Astra G-50 User manual

HEATING BOILER
Astra G-50
ASTRA MACHINERY PLANT AB • ANNO 1929
CONTACT INFORMATION OFTHE FACTORY:
MACHINERY PLANT“ASTRA”AB
ULONŲ G. 33, LT62161 ALYTUS, LITHUANIA
TEL.: [phone]
FAX: [phone]
EMAIL: INFOASTRA.LT
WWW.ASTRAGAS.LT
INSTALLATION AND OPERATION MANUAL

TABLE OF CONTENTS
1. SAFETY REQUIREMENTS.................................................................................. 3
2. TECHNICAL DESCRIPTION................................................................................ 4
• General View of the Boiler................................................................................................................... 4
• Technical Data of the Boiler................................................................................................................. 5
• Ceramic Elements of the Boiler............................................................................................................6
• Turbulence Plates ................................................................................................................................ 6
3. INTENDED USE............................................................................................... 7
4. TRANSPORTATION, STORAGE, UNPACKING ........................................................ 7
5. INSTALLATION............................................................................................... 8
• Accumulation Tank..............................................................................................................................8
• Description of the Emergency Cooling System Diagram....................................................................... 8
• Description of the House Heating System Scheme............................................................................... 8
• Requirements for Connection of the Boiler to the Heating System .................................................... 10
• Circuit Diagram of the Boiler.............................................................................................................. 11
• Connection of the Circulation Pump .................................................................................................. 12
• Connection of the Ventilator.............................................................................................................. 12
• Mounting of the Draught Regulator .................................................................................................. 12
• Regulation of the Secondary Air Damper........................................................................................... 13
• Controlling the Temperature of Water Returning to the Boiler........................................................... 13
• Heating Output, Water Temperature and Water Flow Relationship.................................................... 13
• Installation of the Boiler Room.......................................................................................................... 14
• Requirements for the Chimney.......................................................................................................... 14
6. FUEL ...........................................................................................................15
7. OPERATION ..................................................................................................16
• Front Control Panel ........................................................................................................................... 16
• Rear Control Panel............................................................................................................................. 17
• Preparation for Firing........................................................................................................................ 17
• Kindling Procedure of the Boiler........................................................................................................ 17
• Fire Bed and Tips for Eective Boiler Stoking..................................................................................... 18
• Regulation of the Boiler Temperature................................................................................................ 19
• Addition of Fuel................................................................................................................................. 19
• Combustion Control .......................................................................................................................... 19
• Cleaning the Boiler............................................................................................................................ 19
• Emergency Shut Down of the Boiler .................................................................................................. 20
8. POSSIBLE FAULTS..........................................................................................20
9. WARRANTY AND ITS VALIDITY TERMS..............................................................21
10. ACCEPTANCE CERTIFICATE.............................................................................22
SELLING CARD .................................................................................................22
BOILER INSTALLATION PROTOCOL.......................................................................22
WARRANTY AND POST-WARRANTY REPAIR CARD..................................................23
DECLARATION OF CONFORMITY..........................................................................24

3
INSTALLATION AND OPERATION MANUAL
This user manual was compiled following the requirements of EN 12171 “Heating systems in buildings. Procedure for the
preparation of documents for operation, maintenance and use. Heating systems not requiring a trained operator”.
1. SAFETY REQUIREMENTS
1.1. The room where the boiler is to be installed should be ventilated.
1.2. Free inow of air into the room should be ensured.
1.3. The boiler ue connection with the chimney should be tight. Do not heat up the boiler with leaking ue connections!
1.4. The boiler should be installed in a closed heating system with a closed (membranous) expansion vessel, the volume of
which should be no less than 10% of the total volume of the heating system (including the boiler) (the volume of the
expansion vessel can be calculated according to the standard EN 12828 annex D).
1.5. A safety valve for no more than 3 bar response pressure should be tted onto the boiler in the heating system (please
see Chapter 5, “Requirements for connection of the boiler to the heating system”).
1.6. Remove the accumulated soot and resin from the boiler ues, as instructed in this manual.
1.7. The room where the boiler is installed should have re-extinguishing tools: re extinguishers, sand box, shovel and
other tools.
1.8. Do not place ammable materials on or near the boiler.
1.9. Connect the boiler to the electric system only via a three-pole plug plugged into an adequate three-pole socket with
earthing. Protect connection cable from damages.
1.10. Observe operation of temperature control devices and gauge readings when operating the boiler. In case of faulty
operation of the boiler, stop operation and remove the fault.
1.11. Kindle the boiler and put the rewood into the boiler only as indicated in Chapter 7 of this manual.
1.12. Keep children away from the boiler! The boiler can be serviced only by adults.
1.13. Before kindling the boiler, check if the heating system is lled with water and deaerated.
1.14. The operating pressure in the heating system should not exceed 3 bar.
1.15. The electrical connections are factory tested and the following parameters were conrmed:
• integrity of the protective circuit – electrical resistance of the protective circuit does not exceed 0.1;
• resistance of the electrical insulation – at least 1.0 M;
• resistance of electrical insulation was checked at 50 Hz, 1 000 V voltage.

4
HEATING BOILER: Astra G-50
2. TECHNICAL DESCRIPTION
• GENERAL VIEW OF THE BOILER
Fig. 1 General view of the boiler
A – front view; B – rear view; C – top view; D - section.
1. Front control panel; 2. Rooftop cover; 3. Handle of the upper ue damper; 4. Door of the fuel chamber; 5. Adjustable support legs; 6. Flow water pipe;
7. Rear control panel; 8. Sensor immersion pocket ½” of the safety temperature limiter 95°C valve; 9. Secondary air regulation damper; 10. Ventilator and
ventilator duct inspection aperture; 11. Return water pipe; 12. Water drain nipple; 13. Connections of the cooling serpentine; 14. Flue pipe; 15. Flue cleaning
cap; 17. Safety ventilator shutdown 95°C thermostat sensor; 18. Water temperature sensor; 19. Upper combustion chamber opening to the ue; 20.
Primary air inlet nozzle; 21. Secondary air inlet opening; 22. Ceramic burner; 23. Ceramic chopper; 24. Ceramic segment; 25. Opening to the ue.
Astra G boiler model B L H h k D d N S
Astra G-50 660 1230 1315 1075 150 152 G1 1/2“ 210 180
2
4
5
3
19
20
23
15
25
24
17
d
H
h
12
6
13
B
11
8
10
22
21
1
7
B
S
N
9
18
A
C D
d
k
D
L
14
10

5
INSTALLATION AND OPERATION MANUAL
• TECHNICAL DATA OF THE BOILER
Name of indicator Indicator value
Astra G-50
Nominal heat output, kW 50
Class of boiler according to EN 303-5 3
Class of protection against electric impact 1
Eciency rate,% 81-89
Power of emergency cooling system, kW 20
Water volume in the boiler, l 115
Setting range of the temperature regulator, °C 65-85
Recommended draught, Pa 25
Working pressure of water in the system, bar, max. 3,0
Testing pressure of the boiler, bar 4,5
Max. allowable water temperature in the boiler, °C 108
Max. allowable operating water temperature in the boiler, °C 95
Electric characteristics: voltage, V / frequency, Hz 220/50
average power used, W 50
Level of electric protection of the boiler IP30
Dimensions:
height, mm 1315
width, mm 660
depth, mm 1230
Weight of boiler, kg, 505
Threaded connection diameter 11/2"
Volume of fuel chamber, l 230
Dimensions of the loading aperture, mm 350x285
Flue gas duct diameter, mm 152
Length of wood pieces, mm 750
Average temperature of the ue gases at the nominal heat output, °C 205

6
HEATING BOILER: Astra G-50
• TURBULENCE PLATES
Turbulence plates – a technology invented and patented by “Astra”
engineers, used for capturing more heat from the hot exhaust smoke.
It forces the exhaust smoke to hold, become turbulent and thus transfer
more heat to the adjacent heat exchanger. The core of the device consists
of the turbulence plates, positioned at an angle in the rectangular-
shaped ue channel of the boiler. The inspection aperture 1 is installed
on the top part of the ue channel (Fig. 3), covered with a screw-on cover
with a gasket. This aperture is used for cleaning the ue channel and
placing/removing the turbulence plates. The turbulence plates 2, shown
in Fig. 3, maintain their position in the ue due to their force of gravity
alone. They are inserted into the ue channel or removed using a poker
3, which is provided with the boiler. Poker 3 (Fig. 3) is bent at an angle
of approximately 80° to the handle, so that the hooked plate does not
slide o. In order to be able to hook the turbulence plate 2 with a poker, a
hole has been made in its upper part for hooking with a poker. The plate
rests upon the heat exchanger 4 of the boiler ue on four supports: two
bottom and twoupper supports. When inserting the plate 2 witha poker
3 into the ue channel, rst the lower position is found, and after slightly
loosening the poker, yet without removing it from the hole, the plate is
allowed to descent onto the opposite side of the heat exchanger due to
the force of gravity until it touches the wall of the heat exchanger with
its upper supports. Then the tool can be removed and the next plate can
be installed in a similar way.
Turbulence plates decrease the temperature of the exhaust smoke.
The boiler can be operated without the plates, but then greater losses
of heat through the chimney will occur.
Fig. 3 Turbulence plate technology
1. Inspection aperture; 2. Turbulence plates; 3. Poker;
4. Heat exchanger of the boiler ue.
33
2
1
2
4
• CERAMIC ELEMENTS OF THE BOILER
The boiler has ceramic elements of three types: ceramic burner 1, ceramic chopper 2 and two ceramic segments 3 (Fig. 2). The
chopper 2 must be moved to the back wall of the boiler chamber during operation of the boiler, segments 3 – resting upon the
front edge of the chopper. If needed, the ceramic burner 1 can be removed. For this purpose, use a screwdriver to remove the
sealing rope from between the ceramic burner and the frame of the boiler, then this ceramic insert can be removed.
Fig.2 Ceramic inserts and their positions
1. Ceramic burner; 2. Ceramic chopper; 3. Ceramic segments.
Ceramic
element
Boiler type
G-50
1. Burner
1 a ŠK-50.00.008 1
1 b ŠK-50.07.001 1
2. Chopper
2 a G-32.01 2
2 b G-32.02 1
3. Segments
3G-18.00.004-01 2
2 b
2 a
3
1a
2 a
1b

7
INSTALLATION AND OPERATION MANUAL
3. INTENDED USE
The heating boiler is designed for the heating of residential and public buildings, manufacturing shops and other
buildings where a closed heating system has been installed. Control and regulation devices are installed in the boiler, which
automatically maintain the set water temperature, ensure economically ecient usage of the boiler and safe operation.
Boilers of this type are designed to burn wood, partially generating gases. Gas is extricated (generated) from the burning
rewood in the upper combustion chamber of the boiler and burned in the lower chamber. The intensity of gas generation
and combustion is regulated by the frequency and duration of air inow into the combustion chambers.
Advantages of the boiler are the following:
• gas generating combustion ensures eective burning of wood and a high eciency coecient since the burning process
takes place at a high temperature of 900°C;
• theheatoutputoftheboilercanberegulatedwithintherangeof40-100%.Theboilerisautomaticallycontrolledusinganelectronic
regulator, by switching the ventilator inowing into the combustion chambers o or on, or by regulating the speed of its rotation;
• the combustion period of one fuel load is long due to the large volume of the fuel chamber;
• complete fuel combustion ensures cost-ecient fuel usage;
• the turbulence plates installed in the ue of the boiler enhance heat exchange in the boiler and reduce the temperature
of the smoke in the chimney;
• it is sucient to remove the ashes 1-2 times per week.
4. TRANSPORTATION, STORAGE, UNPACKING
The heating boiler is to be transported and packaged in accordance with the documentation of the manufacturer, protected
from precipitation and dust. It can be transported only in vertical position, fastened to avoid sliding and falling. If the boiler
is transported in other than vertical position, decorative surfaces may be damaged, cladding battered, control and regulation
equipmentbroken,built-inceramicinsertsmayfalldownandsplinter.Theheatingboilershouldbecarefullyloaded,unloaded
and transported, without any signicant impact.
The boiler should also be stored in a vertical position. It is not allowed to put one boiler on top of another, as a packaging
frame is not designed for this purpose. The boiler should be stored in a closed room protected from precipitation. The air
humidity of the room should not exceed 80%, in order to avoid condensate forming on the surfaces of the boiler. Storage
temperature may vary from -40°C to +60°C.
Ifthe boilerwastransportedorstored in minustemperatures,thenbeforeit is kindled, it shouldbe kept in plustemperature
for no less than 2 hours.
After the heating boiler is delivered to the site, take o the packing frame and polyethylene lm, unscrew boiler bolts and,
fastening to the packaging base, remove the boiler from the packaging base.
Open the doors of the boiler and check if all elements listed in a delivery kit are included.
The delivery kit consists of the following: boiler - 1 pc.; poker - 1 pc.; scraper - 1 pc.; draught regulator - 1 pc.; tee - 1 pc.;
ventilator- 1 pc.; operation manual - 1 pc.; support legs - 4 pcs.
Check if painted surfaces have not been damaged during transportation, if the components are not bent and if control and
regulation equipment is intact. In case you notice any inadequacies, present your claims to the vendor company.

8
HEATING BOILER: Astra G-50
5. INSTALLATION
• ACCUMULATION TANK
These solid fuel boilers are intended to be fully loaded during the operation; the most ecient mode of their exploitation is at the
nominal or maximum heat output. It is advisable to install an accumulation tank of sucient size in their proximity, which could
accumulate the excessive heat. If the boiler is operated without the accumulation tank, its lifetime can be shortened because, in
such a case, a relatively low temperature of the outowing water is maintained in the boiler (65-70°C). Therefore, the temperature
of the water returning to the boiler from the heating system is as low as 55-60°C. More water vapour condenses in the boiler at such
operating temperatures, more tar accumulates on the internal walls of the boiler and metal corrosion intensies. When operating
the boiler with an accumulation tank, it is possible and advisable to maintain constantly maximum temperature of outowing and
returning water, respectively 85°C and 72°C, then condensation of water vapour and metal corrosion will be signicantly lower.
Recommended capacity of the accumulation tank is approximately 50 litres per 1 kW of nominal power of boiler:
Boiler model Astra G-50
Required volume of the accumulation tank, litres 2500
The boiler is to be operated only with an emergency cooling system installed!
• DESCRIPTION OF THE EMERGENCY COOLING SYSTEM DIAGRAM
A thermostatic safety temperature limiter 95°C valve (Fig. 4)
protects the boiler form the overheating. If the water temperature
in the boiler exceeds 95°C, the valve automatically opens the ow
of cold water from the public water supply network through the
cooling serpentine, where it absorbs the excessive heat energy and
owsoutintothesewage.Thesensorofthevalvewiththeexternal
thread ½” is screwed onto the socket on the rear wall of the boiler.
Technical data of the thermostatic safety valve are the
following: Opening temperature - 95°C; Maximum operating
temperature- 110°C; Operating pressure - 10 bar; Bulb of the
sensor - L=142 mm, external thread ½“.
The emergency cooling system protecting the
boiler from overheating cannot be used for heating
domestic water.
• DESCRIPTION OF THE HOUSE HEATING SYSTEM
SCHEME
The house heating system with an accumulation tank could be
divided functionally into two circles: heat production and heat
consumption. Both circles operate independently and interact in the accumulation tank. The heat production circle consists
of a boiler, Laddomat 21 thermostatic mixing unit with a circulation pump installed in it, expansion vessel, ttings and
accumulation tank. The intended use of this circle is to charge the accumulation tank only. To charge the tank, the boiler could
operate on its maximum heat output and outowing water temperature 85°C. That mode of boiler operation is optimal for
the boiler and combustion process itself.
1
2 3
5
4
4 pav. Avarinio aušinimo sistemos pajungimo schema
1. Į kanalizaciją;
2.Terminis apsauginis vožtuvas;
3. Filtras;
4.Vanduo iš vandentiekio.
Slėgis 2-6 bar.Temperatūra °C;
5.Terminio apsauginio vožtuvo sensorius.
Fig. 4 Connection diagram of the emergency cooling system
1. To sewage; 2. Thermostatic safety temperature limiter 95°C
valve; 3. Filter; 4. Water from public water supply, pressure 2-6 bar,
temperature 12°C; 5. Sensor of the thermostatic safety temperature
limiter 95°C valve.

9
INSTALLATION AND OPERATION MANUAL
Fig. 5 Principle scheme of the house heating system including heat accumulation
Laddomat 21 Thermostatic Mixing Valve
Pump Control Flow
Control Valve
Heating Boiler
Flow Control Valve
Air Outlet Water Heating
Domestic Water Recirculation
Pump Control Thermostatic Switch
Membrane Expansion Vessel
Thermostatic Mixing Valve
Domestic Water Preparation
From Water Supply Hot Water
Air Outlet
Other Notations:
Automatic Water Addition Valve
Accumulation Tank
Thermometer
3-Way Servo Drive Mixing Valve
Return Overow Valve
Filter
Heating System Supply
Heating System Return
Automatic Air Outlet
Return Valve
Valve
Pressure Relief Valve Pump
Thermometer - Manometer Manometer
With Valve
Water Supply
Programmable Heating System Processor
Min 65oC!
Heat production Heat consumption

10
HEATING BOILER: Astra G-50
Theheatconsumptioncircleusestheheataccumulatedinthetank.Thecircleconsistsofaroomthermostatoraprogrammed
control processor, room or/and outside temperature sensors, 3-way servo drive, mixing valve, underoor heating system,
radiators, piping, ttings. The programmed processor controls a 3-way mixing valve, which allows more or less heat (45-60°
C) into the radiators, according to demand. This way of heat consumption allows the heating of the house as long as the tank
stores heat independently from the boiler.
• REQUIREMENTS FOR CONNECTION OF THE BOILER TO THE HEATING SYSTEM
The following requirements should be fullled when installing the boiler:
•Theboilershould beinstalledin aclosedheatingsystemwith aclosed membranous expansion vessel,thevolume of which should
benolessthan10%ofthetotalvolumeofthesystem.Aclosedheatingsystemisakindofsystemwithnofreeaccesstoatmospheric
air, which actuates corrosion. Due to this, drainage of water from the system without an important reason is undesirable, e. g. in
summer. It is also necessary to ensure watertightness of the system in order to need fewer rells with fresh water containing free
oxygen. The quantity of the additional water let in should not exceed 5% of the system water volume per year;
• The boiler is connected to the heating system through connection pipes 6 – water supplied to the heating system and
11 – water returning from the heating system (Fig. 1);
• Internal threads G 1½” of pipes 6 and 11 ;
• There is a nipple 12 for water lling or draining from the boiler (Fig. 1);
• Internal thread G ½” of the nipple 12;
• A pressure relief valve conforming to norm EN1268-1 is to be installed in the heating system as close to the boiler as
possible at a location easy to reach by hand;
• pressure relief valves and control devices must conform to the following technical characteristics:
Instrument Technical characteristics Type of boiler
Pressure relief valve Connectiondiam. does not exceed¾”, set opening pressure3bar Astra G-50
Thermometer-manometer Range of temperature 0-120°C, pressure 0 – 4.0 bar All boilers
There must be no ball valves installed between the boiler and the pressure relief valve.
• Water from the pressure relief valve should be conducted via an otake pipe. It should be conducted in a way that will
allow the water passing through the pressure relief valve to ow safely, avoiding exposure of people and electrical parts of
the boiler. The diameter of the otake pipe should be no less than the diameter of the otake opening connection nipple of
the safety valve. The total length of the otake pipe should not exceed 2 m. No more than 2 elbow joints at angles of 90° are
to be used when installing this duct. No ball, mixing or other valves are to be installed in the water otake pipe. This otake
pipe is to be installed in a way that will make the ow of the passing water visible. If part of the pipe installed is hidden, e. g.,
in a sewerage pipe, then such a pipe should have a special funnel enabling visual observation of the otake ow of water.
Operation of the pressure relief valve is to be checked at least once a month. The valve is opened
for a short period of time, by turning its head, to reveal a small amount of the otake water. If this is not
done periodically, the parts of the valve can stick together due to high temperature and fail to open, when
required. In case the safety valve fails to open in an emergency situation, serious damage to the boiler and
the heating system can occur as well as hazard to the health and life of people.

11
INSTALLATION AND OPERATION MANUAL
• An electric installation with earthing, in accordance with the electric safety regulations in force, is to be installed when
connecting the electric part of the boiler.
Protect the isolation of the mains cable against damage.
Fig. 6 Circuit diagram of the boiler
S1 - power supply switch; S2 – ventilator switch; SK – emergency ventilator shutdown 95°C thermostat; SK2- circulation pump thermostat;
SK3- operation thermostat; F - fuse; M - ventilator; - circulation pump of the heating system; U - water temperature sensors.
In order to guarantee natural water circulation of water in the boiler, the pipework between the boiler
and the mixing valve in the line boiler–mixing valve–boiler is to be of the same diameter and correspond to
the diameter of the connection pipes of the boiler.
• CIRCUIT DIAGRAM OF THE BOILER
1 2 3 4 5 6 7 8 9 10 11 12
N L N1 L15 N1 L12
M
PNLPN
220V
PNL
L13
L14 S1
S2
SK
L
6 pav. Montažinė katilo elektros schema
S1 - įvadinis jungiklis
S2 - ventiliatoriaus
jungiklis
SK- avarinis termostatas
SK2- siurblio termostatas
SK3- darbinis ternostatas
F - saugiklis 2A
M - ventiliatorius
- šildymo sistemos
cirkuliacinis siurblys
U - temperatūriniai
jutikliai
F
L12
L11 L15
L14
NL
N1 L1
L12
L13
L11
U U U
L1
L11
SK2
SK3

12
HEATING BOILER: Astra G-50
• CONNECTION OF THE
CIRCULATION PUMP
In order to insure a continuous ow of
water,acirculationpumpistobeinstalled
in the system, on the return water pipe
behind the mixing valve. The electronic
controller of the boiler controls the
pump. Before connecting the circulation
pump, remove the rooftop cover of the
boiler (Fig. 7). The cover is removed in
the following sequence: 1) unscrew two
fastening bolts, 2) lift the backside part
of the cover, 3) push the cover forward
and then lift it up. Connect the wire of
the circulation pump to the 12-way
electric terminal connector, contacts No
11 and 12, marked with the sign (See
Fig. 6 “Circuit diagram of the boiler”). Connect the earthing wire of the pump to the contact No. 1 on the same connector.
• CONNECTION OF THE VENTILATOR
The boiler is transported with the ventilator removed and fastened using adhesive tape to the top of the packaging frame
of the boiler.
Unpack the ventilator, screw its case on at the ventilator installation bed 10 (Fig. 1) using the existing bolts and check the
stiness of the connection. The ventilator cable has already been connected during fabrication.
• MOUNTING OF THE DRAUGHT REGULATOR
At rst, mount the tee 1 (Fig. 8) present in the supply set, on the boiler
ow pipe 6 (Fig. 1). Then, install the draught regulator 2 (Fig. 8) into the
lateral pipe of the tee. Connect the lever of the draught regulator with the
ventilator lid. When the temperature of the water in the boiler rises, the
lever descends, and the main air supply damper 4 cloaks the opening of
the air duct, thus restricting the air supply to the combustion chambers.
Damper4(Fig.8)shouldnotcompletelyclosetheairsupply
opening in any mode of the boiler operation. It is recommended
to sustain at least a 9 mm gap to the opening in the lowest
position of the damper.
Thepositionofthedamper4issetbychangingthelengthoftheconnecting
chain of the draught regulator. First, decide at what temperature to keep the
ow water during the boiler’s use. 75° C or even higher is recommended. By
reaching this water temperature, the boiler should considerably lower the
air supply to the combustion chambers and the burning process must slow
down as a consequence. At this moment, the damper 4 must go down to its
lowest position. Fire up the boiler and observe the indications on the boiler
Fig. 7 Removing the rooftop cover of the boiler
1. Unscrew bolts; 2. Lift the backside of the cover; 3. Push the cover forward , then raise.
3
1
1
2
Fig. 8 Mounting of the draught regulator
1. Tee; 2. Draught regulator; 3. Ventilator; 4. Main
air supply damper; 5. Limiter 9 mm; 6. Secondary air
damper.
3
1
2
4
5
6

13
INSTALLATION AND OPERATION MANUAL
thermometer. When the targeted water temperature (75° C) is reached, x the damper 4 to the lowest position by fastening the
lever of the draught regulator and choosing the length of the connecting chain. Remember: a 9 mm gap should be left between
the damper and the air supply opening. The exact size of the gap depends upon the draught of your chimney. The worse the
draught, the greater the gap should be.
• REGULATION OF THE SECONDARY AIR DAMPER
The secondary air damper 6 (Fig. 8) is set up in the factory. To inspect the positioning of the damper: loosen the xing screw
and push the shaft of the damper forward until it gets stuck. Then pull the shaft 5 mm backwards and x it with the screw.
• CONTROLLING THE TEMPERATURE OF WATER RETURNING TO THE BOILER
It is absolutely necessary to maintain the
temperature of the water returning from the
heating system to the boiler at a constant
level, no less than 65°C, as this will prolong
the lifetime of the boiler and will make the
combustion process more eective. This is
because when a constant high temperature
of water returning to the boiler is maintained,
there arises signicantly less water vapour
condensation inside the boiler. The heavy water
condensation is harmful to the boiler, because
deposits of tar, pitch and soot accumulate on the walls of the heat exchanger, causing intense metal corrosion. Moreover, the
resulting layer of soot impedes eective heat transfer and the eciency of the boiler falls.
In order to maintain the temperature, we recommend installing the small circulation circle together with a Swedish-made
thermoregulation device, “Laddomat 21-100”. Makesurethatthe“Laddomat” is supplied with the 72°Cthermostatcartridge.
The mentioned temperature is the one at which the valve of the device opens completely. However, the actual temperature
of the water returning from the system and getting into the boiler after mixing, is 5-6°C lower. The higher the temperature
of the return water is, the better it is for the boiler. Thermoregulation devices of other manufacturers could be used for
maintaining the temperature of the returning water as well.
• HEATING OUTPUT, WATER TEMPERATURE AND WATER FLOW RELATIONSHIP
Theheatingoutputsuppliedtoaheatingsystemdependsdirectlyuponthedierenceofowandreturnwatertemperatures
tandtheintensityofthewater owcirculatingthroughthe boiler.Theboiler willfailtoreachthedesiredtemperatureof the
ow water if the returning water temperature is too cold or the circulation pump is too powerful. This will happen because
the boiler will be forced to produce a larger heating output than it has been designed for. The most eective boiler operation
occurs when the dierence between the ow and return water temperatures is 13-18°C. If the boiler is forced to operate
with a 20°C or even greater temperature dierence, it will work ineectively, consume too much of fuel, and the combustion
period of one fuel load will consequently shorten. If the previously mentioned dierence of temperatures is kept less than
10°C, the fuel in the boiler will again burn ineciently and fume because of a lack of air supply. If you know the water ow
intensity near your boiler, in the above presented table you can check, what the dierence of ow and return temperatures
your boiler is capable to maintain, when operating at the nominal heating output.
Do not forget to keep the returning water temperature as high as possible, at least 65°C or even higher!
It is necessary to assure that a thermometer is installed on the returning water pipe, in order to be able to
observe this temperature at any time!
Dierence of water temperatures
t, °C
Heating output, kW
50
Water ow, l/min
11 67
12 61
13 56
14 52
15 49
16 46
17 43
18 41

14
HEATING BOILER: Astra G-50
• INSTALLATION OF THE BOILER ROOM
The boiler room should be ventilated. The required air inow necessary for combustion should be also ensured. For this
purpose, boiler room doors should have ventilation grating or there should be a sucient gap between the doors and the
oor. If there is no possibility to supply air in from another rooms or the house is very tight, it will be necessary to install an
opening in the exterior wall. The cross-section area of the opening should be at least 0.001 m2/kW.
Place the boiler as close to the ue as possible on a hard concrete levelled basement. Leave at least 600 mm gap between the
backside casing of the boiler and the room wall for boiler servicing and cleaning. The smallest distance between a lateral casing
of the boiler and a building structure is 400 mm. If the building structure is made of ammable materials, this distance should be
doubled. A freely approachable space of at least 800 mm should be then left from the opposite side of the boiler to ensure access
tothe backsideof theboiler, forits servicing and cleaning. Theoor under the boiler, within the distance of 50 cm infrontof itand
within the distance of 30 cm around the boiler should be made of inammable materials. Screw supporting legs onto the base of
the boiler and level the boiler with screw nuts using a level; then connect the heating system circulation pump to the boiler.
The smoke exhaust pipe of the boiler should be connected to the chimney through a metal duct. The internal diameter of
the metal connecting duct should be at least the same as the external diameter of the smoke exhaust pipe of the boiler. To
improve the draught, the connecting duct between the boiler and the chimney should be installed at an inclination towards
the boiler. All junctions should be carefully tightened using a heat-resistant material and insulated using thermal insulation.
If an additional damper is installed between the boiler and the chimney for the draught control purpose,
the damper should not close more than 2/3 of the cross-section area of the opening in its fully closed position.
• REQUIREMENTS FOR THE CHIMNEY
It is recommended to insert acid-resistant stainless steel liner, if the chimney is made from masonry. It improves draught of
Fig. 9 Positioning of a chimney in respect to vicinity objects

15
INSTALLATION AND OPERATION MANUAL
the chimney and protects the masonry from destruction due to the impact of condensate. Internal diameter of the liner should
be no less than the external diameter of the smoke exhaust pipe of the boiler. The chimney liner can be round or oval. It is not
recommended to use rectangular-shaped liner as, due to the temperature uctuations, its walls deform, gaps appear at the
element junction points, through which the condensate falls on the walls of the bricks chimney. Additional air is sucked in, which
reduces draught of the chimney. Draught for each boiler model should correspond to the referred value of draught in the table
“Technical data”. The liner should be factory made. Minimum permissible height of the chimney should be at least 6m. The top
of the chimney should be above the ridge at least by 0.5m. If the chimney is further from the ridge than 1m, the angle horizon-
the ridge- the cap of the chimney should consist 10° or less degrees. Draught of the chimney can also be negatively aected by
various obstructions nearthe building: trees,hills, other buildings.Fig.9 presents the recommended minimalanglesbetween the
chimney, nearby objects and the horizon. Angles larger than those indicated will cause reduction of draught of the chimney.
The connection of other devices to the chimney to which the boiler is connected is prohibited.
The chimney should be cleaned at least once a year!
6. FUEL
Theboilerisredonlybywoodlogsandwoodbriquettes.Itispossible toreitwithfuelpeatbriquettes,howevertheoperation
of the boiler becomesless comfortable forthe user as itis necessary to removethe ashes of these highly ash-producing briquettes
after each loading. The ceramic elements of the lower chamber can be damaged if they are removed every day when cleaning,
thus their lifetime will be shorter. Therefore, we recommend usage of fuel peat briquettes only in rare, exceptional cases.
It is recommended to re dry rewood with a moisture content of 12-20 %. The drier the rewood, the larger its caloric capacity.
When the moisture content of the rewood is 20%, the heat potential of 1 kg is approximately 4 kWh; when the moisture
content is 50%, its heat potential is reduced by half.
The length of the rewood should be at least 5cm shorter than the length of the boiler combustion chamber.
Type of boiler Astra G-50
Length of rewood, mm 750
The recommended thickness of the wood logs is 100-150mm. Thicker pieces of rewood should be split at least once. Up to
15% of the fuel load can consist of ne wooden splinters and sawdust. However, they must be loaded in such a way so as not
to block the opening of the ceramic burner 22 (Fig. 1) connecting the upper and lower chambers of the boiler.
Do not re freshly prepared and excessively damp pieces of rewood. The operation of the boiler
becomes inecient, deposits of resin emerge on its inside walls as well as excessive condensate. Corrosion of
the boiler takes place several times faster when ring it with freshly prepared wood or wood that has been
dried outside for several months only!
Recommendations for rewood preparation:
• put split wood in a properly-ventilated place – if possible, in a sunlit place;
• rewood should be well sheltered from rain and snow;
• pieces of split wood should be stacked with sucient gaps between them so that the freely-circulating air can blow away
the moisture evaporated from the pieces of rewood;
• there should be sucient space above the heap of rewood below the roof and sucient ventilation to remove the moist air;
• it is not advisable to store freshly-cut rewood in a basement since the rewood needs sun and free air movement to dry.
Dry wood can be stored in the basement where sucient ventilation is guaranteed;

16
HEATING BOILER: Astra G-50
• itis recommendedto dry thesplitrewoodoutdoors under theabove-mentionedconditions. Dependingon thetype ofwood,
soft wood (alder, asp, r, poplar) must be dried for at least 8 months, and hard wood (oak, ash, birch) for at least 20 months.
Firing the boiler with coal, rubber or plastics is prohibited. However, loading wood briquettes into the
boiler together with their plastic packaging bags is allowed.
7. OPERATION
• FRONT CONTROL PANEL
The front control panel contains the operation thermostat 1 (Fig. 10), the thermometer 2, the green button 3 of the main
supply and the red button 4 for switching on the ventilator. The buttons light up in the ON position.
The function of the operation thermostat 1 is to switch o the boiler ventilator when the targeted water temperature
is reached. Then, the combustion in the boiler slows down and the water temperature in the boiler does not rise further.
The position of the operation thermostat 1 knob should be set so that its targeted temperature would be several degrees
less than targeted temperature of the draught regulator (see the chapter “Mounting of the draught regulator”). Then the
operation thermostat 1 will switch o the ventilator a little bit earlier than the draught regulator would descend the damper
4 (Fig. 8) into its lowest position. The appropriate position of the operation thermostat knob should be found and marked
with a pencil, or a scratch should be made on the case of the knob. This position should be dened in the next way: rst, turn
the thermostat knob to maximum. Then, set the draught regulator 2 (Fig. 8) to the targeted temperature, for example to 75°
C. Start the boiler and allow it to reach a 75° C temperature. Then, turn the thermostat knob in the direction of the lower
temperature until you hear a “click”sound. Turn the knob a little bit further and mark this position on the knob case with a
pencil. Now you have found the appropriate setting position of the operation thermostat 1 (Fig. 10).
The green ventilator button 4 (Fig. 10) has three positions. The position 0-60° C is used to turn on the ventilator during the
ignition of the boiler. At this state, the ventilator will be operating permanently. The central position , “OFF,“ is intended to
switch o the ventilator, the button lamp then does not light. After the initial phase of kindling the boiler, when the water
temperature in the boiler overlaps 60° C, the ventilator is usually turned to the position 60-90° C. This setting switches o the
ventilator automatically after the combustion in the boiler has ended and the water temperature has dropped below 60° C.
If you forget to switch the ventilator to the 60-90° C position, nothing serious will happen, just the ventilator will be rotating
permanently even after the combustion in the boiler will come to the end.
The ventilator will be switched o equally in both the 0-60° C and the 60-90° C positions when the safety
temperature limiter 95° C thermostat 2 (Fig. 11) trips, the operation thermostat 1 (Fig. 10) switches it o.
Fig. 10 Front control panel
1. Operation thermostat knob; 2. Thermometer; 3. Green button for switching the voltage of the boiler on and o; 4. Red button for switching on the ventilator.
21 3 4

17
INSTALLATION AND OPERATION MANUAL
The circulation pump control thermostat SK2 (Fig. 6) is also located inside the front control panel and is not observable
from the outside. It has two functions: 1. Turn on the circulation pump when the water temperature in the boiler reaches
60° C, 2. Turn on the ventilator if the button 4 (Fig. 10) is in the 60-90° C position and the water temperature in the boiler is
higher than 60° C. Consequently, this thermostat will switch o both the ventilator and the circulation pump, when the water
temperature in the boiler drops below 60° C. To learn more about the control devices of the front control panel, please, refer
to the chapter “Kindling procedure of the boiler”.
• REAR CONTROL PANEL
The following safety devices are installed in the rear control panel: thermal fuse 1 and electric fuse 2 (Fig. 10). The purpose of
the thermal fuse, otherwise called the maximum boiler temperature emergency thermostat, is to switch o the boiler ventilator if
water temperature in the boiler exceeds the maximum permissible 95°C due to unforeseen reasons. The temperature sensor of the
thermostat is installed in a dedicated sleeve 16 (Fig. 1). The burning intensity decreases when the ventilator is switched o and the
water temperature decreases. When the emergency thermostat trips, the lamp of the ventilator switch 3 on the front panel switches
o (Fig. 9) and the lighting indicator bulb 4 “Firing o” on the electronic regulator lights up (Fig. 11). In this case, it is necessary to nd
out the causes of tripping and to remove them. After the boiler cools down, the emergency thermostat can be returned to its normal
operating mode. For this purpose, unscrew its cover and depress the red button.
The cause of overheating of the boiler and tripping of the emergency thermostat must be found
and removed. If this is not done, the risk of serious damage to boiler
equipment as well as hazard to human health and life remains. If the
user cannot locate and remove the cause of tripping of the emergency
thermostat, a professional servicing company must be consulted!
The electric fuse is designated to protect the elements of the electric circuit in case
the current in the mains exceeds2 A. If the fuse is damaged, the boiler willnot switch
on and its indicator lamps will not light. In this case, remove and replace the fuse.
The rear control panel of the boiler is grounded.
• PREPARATION FOR FIRING
Before kindling the boiler, check the position of the ceramic chopper 2 in the lower combustion chamber: the edge of the
chopper must be in contact with the rear wall of the boiler (Fig. 2). Place two ceramic segments 3 (Fig. 2) on the chopper so
that they contact the walls of the boiler chamber.
Fill the heating system with water. The lling pressure should be 0.2 bar bigger than the hydrostatic pressure, yet it must
not exceed the operating pressure of the boiler. After lling the system with water, perform a visual check of the tightness of
the entire system. Perform it before kindling the boiler, then again after kindling and reaching the nominal operating mode.
Check if the heating system is properly deaerated.
• KINDLING PROCEDURE OF THE BOILER
Before kindling the boiler, check whether all requirements indicated in the section 1 are executed.
Open the damper of the upper ue 19 by pulling the handle 3 (Fig. 1) towards yourself. Open the door of the upper
combustion chamber, put dry smaller kindling wood pieces and paper on the ceramic bottom so that the paper protrudes into
the lower combustion chamber through the rectangular opening of the ceramic burner 1 (Fig. 2) – this way, it will be easy
to kindle the boiler through the lower combustion chamber. Put some of the easily ammable materials and larger pieces of
kindling wood and rewood atop. Load the wood without any large gaps at the top of combustion chamber. Bigger pieces of
1 2
Fig. 11 Rear control panel
1. Thermal fuse ; 2. Electric fuse.

18
HEATING BOILER: Astra G-50
rewood should be loaded in the middle and smaller prices at the sides, because the walls of the combustion chamber slow
down the combustion of the bigger pieces of wood, due to their lower temperature.
Donot cover theentire openingof the upperue 19 (Fig.1) with thewood,because itwill makekindling
more dicult.
The rst time, kindle the boiler using only paper and small pieces of wood in order to safely remove the
moisture remaining in the ceramic elements.
Switch on the voltage, using button 3 (Fig. 10) on the front control panel. Set the required outowing boiler water
temperature using the operation thermostat knob and draught regulator (see more in the chapter “Front control panel”); we
recommend a temperature of at least 75°C or – even better – a higher temperature. Close the door of the upper combustion
chamber, open the lower door and set the kindling material on re. Observe the rising water temperature in the thermometer
2 (Fig. 10) display. Keep the lower door open until the boiler water will heat up to 40°C. Then, close the lower door, close the
damper 19 of the upper ue by pushing its handle 3 (Fig. 1). Then, switch on the ventilator switch 4 on the control panel
(Fig. 10) into the position 0-60° C. The ventilator will start rotating and the water temperature will rise further. After the
temperature passes 60° C, turn the ventilator switch to the 60-90° C position. The boiler then will operate in automatic mode:
it will try to reach and maintain the setpoint temperature of the water outowing from the boiler.
When ring the boiler for the rst time, the condensation of the residual moisture and drainage of water in the lower
combustion chamber occurs. This is not a shortcoming. After kindling the boiler several times, this phenomenon disappears.
The doors of the boiler combustion chambers should be tightly closed, there should be no ue gases
seeping into the ambience through them. Door tightness is regulated by screwing or unscrewing the hinge
and lock screws of the door.
• FIRE BED AND TIPS FOR EFFECTIVE BOILER STOKING
The hot embers and charcoal in the boiler are called the re bed. Combustible gases emerge from there and are further
burned in the lower chamber of the boiler. The optimal re bed height during boiler operation is approximately 4-5 cm above
the bottom of the fuel chamber. The output of the boiler ventilator is deliberately chosen with the purpose of suciently
supplying the re bed with air. Then, the most eective combustion of wood gases takes place. Avoid a situation when the
volume of the re bed expands several times. This situation can occur if very dry and thinly cut wood gets loaded into the
fuel chamber. Consequently, the volume of the re bed increases rapidly during the burning process and soon a lack of air
occurs, allowing the combustible gases to escape unburned through the chimney into the atmosphere. An indicator of this
undesirable course is dense fumes emerging from the chimney.
The best way to stoke a boiler is the so-called two stages method. During the rst stage, the boiler is stoked with a small
amount of fuel. The aim of this phase is to warm up the boiler and form the optimal re bed. The second stage is intended for
full fuel loading and to perform the main combustion.
The rst stage: Prepare thin-cut wood and paper for an easy start. The volume of loaded fuel should be about 15-20 %
of the fuel chamber’s capacity. Open the upper ue damper 3 (Fig.1) and both boiler doors, put the wood and paper inside.
Kindle the paper, make sure that the ring starts and close the upper door. After the temperature of water in the boiler
reaches 45° C, close the damper and the lower door and turn on the ventilator. Let the boiler burn further for 30 minutes.
The second stage: Load the boiler fully. If wood briquettes are used for stoking, load approx. 70 % of the fuel chamber’s
capacity. Before opening the door, turn o the ventilator. Open the damper 3 (Fig. 1) by pulling the handle towards yourself,
and after some time, open the upper boiler door very slowly to avoid smoke escaping into the room. Load the fuel, close the

19
INSTALLATION AND OPERATION MANUAL
door and push the handle of the damper 3 (Fig. 1). Press the ventilator knob 4 (Fig. 10) on the front control panel into the
„60-95° C“ position. The ventilator will start and the boiler will continue its ring mode.
If you lack time to stoke the boiler inthe two stagesmode asdescribed above,then stoke it by onestage. Theboilerwill operate
as usual. But if there is the possibility to do so, use the two stages mode in order to achieve an even more eective combustion.
• REGULATION OF THE BOILER TEMPERATURE
See the chapters “Mounting of the draught regulator”and “Front control panel”.
• ADDITION OF FUEL
While adding rewood into the combustion chamber, during boiler operation or after a load has burned o, keep strictly
to the following procedure:
1. Open the damper of the upper ue 19 by pulling the handle 3 towards yourself (Fig. 1).
2. Switch o the ventilator switch 3 (Fig. 9).
3. Wait at least 20 seconds, allowing the smoke to be removed by draught; then slowly open the upper door.
4. Put the rewood in and close the door tightly.
5. Switch on the ventilator to the 0-60° C position, if the actual water temperature is lower than 60° C.
6. Close the damper of the upper ue 19 by pushing handle 3.
7. Switch the ventilator button to the 60-90° C position, after the actual water temperature has rised over 60° C.
If operated following this order, smoke and carbon monoxide will not enter the room. Water temperature and pressure in
the system are checked by readings of the thermometer-manometer, installed in the heating system.
• COMBUSTION CONTROL
The status of the boiler ring process can be seen from the indications of the thermometer 2 (Fig. 10). The ring is active if
the temperature of water in the boiler exceeds approximately 60° C. The ame in the boiler can be checked by opening the
door of the lower combustion chamber when the ventilator is on. The visible tongue of ame has to be yellow or yellow-red
and reach the ceramic element; this means the ring is proceeding in an optimal manner.
Donotkeepthelowerdooroftheboileropenforextendedperiodsoftimeduringring:thelowerchamber
contains gases which, when escaping into the boiler room in larger amounts, can impair human health.
• CLEANING THE BOILER
Ashes are removed from the boiler every 4-7 days. Open the door of the upper combustion chamber and shovel ashes down to the
lower chamber. Open the door of the lower chamber, take out only ceramic segments 3 (Fig. 2), pour ashes to a metal box. It is not
necessary to take out the triangle ceramic chopper 2 (Fig. 2) at the time of cleaning, ashes underneath it may be raked using scraper.
In any case, strictly follow the established procedure when opening the upper door: open the damper
of the upper ue, then after 20 seconds, open the boiler door.
Clean boiler chambers from tar, pitch and scurf once or twice a month. Clean the boiler when the fuel has been completely
burned and the boiler is cooled down to at least +40°C.
Open the upper cap 15 for cleaning the ue (Fig. 1). Remove the turbulence plates from the ue by hooking them and
pulling them out with the poker, then clean them using a scraper. Clean tar and scurf from combustion chambers and ue
walls using a scraper and metal hog. Clean with the doors of the combustion chambers open. The soot residues falling down
from the ue walls during the cleaning process are raked out of the boiler through the lower opening of the combustion
chamber 25 (Fig. 1), pulling them outwards. When nished, place the turbulence plates back and close the cleaning cap.

20
HEATING BOILER: Astra G-50
Control water pressure in the heating system at least once every two weeks. If the pressure drops,
raise it by lling up the system with more water. If the boiler is not being heated for a longer time, drain the
water out of the system when air temperature is below 0°C!
• EMERGENCY SHUT DOWN OF THE BOILER
If for some reason you must immediately shut down the operating boiler, by any means do not pour water on the kindling
wood! The boiler can burst!
It is very convenient to use dry sand for emergency extinction. There should be ~50kg of dry sand in the boiler room. Sand
not only isolates burning rewood well from the air oxygen but also cools down the burning zone. Then, when the boiler
cools down, sand can be easily cleaned and removed.
8. POSSIBLE FAULTS
Fault Cause Problem solution
1. The set
temperature
cannot be
reached
Not enough water in the heating system Fill up
Too low temperature of the return water Raise the return water temperature
Thermoregulator or ventilator is defective Repair or replace
Poor quality fuel: high moisture content,
too large pieces of rewood
Use dry fuel, split rewood
Heating surfaces of the boiler are very dirty Clean
No draught in the chimney due to accumulated
impurities
Clean
The ceramic burner is congested Clean
Ventilator damper is stuck Move or clean
2. Smoke escapes
through the
boiler door
The door-sealing rope is damaged Replace with a new one
Door is not tight along the entire perimeter Adjust hinge supports and door lock (regulated
screwing or unscrewing of door hinge or lock
screws) (see Fig. 13)
Fig. 13 Adjustment of the door and lock mechanism
No draught in the chimney due to accumulated
impurities
Clean
3. Ventilator is
not operating
Emergency thermostat has tripped, light of the
ventilator switch is o
Unsrew the thermostat 1 (Fig. 10) cover and
press the button under it. It is absolutely
required to dene and remove the causes of
tripping of this thermostat in order to avoid
hazards to property and human health!
Power supply failure Check electric fuses of the electric panel of the
building; call electrician