Combi System Package II with Celsius Combi 23-25 Boiler and Oxi ECO 20C Pellet Burner

Combi System Package II with Celsius Combi 23-25 Boiler and Oxi ECO 20C Pellet Burner
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Combi System Package II with Celsius Combi 23-25 Boiler and Oxi Eco 20C Pellet Burner

Package Contents:

  • Celsius Combi Wood/Pellet Boiler (25 kW)
  • Adapter Door (for Burner Attachment)
  • Oxi Eco 20C Pellet Burner (20 kW)
  • Celsius F Boiler Protection Package 65 kW (for Condensation Prevention)
  • Safety Package
  • 3-Way Motorized Switching Valve
  • Buffer Tank Controller (Euroster 813)
  • Buffer Tank (800l)
  • Pellet Tank (175 kg)




*(It need to check the boiler condition annually and every non eletric part annually.)


Detailed product description


Celsius Combi 23-25 kW solid fuel plate boiler

Recommended fuels:

  • Firewood, pellets, and other wood waste

Boiler accessories:

  • Boiler thermometer
  • Filling and draining tap
  • Fire grates (grates)

Additional accessories available for purchase:

The boilers are suitable for burning wood and pellets in automatic mode. Thanks to the special design, we can achieve outstanding efficiency with both fuels. The system can be assembled easily and quickly. When burning wood, you can take advantage of the large combustion door. Thanks to the wide cleaning door, cleaning the boiler has become more comfortable. The 5 cm thick insulation and the multi-layer steel door contribute to higher efficiency.







Height of boiler


Width of boiler


Depth of boiler


Boiler body


Exterior cover


Return water connection


Filling/draining tap connection


Upper door


Ash pan


Firing door (wood burning)


Pellet burner adapter door


Ash removal door (primary draught regulator)


Door opening handle




Heat exchangers


Grate (grill)


Safety valve or pressure guage


Uptake connection


Forward water connection


Thermometer connection


Automatic draugh regulator connection




Modul Combi 23 - 25
Firing door size (mm) 310*330
Maximum heat output (kW) wood/pellet 25/26
Heating-system dependant heatable air-space(m3) 250-450
Fuel-dependant efficiency (%) wood/pellet 83/91
Heating water connection (") 2
Uptake connection (mm) 132
Height (mm) 1140
Width (mm) 555
Depth (mm) 505
Weight (kg) 174
Water volume (l) 65
Max. operating pressure (bar) 2
Max. operating temperature (°C) 90
Test pressure (bar) 4
Draught demand (g/s) 28
Firebox size (mm) (height*width*depth) 520*330*340





Celsius safety heat exchanger



It protects the boiler and environment if the boiler is overloaded and the heating system can not heat distribute (There is not buffer tank and irregular usage).


Content of equipment:

  • Celsius safety heat exchanger
  • Vent valve
  • Thermostatic security valve (opening temperature 98°C)
  • Pressure security valve (2bar)


Applicable to the following boiler types:
Celsius classic, Celsius C and Celsius Combi boiler




F-Celsius anticondensing package to 65 kW


Kazánvédő csomag



Boiler protection unit to prevent condensation
Condensation is an often experienced phenomenon during the use of the solid fuel boilers which is always harmful, will cause lifespan shorthening, efficiency drop, and higher heating costs.


Content of equipment:

  • circulation pump (Grundfos UPM3 25-70 Hybrid)
  • pump hollander (ball tap) 1 piece
  • Celsius boiler protection valve
  • to 65kW KVS 7,2


Principle of operation:



1. Starting the system (heating the boiler)
After the launching of the boiler, the thermic valve is fully closed towards the user (gate A) and remains in this condition until the fluid is warmed up by the heating source, gets the opening temperature of the thermic valve (corresponding to the calibration value, f.i. 55°C). During this step the fluid sent by the boiler fully recycles through the by-pass (gate B) so the boiler temperature rises very quickly.



2. Loading the system (heating the tank)
Reaching the opening temperature (f.i. 55C), gate A proportionally starts to open while gate B proportionally starts to close. The boiler temperature slowly rises, giving energy to the end user, but the returning temperature will not decrease below the calibrated temperature (f.i. 55°C).



3. System operation
Starting from point 2, the flow temperature progressively increases to fully open gate valve A. This will correspondingly close gate valve B. This happens at approximately circa 10k higher than the calibration or opening temperature (therefore in this example at 65c). Now the installation is fully operational the supply fluid temperature can increase to set value.
For example, if the valve opening temperature is 55°C, then it is totally opened in the direction of A → AB in case of +10°C.







Celsius insulated buffer tank



Celsius buffer tanks:

To maximise the efficiency of a solid fuel heating system a buffer tank should be installed. When the boiler has produced energy to satisfy the heat demand, excess energy produced by fuel in the combustion chamber can be captured and stored in the buffer tank. The exception to this is when using wood pellets, where the pellet burner will automatically stop when the heat demand has been satisfied.
When the heating system have surplus heat ,the buffer tank stores it, therefore the wood boiler doesen't need an automatic draft regulator which ruins the burning efficiency.


Advantages of Celsius insulated buffer tank:

  • High quality insulation (C energy rating, EU complaint)
  • More economical burning
  • Lower pollutant emissions
  • Aesthetic design
  • Guaranteed continuous heating (for example: It can heat all night)
  • Hot domestic water modul can be connected











Motorized 3-way zone valve



Motorized 3-way zone valve with spring return for closed hydraulic systems.


Technical features:

  • Area of use: heating, conditionning and solar thermal (glycol max. 50%).
  • Power supply 230 VAC, 50Hz, absorbed power: 6W
  • Protection IP22
  • Nominal pressure PN10
  • Room temperature Max. 60°C
  • Fluid temperature: 5÷120°C; short time: 150°C;
  • Nominal opening time: 20 s. Springclosing: 6 s.
  • Kvs value 12,6
  • Without power AB->B
  • Weight 1,3 kg/piece







Euroster 813 controller



Operating principle:
The EUROSTER 813 control unit is a universal microprocessor controller with graphical display. The controller is responsible for the pump to operate on the basis of the difference between the set temperatures. It is possible to set up in the control an automatic disinfection function.


The control is responsible to turn on the pump on the basis of the difference between the set temperatures to ensure that the container is warmed by only the surplus heat, thus making energy savings.
The controller has a variety of automatic emergency circuit options.


You can set the emergency value of solar ebullience. There's an automatic vacation mode available, which takes care of cooling the storage to the set value, overheated by the solar system. This mode is important, if the storage is not used on a daily basis and ebullience of the solar panel will be induced. The keyboard of the control unit is lockable in the purpose of protection of your set parameters, which can cause an error.


The controller has a security sensor testing, if sensor sings, it will automatically trigger the pumps, preventing the ebullience. The controller has a sensor calibration mode, which allows you to avoid false temperature measurement by the long lines.


Treatment of controller
The graphics display of the EUROSTER 813 controller makes it easy to set up the controller. The options of setting the controller:
- Pressing the +/- buttons at the same time you can reach the menu.
- Pressing the -/ok buttons at the same time you can lock the keyboard.
- Pressing the +/ok buttons at the same time you can reach the manual mode, pressing the /+ button you can select the manually accessible devices.


After entering the menu you can set the following values:

  • time
  • disinfection (on/off)
  • modes
  • maximum emergency starting temperature of collector or boiler
  • minimal starting temperature of pump
  • maximum temperature of storage
  • starting and shutdown temperature of solar delta T
  • temperature of storage/hysteresis
  • calibration of solar sensor
  • calibration of storage sensor


Controller can be applied to:
In the case of Vacuum-tube control plane collector, mixed-fired boilers and buffers.
The pump must not be interrupted by other equipment!








Operating voltage

230V, 50Hz

Rated vattage


Output load of circuit pump


Emergency starting temp

60-190 C

Min. starting temperature of pump

15-40 C

Storage max. temperature

0-100 C

Delta T pump starting (on)

3-20 C

Delta T pump shutdown

1-18 C

Storage temperature

10-100 C

Storage hysteresis

2-20 C






Cables and sensors of E 813 controller:










Celsius pellet burning equipment


The high-quality OXI burner ensures optimal performance! Thanks to its WiFi-connected controller, it can be easily operated from a mobile application! The self-cleaning head does the dirty work, so it does not require constant attention (also environmentally friendly). Due to its user-friendly design, you can easily install and remove it from your boiler in seconds! It also works perfectly with lower quality pellets! Maximum safety and minimum maintenance! The OXI burners can also be purchased in a system package, so you can easily and conveniently ensure the warmth of your home! Our burners with different performance levels are compatible with our boilers! The weight of the product is 50 kg.

You can find out more about the Oxi ECO 20C pellet burner here.










Wood pellet tank


Celsius pellet tank



Celsius wood pellet tank with wheels and  cover. Easy to take out pellet.



  • Height: 1270 mm
  • Width: 820 mm
  • Depth: 820 mm
  • High width screw feeder: 1900 mm