BW Type Solid Fuel Boilers

Installation and Maintenance Instructions

This Installation and Maintenance Instructions contain important information for the safe and correct installation, start-up and trouble-free operation and maintenance of BW type solid fuel boilers (BW-Classic &


This installation and maintenance instructions are intended for qualified technicians with experience and training in heating systems.

The information about boiler’s operation is intended for the end users and is designated as such in the respective way.

The authorized service specialists must undergo training by the boiler’s manufacturer for the product’s specific features and maintenance requirements.

Customer (boiler user) must undergo boiler operation/maintenance training by authorized installer/service shop who has installed the boiler.

1. Explanation of Symbols

Safety instructions in this document are framed and identified by a warning triangle and are printed on a grey background.

Electrical hazards are identified by a lightning symbol surrounded by a warning triangle.

Notes containing important information in cases where there is no risk of personal injury or material loss and are identified by the symbol shown on the left. They are bordered by horizontal lines above and below the text.

Instructions to the qualified heating technicians:

During installation and operation, the country-specific requirements and regulations must be observed:

 local construction regulations on installation, air supply and flue gas extraction as well as chimney connection.

 regulations and norms concerning the fitting of the heating installation with safety devices.

Installation requirements for the boiler room

DANGER of intoxication or suffocation.

Inadequate inflow of fresh air to the boiler room may result in dangerous leak of exhaust gases during boiler operation.

- Make sure the air inlets and exhaust gas outlets are not clogged or closed.

- If faults are not remedied immediately, the boiler must not be operated.

- The user must be provided with written instructions on the faults and the hazard it entails.


- Boiler rooms must be frost-proof;

- Boiler rooms must allow for continuous access of the air necessary to maintain combustion;

- Boilers must not be placed in inhabitable rooms;

- All boiler rooms must have correctly calculated vent depending on the boiler output. The vent must be protected by means of a net or grate. The size of the vent is calculated according to the following formula:

S = 6,02*P


S = Area of the vent in cm



P = Boiler output in kW

- The boiler must be placed in a position which allows for the easiest possible cleaning and servicing;

- Installation must be carried out according to installation drawings;

- Do not place flammable materials or liquids on/near the boiler;

Recommended minimum wall clearances

Wherever possible, position the boiler with the following recommended wall clearances:

А – 1000

В – 600

С – 600

Install the boiler on a non-combustible base (foundation) which is larger than the boiler footprint by at least 300 mm in the front and approximately 100 mm on the side and rear walls.

Observe building supervision instructions, in particular the existing regulations on combustion devices and storage of combustion materials, as well as the building requirements applicable to installation sites and ventilation.

Caution: Risk of system damage due to frost!

- Install the heating system in a frost-free room.

Danger: Risk of fire due to flammable materials and liquids!

Minimum clearances for installation and flammability of construction materials

- The applicable minimum clearances in

- Do not store easily-flammable materials and liquids near the boiler.

- Users must maintain the minimum distances to easily-flammable or hardly flammable materials. your country may differ from the ones specified bellow. Please, consult your boiler installer.

- The minimum distance from the heating boiler or flue gas pipe to materials with difficult, problematic and medium flammability must be at least 100 mm.

- The minimum distance from the heating boiler or flue gas pipe to easily- flammable materials must be at least 200 mm. If you do not know the flammability class of a material, for safety reasons maintain a distance of at least 200 mm.

Class А – nonflammable

Class В – difficult flammability

Class С


– problematic flammability

Class С


– medium flammability

Class С


– easily flammable

Flammability of building materials

Asbestos, stone, masonry, ceramic wall tiles, fired clay, mortar, plaster

Gypsum board panels, basalt fiber needled felt, fiberglass board, AKUMIN, IZOMIN, RAJOLIT, LIGNOS, VELOX and


Deciduous wood, beech, oak, plywood, felt, Hobrex,

Werzalit or Umakart boards

Coniferous wood, pine, larch and spruce wood, laminated wood

Asphalt, cardboard, cellulose materials, tar paper, wood fiber boards, cork, polyurethane, polyethylene, carpet tiles

Connecting the boiler to the chimney

Please note that the boiler must be connected to the flue gas system in accordance with the relevant local building code regulations and in consultation with an approved flue installer (chimney sweeper).

A sufficient flue draft of the flue gas system is the basic requirement for the correct functioning of the boiler. It can fundamentally affect its performance and efficiency. The draft depends on the diameter, height and roughness of the chimney walls.

The recommendable minimum draft of the chimney should be 20 Pa.

No other appliance may be connected to the chimney serving the boiler.

Chimney diameter must not be smaller than the flue outlet of the boiler.

Flue outlet must be connected to the chimney opening. In terms of mechanical properties, the flue outlet must be sturdy and properly sealed (to avoid gas leaks) and allow for easy access for cleaning on the inside. The inner section of the flue outlet must not be greater than the effective section of the chimney and must not narrow. Avoid using elbow joints. If it is not possible, use no more than two elbows with cumulative angle of

135° (45°) (please note that each right angle elbow (90°) reduces draft twice). The recommended distance between the boiler and the chimney is 300-600 mm. We do not recommend the use of longer horizontal sections of connecting flue pipes Pipe counter-slopes are absolutely prohibited.

The chimney cleaning opening has to be in its lowest part. The chimney‘s walls have to be three-plied where the medium layer is from mineral wool. The thickness of the insulation shall be not less than 30 mm when the chimney is inside the house and 50 mm, when the chimney setting-up is outside.


Use flue pipes made of non-combustible materials to connect the boiler with the chimney. Pipes longer than 2 m must be additionally supported.

Safety coil connection

In the countries which apply EN 303-5 standard, boilers must be provided with a system enabling a safety evacuation of the excess heat without additional energy.

The BW type heating boilers are equipped with safety heat exchanger (cooling circuit). It is connected to the water mains through a thermostatic valve. In case of overheating, the thermostatic valve feeds in cold water from the water mains which passes through the heat exchanger and absorbs the heat from the boiler. The water is then discharged into the sewage system. This guarantees that the water in the boiler will not exceed the maximum safe level of 95°C. The minimum operating pressure of the cooling water in the safety heat exchanger must be within the range of 2÷10 bar. A flow rate of at least 12 l/min is required.

Installation of the thermostatic valve:

1. Remove the sensors cover;

2. Unscrew the zinc-plated G ½ plug;

3. Screw in the thermostatic valve probe to the same socket;

4. Install the thermostatic valve at the safety heat exchanger inlet. Install a water filter upstream the thermostatic valve. Connect the filter with the water mains;

5. Connect the heat exchanger outlet with the sewage system.

The safety heat exchanger does not have predefined inlet and outlet.

Both exchanger ends can serve as inlet or outlet, so the terms “inlet” and “outlet” are conditional only. Connect the heat exchanger taking into account the specific features of the heating installation.

Connecting the boiler to the heating installation


Risk of system damage due to leaking connections!

Support the pipes to the boiler to prevent them from being under stress.

When the boiler is connected to a closed loop heating system, it is mandatory to install a 3 bar relief valve and expansion tank.

If it is an open vented heating system, only expansion tank is needed. No shut-off fittings may be installed between the relief valve and the expansion tank.

The return flow temperature should not fall below 65 °C to ensure the normal operation of the heating system.

Therefore, a thermostatic mixing valve shall be installed on the return water line to ensure that the temperature of the heating medium fed into the boiler from the heating system is at least 65°С.


Feeding low temperature water to the boiler may cause profound condensation that could seriously damage your boiler.

Please find below some installation examples showing how to connect the boiler to various types of heating systems:

Connecting the boiler to the power supply

Caution! Electric appliance!

Before taking any action connected with the device power supply

(connecting of power cables, installation of the device, etc.), make sure that the controller is disconnected from the power outlet.

Make sure that your power outlet is earthed.

In order to size the power supply cables properly, take into account the power consumption of the controller and pumps. In case of a power outage (power failure), the boiler may overheat. To avoid this, ensure a backup power generator capable of providing the necessary rated power for the boiler.

Using the BW type boilers with a burner

Remove the burner opening covers from the outside and inside surfaces of the boiler’s lower door. Remove the lower safety door (grill). Remove the insulation material from the opening area. You will need a specially designed transitional flange to install the burner. The transitional flange shall be compatible with the threaded studs of the boiler and the fixtures of the purchased burner.

The burner shall be operated in compliance with the burner manufacturer’s instructions.

There are no specific restrictions for the use of burners with BW type boilers. To ensure the boiler’s normal operation, please keep the operating instructions contained herein as well as, operating instructions provided by the burner’s manufacturer.


When installing a burner to the BW-A type boiler, make sure that the fan is disconnected from the power socket. Unintentional start of the

Filling the heating installation

fan during burner operation may cause back draft and discharge of exhaust gases in the room. This can seriously affect the burner

Possible installation damage due to strains operation or damage it. in the material caused by temperature differences. Fill the heating installation only when it is cold (inlet temperature must not exceed


Danger of installation damage due to accumulation of deposits. Condensation and tar formation may shorten boiler’s life span.

Do not operate the heating boiler in partially loaded mode for long periods of time. The temperature at the boiler inlet must not be less than 65°C, while temperature at the boiler outlet must be between 70°C and 85°C.

In the summer, use the boiler for short periods of time to heat already warm water.


Any activity related to the boiler installation, connecting to the existing heating or power supply systems, assembly and start-up of the burner and various other blocks or devices to the heating system shall be carried out by an authorized technician (service company).

Any unauthorized access to the boiler installation and assembly procedures shall make all warranty claims null and void.

Tools, materials and accessories

For the installation boiler and maintenance, you will need the standard tools and materials used for central heating and water systems. No special tools are required.


We recommend you to transport the heating boiler to the installation site in its original packing placed on the pallet. For transportation purposes, the boiler is secured with fixtures on a wooden pallet.

Depending on the boiler’s weight, during transportation and installation appropriate safety equipment must be used in accordance with Directive 2006/42/EC.

When handling items weighing more than 30 kg, the use of pallet trolley, fork lift or other hoisting devices is a must.


When installing the boiler, the wooden pallet onto which the boiler is placed must be removed by unscrewing the bolted connections using flat ring wrench S13.

Dispose of packaging in an environmentally responsible manner.

Packing materials made of wood and paper can be burned in the boiler.

Dispose of the remaining packing materials at an authorized disposal site.

Instructions to installation user

DANGER of intoxication or explosion!

- Operate the heating boiler at a

- As a user, you are only allowed to start the boiler up, adjust the temperature of the boiler, shut the boiler down and clean it.

- Unattended children must not be allowed to the boiler room when the boiler is running. maximum temperature of 85°C and monitor its operation from time to time.

- Do not use flammable liquids to increase boiler’s output.

- Collect ash in lid-covered fireproof containers.

- Clean the heating boiler surface by using non-flammable agents only.

- Do not place flammable objects onto the heating boiler or in close proximity (in view of the minimum safety clearances).

- Do not store flammable materials in the boiler room (e.g. wood, paper, gas, oil, etc.)

Loading and ignition the boiler

When igniting the boiler for the first time, a condensation is formed which is later drained (this is not considered a fault in the boiler).

Fuel is loaded in the combustion chamber. It is recommended to load logs of length equal to the combustion chamber’s length and stack them tight inside with least possible air gaps. Both boiler doors must be closed and sealed. Switch on the controller and set the maximum boiler temperature. The gas probe adjusts the fan speed and chimney draft depending on the used fuel.

When burning wood with increased moisture content the boiler efficiency decreases which results in:

- significantly increased fuel consumption;

- insufficient power output;

- decreased life span of the boiler and chimney.

Cleaning of the boiler

Boiler cleaning must be carried out periodically and adequately at every 3 to 5 days (depending on the power output and used fuel). Ash accumulated in the combustion chamber, condensed moisture and tar deposits significantly reduce the life span and performance of the boiler and result in deterioration of the properties of the heat exchange surface.

It is recommendable boiler to be cleaned by an authorized service company at the beginning of each heating season.

Where necessary scrape the ashes and the soot from combustion chamber walls. Remove the turbulators and clean the flue pipes. Use scraper and brush for the purpose.

Caution: Hot surfaces!

Before cleaning the boiler, make sure the fire in it has died out and the boiler has cooled down.

Caution! Ashes may contain smouldering charcoal. Dispose of ashes only in specially designated palces.

Disposing of ashes into public garbage containers may cause fire.

Caution: The Authorized technician who has installed and started-up

Description of the BW

the boiler must train the user how to operate and maintain the boiler in a correct and safe manner.

The end user must be informed for the immediate threats for his life

type boilers

BW-С and BW-A water or property caused by the incorrect use of the heating boiler. heating boilers are designed for use in local heating systems of single or multi-family houses, small hotels, etc.

They can utilize natural and untreated fire wood (logs with length of 350 to 500 mm and moisture content of less than 25%), coal, briquettes and eco briquettes.

High moisture content of the wood decreases its heating value which in turn reduces boiler output.

The heating boilers can be adapted to use other fuel types by mounting a gas-, oil- or pellet-fired burner on the lower door by use of a specially designed kit (flange).

BW-С and BW-A boilers’ bodies are made of high-quality boiler steel sheets with thickness of 5 mm for the combustion chambers and 3 or 4 mm for the water mantles.

To increase the boiler efficiency, flue gas makes a three-pass movement on its way to the chimney. The third pass is through fire tubes with built-in turbulators. The water mantle embraces the combustion chamber in full to utilize the emitted heat most efficiently. The boiler is insulated by 50 mm high-temperature wool to keep heat from escaping into the ambient atmosphere.

To prevent boilers from overheating, they are equipped with a safety heat exchanger and a 3 bar relief valve.

To provide for the trouble-free evacuation of flue gases and ensure low chamber resistance, the heating boilers are supplied with a specially designed flue pipe with a draft regulating valve.

The BW-C boilers are atmospheric boilers, provided with automatic heat regulator to control the air intake and thus the generated heat. Each boiler is provided with a thermometer probe to monitor the current temperature.

The BW-A boilers are forced draft boilers which use a draft fan. They have a built-in digital controller which controls the fan speed, the heating circuit pump and the hot consumption water pump by monitoring the current temperature values of the heating installation, the hot consumption water, flue gases and taking into account the used fuel. The innovative proportional-integral-derivative controller (zPID-controller) improves the burning process, increases the efficiency and reduces fuel consumption.

It is important to note that BW type boilers are modular, i.e. a BW-C type boiler can easily be converted (upgraded) to a BW-A type boiler and vice versa. Conversion is made by replacement of several modules at user’s discretion. This, together with the option for fitting a pellet burner provides users with the opportunity to select and take advantage from a wide variety of fuels.

1 - Combustion chamber

2 - Fuel filler door

3 - Ash pan door

4 - Draft fan (BW-А type boilers)

5 - ST-81 zPID controller (BW-А type boilers)

6 - Flue

7 - Butterfly valve for draft regulation

8 - Manhole for flue pipe cleaning

9 - Thermometer probe (BW-С type boilers)

10 - Safety heat exchanger

11 - Secondary air valve

12 - Air intake valve (BW-С type boilers)

13 - Thermostatic draft regulator (BW-С type boilers)

14 - Cable connectors cover

15 - Sensors cover

16 - Water inlet connector G 1½“

17 - Water outlet connector G 1½“

18 - Connector for boiler filling and/or draining G ½“

19 - Cover of the burner opening

20 - Ash pan safety door

21 - Flue outtake

22 - Upper safety door

23 - Ash and soot pan

24 - Air distributor

25 - Fuse

26 - Safety thermostat

Scope of delivery

Upon purchasing of BW type boiler, check if all components have been delivered to you. The boiler scope of delivery includes:



BW boiler


1 1





Thermostatic draft regulator

3 bar relief valve

Fire iron

Wire brush











Ash pan

Installation and

Maintenance Instructions

Warranty Card






1 1

The lack of any of the above components may lead to the incorrect boiler operation.

Setting the thermostatic draft regulator

The thermostatic draft regulator is a mechanical device delivered with the type BW-C atmospheric boilers only. It automatically regulates the airflow to the boiler fire chamber depending on the pre-set temperature.

Install the thermostatic draft regulator to the G ¾ “connector located on the boiler’s right wall. Use sealing tape to make connection watertight.

Use the chain to connect the thermostatic draft regulator lever with the air intake valve.

Ignite the boiler and heat the water up to 70°С. Use the boiler thermometer to monitor the temperature. Turn the thermostatic draft regulator’s wheel until it indicates 70 °С.

Adjust the chain length in such a way that the air intake valve is fully closed at that temperature, while the chain is tense.

If you have adjusted the thermostatic draft regulator correctly:

- If you turn the regulator wheel to a higher temperature, the air intake valve will open.

- If you turn the regulator wheel to a lower temperature, the air intake valve will remain shut, and the chain will slacken.

Thus the thermostatic draft regulator is adjusted for normal operation. Now you can turn the wheel to the water temperature desired by you and the boiler will maintain it.


The controller (ST-81zPID) and the draft fan are delivered with the

BW-A type boilers only.

ST-81 zPID controls the draft fan speed (the air inflow) the operation of two pumps: the heating circuit pump (CH Pump) and the hot consumption water pump (HCW Pump). The fan works constantly and its speed depends on the boiler temperature and the flue gases temperature.

Controller’s view; Explanation of buttons and light indicators

Caution! Electric appliance!

Do not touch with wet hands. If there is moisture or leakage near the boiler, shut off the power supply and call an authorized service company. Do not operate the boiler until all damages are repaired.

This controller can save up to 15 % fuel and provide a constant water temperature and longer life of your boiler. The heat of the flue gas is used for heating rather than lost through the flue.

Technical specifications of controller ST 81

1. Supply


Power consumption


Ambient temperature


Maximum output load of CH pump


5 W

5 ÷ 50°C



Maximum output load of fan


Temperature measurement range




Measurement accuracy

Temperature strength of the sensor

Fuse insert


0 ÷ 90°C




Explanation of buttons:

↑ - Navigation arrow UP/PLUS;

↓ - Navigation arrow DOWN/MINUS;

MENU button – To enter menu/confirm settings;

EXIT button – To cancel settings;

- ON/OFF power switch

- Fan light indicator

- Central heating pump (CH Pump) light indicator

- Hot consumption water pump (HCW Pump) light indicator

- Manual operation


The cycle begins when you activate the Fire-up function in the controller’s menu and is active until the central heating boiler temperature reaches 40°C (the default fire-up threshold), provided that the temperature does not drop below this value for at least 2 min. (the default fire-up time). If these conditions are met, the controller will switch to operation (duty) mode and the manual operation light on the control board will go off.

If the controller fails to reach the parameters required for entering into the duty mode within 30 min. from activation of the Fire-up function, the „Unable to fire up” message will appear on the display. In such a case, the fire-up cycle will need to be restarted.

Operation (duty) mode

The operation cycle is the basic functionality of the controller. It follows immediately after the Fire-up mode.

The fan speed is regulated automatically by the zPID controller depending on the water and flue gases temperature. If the temperature rises above the set temperature, the suspension mode is activated.

Suspension mode

This mode will be activated automatically, if the temperature is equal or higher than the set temperature. In such a case it is necessary to properly set operation times of the fan in order to ensure smooth decrease of temperature of circulating water.


If boiler temperature drops by 2°C below the fire-up threshold and fails to rise above this value for 30 min.

(default damping time), the controller will switch to damping mode. While in this mode, the fan is deactivated and the display shows “Damping”.

Main page

42 °С 55 °С *


During normal operation (in CH mode only) the LCD display shows the main page which presents the following information:

Boiler temperature (on the left side of the display)

Set temperature (on the right side of the display)

Symbol of non-operating fan (*)

Symbol of the current operation mode (in the lower right corner):

– house heating; – parallel pumps;


– HCW priority; * – summer mode.

This screen allows for quick change of the set temperature, by the means of the PLUS and MINUS buttons.

Pressing down the MENU button moves the user to the 1st level menu. In each menu the user can scroll up and down by the means of the PLUS and MINUS buttons. Pressing down the MENU button again moves the user to the next menu or enables a specific function. Pressing down the EXIT button moves the user back to the root menu or cancels certain function.

The user may select between three main screens: central heating screen (C.H. Screen), hot consumption water screen (H.C.W. or D.H.W. Screen) and flue gas screen (Flue Gas Screen) by pressing down the EXIT button for at least 3 seconds:

C.H. Screen H.C.W. Screen

H.C.W. Screen Flue Gas Screen

33°C 45°C 65%

C.H. Flue Gas Fan

H.C.W. Screen

Flue Gas Screen

In the H.C.W. Screen the user may quickly set the water temperature to the required value (in the right part of the screen) by pressing the PLUS and MINUS buttons, while the left part of the screen displays the current water temperature.

The Flue Gas Screen is for user’s reference only. It does not allow quick change of parameters. On that screen the user can monitor (from left to right) the water outlet temperature, the flue gases temperature and the fan speed expressed as a percentage.


When firing-up the boiler, the pressing of MENU button switches on the controller. In case the boiler is already operational, pressing the MENU button switches on/off the fan (Fan - ( ) ON, ( ) OFF).


If the fan is turned on, do not open the boiler door. Temporarily switch off the fan in the described way, if you need to open the boiler door (e.g. for feeding fuel)

If, during the fire-up sequence the boiler does not reach 40°C

(default damping threshold) for 30 min., the display will present the following alarm:

22 °С 55 °С


In such case, the user has to reset the alarm and restart the fire-up mode.

Manual mode

The manual mode provides user with many advantages.

Fire up

Manual Mode

In this mode each executive element can be switched off and on independently from all the other elements.

In manual mode, the “Blow force” menu allows user to select the fan speed expressed in percentage.

Blow force


Pressing down the MENU button starts the fan which remains turned on until the MENU button is pressed again.


C.H. Pump

Pressing down the MENU button turns on/off the central heating water pump.

C.H. Pump

H.C.W. Pump

Pressing down the MENU button turns on/off the hot consumption water pump.

H.C.W. Pump


Pressing down the MENU button turns on/off the alarm signal.

Fuel type

42 ° 55 °С


Manual Mode




This menu allows user to select the type of fuel to be used for the heating boiler. Setting the right type of fuel provides for the correct control of the burning process.

Selecting the CH and HCW pumps switch on temperature

This option is used to set the switch on temperature of the CH pump (measured at the CH boiler) and HCW pump (measured at the HCW water heater).

42 ° 55 °С Fuel type

55 °C


C.H. Pump on temp

C.H. Pump activation

The CH pump control is based upon the readings of the CH sensor which measures water temperature at the

CH boiler. In the above example, the CH pump will switch on when the temperature reaches 55°С. The pump will switch off after the temperature drops below the set temperature (minus 2°С of hysteresis), in this case the pump will switch off when the temperature in boiler drops below 53°С, and will switch on again, if water temperature reaches the set temperature.

42 ° 55 °С C.H. Pump activation

60 °C


H.C.W. Pump on temp

H.C.W. Pump activation

The HCW pump control is based upon the readings of the CH sensor which measures the water temperature at the CH boiler and HCW sensor which measures the temperature at the water heater. To activate the HCW pump, the following two conditions must be met:

1. The water temperature at the CH boiler outlet must be higher than the set one (in this case, more than 60°С);

2. The temperature at the water heater must be lower than the set one. i.e., the pump will switch on when the CH boiler’s temperature reaches 60°С and will stop when the water heater’s temperature reaches 60°С. At a hysteresis set to 3°С, the HCW pump will stop, if water temperature at the CH boiler drops below 57°С. Once heated up to 60°С, the water heater will deactivate the HCW pump and will reactivate it when the water heater cools down to 57°С.

Fan speed

This function allows selection and setting of the fan operation speed. The speed is expressed in percentage.

Selection is made by use the PLUS and MINUS buttons.

This option can be used only, if the ZPID control is turned off. If the zPID function is active, the fan speed is adjusted automatically and cannot be controlled by the user.

Modes of operation

The user can select one of the four operation modes. The currently active operation mode is marked by a symbol in the lower right corner of the display.

– house heating; – parallel pumps;


– HCW priority; * – summer mode.

House heating priority

If you select this option, the central heating pump starts running in the manner described above for the CH pump.

42 ° 55 °С


House heating *

H.C.W. priority

H.C.W. priority

If you select this option, the hot consumption water pump will activate until the set HCW temperature is reached. Then the HWC pump switches off and the CH pump is activated. The CH pump will run until the circulating water temperature drops below the set value. The fan is operated as long as the temperature is below 62°C, to prevent the boiler from overheating. The H.C.W. priority mode gives priority to the hot consumption water heating over the house heating.


The boiler should have non-return valves mounted on the central heating pump circuit and the hot consumption water pump circuit to

Parallel pumps

prevent mixing of the water from both circuits.

When this mode is selected, the pumps start running in parallel whenever the set switch on temperature is reached. The user may set, at his discretion, different switch on temperatures for both circuits. This will cause pumps to switch on at different times, but at a certain moment they will run simultaneously. The central heating pump runs continuously, while the hot consumption water pump stops after the set point temperature is reached at the water heater. The operating principle has been described in details above.


In this mode, a non-return valve should be fitted to maintain different

Summer mode

temperatures for the hot consumption water heating and for the house heating.

When this function is enabled, only the hot consumption water pump is running in order to heat water in the water heater.

The pump is switched on above a predefined activation threshold (see the pump activation temperature function) and will run until the set temperature has been reached. The pump will start again when the temperature drops below the set hysteresis. While in the Summer Mode, the symbol, (*) is displayed in the bottom right corner of the main screen.

Language selection

This function allows user to change the language version.


Factory settings

Factory Settings

The device has predefined (default) settings, also called factory settings, which can be changed by the user.

There is a possibility to return to the factory settings at any time. By selecting the factory settings option, the user will lose all his personal settings, which will be replaced by the settings saved by the manufacturer. At this point the user may start re-setting his personal settings to the controller again.

Controller safeguards

In order to ensure a safe and faultless operation, the controller has been provided with numerous protections.

In the case of an alarm, an acoustic warning is sounded and the display shows a corresponding message. Press

MENU to restore the controller operation. In the case of the C.H. Temperature Too High alarm, wait until the temperature drops below the alarm value.

Thermal protection

The boiler is protected with an additional bimetal sensor (located at the boiler temperature probe) which disables the fan when temperature exceeds the critical value of 92°C. This is to prevent water from boiling in the system when the boiler is overheated or the controller is damaged. When the protective function is enabled and temperature drops to a safe value, the sensor has to be reset manually.

Automatic sensor check

In case the CH temperature sensor is damaged, an alarm is activated which additionally reports the fault on the display e.g.: “C.H. Sensor Damaged”. The fan stops running, while both CH and HCW pumps start operating simultaneously, each in accordance with its specific settings. In case of CH sensor damage, the alarm will remain active until the sensor is replaced. If the HCW sensor is damaged, the user should press MENU which will turn off the alarm and the controller will return to one pump operation (house heating) - the only safe operation in such situation. In order for the boiler to operate in all modes again, the damaged HCW sensor has to be replaced.

Temperature protection

After the temperature exceeds 85°C, the alarm is sounded with the display showing the following message:

ALARM Temperature too high. The current temperature is read from an electronic sensor and processed by the thermo controller. When the alarm temperature is exceeded, the fan is shut off and both pumps begin to run in order to distribute the hot consumption water throughout the system.


The controller is equipped with a tube fuse WT 3.15 A. Higher current values can damage the controller.

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