Thermona THERM 24 KDNS Owner's manual

Manual for installation,
operation and maintenance
of boiler
Stationary gas condensing boiler
THERM 24 KDNS

THERM 24 KDNS
Manual for installation,
service and maintenance
of boiler

CONTENTS
1. General information ..................................................................................4
1.1 Use ........................................................................................................4
1.2 Equipment details .........................................................................................4
1.2.1 Equipment description..............................................................................4
1.2.2 General description .................................................................................4
1.2.3 Simplied hydraulic diagram and functional diagram (is not source material for assembly) ............5
1.3 Operational safety .........................................................................................5
1.4 Technical parameters ......................................................................................6
1.5 Set of boiler................................................................................................7
2. User manual ..........................................................................................8
2.1 Control and signalling......................................................................................8
2.1.1 Boiler control panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1.2 Description of the boiler panel controls..............................................................8
2.1.3 Information menu .................................................................................10
2.1.4 Error messages ....................................................................................11
2.2 Commissioning of the boiler to operation..................................................................12
2.3 Disconnection of the boiler from operation ................................................................12
2.4 Regulation................................................................................................13
2.4.1 Operation of the boiler without the room thermostat or regulator ...................................13
2.4.2 Operation of the boiler with spatial thermostat .....................................................13
2.4.3 Operation of the boiler using built-in equithermic regulation........................................14
2.4.4 Operation of the boiler using master equithermic regulation ........................................15
2.4.5 Heating of utility water (DHW) .....................................................................16
2.5 Selected protective and additional functions of the boiler ..................................................17
2.6 Maintenance and service..................................................................................18
2.6.1 Additionally lling the heating system..............................................................19
2.7 Warranty and warranty terms..............................................................................19
3. Installation manual ..................................................................................20
3.1 Basic instructions for assembly of the boiler................................................................20
3.2 Complete character of the delivery ........................................................................20
3.3 Location of the boiler .....................................................................................21
3.4 Installation of the boiler ...................................................................................22
3.5 Connecting the boiler to the hot-water system.............................................................22
3.5.1 Dimensions and connection........................................................................22
3.5.2 Graphs of the connecting overpressure of heating water (on the output for heating water)...........23
3.5.3 Expansion tank ....................................................................................24
3.5.4 Using anti-freeze mixtures .........................................................................24
3.5.5 Safety valve........................................................................................24
3.6 Connection of the boiler to the gas distribution ............................................................24
3.6.1 Conversion to other fuels...........................................................................24
3.7 Filling and discharging of the heating system ..............................................................25
3.7.1 Procedure for lling the heating system ............................................................25
3.7.2 Additional lling of water into the heating system ..................................................25
3.7.3 Discharging of water from the heating system ......................................................25
3.8 Condensate outlet ........................................................................................25
3.9 Design of gas exhaust.....................................................................................26
3.10 Connection of the boiler to the storage tank ...............................................................28
3.11 Connection of the boiler to the electricity network .........................................................29
3.11.1 Connection of the room thermostat ................................................................29
3.11.2 Connection of aroom regulator with OpenTherm+ communication .................................29
3.12 Variants for the installation of the boiler ...................................................................30
4. Additional information for service ....................................................................31
4.1 Gas tting SIT 848 SIGMA - setting .........................................................................31
4.2 Adjusting boiler combustion ..............................................................................32
4.3 Electrical connection diagram .............................................................................34
5. Record of warranty and post-warranty repairs and annual controls......................................35
6. Production information sheets........................................................................36
7. Certicate of quality and completeness of the product .................................................39
!
Graphic symbols
used in the text:
Notication of the producer directly related to the
operational safety of the consumer appliance
Information recommended
by the producer

4THERM 24 KDNS
1.2.2 General description
The basic element of the THERM stationary gas condensing boilers is aframe that forms the load-carrying part of the boiler,
onto which the individual boiler components are installed. In the upper part of the boiler is acondensing body, which
associates the combustion chamber with the burner and the stainless exchanger. The removable front wall of the body is
tted with two electrodes (ignition and ionizing), an inspection sight-glass, aburner and shaped piping for the supply of gas
mixed with air.
Asuitable ratio of gas mixed with air is ensured by the mixer in cooperation with agas tting. It consists of agas pressure
regulator, two solenoid blocking valves and ratio regulation of the output volume of gas with elements for mechanical setting.
The whole mixture preparation system also includes afan with electronically controlled speed.
Condensate is created during the operation of the condensation boiler. The outow of condensate from the condensation
body and the exhaust piping for burnt gases are directed by hoses into the odour closure if the condensate ows outside
the boiler.
To ensure the ow of water through the boiler, the return water inlet is equipped with aWilo energy-saving pump with
electronically controlled speed. The circulating pump is integrated in acompact hydro-block, which also includes abypass,
avalve for lling up the heating system, apressure sensor, asafety valve, the connection to the expansion vessel etc.
In the upper part of the boiler, under the hinged cover, there are control elements and display (see “User Manual“ chapter).
The control panel includes control microprocessor automatics for controlling the activities of the boiler, control, boiler safety
and regulation.
1.1 Use
The stationary condensing boilers THERM 24 KDNS are gas hot water boilers that burn natural gas. They are constructed as
consumer appliances using condensed water steam in the combustion process with excellent eciency, minimum emissions
into the air and the minimum consumption of electricity. Operation is economical and does not strain so the environment.
The output can be uently regulated within the scope of 20 – 100% and adapted automatically to immediate thermal losses
from the object.
In addition to heating, the THERM condensing boilers can be used for heating hot water as well (hereinafter referred to as
DHW) in indirect-heating storage tanks under the condition that the required additional equipment is provided.
!The boiler is designed for closed heating systems tted with an expansion vessel or open expansion vessel in
min. height of 8 m above the boiler.
1. GENERAL INFORMATION
stationary condensing boiler designed for heating
buildings with athermal loss of up to 27 kW
option to heat water – heating in indirect heating
storage tank
natural gas operation or propane
fully automated operation
low consumption of electricity
automatic uent output modulation
simple boiler control
high comfort level
built-in equithermic regulation
built-in automatic by-pass
ability to control by the superior indoor thermostat or
intelligent indoor control unit
high level of operational safety
security elements of the boiler prevent overheating of
the boiler or the escape of the eects of burnt gases
built-in energy-saving circulating pump with electronic
speed modulation
safety valve 3 bar
protective functions (anti-freeze protection, pump
protection, etc.)
electric ignition (saving of fuel)
1.2 Equipment details
1.2.1 Equipment description
!Please note that it is necessary to follow the notications given.

5
THERM 24 KDNS
1.2.3 Simplied hydraulic diagram and functional diagram (is not source material for assembly)
THERM 24 KDNS
1 - Gas valve
2 - De-aerating valve
3 - Circulation pump
4 - Expansion heating vessel
5 - Ventilator
6 - Pressure sensor
7 - Thermal probe
8 - Flue gas temperature probe
9 - Mixer
10 - Condensate pumping station
(optional equipment)
11 - Hydroblock
12 - Condensing body
A- Input for gas
B - Input for returned water
C - Output for heating water
D - Input for additional lling
C
B
A
In the case of gas odour
close the gas valve under the boiler
ensure ventilation of the room (windows, door)
donot manipulate the electric switch
liquidate any naked ame
immediately call service (the boiler must not be used until after the service inspection)
In the case of an odour of combustion burnt gases
disconnect the boiler
ensure ventilation of the room (windows, door)
call service (the boiler must not be used until after the service inspection)
In the case of aconsumer appliance re
close the gas valve under the consumer appliance
disconnect the consumer appliance from the electricity network
liquidate the re with powder extinguishing equipment or afoam extinguisher
!THERM boilers are tted with all safety, emergency and protective elements to ensure completely safe boiler
operation. If irrespective of this, e.g. due to unprofessional intervention, irregular inspections and revisions of
the boiler, etc., there is anon-standard status then we recommend proceeding as follows:
1.3 Operational safety
1
2
3
4
5
6
7
8
9
10
11
12
D

6THERM 24 KDNS
1.4 Technical parameters
Technical description Unit THERM 24 KDNS
Fuel -natural gas propane
Consumer appliance category - I2H , II2H3P I3P , II2H3P
Nominal thermal input for heating QnkW 24.5 24.5
Minimal thermal input for heating QnkW 4.6 4.6
Nominal thermal output
for heating Pn
Δt = 80/60 °C kW 24.0 24.0
Δt = 50/30 °C kW 26.0 26.0
Nominal thermal input for heating DHW Qnw kW 24.5 24.5
Nominal thermal output for heating DHW kW 24.0 24.0
Minimal thermal output
Pn
Δt = 50/30 °C kW 4.7 4.7
Δt = 80/60 °C kW 4.5 4.5
Drilling gas curtains mm 5.9 4.3
Gas overpressure on the consumer appliance
input mbar 20 37 (50)
Consumption of gas m3.h-1 0,46 – 2,70 0,20 – 1,03
Maximum overpressure of heating system
PMS bar 3 3
Minimum overpressure of heating system bar 0.8 0.8
Max. output temperature of heating water °C 80 80
Flue-gas installation alternatives mm 80/125, 2x 80
Average temperature of burnt gases °C 64 64
Flue gas temperature in case of overheating °C 75 75
Lowest ue gas temperature at min. heating
output °C 46 46
Weight ow of burnt gases g.s-1 2,3 – 10,1 2,3 – 9,4
Acoustic performance level dB (A) 52 52
Boiler eciency % 98 – 107 98 – 107
NOx class of boiler - 6 6
Type of electricity supply - ~ ~
Nominal supply voltage / frequency V/ Hz 230 / 50 230 / 50
Auxiliary
electricity at
nominal heat input power W 70.0 70.0
partial loading W55.0 55.0
emergency status W4.0 4.0
Nominal current of the circuit breaker for
consumer appliance A 2 2
Level of coverage of electrical part - IP 41 (D) IP 41 (D)
Environment according to ČSN 332000 – 3 - basic AA5 / AB5
Volume of expansion unit l 7 7
Filling overpressure of expansion vessels bar 1 1
Dimensions of boiler: height / width / depth mm 935 / 510 / 458
Weight of boiler kg 33 33

7
THERM 24 KDNS
1.5 Set of boiler
THERM 24 KDNS
1 - Condensing body
2 - Ventilator
3 - Heating temperature probe
4 - Condensate pumping station
(optional equipment)
5 - Pressure sensor
6 - Circulation pump
7 - Gas valve
8 - De-aerating valve
9 - Control panel
10 - Emergency thermostat
11 - Manometer
12 - Gulley trap (siphon)
5
3
8
6
9
1
4
2
7
10
11
12

8THERM 24 KDNS
2.1 Control and signalling
2. USER MANUAL
Operating mode switch - function
Boiler shut-down (standby) – the protective functions of the boiler remain in
operation (when the boiler is connected to the electricity network and the gas supply
is opened). The selection of the mode is indicated by “--”, heating and DHW heating are
disconnected. The boiler is disconnected by pressing down the button for 5 s
Starting the boiler – is done by pressing down the button for about 2 s. The boiler starts in the winter
mode. When summer mode is required, press down the button again for 2 s
Winter mode – active heating and heating of DHW
Summer mode – active only heating of DHW, heating is OFF
RESET Resetting the fault conditions of the boiler – it is done by pressing down the button
1. DHW temperature increase *
2. DHW temperature decrease *
3. Operating mode switch
6. Display
4. Heating water temperature
increase (equithermic curve
shift)
5. Heating water temperature
decrease (equithermic curve
shift)
2.1.2 Description of the boiler panel controls
2 s 2 s 2 s
2.1.1 Boiler control panel
The boiler control panel is integrated into the top boiler cover, which makes the individual control elements ideally accessible.
!
This appliance may be used by children at the age of 8 and above and by people with impaired physical, sensory
or mental abilities, or lack of experience and knowledge provided that they are supervised or that they have been
instructed on the safe use of the appliance, and that they understand the potential risks. Children must not play
with the appliance. Children must not perform cleaning and maintenance of the appliance without supervision.
* Only used when an external DHW storage tank is installed.

9
THERM 24 KDNS
LCD display – displaying the operating parameters of the boiler
Indication of set temperature
After pressing the buttons for setting the temperature of the
heating system or DHW, the respective symbol of the mode will
start to ash along with the numeric display of the temperature on
the LCD display. In this case, the value of the last temperature set is
indicated. After the termination of the setting, the indication of the
set temperature remains for about 5 seconds. The following permanent display of the numeric value and the
symbol, the real temperature of the respective mode is indicated again
Setting the heating temperature – setting of the output temperature of water in the heating system within the
range 25 – 80 °C. In the case of selected equitherm regulation, the shift in the heating curve is set by the control
indicators (within the range ± 15 °C from the selected equithermic curve)
Setting DHW temperature – setting the required hot water temperature between 35 to 60 °C. Only used when an
external DHW storage tank is installed. When DHW temperature is read in the storage tank using athermostat (ON/
OFF), it is used for setting the required heating water temperature that heats up the storage tank
DHW heating shut-down – the DHW heating can be permanently shut down by setting the required DHW
temperature at “0”. DHW heating is activated again by setting the required DHW temperature.
SYMBOL MEANING
The eld for displaying temperatures, fault
conditions, service values and other data
Constantly lit - the boiler is in summer mode
- displays the primary circuit temperature
Flashing – displays the DHW temperature or
the requested DHW temperature by setting
Constantly lit – the boiler is in winter mode
Flashing – displays the heating temperature
or the required heating temperature during
the setting
Constantly lit - the burner is working
Flashing - the burner is being activated
Flashing - the boiler requires service
Flashing (every 4 s) - active communication
of OpenTherm with asuperior regulator
Flashing alternately - the boiler is o
(standby)
Description of symbols shown on the display
SYMBOL MEANING
Active anti-cycling function
Active pump run-out function
Active anti-freeze boiler protection
function
Request for relling the heating system
Boiler error - ashing alternately with
an error code
Forced heating function
Boiler reset required

10 THERM 24 KDNS
2.1.3 Information menu
It is used for displaying the current boiler parameters and other available information.
3.
4.
4.
5.
The menu is entered by shortly pressing
button 3 and 4 at the same time.
Move in the menu by using button 4
and5.
The information menu closes automatically when inactive for 60 s. The menu can be immediately closed by shortly pressing
button 3 and 4 at the same time.
DISPLAY MEANING
d0 Heating system pressure (/10)
d1 Outside temperature (1)
d2 Equithermic curve (factor „K“)
d3 Equithermic curve shift
d4 Required temperature of heating
water
d5 Measured temperature of heating
water
List of displayed information parameters
DISPLAY MEANING
d6 Temperature of return water
d7 DHW temperature
d8 Flue gas temperature
d9 Fan speed (x100)
(1) - an outdoor temperature display is only available in the case of the correction of the outside sensor and the selection
of equithermic regulation

11
THERM 24 KDNS
* The boiler is blocked. To reactivate the boiler, manually reset by pressing the button .
2.1.4 Error messages
Any error or other anomaly is indicated by flashing of the backlit LCD display. The following is lit on the display
symbol or and this ashes alternately and the error code with description according to the table.
The error code is saved into the memory of the processor where it is also saved in the case of asupply failure. The service
technician can check the memory and ascertain the history of failure statuses.
Error code displayed on the LCD screen and its meaning
ERROR CODE MEANING
Er 01 * Activity blocked after the burner
did not ignite (5x without ionisation
detection)
Er 02 Low pressure of heating water
Er 03 Indication of false ame
Er 04 Defect in thermal heating probe
(interruption of short-circuit)
Er 05 Defect to the thermal DHW probe
Er 06 * Blocking of activity after
overheating of the boiler
(emergency thermostat)
Er 07 Defect to the outside temperature
sensor
Er 08 Fan control failure
Er 11 * Blocking - unspecied error
ERROR CODE MEANING
Er 13 Defect of the thermal probe of burnt
gases
Er 14 Quick increase in heating water
temperature (> 4 °C / s), or high
heating water temperature (> 105 °C)
Er 16 * High temperature of burnt gases in
the condensing body
Er 21 Defect of the thermal probe of
return water
Er 25 * Repeated loss of ame (3x) during
the burner’s operation (after
ionisation detection)
Er 69 Error in the connection of the
heating water pressure sensor
Er 99 Controlling automatics
conguration error
Li 01 High heating temperature when
heating DHW

12 THERM 24 KDNS
!
2.2 Commissioning of the boiler to operation
The boiler must only be commissioned by aservice employee authorised by the producer! The list of service
technicians is attached to the product.
The procedure for the rst ignition of the boiler is as follows
insert the network supply into the socket and switch on the boiler with the switch for operating modes
inspect the correct activity of all thermostats and control elements
inspect all functions of the boiler
adjust the burning of the boiler using the burnt gas analyser, or modify the setting according to demands of the area to
be heated and the character of gas collection
train the user
Action to be taken before and during the activation of the boiler
Before the rst activation of the boiler it is necessary to take the following measures
check that the heating system is lled with water and the boiler is correctly de-aerated
ensure that all valves under the boiler and in the heating system are open
check that the trap with amagnet is installed
open the gas valve and, using the gas escape detector or foam-making solution, test the tightness of the gas distribution
in the boiler
2.3 Disconnection of the boiler from operation
It is possible to disconnect the boiler for ashorter period by the operating mode switch, or using superior regulation.
For longer disconnection of the boiler outside the heating season (e.g. during summer and holidays) it is recommended
to close the gas valve. However, leave the boiler connected to the electricity network. Only in this case will the protective
functions of the boiler be active.
Any full disconnection of the boiler (closing of gas supply, disconnection from electricity network) must be done with respect
to the ambient temperature of the environment in the respective season! There is arisk of the heating system or DHW circuit
freezing due to damage to the boiler or other elements of the heating system.
The setting of output range of the boiler and other parameters must be in accordance with the technical data.
Any overloading and incorrect use of the boiler may cause the devaluation of its components. The warranty
cannot be applied for such damaged components!
The boiler must not be operated with the emergency thermostat or another safety element excluded from
operation or replaced by other equipment than that stated by the producer! Otherwise, an accident or other
hazardous statuses may occur!
Aservice technician authorised by the producer must familiarize the user during activation with the operation of
the boiler, the individual parts, the safety elements and the manner of control, complete the Warranty Certicate
and give this user manual to the user.
The user is obliged to ensure of the correct use of the boiler in accordance with this manual which is aconditions
of acceptance of the warranty. In addition, it is strictly forbidden to intervene in any manner into the secured
parts in the boiler!
!

13
THERM 24 KDNS
2.4 Regulation
The boiler is fitted with internal regulating elements at ahigh level for such basic equipment. Integrated equithermic
regulation is provided as standard. The heating in the heating system can be controlled in several ways: regulation of the
room temperature in aselected reference room; equithermic regulation of heating water, regulation according to the boiler
temperature etc.
The operation of the independent boiler (without selection of equithermic regulation) is recommended to be
controlled using at least asimple room thermostat. The room temperature is time stable and keeps the boiler
in the operating modes. It is recommended to use the built-in equitherm regulation either independently or
completed by the spatial regulation, as mentioned below.
2.4.2 Operation of the boiler with spatial thermostat
In this manner of regulation, the boiler maintains the selected temperature of heating water. The room thermostat is connected
instead of the connection of the terminal labelled as RT inside the control panel of the boiler. The operation of the boiler is
consequently controlled according to the inside temperature in aroom where the room thermostat is located (the reference
room).
For control according to room temperature, Thermona delivers and recommends the whole series of room
thermostats: e.g. THERM Home S, THERM Home SR (wireless version), BT52 WiFi etc.
!
The mentioned ad-in regulators are not (with the exception of special oers) included in the delivery of the boiler!
Description of the activity of the boiler in the mentioned mode
The working phase of the boiler starts by switching on the room thermostat (the thermostat evaluated low temperature
compared with requested) at the moment when the mode control knob is in the winter mode position. The three-way valve
relay is disconnected (for boilers with water storage heating); the of circulating pump is activated, as well as the ignition system
and ventilator. Ignition of the boiler is for the adjusted starting output. It remains for 2 seconds after activation of the boiler.
The output is then decreased to the minimum with aslow linear start to the modulation point stated by service for setting the
maximum heating output. The regulation of output of the boiler in this phase is by PID (proportional/integral/derivative) with
keeping the temperature set by the button on the control panel (within the range 25 – 80 °C). During the whole time of heating,
the regulation limit of the output temperature is checked. When heating the system with lower input power than the minimum
output of the machine, there is an increase of the output temperature of heating water by 3 °C above the adjusted temperature
(for 30 seconds from ignition, this value is increased to 10 °C). In this phase the boiler interrupts the burning while still running
the circulating pump and activates the restriction of reignition (service setting within the range 0 – 10 min.). In this manner
the boiler becomes ahighly adaptable source of heat due to the high variability of the consequently regulated heating sets
(e.g. use of zone regulation, thermostatic valves, etc.).
After turning o of the space thermostat or switching the boiler to the "SUMMER" mode, the burner is stopped and the
pump is further turned on for aset time of the pump run-out function. This function is used for taking the heat from the
condensing body and for improving the allocation of temperatures of bodies when using thermostats with PI linkage with
short working cycles.
In the case of the installation of the room thermostat or regulator in the reference room, aminimum of one
radiator must be left without athermostat head. To increase thermal comfort, we recommend not to mount
thermostatic heads on radiators in the reference room at all.
2.4.1 Operation of the boiler without the room thermostat or regulator
In this mode the boiler maintains the selected temperature of the heating water. The room thermostat or the regulator is not
connected; the terminals for connection must be mutually interconnected (set in production).
In this mode, set the temperature of the heating water directly on the boiler control panel with the button 4 and 5.

14 THERM 24 KDNS
2.4.3 Operation of the boiler using built-in equithermic regulation
This mode is accessible in the boiler in the standard variant but it is not activated! The activation and the primary setting of
the regulation is performed at the request of the client by an authorized service technician.
During equithermic regulation, the boiler changes the temperature of the heating water automatically according to the
changes in the outside temperature.
This manner of regulation can only be used with the connected outside temperature sensor. The outside sensor is located on
the coldest wall of the object (north or north-west) approximately 3m above the ground. The sensor must not be inuenced
by any other thermal inuence such as open windows, sunlight, ventilation shafts, etc.
Description of the activity of the boiler in this mode
The working phases of the boiler are identical with the previous mode with the dierence that the temperature for the
heating system is automatically set according to the outside temperature (ascertained by the sensor). The calculation of the
requested temperature of the heating system is the function of the ambient temperature and the function of the “K“ factor
(declination of equithermic curve), which is set by the service technician with respect to the locality and nature of the object
and the heating system. Using the buttons for setting the heating water temperature on the control panel, the user sets the
requested thermal comfort (correction of the equithermic curve shift within the range ± 15°C of the heating water). In the
case of failure of the ambient temperature sensor, this status is signalled by Er 07 failure and the boiler continues in operation
with the temperature of the heating system according to the setting in the previous mode (without equithermic regulation).
Adjustment procedure
When setting the equithermic regulation, it is necessary to distinguish the declination and the shift of the equithermic curve.
When setting the declination of the equithermic curve, the following rule applies: in the case of poor thermal-insulating
properties of the object, change the parameters of the declination of the curve in the direction of the higher values (the curve
is moved upward); in the case of good thermal insulation, the parameter can be decreased (the curve is moved downward).
The declination of the curve is set by the authorized technician in the service menu of the automatic control system
of the boiler!
It results from the mentioned facts that using the button to set the temperature of the heating on the control panel in
this mode indirectly sets the requested temperature of the space to be heated. At the beginning (in the production) the
equithermic curve is set at “K” =1.6. After inspection of the temperature of the heated space (after approximately 24 hours),
it is possible to perform additional setting according to all requirements for thermal comfort. Due to the inuence of the
equithermic regulation the change of ambient temperatures will be compensated and the level of temperature of the heated
space will be automatically kept at aconstant level.
Using this mode of regulation, afurther decrease of operating costs can be achieved while improving thermal comfort
(continuous heating of heating bodies). Finally, this option can be appreciated as pre-regulation of the primary heating circuit
when using zone regulation (by mixing valves), etc.
!During the activated equithermic regulation the meaning of the function of the button 4 and 5 on the control
panel of the boiler is changed. In this case, the mentioned buttons is used to set the shift of the heating curve
(within the range ±15 °C from the equithermic curve set by the service technician).
4.
5.
Shift the equithermic curve using
buttons 4 and5.

15
THERM 24 KDNS
K=0,5
K=1,0
K=1,5
K=2,0
K=3,0
K=4,0
K=6,0
20.00
30.00
40.00
50.00
60.00
70.00
80.00
-25-20-15-10-505101520
Outdoor temperature (°C)
Heating water temperature (°C)
K=1,0
K=3,0
+15°C
-15°C
+15°C
-15°C
20.00
30.00
40.00
50.00
60.00
70.00
80.00
-25-20-15-10-505101520
Outdoor temperature (°C)
Heating water temperature (°C)
Example of the course of selected
curves during correction of the shift
Graph of the course of equithermic
curves (zero shift)
2.4.4 Operation of the boiler using master equithermic regulation
After ensuring “full value“ equithermic regulation (including setting the time programmes, etc.), it is recommended to use
intelligent programmable regulator CR 04 or PT 59, which regularly communicates with the microprocessor of the automatic
boiler system.There is the transfer of information not only about the required temperature of the heating system depending on
the spatial and outside temperature, but also the display of operating information about the boiler (work mode, performance,
temperatures, possible failures, etc.). This system is characterized by many adjustable and displayed parameters for optimal
control of the heating equipment with modulation of the boiler output.
The mentioned add-in regulators are not (with the exception of short-term special oers) included in the
delivery of the boiler!

16 THERM 24 KDNS
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OKC 100 NTR
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detail
2.4.5 Heating of utility water (DHW)
THERM 24 KDNS boilers may be used, when the required additional equipment is installed, for heating water in an external
indirect-heating storage tank.
DHW HEATING ACTIVITY DESCRIPTION
The operating phase of DHW storage tank heating starts when the storage tank sensor or thermostat detects adecreased
DHW temperature. The pump is activated after the three-way valve is readjusted (within the time interval of 8 seconds). After
the sequence for the inspection of security elements, the ignition of the burner is enabled.
From detecting the presence of the ame, the starting output of the boiler is kept for 2 seconds and then there is the phase
of uent modulation of the output with PID regulation with the stated value of the temperature of heating of 80 °C (unless
reduced). During the whole time of heating, the regulation limit of the output temperature is checked. The operating phase
in the DHW heating mode ends when the required DHW temperature is reached.
This is followed by stopping the burning and then there is the additional cooling of the exchanger with the time function for
the running of the circulating pump. After termination and stopping of the pump, there is switching of the three-way valve
and resetting is activated. Then the requested heating of the heating system can be run.
1 – Gas boiler THERM 24 KDNS
2 – Indirect heating storage tank
3 – Air release valve
4 – Heating system
5 – Supply of cold water
6 – Connection of the thermostat for the
storage tank
7 – Output DHW
8 – Discharging valve
U– Closure on the cold water inlet
Z– Testing valve
K– Return valve
P– Safety valve
M– Pressure meter
E– Expansion tank (recommended)
The informative connection diagram of the indirect heating storage tank to the gas boiler
In the case of parallel requests, the water heating mode takes priority over the heating of the heating system.

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THERM 24 KDNS
2.5 Selected protective and additional functions of the boiler
!
!
The anti-cycling time within the range 010 minutes can be only be changed by an authorized service technician!
Run-out of the pump
When the request for heating or DHW heating ends, the pump continues to operate during the adjusted run-out of the pump.
The factory setting of the pump run-out is 1 minute after the end of heating, and also 1 minute after the end of DHW heating.
When the boiler is operated without the room thermostat in the winter mode, the pump continues to be ON.
The pump run-out time within the range 0 - 10 minutes can be only be changed by an authorized service
technician.
Anti-cycling
The function that prevents the cycling of the boiler in the heating mode when re-ignition of the boiler is not permitted in
the case of operating boiler shut-down before the expiration of the adjusted, anti-cycling time (5 minutes are set in the
production). This function is mostly used in such heating systems where the maximum thermal loss of the stated object
corresponds to the lowest limit of the power range of the boiler.
Storage tank anti-freeze protection (only when DHW temperature is read by asensor)
The anti-freeze protection of the storage tank protects the hot water storage tank (not the hot water distribution) against
freezing. The anti-freeze protection of the storage tank is activated when DHW temperature in the storage tank decreases
below 8 °C. The pump is activated, the boiler is ignited and the storage tank is heated until the temperature of 10 °C is reached.
Run-out of the ventilator
After termination of burning, the ventilator is in operation for 30 seconds while keeping the revolutions corresponding to the
starting output (taking the remaining of burnt gases from the combustion chamber).
Anti-Legionella function (only when DHW temperature is read by asensor)
The function is activated at the moment when the DHW temperature in the storage tanks drops below the set limit temperature
and does not exceed it during ameasured time interval (two or three days). When activated, the storage tank is automatically
heated to 60 °C, then the function is deactivated. The default setting of the function is OFF, it may be activated in the service
menu of the boiler.
Anti-blocking functions
After 24 hours of inactivity, the pump runs for 30 seconds to prevent any blocking. In the case of arequest for heating (heating
or hot water) during the execution of this function, the anti-blocking function is automatically terminated and the request
runs. The anti-blocking function is also active when blocking the activity of the boiler in the position of the driver in the mode
“OFF“ (if the boiler is still connected to the electricity network).
Anti-freeze boiler protection
The boiler is equipped with anti-freeze protection system that protects it from freezing. Anti-freeze protection is activated
in the case of adecrease of the temperature in the boiler under 6 °C. The pump is activated, the boiler is ignited and heats
the heating circuit with aminimum output of 15 °C. The burning is stopped at this temperature and the pump continues
running during the function for running the pump. If the boiler is in the status for blocking burning (failure), only the pump
is activated. The anti-freeze function is also active in the position “OFF“ or in the “SUMMER MODE”.
Notification: All the above-mentioned security and protective functions, including the anti-freeze boiler
protection, are only active when the boiler is connected to the electricity!
!
!The anti-freeze storage tank protection is not active in the standby mode - the display shows “- -”.

18 THERM 24 KDNS
With respect to the request for increased checking of the microprocessor once every 24 hours of operation,
the forced reset of electronic system is performed with the consequent initialization (it is reected by short-
term interruption of the boiler and deactivation of data on the display similarly as during the activation of the
network inlet of the boiler into the socket).
2.6 Maintenance and service
Regular maintenance is very important for reliable operation, to achieve along service life, and ecient combustion. The
owner or the operator of the gas equipment shall provide annual revision through aservice company in compliance with
Ordinance No. 21/1979 Coll. of the Czech Work Safety Authority and the Czech Mining Authority, and CSN 386405. The service
organisation shall check, for example, the control and safety elements of the boiler, tightness of the gas and water distribution,
or clean the boiler and exchanger from burnt dust particles, adjust combustion, etc.
For error-free operation of the heating system, it is also necessary to regularly inspect the initial water pressure in acold
condition. In the case of adecrease of pressure below 0.8 bar, it is necessary to additionally ll the heating system. The current
heating system manometer be read in the information menu of the boiler or the pressure gauge, located under the boiler
casing.
Location of the heating system manometer
Forced heating function – it allows for manual activation or deactivation of heating for aperiod of 24 hours.
Function activation
Function deactivation
2 s
2 s
,
,
When activated, the display shows the function symbol “th” and the current heating water temperature alternately. The
function is automatically deactivated after the lapse of 24 hours.
For immediate deactivation, follow this procedure:
,
The external casing of the boiler can be cleaned with adamp cloth and mild detergent. Donot use cleaning agents based
on sand and solvents that could damage the nish.

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THERM 24 KDNS
!
During additional lling it is necessary to take the following conditions into consideration
2.7 Warranty and warranty terms
The producer is not liable for any mechanical damage to individual components by rough handling, for damage caused by
unprofessional intervention into the electronic system during the adjustment and connection of the add-in regulation, for
damages caused by the use of other parts and components than the original components used by the producer.
The warranty is also not applicable to defects caused by non compliance with the binding notications and terms stated in
individual parts of this manual.
The warranty is not applicable to non-standardized relations in distribution networks (variation of electrical voltage – in
particular voltage peaks, pressure and cleanliness of gas, etc.), defects to equipment outside the boiler that inuence activity,
improper collection of burnt gases, dirt in the combustion air, damage from outside inuences, mechanical damage, storage,
transport and defects originated by natural disasters.
In such cases the service organisation may require that the client pays for the repair.
THERMONA spol. sr. o. provides awarranty according to the stated in the Warranty Certicate delivered with the product.
Terms for application of the warranty
1. Regular, 1x per year, inspection of the gas boiler. Inspections must only be performed by an authorized organisation,
i.e. contractual service. The list of service centres is attached to each boiler. The actual list of service centres is available
fromwww.thermona.cz
2. Documentation for all records of warranty repairs and annual inspections of boilers is in the appendix to this manual
3. Submitting completed and conrmed warranty certicate and protocol on commissioning into the operation of THERM
products
a) the pressure of utility water supplied into the boiler must be higher than the water pressure in the heating
system (otherwise the heating water can ow back to the water mains!)
b) the additional lling of water is necessary to be done exclusively under acold status (the temperature of
the heating water in the boiler is amaximum of up to 35 °C)
Manometer – displays the measured water pressure in the heating system
2.6.1 Additionally lling the heating system
Additional lling into the heating system (additional pressurizing of the system) can be done through the lling valve which
is directly integrated on the boiler. Water for lling must full certain parameters, see chapter 3.8.
Procedure for additionally lling the heating system
with water
1. Disconnect the boiler from electrical voltage
2. Remove the front cover of the boiler casing by pulling
lightly
3. Slowly open the valve for additional lling with your hand
and monitor the manometer on the bottom of the boiler
4. Set the system pressure to the necessary value (according
to the heating system, recommended 1.0 – 1.5 bar)
5. Close the valve for additional lling
6. Connect the boiler to the electricity network and connect
the boiler again

20 THERM 24 KDNS
3.2 Complete character of the delivery
THERM hanging boilers are delivered fully assembled. All parts of the boiler
are checked and set by the producer before assembly. Each boiler is tested
for leakage of the water circuit, leakage of the gas circuit and the regulating
and protection parts are set and tested.
Before installing the boiler the assembly company is obliged to check
the type of the boiler corresponds to the ordered boiler
the selection of the boiler is correct for the stated use (type of gas, heating system, collection of smoke, air suction)
the delivery is complete
3. INSTALLATION MANUAL
3.1 Basic instructions for assembly of the boiler
Stationary condensing boilers THERM 25 KDNS series are designed for operation in standard hot-water heating systems.
The standard delivery of the boiler includes
1. Boiler
2. Manual for installation, service and maintenance of boiler
3. Service network (valid for CZE teritory)
4. Warranty certificate (3 copies)
5. Protocol on the commissioning of THERM products into operation
(valid for CZE teritory)
6. Confirmation of completing 1. and 2. service inspection (valid for
CZE teritory)
!
Assembly must only be performed by aqualied professional company and it is necessary to pay attention to
all advice and notications contained in this manual. Assembly must be in accordance with valid standards and
regulations – see ČSN EN 1775, ČSN 386462, ČSN 332000 – 7 – 701 ed.2, ČSN 061008, ČSN 734201, TPG 70401,
TPG 80002, TPG 90802, Regulation No. 48/1982 Coll.
Accessories
Necessary accessories (collection of gases, regulation, outside sensor, etc.) can be ordered on request. Detailed information
can be found in the catalogue of products and accessories or at www.thermona.cz.
!To collect smoke it is necessary to exclusively use equipment to collect gases delivered by the producer of the
boiler. Only by doing this will the boiler report the stated parameters for burning, output, eciency, etc.
In the case of any doubt or inquiries, contact the producer or supplier before assembly.
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Content of delivery