23

Nominal heat output kW 7.5 15 22.5
Rated current A 11 22 33
El. components degree of shielding IP 40
Power voltage / frequency

V/Hz

3 x 230 + N + PE/50
Max. rated current A 3 x 12 3 x 24 3 x 36
Wiring main circuit breaker A 16 A 32 A 40 A

Rated current of the control system fuse

A 1.25

Electric durability of the relay - 1.105 cycles (16 A. 250V/50 Hz)

Mechanical durability of the relay - 10.106 cycles

Heating water inlet/outlet - male G 3/4"
Min. service overpressure of the

heating assembly

bar 0.8

Max. service overpressure of the
heating assembly

bar 2.5

Max. heating water temperature °C 80
Boiler water capacity 1 14.5
Effectiveness for nominal output % 99
Expansion vessel capacity 1 7
Max. number of boilers in the cascade pcs 32
Dimensions (height/ width /depth) mm 805/475/235

Boiler weight without water kg 39.5 42.5 45.5

Higher performance series:

THERM EL 30 THERM EL 38 THERM EL 45

Nominal heat output kW 30 37.5 45
Rated current A 44 55 66
El. components degree of shielding IP 40
Power voltage / frequency

V/Hz

3 x 230 + N + PE/50
Max. rated current A 3 x 48 3 x 60 3 x 72
Wiring main circuit breaker A 50 A 63 A 80 A

Rated current of the control system fuse

A 1.25

Electric durability of the relay - 1.105 cycles (16 A. 250V/50 Hz)

Mechanical durability of the relay - 10.106 cycles

Heating water inlet/outlet - male G 1"
Min. service overpressure of the

heating assembly

bar 0.8

Max. service overpressure of the
heating assembly

bar 2.5

Max. heating water temperature °C 80
Boiler water capacity 1 28.0
Effectiveness for nominal output % 99
Expansion vessel capacity 1 to order (placed outside the boiler!)
Max. number of boilers in the cascade pcs 32
Dimensions (height/ width /depth) mm 805/475/235

Boiler weight without water kg 56.5 59.5 62.2

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♦ Manufacturing control

All boiler parts are checked and correctly set by the manufacturer prior to final assembly. Each boiler is
tested on water circuit tightness and the function of the regulating and safety components is set and tested as
well.

The boiler was manufactured in line with:

Standards: CSN EN 60 335-1, CSN EN 60 335-2-30, CSN 06 1008, CSN 07 7401, CSN 06 0810, CSN 07
0240, CSN 06 0310, CSN EN 60 730, CSN 06 0830, CSN EN 60 730-1, CSN 06 1010; Government
Regulations: No. 163/2002 Coll., 17/2003 Coll. and 18/2003 Coll.

5. Basic instructions for boiler installation

Electric boilers are designed for permanent connection to a fixed mains supply voltage. A disconnecting
device – main circuit breaker and a corresponding electric line protection – must be installed in the permanent
electric boiler mains.

Installation of electric boilers can be carried out only by a qualified expert company or authorized worker
with the required qualification level in the field of electrical equipment maintenance. In the process of
installation, all pieces of advice as well as warnings included in this Manual must be observed. It must be
performed in compliance with the valid standards and provisions! The connection of an electric heating is
subject to authorization issued by the local power distribution plant. An applicant must ask for a provisional
approval with the connection of a higher energy input and for a relevant direct heating dwelling unit tariff. In
the case of construction of a new or repair of an old central heating system, we suggest that the design is
elaborated by an expert. Performance of an expert installation by an authorized service organization is always
the precondition for warranty provision by the manufacturer! Connection to the electric network and the wiring
can be carried out only by an expert worker qualified in line with the Czech Decree No. 50/1978 Coll.

Installation location must be chosen for the electric boiler which will enable necessary access for the
operator or for the purposes of a service inspection. Minimum distances between the boiler and a solid obstacle
are shown in the Figure in the Chapter “Wall-mounting of a boiler”. Ask an expert worker of the company
which performs the installation for a demonstration of the system function and training for operation. Once the
boiler has been put into operation, a letter of guarantee must be certified by the authorized expert service
worker.

In the location of the electric boiler installation pressure water for filling the heating system and water
discharge point must be available. It is further necessary that the room has a sufficiently even wall (electric
boiler is wall-mounted).

♦ Boiler location

Electric boilers can be installed in the basic
environment AA5/AB5 according to the standards CSN
2000-3 and CSN 33-2000-5:51 (range of temperatures
between +5 and 40°C, humidity depending on the
temperature of maximum 85 %, no harmful chemical
influences). It can be installed in residential as well as
non-residential spaces with the exception of rooms with a
bathtub or shower, in bathrooms and wash rooms in
general in zones 1 and 2 according to CSN 33 2000-7-

701. It cannot be however installed in zone 3 in locations
where a water jet designed for cleaning can form. If the

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boiler is installed in the permitted zones, relevant electric current accident protection must be concurrently
performed in accordance with the same standard, too.

The installation location must be chosen which will allow sufficient access for the operator as well as service
inspector.

Degree of shielding of the boiler electric components is IP 40.

♦ Wall-mounting of the boiler

Electric boiler is mounted on the wall by means of a
fixing strip (1) supplied with the boiler according to the
Figure in the Chapter “Wall-mounting of the boiler”. If
the boiler is mounted on a wall with a lower carrying
capacity, it is recommended to consult the installation
with a civil engineering technician. Free space of at least
200 mm below and 750 mm above the lower and upper
edges of the jacketing shall be left for the purposes of
inspecting the boiler or replacing the heating bodies (see
Figure depicting the boiler wall-mounting and
installation).

♦ Connecting the boiler to the hot-water heating system

Electric boiler must be connected to the distribution network in a manner preventing its aeration.

Connection to the heating system must be tackled in a project design calculating hydraulic ratios of the
whole system because the installation involves a hot-water flow-through boiler fitted with an integrated pump.
It needs be noted that minimum flow through the boiler must be constantly assured for the designated boiler
output at maximum thermal gradient of the heating system amounting to 20°C. Any reduction of this flow (due
to integrated high hydraulic friction elements) results in insufficient circulation and drop in life-time of some
boiler parts. To utilize the maximum output of the heat exchangers, ensure correct functioning and high
durability, the minimum heating system overpressure must amount to 0.8 bar.

Proper rinsing of the heating system resulting in the removal of all impurities must be performed prior to
testing and launching the operation of the whole system in line with CSN 06 0310 within the framework of the
installation. A suitable filter must be unconditionally fitted in the recuperative water inlet from the heating
system into the boiler to prevent impurities from entering the boiler system.

The heating system must be installed in accordance with CSN 06 0830 -- Safety equipment for central
heating and domestic hot water heating and CSN 06 0310 – Central heating – designing and assembly.

Shall the boiler be connected to a sealed heating system, such system must have a pressure expansion vessel
of sufficient capacity (higher performance series boilers are not equipped with their own expansion vessel).

!!! We recommend:

 fill the system with soft water in line with CSN 07 7401;
 fit the boiler outlet with a bleeding device;
 mount a filter or a sludge device into the pump suction section;
 overflow valve should be installed in heating systems with thermostatic valves

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 mount a heating system charge and discharge cock and a sludge cock at the lowest point of the system

in the very proximity of the electric boiler

 separate all electric boiler types on inlet and outlet by stop valves, too (see standards CSN 06 8030), not

to be forced to discharge the whole system in case of inspection or repair of the boiler or during filter
replacement

 remove control levers from stop valves and secure them against manipulation.

♦ Boiler connection to electric network

Wiring can be installed only by an authorized person in the sense of the Decree No. 50/1978 Coll. on
professional qualification in electrical engineering. Certification of the boiler installation and putting into
operation must be noted in a proper manner on the letter of guarantee. Any interference with internal boiler
wiring (with the exception of wiring specified in this Manual, e.g. the external regulator connection instead of
jumper wire) are inadmissible!

The boiler control box must be connected according to the relevant CSN standard by means of a
separately protected line which enables its disconnection and which is located in the very proximity of the
electric boiler!

Current protective switch must be used if the electric boiler is installed in a bathroom.

The power wiring is connected by a 5-conductor system to the U, V, W, N and PE terminals. In the case of a
4-conductor system the N and PE terminals shall be connected together and the power wiring matched with the
U, V, W and PE terminals.

If MRC is connected to the boiler control box, the MRC receiver outlet is matched with the terminal marked
HDO/N.1

WARNING! When using the MRC receiver signal on the HDO/N terminal, it must be made sure that all
contactor coils of other appliances (e.g. of the boiler if it is connected to the common MRC signal) are
energized with the same phase!

When operation must be delivered also outside the so-called “low tariff”, the maximum boiler output
limit can be switched off in the service menu also without the MRC signal (P4.4)!

Recommended cable cross sections under the plaster:

Boiler output [kW] 8 15 23 30 38 45

Power take-off [A] 12 24 36 48 60 72

PVC insulated cable with copper

conductors 5 [sq.mm]

2,5 4 6 10 16 25

♦ Charging the heating system

For the duration of the heating system charging, the boiler must be unplugged from the electric network by
disconnecting it by the main circuit breaker. It is useful to maintain the level of filling pressure in a cold system
in the range between 1 and 1.5 bar. Filling must proceed slowly in order to let the air bubbles escape through
the respective valves. According to CSN 07 7401 the water used for the first filling as well as for refilling must
be clear, colourless, without any suspended substances, oil or chemically aggressive admixtures, with a
minimum carbonate hardness (max. 3.5 mval/l) and it cannot be acidic (pH cannot be below 7). Only approved
agents can be used for water hardness adjustments.

1

HDO is the Czech abbreviation for MRC: translator's note.

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Non-observance of the aforementioned requirements results in cancellation of the undertaking for

the damaged components!

♦ Choice of the regulating and controlling components

The boiler is fitted with basic regulatory and safety elements as the following electric diagrams show.
Therm-EL boilers can regulate their outputs. They are equipped with their own PID regulation which does not
allow heating over the set temperature. Even if the TOP temperature is set to 80°C, electric boilers frequently
overheat up to the temperature of 96°C, while THERM-EL boiler heats up to the maximum temperature of
84°C.

It is always suitable and economical to let the electric boiler be controlled by a superior regulatory element
(room thermostat or an OpenTherm communication regulator). These regulators are not included in the boiler
delivery package!

Connection of a room thermostat and servicing of the boiler electric section may be carried out only
by authorized service organizations!

Regulation based on temperature in a referential room (room regulator) or an equitherm regulation of the
heating water, or potentially both, can be used as further extensions to the regulatory option. A whole series of
regulatory or switch thermostats can be used to control the room temperature: E.g. PT 10, PT 21, PT 30, BPT
30, PT 30 GSM, REV 23, CM 707, CM 907 or OpenTherm communication regulators such as Therm RC 03,
PT 55 (Elektrobock), QAA 73.110 (Siemens) or CR 04 Honeywell.

Regulators (room regulator, water temperature thermostat, trip relay of the current value monitor or an
OpenTherm regulator) can be connected to the boiler's input terminals (24V= circuits).

Current value monitor is a device used for disconnecting or reducing the output of the electric boiler when
other high power input electrical appliances (e.g. flow-through water heater, washing machine, dish-washer,
stove etc.) are connected to the network. Such a device is rules out the necessity of purchasing a high-capacity
main circuit-breaker which also means the payment of a high lump fee.

If a part of the electric boiler needs to be disconnected, the tripping device becomes connected to the
terminals for a trip relay (see the wiring scheme). The output size which becomes disconnected by individual
trip relays is set by changing the parameters in the control panel (from zero to maximum) in the service menu.

If the contact of the external tripping device should disconnect the whole boiler, it shall be either connected
serially in combination with the room thermostat (24V=) or to the terminals of the blocking element
(230V/50Hz).

Equitherm regulation

Heating water temperature in the equitherm regulation system is controlled on the basis of outdoor temperature.
The regulation takes place according to equitherm curves which specify the dependence between outdoor
temperature and the temperature of heating water required to reach the desired room temperature. An equitherm
curve must be drawn on the basis of designed, calculated or measured heat losses of the building. This type of
regulation does not have any feedback which would take into account higher cooling on one side of the house
by wind or heating by sun and, as a result, it cannot safeguard accurate temperature regulation in all parts of the
house.
Boiler connection to room thermostat and Therm Q01 outdoor sensor enables utilizing the equitherm regulation
which leads to additional energetic cost-cutting. THERM-EL boiler is moreover capable of cooperating with
OpenTherm communication interface regulators without any further communication interface installation.
The inclination and shifting of equitherm curves can be modified in the automatic control user menu.

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Regulation according to room of reference

Used in family houses. Only temperature of a selected room is monitored on the basis of which the
entire flat environment is regulated. Other rooms with diverse heat losses will be heated to different temperature
unless further thermoregulating knobs are not installed on the radiators. This method has the advantage of a
more flexible regulation. If an NTC temperature sensor located in the room of reference is connected to the
boiler automatic control system – without any other external regulator – the automatic control system can be
used as a simple room regulator (adjustable in the user menu – a Prt heating mode).

Cascade connection of boilers

The cascade connection format means connecting the boilers by means of technical elements into one
set the task of which is common heating of large spaces in a manner which complies with requirements for a
desired heat comfort. Boilers can be arranged in a cascade (see wiring diagrams) by way of a simple interface
which divides the actual electronics from the surrounding environment. Boiler electronics enable connecting up
to 32 boilers in one single intelligent cascade which will modulate the output ranging from the minimum
performance of the first boiler to the sum of maximum outputs of all boilers.
REKAS 1 interface (not included in the delivery package!) needs to be installed in both master and slave
boilers. The master boiler is in addition fitted with a master regulator (selection of the master and slave boiler is
done in the service menu).

♦ MRC – mass remote control

Mass remote control (MRC) enables transmission of electricity as well as various commands to the
users regarding tariff switching on the electrometer and operation of some appliances via standard distribution
network. Mass remote control is a set of technical means (e.g. emitters, receivers, central automatics,
transmission routes etc.) serving the emission of commands or signals for switching on or off electrical
appliances. The MRC system has replaced the switch clock used in the past. Each customer who makes use of
tariff switching must be equipped with a respective device which ensures this activity. This device is placed on
the electrometer panel and cooperates with the electric boiler. The MRC receiver is an apparatus which
performs the required switching operation (it for example blocks or unblocks an electrical appliance) as a result
of a processed MRC signal.
Depending on the service setting, the boiler can be operated either only if the cheaper tariff signal is activated
(the “HDO” LED is turned on) or if the user requires so (Ph¯ parameter, P4.4).

Heating water temperature [°C]

Outdoor temperature [°C]

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6. Boiler operation

Description of the control panel:

Control panel is simple and intuitive and displays the boiler functions.
The panel uses colour-coding and graphical division of the heating and DHW preparation sections. LEDs
positioned between the buttons for setting the temperature higher/lower (up/down arrows) are turned on if the
particular mode is selected (i.e. either the DHW2 preparation mode or the heating water mode marked TOP).
If the display shows any other variable, pressing one of the ▲ , ▼ buttons (1) displays the heating water
temperature (the LED “°C” TOP is turned on).
If the display shows any other variable, pressing one of the ▲ , ▼ buttons (2) displays the DHW temperature
(the LED “°C” TUV is turned on).

Changing the value of the desired variable: When the heating water temperature is displayed (the LED “°C”
TOP is on), the first pressing of one of the heating temperature setting buttons displays the setting for the
required value of this temperature. This is indicated by the flashing of LED “°C” TOP. Required value can be
changed within the ranges defined in the service menu. The set value becomes automatically registered in the
memory after 15 seconds of inactivity (measured after the last button was pressed).
The required DHW temperature is set in a similar fashion (by the DHW temperature setting buttons).
The five LEDs below the main display show the variables which are currently set or indicated on the 3-digit
display:

- if the LED “°C” (TOP or TUV) is on, the display shows the temperature of water in the heating or DHW
circuits

- if the LED “

IN

/

OUT

°°°°C ” is on, the display shows the temperature of the outdoor or room temperature sensors

- if the LED “HDO” is on, the MRC signal is activated and the boiler produces heat in the low tariff

- if the LED “bar” is on, the display shows the pressure in the TOP system in bars

Automatic control elements (user access):

1. Buttons for displaying heating temperature settings ▲ , ▼ (1) – higher/lower, additionally, if
selected, browsing through the service MENU

2. Buttons for displaying DHW temperature settings ▲ , ▼ (2) - higher/lower, the flashing value of
the selected variable can be also changed in the menu)

3. Heating on/off button O/I (MENU) (3) (press shortly), open the MENU (press for more than 2
seconds), exit the MENU (press shortly)

4. DHW heating on/off button O/I (ENTER) (4) (press shortly), ENTER (press shortly only in the
MENU)

5. SELECT – main display selection button (SELECT) (5):

•

temperature (according to the menu and selected option)

• water pressure (bar)

• output (kW)

• error messages (last error)

• heating mode

6. 3-digit 7-segment LED display

7. 7 LED indicators for the selected functions

2 The Czech abbreviation for DHW is TUV: translator's note.

14

HDO

bar

SELECT

°C

IN

OUT

(ENTER)

O/I

°C

O/I

(MENU)

°C

SELECT

(ENTER)

O/IO/I

(MENU)

HDO

bar°C

OUT

°C

IN

°C

DHW temperature

setting

buttons

DHW

heating

on/off

Button for

the display mode

and mode

and parameters

settings

7x LED indication

for the selected

functions

Heating

temperature

setting

buttons

Heating

on/off

buttons

5

6

2

4

1

3

7

LED display

♦ Error indication

ERROR MESSAGES:

Error code Type of defect

E.00 NO DEFECT

E.01 DEFECT ON THE POWER RELAY CONTACT

E.02 LOW PRESSURE (detected by the analogue pressure sensor)

E.03 BLOCKING ELEMENT

E.04 HEATING WATER (TOP) NTC TEMPERATURE SENSOR DEFECT

E.05 DHW (TUV) NTC TEMPERATURE SENSOR DEFECT

E.06 EMERGENCY THERMOSTAT (manual reset directly on the thermostat!)

E.07 OUTDOOR/ROOM TEMPERATURE SENSOR DEFECT

E.08 reserve

E.09 PRESSURE SENSOR DEFECT – analogous pressure sensor

E.10 COMMUNICATION PROBLEM between boilers in the cascade – master boiler

E.11 COMMUNICATION PROBLEM between boilers in the cascade – slave boiler

- past defects register (1–20)

Apart from the E.06 defect (emergency thermostat temperature becomes exceeded), all other defects shut down
the boiler and bring it to the defect state (heating bars become disconnected) which is automatically revoked
only after the defect has been removed. The boiler's operation is then automatically re-initiated.

Defect detected by the emergency thermostat is irreversible (the thermostat is equipped with manual
reset function which can be used only by an authorized service worker after the defect has been properly
detected and addressed).

15

♦ Menu parameters

It can be always selected (in the user menu by the diS / P3.2 parameter) whether the item is displayed in the

numerical format (more suitable in foreign language versions of the automatic control system) or in the
mnemotechnical format (closer to the Czech language).

MENU PARAMETERS:

Mnemo

format

Numerical

format

USER MENU

Initial

settings

Et1 P1.1

CURVE SLOPE AT BININ N.UTL = 0 (night moderation – disconnected)

1.6

Et2 P1.2

CURVE SHIFT 1

0

Et3 P1.3

CURVE SLOPE 2 AT BININ N.UTL = 1 (night moderation – connected)

1.6

Et4 P1.4

CURVE SHIFT 2

-5

ti1 P2.1

ROOM TEMPERATURE 1 AT BININ N.UTL = 0 (night moderation –

disconnected) for rto=Prt

21

ti2 P2.2

ROOM TEMPERATURE 2 AT BININ N.UTL = 1 (night moderation – connected

for rto=Prt

19

tdr P2.3

DIFFERENCE – REGULATORY RANGE (PROPORTIONAL)

3

tdf P2.4

DIFFERENCE – HYSTERESIS OFF/ON

0.5

rto P3.1

HEATING OPERATION MODE (tEr,EtE,Prt,otP,ot-)

tEr

diS P3.2

DISPLAY TYPE FOR THE MENU

AbC

Mnemo

format

Numerical

format

SERVICE MENU

(opening this MENU is permitted only to the service engineer with the

authorization of the manufacturer!)

rtU P3.3

DHW (TUV) HEATING OPERATION MODE (temperature probe/thermostat)

to_ P3.4

LOWER LIMIT FOR THE HEATING WATER TEMPERATURE SETTING

to¯ P3.5

UPPER LIMIT FOR THE HEATING WATER TEMPERATURE SETTING

tU_ P3.6

LOWER LIMIT FOR THE DHW TEMPERATURE SETTING

tU¯ P3.7

UPPER LIMIT FOR DHW TEMPERATURE SETTING

PSt P4.1

START OUTPUT

Pt¯ P4.2

MAX. OUTPUT DURING HEATING

PU¯ P4.3

MAX. OUTPUT DURING DHW HEATING

Ph¯ P4.4

MAX. OUTPUT WITHOUT MRC SIGNAL

P0¯ P4.5

MAX. OUTPUT AT DISCONNECTED CONTACTS OF RELIEF RELAY 1 AND 2

P1¯ P4.6

MAX. OUTPUT AT CONNECTED CONTACT OF RELIEF RELAY 1

P2¯ P4.7

MAX. OUTPUT AT CONNECTED CONTACT OF RELIEF RELAY 2

P3¯ P4.8

MAX. OUTPUT AT CONNECTED CONTACTS OF RELIEF RELAY 1 AND 2

tSt P5.1

LIMIT OF THE REQUIRED VALUE OF TOP HOT-WATER OUTLET (to start heating)

ttU P5.2

REQUIRED OUTLET TEMPERATURE DURING BOILER HEATING

bdF P5.3

DIFFERENCE BETWEEN DHW HEATING ON/OFF

C_T P5.4

TIME LIMIT FOR THE OUTPUT/TEMPERATURE AFTER HEATING START

dCt P5.5

PUMP DECELERATION TIME AFTER HEATING IS FINISHED

dCU P5.6

PUMP DECELERATION TIME AFTER DHW HEATING IS FINISHED

AF_ P5.7

SYSTEM ANTI-FREEZE PROTECTION

tYP P6.1

BOILER TYPE SETTING

16

Adr P6.2

MULTIPLE BOILER FORMAT (CASCADE) CONTROL PARAMETER

h.01-h.21

ERROR HISTORY DISPLAY

i.01-i.12

SERVICE AND DIAGNOSTIC INFORMATION

7. Boiler control and display of basic operational information

(more detailed user instructions)

♦ Heating water temperature display

After its connection to the power network, the display shows heating water temperature in °C which is

indicated by the pilot light °C above the

O/I (MENU)

button (3). If any other variable is displayed at the

moment (DHW temperature, output, error message etc.), pressing any of the buttons ▲ , ▼ (1) opens the
heating water temperature dialogue.

In the case of sensor defect, the numerical data become replaced with dashes: _ _ _ during disconnection or interruption of the sensor or

wiring, ¯ ¯ ¯ after short circuit on the sensor or wiring.

♦ Displaying and changing (setting) the desired temperature of heating water

If you press any of the ▲ , ▼ buttons (1) with the display showing the heating water temperature dialogue,

you can display its desired value. Slow flashing of the °C pilot light above the

O/I (MENU)

button (3) shows

the desired value. The currently valid desired temperature value according to the operational mode is displayed
(e.g. calculated by means of the integrated equitherm regulator or integrated room thermostat by way of a
communication line from the external regulator).

If you press any of the ▲ , ▼ buttons (1) with the display showing the desired heating water temperature,
you can set the desired value. Faster flashing of the °C pilot light above button 3 indicates the setting process.
The desired temperature value can be set by means of ▲ , ▼ buttons (1) within the range defined by TO_ a
TO¯ (P3.4 a P3.5) items in the service menu. The set value does not need to be confirmed. The mode of setting
the desired value terminates 15 seconds after any of the ▲ , ▼ buttons were last pressed (1).

The set desired value is valid in the following situations:

- rto heating mode is set to tEr (P3.1 = 1) (control performed by contact of the external room thermostat),

- rto heating mode is set to EtE (P3.1 = 2) (equitherm regulation) but the outdoor temperature sensor defect has been reported,

- rto heating mode is set to Prt (P3.1 = 3) (integrated room thermostat) but the room temperature sensor defect has been reported,

- rto heating mode is set to otP or ot- (P3.1 = 4 or 5) (external OpenTherm protocol regulation) but communication has failed.

PARAMETERS SET FOR THE MASTER CASCADE BOILER

PCC P7.1

NUMBER OF BOILERS IN THE CASCADE

dCC P7.2

SYSTEM CASCADE PUMP DECELERATION

dC1 P7.3

BOILER PUMP DECELERATION, IN THE CASCADE, AFTER ITS HEATING

OPERATION IS FINISHED

AFC P7.4

CASCADE SYSTEM ANTI-FREEZE PROTECTION FREEZE

PhC P7.5

MAXIMUM CASCADE OUTPUT WITHOUT MRC SIGNAL

P0C P7.6

MAXIMUM CASCADE OUTPUT AT DISCONNECTED CONTACTS OF RELAY 1

AND 2

P1C P7.7

MAXIMUM CASCADE OUTPUT AT CONNECTED CONTACT OF RELAY 1

P2C P7.8

MAXIMUM CASCADE OUTPUT AT CONNECTED CONTACT OF RELAY 2

P3C P7.9

MAXIMUM CASCADE OUTPUT AT CONNECTED CONTACTS OF RELAY 1

AND 2

17

♦ DHW temperature display

If any other variable is displayed at the moment (heating water temperature, output, error message etc.),
pressing any of the buttons 2 opens the DHW temperature dialogue. This display is indicated by the °C pilot
light above button 4.

In the case of sensor defect or absence, the numerical data become replaced with dashes: _ _ _ during disconnection or interruption of the

sensor or wiring, ¯ ¯ ¯ after a short circuit on the sensor or wiring.

♦ Displaying and change (setting) of the desired DHW temperature value

If you press any of the ▲ , ▼ buttons (2) with the display showing the DHW temperature dialogue, you can
set its desired value. The setting process is indicated by flashing of the °C pilot control above the

O/I

(ENTER)

button (4). You can set the desired temperature value by pressing the ▲ , ▼ button (2) within the
range defined by the TU_ a TU¯ (P3.5 a P3.6) items of the service menu. The set value does not need to be
confirmed. The setting mode for the required values terminates 15 seconds after any of the ▲ , ▼ (2) buttons
has been last pressed.

The desired DHW temperature value can be set only if the rtU DHW heating mode is set to b_c (P3.2 = 2) (storage tank with the

temperature sensor).

♦ Switching the heating on or off

The heating mode can be switched on or off by pressing the

O/I (MENU)

button (3). The on-mode is

signalled by the pilot light between ▲ , ▼ buttons (1); the pilot light in the off-mode is turned off.

Heating can be switched on only if its operation is pre-set in the user menu; the rto item must be set to tEr, EtE, Prt, otP or ot- (P3.1 =

1 – 5).

♦ Switching the DHW heating on or off

The DHW heating mode can be switched on or off by pressing the

O/I (ENTER)

button (4). The on-mode

is signalled by the pilot light between ▲ , ▼ buttons (2); the pilot light is off if the DHW is in the off-mode.

The DHW heating can be switched on only if its operation has been pre-set in the service menu; the rtU item must be set to b_n or b_c

(P3.3 = 1 or 2).

♦ Displaying the outdoor/room temperatures

To display any other operational variables (except for the heating water and DHW temperatures), use the

(SELECT)

button (5). If you press (or double press) it, the outdoor/room temperature display dialogue opens.

This dialogue is indicated by the IN/OUT °C pilot light.

In the case of sensor defect or absence, the numerical data become replaced with dashes: _ _ _ during disconnection or interruption of the

sensor or wiring, ¯ ¯ ¯ during short circuit of the sensor or wiring

The difference between displaying the room or outdoor temperature rests only in the location of the sensor. Shall the boiler operation be

controlled on the basis of its data, the respective mode must be selected in the user menu:

- for rto = EtE (P3.1 = 2) (integrated equitherm regulation) outdoor sensor must be used,

- for rto = Prt (P3.1 = 3) (integrated room thermostat) sensor in the room of reference must be used.

If the sensor is connected but the boiler operation is not controlled on the basis of its data, these data are used at least for protecting the

system against freezing.

♦ Displaying the heating system pressure

If you press (or double press) the

(SELECT)

button (5), the system pressure dialogue opens. This display

dialogue is indicated by the bar pilot light.

Minimum operation pressure of the system is 0.5 bar.

18

♦ Signal indication of the mass remote control (MRC)

The presence of the MRC signal is indicated by the HDO (MRC) pilot light. If it is turned on, it means that

the full boiler input is allowed.

Reduction of the boiler input by way of MRC signal can be set in the service menu by means of the Ph¯ (P4.4) item.

♦ Displaying the error messages

If you press (or double press) the (SELECT) button (5), the error message dialogue opens. This display
dialogue is indicated by the letter E in the first position of the digital display. If an error message is generated, it
is displayed automatically. To display any other variable, press buttons 1, 2 and 5.

If several simultaneous error messages occur, all of them are displayed (each for one roughly second): e.g.

E.02 – E.04 – E.05 – E.02 – E.04 – E.05 – ...

E.00 no defect

E.01 is a defect of one of the power relay contacts.

Boiler operation is not possible in any mode.

E.02 is low TOP water pressure in the heating system.

Boiler operation is not possible in any mode.

Water pressure measured by analogous pressure sensor is below 0.5 bar.

E.03 is a disconnection of the blocking element 2.

Boiler operation is not possible in any mode.

E.04 is a defect on NTC sensor for the TOP heating water temperature.

Boiler operation is not possible in any mode.

When the respective value is displayed, the lower dashes ( _ _ _ ) are displayed in the case of disconnection or
interruption of the sensor or its wiring, the upper dashes ( ¯ ¯ ¯ ) if there is a short circuit on the sensor or its
wiring.

E.05 is a defect of NTC sensor for DHW temperature. The boiler operation in the heating mode is possible,
DHW heating is not possible in the b_c (storage tank with sensor) mode and it is possible in the b_n (storage
tank with thermostat) mode. For further details see the rtU parameter for the operation of the DHW heating in
the service menu.

If the respective temperature setting is selected, lower dashes (_ _ _) are displayed if the sensor or wiring have
been disconnected or interrupted, upper dashes ( ¯ ¯ ¯ ) are displayed for short circuit on the sensor or wiring.

E.06 defect – emergency thermostat of TOP heating water temperature.

Boiler operation is not possible (only after

a manual reset!).

E.07 is a defect of the NTC sensor for outdoor/room temperature. Boiler operation in the heating mode is
possible. If, however, the EtE heating mode (equitherm regulation) or Prt (integrated room thermostat) are
selected, the boiler automatically switches to the boiler thermostat mode (outlet water temperature control
according to a value set by buttons 1). DHW heating is possible in any of the modes.
If a respective display is selected, the lower dashes ( _ _ _ ) are displayed if the sensor or wiring have become
disconnected or interrupted, upper dashes ( ¯ ¯ ¯ ) stand for short circuit on the sensor or wiring.

E.08 reserve

E.09 is a defect of the TOP heating water pressure sensor – analogous sensor.

Boiler operation is not possible in any

of the modes.

E.10 is a defect of the communication between boilers connected in a cascade which has been detected by the
master boiler. To display the details about this defect, press button 5. Addresses of all boilers are alternately

displayed (each for the time of approximately 1 second) which do not communicate with the master boiler:

E.10 – c.04 – c.05 – E.10 – c.04 – c.05 – ...

E.11 is a defect of communication between boilers connected in a cascade which has been detected by one of
the slave boilers.

19

♦ Displaying the instantaneous boiler output

If you press (or double press) the (SELECT) button (5), the display dialogue of the instantaneous boiler
output opens. This dialogue is indicated by the letter P in the first position of the display. The output is shown in
kW (P.2.5 =2.5 kW, P.18 = 18 kW etc.).

8. User menu

♦ Accessing the user menu

To access the user menu, press the

O/I (MENU)

button (3) for more than 2 seconds. To move between the

menu items, press the ▲ , ▼ buttons (1). If you want to change the input values, press the ▲ , ▼ buttons (2).
The entered value in the menu must be confirmed by pressing the

O/I (ENTER)

button (4). Exit the menu and

data input by pressing the

O/I (MENU)

button (3).

The menu item (the set variable) and its value display alternately (e.g. Et1 – 1.6 – Et1 – 1.6...). The menu
item is displayed either by means of mnemotechnical texts (Et1) or numerical parameters (P1.1). The display
mode is set in the menu by way of the diS (P3.2) item.

♦ User menu items

Group 1: Integrated equitherm regulation parameters

Equitherm regulation defines the desired value of heating water temperature depending on the outdoor
temperature. The selection of parameters for the calculation depends on the specification of the binary NU
(night moderation).

If NU is disconnected, the following is true:

the desired heating water temperature value = (20 – outdoor temperature) * Et1 + 20 + ET2

If NU is connected, the following is true:

the desired value of heating water temperature = (20 – outdoor temperature) * Et3 + 20 + ET4

The desired outlet heating water temperature value is limited in the range between to_ (P3.3) and to¯ (P3.4).
Equitherm regulation always requires the connection of an outdoor temperature sensor and the heating mode
setting of rto = EtE (P3.1=2).

Et1

P1.1 Equitherm regulation parameter, curve slope. True for a disconnected NU.

The setting range falls between 0.1 .. 6.0, step of 0.1, leading value is 1.6.

Et2

P1.2 Equitherm regulation parameter, curve shift. True for a disconnected NU.

The setting range is -20°C .. +40°C, step of 1°C, leading value is 0.

Et3

P1.3 Equitherm regulation parameter, curve slope. True for a disconnected NU.

The setting range falls between 0.1 .. 6.0, step of 0.1, leading value is 1.6.

Et4

P1.4 Equitherm regulation parameter, curve shift. True for a connected NU.

The setting range falls between -20°C .. +40°C, step of 1°C, leading value is -5.

20

Group 2: Integrated room thermostat parameters

An integrated room thermostat can control heating operation according to the data from internal temperature
sensor. It uses proportional control to set the outlet water temperature within the range defined by the tdr (P2.3)
parameter:

- if TM < ti1 - tdr (TM < P2.1 – P2.3), heating is controlled to reach the maximum heating water temperature
to¯ (P3.4),

- if TM > ti1 (TM > P2.1), heating is controlled to have the minimum heating water temperature to_ (P3.3),

- if ti1 - tdr < TM < ti1 (P2.1 – P2.3 < TM < P2.1), the desired heating water temperature is calculated by the
interpolation between to_ and to¯ (P3.3 a P3.4),

- if TM > ti1 + tdF, the heating is switched off completely.
The aforementioned is true if the NU binary input specification is “disconnected”. If the NU binary input
specification is “connected”, a value of ti2 (P2.2) is used instead of ti1 (P2.1).

ti1

P2.1 Desired value of the room temperature. True if NM is “disconnected”.

The setting range falls between 10 and 30°C, step of 1°C, leading value is 21°C.

ti2

P2.2 Desired value of the room temperature. True if NM is “connected”.

The setting range falls between 10 and 30°C, step of 1°C, leading value is 19°C.

tdr

P2.3 Temperature range of room in which the proportional control of the desired outlet water

temperature value takes place.

The setting range falls between 2 and 10°C, step of 1°C, leading value is 3°C.

tdF

P2.4 Difference (hysteresis) between the shut-down and repeated initiation of heating when the

desired room temperature has been exceeded.

The setting range falls between 0.25 and 2.50°C, step of 0.25°C, leading value is 0.5°C.

Complete heating shut-down occurs if the room temperature exceeds the set value by more than tdF (P2.4).
Heating is again switched on only when the room temperature drops below the set value.

Group 3: Heating setting and display mode

rto

P3.1 Heating mode (TOP)

The boiler operation is conditioned by the connection of the external room thermostat PT terminals at all
possible settings. If the thermostat is not used at all, it is necessary to create a permanent connection between
the PT terminals.

Settings options:

--- 0 Heating switched off. It is not possible to switch it on even by means of button 3. Anti-freeze

protection is active.

tEr 1 Heating is controlled by the external room thermostat contact and the outlet water temperature

is set by buttons 1.

EtE 2 Heating is controlled by integrated equitherm regulator. Outdoor temperature sensor must be

connected.

In the case of a defective sensor or if it is not connected, the boiler is controlled in the tEr (like at P3.1 = 1) mode.

Prt 3 Heating is controlled by integrated room thermostat. The room temperature sensor must be

21

connected.

In the case of a defective sensor or if it is not connected, the boiler is controlled in the tEr (like at P3.1 = 1) mode.

otP 4 Heating is controlled by external regulator which is connected by way of the OpenTherm Plus

interface.

In the case of defective communication or regulator, the boiler is controlled in the tEr (like at P3.1 = 1) mode.

ot- 5 Heating is controlled by external regulator which is connected by way of the OpenTherm Lite

interface.

In the case of defective communication or regulator, the boiler is controlled in the tEr (like at P3.1 = 1) mode.

diS

P3.2 Menu display type (mnemotechnical texts/numerical parameters)

Settings options:

diS = 012, AbC (P3.2 = 0, 1

), leading value

AbC (1).

9. Putting the boiler into operation

Service engineer with authorization from the manufacturer is obliged to make a verifiable
demonstration for the user of the boiler operation, its individual parts, safety components and control
methods prior to putting the boiler into operation and fill in the letter of guarantee and hand over this
Operation and Maintenance Manual to the user.

User is bound to observe the correct use of the boiler in accordance with this Manual; this is a basic
precondition for acknowledgement of the warranty. It is further strictly forbidden to interfere with any of the
sealed parts inside the boiler!

Warning:

The settings of the boiler output range and other parameters must be in compliance with the technical data.
Any excess loads or incorrect use of the boiler can cause damage to its components. Warranty does not apply to
the components which suffer this kind of damage!

♦ General instructions:

The following must be checked before the electric boiler is set into operation:

 connection to the heating system
 opening of the fittings separating the electric boiler from the system and securing them against

manipulation

 charging (may be followed by pressurizing) the system by soft water and subsequent bleeding
 electric connection and protection in line with the CSN standards. For further details refer to the

Chapter “Wall-mounting of the boiler”.

The procedure for setting the boiler into operation is as follows:

 switch on the main circuit breaker (switch) in the power intake, switch on the boiler by pressing the O/I

button for heating actuation

 set the desired outlet boiler temperature to maximum
 check the correct functioning of all safety thermostats and control components
 check the settings of the boiler output range, potentially adjust the settings on the basis of the heated

building.

22

Electric boiler operation is very simple and fast and does not require any special qualification. The boiler can

be nevertheless controlled only by adults who have been demonstrably explained the boiler function and
operation. This demonstration must be performed by the worker who carried out the installation and set the

boiler into operation.

 If the display is turned on, the control supply voltage is fed to the boiler.
 Set the room thermostat (or other control element) to the required temperature.
 Display the current heating water temperature by pressing the Arrow Up button. To switch on the boiler

press the O/I button in the heating temperature setting section. Concurrently, the circular pump is
switched on which runs for the period defined by the set parameters. The heating function is indicated
by the LED pilot light in the left section of the control panel = “HEATING”.

 After the set temperature has been reached, the automatic controlling system gradually switches off the

heating bodies in order to maintain the heating water temperature within the range specified by the
parameters.

 First heating: maintain the highest possible service temperature of the heating medium in the system for

the first four hours. The system must be carefully deaereated while in operation to rid it reliably off the
remaining air after the previous bleeding in the cold state. When the system cools down, refill it with
water.

 If a power outage (or MRC signal interruption) occurs, the boiler is shut down. When the power supply

is renewed, the electric boiler restarts its operation.

 No objects can be placed on the jacketing or inside the electric boiler. Cleaning of the electric boiler

external surface is recommended only by a damp cloth.

 It is recommended to bleed the heating system regularly and remove the deposited impurities by

discharging small amounts of the liquid through the discharge cock assuring that also sediments at the
bottom of the boiler vessel are washed out.

 Switch off the boiler after the end of the heating season by the circuit breaker. It is recommended to

start the boiler for roughly 30 seconds every month to spin the pump outside the heating season.

 Minimum water pressure at the circular pump inlet must be 5 kPa (the water temperature must not

exceed 75°C).

 Check whether the air charge pressure specified on the expansion vessel label is sufficient for the

heating system (system static height of 5 m corresponds to the air charge pressure of 50 kPa, 10 m =
100 kPa, 15 m = 150 kPa) prior to the boiler connection to the heating system.

Setting the pressure in the expansion vessel

When the system is filled with the heat carrier and properly vented, write down the displayed system water
pressure value. Correct the air charge pressure in the expansion vessel to the same value by bleeding. Adjust the
system pressure value to at least 10 kPa by filling more water into the system. If the air charge pressure in the
expansion vessel is not correctly adjusted, similar defects – big changes in pressure during operation – occur as
in the case of an insufficiently rated expansion vessel.

♦ Maintenance

Regular maintenance is very important for a reliable operation and high durability of the boiler and its
components. The user is recommended to contact the manufacturer via a local authorized service organization
and ensure regular inspections after every year of operation (which is one of the conditions for warranty
acknowledgement). Service engineer will also carry out an inspection of the control and safety elements of the
boiler. To safeguard faultless heating system service, it is necessary to regularly check the initial water pressure
in the cold state. Shall any drop in pressure occur, the heating system must be replenished with water.

The outer jacketing can be cleaned by a dishcloth dipped in soap-suds and subsequently dried.

23

♦ Boiler shut-down

You can switch off the boiler for a shorter period by pressing the 0/1button or potentially by the room
thermostat switch.

If you want to shut the boiler down for an extended period of time outside the heating season (i.e. during
summer holiday), it is suitable to switch off the boiler by the external main circuit-breaker (switch) unless there
is a potential risk of system freezing or pump clogging (these functions are naturally not available during the
complete boiler shut-down).

10. Diagram for serviceable connecting charge pressures of heating water

Warning: The curves of serviceable charge pressures of heating water are calculated for Grundfos 15/60
pumps to the higest regulation grade.

THERM EL Charge pressure

100

150

200

250

300

350

400

450

500

550

600

0.4 0.8 1.2 1.6 2.0 2.4

Water flow (m3 / h)

Outlet excess pressure (mbar)

8 kW

15 kW

23 kW

30 kW

38 kW

45 kW

24

11. Therm EL boilers connection to the power supply

♦ Therm EL 8 boiler connection to the power supply

REKAS1

PT BT NU TL TB TV OT

BL

HDO

L1L2L3

N

Pe

VENTIL

N

TUV

TO

CA+1 2

GND

OR

REKZOB

REKREL

REKCPU

B-

1,25A

K7K6

K5

h

K2

K4K3

K1

Re1 Re2 Re3

1

1

Safety

thermostat

Night

moderation

DHW

Heating water

sensor

Relief

relay 1

Relief

relay 2

Storage tank

thermostat

DHW

sensor

Outdoor

temperature

sensor

OT communication

Three-way

valve

Blocking

element

MRC

Heating

Circulation

pump

Cascade

Contac tor

Room

thermostat

Pressure

sensor

Contact functions:

1/ contacts of the Room thermostat must be permanently connected during the boiler operation
2/ contacts of the “blocking element” must be permanently connected during the boiler operation
3/ contacts of the Emergency thermostat must be constantly connected during the boiler operation
4/ if the storage tank Thermostat

is connected, the boiler heats the DHW in the storage tank

25

♦ Therm EL 15 connection to the power supply

REKAS1

PT BT NU TL TB TV OT

BL

HDO

L1L2L3

N

Pe

VENTIL

N

TUV

TO

CA+1 2

GND

OR

REKZOB

REKREL

REKCPU

B-

1,25A

K7K6

K5

h

K2

K4K3

K1

Re1 Re2 Re3 Re6

2 1

1 2

Safety

thermostat

Night

moderation

DHW

Heating water

sensor

Relief

relay 1

Relief

relay 2

Storage tank

thermostat

DHW

sensor

Outdoor

temperature

sensor

OT communication

Three-way

valve

Blocking

element

MRC

Heating

Circulation

pump

Cascade

Contac tor

Room

thermostat

Pressure

sensor

26

♦ Therm EL 23 boiler connection to the power supply

REKAS1

PT BT NU TL TB TV OT

BL

HDO

L1L2L3

N

Pe

VENTIL

N

TUV

TO

CA+1 2

GND

OR

REKZOB

REKREL

REKCPU

B-

1,25A

K7K6

K5

h

K2

K4K3

K1

Re1 Re2 Re3 Re6 Re7 Re8 Re9

2 13

1 2 3

Safety

thermostat

Night

moderation

DHW

Heating water

sensor

Relief

relay 1

Relief

relay 2

Storage tank

thermostat

DHW

sensor

Outdoor

temperature

sensor

OT communication

Three-way

valve

Blocking

element

MRC

Heating

Circulation

pump

Cascade

Contac tor

Room

thermostat

Pressure

sensor

27

♦ Therm EL 30 boiler connection to the power supply

REKAS1

PT BT NU TL TB TV OT

BL

HDO

L1L2L3

N

Pe

VENTIL

N

TUV

TO

CA+1 2

GND

OR

REKZOB

REKREL

REKCPU

B-

1,25A

K7K6

K5

h

K2

K4K3

K1

4

2413

Re1

Re1

Re2

Re2

Re3

Re3 Re6 Re7 Re8 Re9

1 2 3

Safety

thermostat

Night

moderation

DHW

Heating water

sensor

Relief

relay 1

Relief

relay 2

Storage tank

thermostat

DHW

sensor

Outdoor

temperature

sensor

OT communication

Three-way

valve

Blocking

el ement

MRC

Heating

Circulation

pump

Cascade

Contactor

Room

thermostat

Pressure

sensor

28

♦ Therm EL 38 boiler connection to the power supply

REKAS1

PT BT NU TL TB TV OT

BL

HDO

L1L2L3

N

Pe

VENTIL

N

TUV

TO

CA+1 2

GND

OR

REKZOB

REKREL

REKCPU

B-

1,25A

K7K6

K5

h

K2

K4K3

K1

1 2 3

4 5

241

5

3

Re1

Re1

Re2

Re2

Re3

Re3

Re6

Re6 Re7 Re8 Re9

Safety

thermostat

Night

moderation

DHW

Heating water

sensor

Relief

relay 1

Relief

relay 2

Storage tank

thermostat

DHW

sensor

Outdoor

temperature

sensor

OT communication

Three-way

valve

Blocking

el ement

MRC

Heating

Circulation

pump

Cascade

Contactor

Room

thermostat

Pressure

sensor

29

♦ Therm EL 45 boiler connection to the power supply

REKAS1

PT BT NU TL TB TV OT

BL

HDO

L1L2L3

N

Pe

VENTIL

N

TUV

TO

CA+1 2

GND

OR

REKZOB

REKREL

REKCPU

B-

1,25A

K7K6

K5

h

K2

K4K3

K1

4

1

5

2

6

3

526

1

4

3

Re1

Re1

Re2

Re2

Re3

Re3

Re6

Re6

Re7

Re7

Re8

Re8

Re9

Re9

Safety

thermostat

Night

moderation

DHW

Heating water

sensor

Relief

relay 1

Relief

relay 2

Storage tank

thermostat

DHW

sensor

Outdoor

temperature

sensor

OT communication

Three-way

valve

Blocking

el ement

MRC

Heating

Circulation

pump

Cascade

Contactor

Room

thermostat

Pressure

sensor

30

♦ 2 Therm EL cascade format

REKAS1

L1

L2

L3

N

Pe

REKZOB

REKREL

REKCPU

1,25A

REKAS1

L1

L2

L3

N

Pe

REKZOB

REKREL

REKCPU

1,25A

L2

L1NPE

L3

L2

L1NPE

L3

Safe ty

t hermostat

Night

moderation

DHW

He ating water

sensor

Relief Rel ay 1

Relief Rel ay 2

DHW senso r

Outdoor

temperatur e

sensor

OT communicat io n

Thr ee-wa y

va lve

Blocking el emen t

MRC

Heatring

Cir culati on

pump

Cascade

Contactor

Storage tank

tthermostat

Master boiler

Slave boiler

Pressure

sensor

Room

thermostat

He ating water

sensor

Pressure

sensor

Night

moderation

Relief Rel ay 1

Relief Rel ay 2

Storage tank

thermostat

Room

thermostat

DHW senso r

Outdoor

temperatur e

sensor

OT communicat io n

DHW

Thr ee-wa y

va lve

Blocking el emen t

MRC

Heatring

Contactor

Safe ty

t hermostat

Cir culation

pump

Cascade

31

♦ Connection of the current maximum value monitor to the boiler relief relay terminals

2A

1 2

1 3

HJ 102

1.st

2.st

3 x 400 V

1st degree disconnection

2nd degree disconnection

Boiler terminals OR

Mains (from the electrometer)

L1,L2,L3

N

OR

12. Warranty and responsibility for defects

The manufacturer is not liable for any mechanical damage to individual components by harsh treatment,
neither for any damage caused by unprofessional interference with the electronics during setting or connecting
of accessory regulations or by using other than original components used by the manufacturer.

The guarantee does further not apply to defects brought about by nonobservance of the binding conditions
specified in the individual sections of this Manual regarding operation and maintenance of the boilers.

The guarantee equally does not apply to non-standardized ratios in the distribution networks (fluctuation of
the supply voltage – chiefly during overvoltage peaks etc.), defects outside the boiler which affect its operation,
damage incurred due to external factors, mechanical damage, storage, transport and defects originating during
natural disasters etc.

In such situations the service organization can ask the user to reimburse the repair.

THERMONA spol. s r.o. guarantees the correct operation of the boiler for the period of 24 months after it
has been first put into operation.

Conditions which must be observed for the guarantee acknowledgement:

1. Boiler inspection must be performed regularly once per year. The inspections can be effected only by an

authorized organization, i.e. by a contractual service body (these inspections are not included in the boiler
price!).

2. It is necessary to document all records with respect to the performed guarantee repairs and annual boiler

inspections in the appendix to this Manual.

13. Domestic hot water storage tank heating mode

External indirect DHW heating storage tank can be connected to the THERM EL boiler. Storage tank
heating is ensured by changing the position of the three-way valve. The boiler electronics can communicate
with the temperature sensor (continuous DHW temperature regulation) as well as with the traditional storage
tank thermostat (to be set in the service menu). Service with a connected DHW storage tank is always of

32

superior position with regards to heating and the maintenance of the set temperature always proceeds without
time limits (with the exception of the MRC signal). Shall the temperature in the storage tank fall below the set
value, the boiler system three-way valve position is set preferentially and the boiler water heats up the external
indirect heating DHW storage tank. The DHW preparation can be deactivated by setting the boiler in the
SLEEP mode. If the operation mode is set after the termination of the MRC signal, the DHW preparation
becomes interrupted.
Connections of the storage tank and the three-way valve are shown in the electric diagram.

♦ Connection diagram of an electric boiler with indirect heating storage tank for informational

purposes

T1

MV

AB

B

A

DHW

T

Electric boiler

Indirect heating

storage tank

Thermostat or DHW NTC sensor

MV – valve servomotor
AB – heating water inlet from the boiler
A – heating water outlet to the storage tank
B – heating water outlet to the heating circuit
T1 – storage tank thermostat
T – NTC sensor of the storage tank
TUV – DHW outlet

33

14. THERM EL 8, 15, 23 boiler assembly (kW)

1 – Boiler frame

2 – Pump

3 – Safety valve

4 – Pressure sensor

5 – Discharge valve (1/2")

6 – Boiler heat exchanger

7 – Emergency thermostat (the sensor is placed in the cup together with the temperature sensor)

8 – Temperature sensor

9 – Vent valve

10 – Heating bar

11 – Control display

12 – Boiler automatic system

13 – Expansion vessel (7 l)

34

15. THERM EL 30, 38, 45 boiler assembly (kW)

1 – Boiler frame

2 – Grundfos pump

3 – Safety valve

4 – Pressure sensor

5 – Discharge valve (1/2")

6 – Boiler heat exchanger

7 – Emergency thermostat (the sensor is placed in the cup together with the temperature sensor)

8 – Temperature sensor

9 – Vent valve

10 – Heating bar

11 – Control display

12 – Boiler automatic system

35

16. Wall-mounting of the boiler

17. Boiler dimensions and connection

1 – Recuperative water inlet - Therm 8, 15, 23 - ¾´´

- Therm 30, 38, 45 - 1´´

2 – Heating water outlet - Therm 8, 15, 23 - ¾´´

- Therm 30, 38, 45 - 1´´

3 – Safety valve outlet

4 – Blow valve outlet

36

18. Record of repairs and annual inspections

Performed operation Contractual org. Customer signature Date of record

Warning regarding the disposal of the packaging and the product after the end of its service life-time

All applied materials comply with the requirements specified in Section 10 of the Act No. 185/2001 Coll. and
Section 6 of the Act No. 477/2001 Coll.
The product packaging is commonly disposed of in scrap paper collection centres. The packaging foil can be
disposed of in collection containers for plastics.
Boiler parts made from steel, copper and copper alloys are to be delivered to sorted metal waste scrapyards.
Heat insulation of the combustion chamber is in accordance with the health safety and shall be liquidated in
common home waste.
Standard storage conditions must be assured (non-aggressive and dust-free environment, temperature range of
5 to 50°C, atmospheric humidity of maximum 75%, prevention of biological influences, shocks and vibrations)

37

CERTIFICATE OF QUALITY AND

COMPLETENESS OF THE PRODUCT

Electric direct heating THERM EL boiler

Type designation: THERM EL ..................

Product number: ..................................................

The appliance complies with the requirements of the European Directives No. 89//336/EHS, 73/23/EHS and

other related technical regulations, standards and recommendations. Its operation under the service conditions

in line with manufacturer recommendations is safe. Measures were adopted which assure the conformity of this

appliance now introduced to the market with technical documentation and basic technical, safety and hygienic

requirements.

Technical incpection:

date: .....................................................................................

stamp and signature: .......................................................................

THERMONA, spol. s r. o.

Stará osada 258, Zastávka u Brna, 664 84

Czech republic

Phone: [phone] fax: [phone]

[e-mail]

www.thermona.cz