Centrometal BioTec-C Series Owner's manual

TECHNICAL INSTRUCTIONS
for installation, use and maintenance
of hot water boiler
BioTec-C 25/31/35/45
HEATING TECHNIQUE
Centrometal d.o.o. - Glavna 12, 40306 Macinec, Croatia, tel: [phone], fax: [phone]
TUBT-C-01-2020-ENG
THE FIRST START-UP MUST BE DONE BY AUTHORIZED PERSON
OTHERWISE PRODUCT WARRANTY IS NOT VALID

Technical instructions BioTec-C
2
READ THESE INSTRUCTIONS CAREFULLY BEFORE
INSTALLING THE BOILER TO HEATING SYSTEM!
Boiler must not be used by children or disabled persons (either physically
or mentally), as well as by person without knowledge or experience,
unless they are under control or trained by s person responsible for
their safety. Children must be supervised in the vicinity of the product.
Boiler must not operate in flammable and explosive environment.
Before any work on the boiler it must be switched off and power
supply must be disconnected.
Important
These instructions are an integral part of this product. All rights reserved. Reproduction of content of this
document and transfer to third parties is not allowed without written approval from manufacturer.
Make sure the instructions are always with the device, even if its sale/transfer of another owner to the
user or staff authorized for maintenance or repairs to consult.

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3
Technical instructions BioTec-C
TECHNICAL DATA
Technical data
BioTec-C 35 45
TYPE
(kW)
(mbar)
(l)
(°C)
(kg/s)
(h)
(°C)
(°C/bar)
(°C)
(mbar)
(%)
(mm)
(l)
(mm)
(W)
(W)
(W)
(V~)
(Hz)
(kg)
(bar)
(bar)
(°C)
(mm)
(pcs)
(R)
(R)
(R)
(R)
25
25
115
0,019
3,5
9
90
135
110
517
150
8
5
0.08
1 00 -180
60
10-15°C / 2 bar
75-90
WOOD: A - according 303-5:2012;
B - according ISO 17225-5:2014-09
max 25 %
(450-550) x 70 x 50
underpressure
by EN 303:2012-point 4.4.6
5
230
50
~
2,5
5,5
90
6/4"
3/4"
3/8"
1/2"
with fan
under non-condensing conditions
45
150
0,027
4
14
176
135
122
675
180
10
600×250×600 600×400×600 600×400×735
Boiler
connections
Flow and return pipe (male thread)
Charge/discharge (female thread)
Heat exchanger connector (male thread)
Connector of exchanger sensor (female thread)
Nominal heat output
Boiler class
Required chimney underpressure
Water amount in boiler
Exhaust gas temp. at nominal heat output
Exhaust mass flow at nominal heat output
Min. operating time at rated power (nominal Q )
N
Min. inlet water temp. at the boiler supply water conn.
Cold water temp. and pressure for safety heat ex.
Setting range for temp. controller
Boiler resistance on water side at nominal output
Fuel moisture content
Fuel size
Fuel loading chamber capacity
Fuel loading chamber dimensions (D×W×H)
Combustion chamber type
Required min. accumulation volume(tank) next to boiler
Nominal electrical power input
Auxiliray power requirements at QN
Standby el. power
Supply voltage
Frequency
Current type
Total mass - (boiler with casing and accessories)
Max. operating overpressure
Test pressure
Max. operating temperature
Flue gas tube - external diameter
Number of turbulators
Heating appliance working
Heating appliance working
Fuel type
31
31
130
0,020
4
11
144
135
114
604
160
10
35
130
0,022
4
11
144
135
116
604
160
10
600×400×600

Dimensions, basic parts
BioTec-C 25 BioTec-C 45
BioTec-C 31
Boiler dimensions
BioTec-C 25
B
C2
C1
C
A
BioTec-C 31 / 35
B
C2
C1
C
A
BioTec-C 45
B
C2
C
A
OK
ESC
OK
ESC
OK
ESC
ZP KR
ST
PV DM
VD
VT
PR
PP
DO
DC
GO KA TO TVPL
ZP KR
ST
PV DM
VD
VT
PR
PP
DO
DC
GO KA TO TVPL
ZP
KR
ST
PV DM
VD
VT
PR
PP
DO
DC
GO KA TO TVPL
(A)
Depth
(B)
Width
(C)
Height
(C1)
Height
(C2)
Height
1400
585
1375
1040
785
1385
700
1615
1295
1290
1445
700
1420
1075
785
BioTec-C 35
1445
700
1420
1075
785
C1
Technical instructions BioTec-C
4

Basic parts
Lateral sides of bottom combustion chamber
Flue gas tubes cleaning brush
Flue gas chamber with tubes and turbulators
Flue gas tube connection
Cover of lower openings of the flue gas chamber
Lower refractory stone (2 parts)
Lower boiler door
Scraper for upper refractory stone and flue
gas channels cleaning
Upper opening for flue gas tube cleaning
Scraper for cleaning of the lower refractory stone
Upper boiler door
Heat exchanger connection
Digital boiler controller
Primary air intake
Primary air intake regulation
(only BioTec-C 25)
BL
CC
DC
DM
DO
DS
DV
GG
GO
GS
GV
KA
KR
MP
RP
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Secondary air intake
Main flow
Filling / draining
Return flow
Cover door
Main switch
Safety thermostat
Middle boiler door
Thermal safety valve sensor connection
Heat exchanger connection - thermal
safety valve connection point
Opening for cleaning the flue gas chamber
Fan
Sheet metal protecting covers
Holder for cleaning set
Flue gas tube cleaning lever (can be
installed on the left or right boiler side)
MS
PL
PP
PR
PV
SK
ST
SV
TO
TV
VD
VT
ZL
ZN
ZP
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
LEGEND:
GS CC
GG
Detail 1. - Flue gas tube
cleaning lever
Detail 2. - Lower opening lid for
flue gas chamber cleaning
PV
GV
SV
MP
MS
DS
BL
SK
ZL
ZN
DV
BioTec-C 31/35/45
GS CC
GG
Detail 1. - Flue gas tube
cleaning lever
Detail 2. - Lower opening lid for
flue gas chamber cleaning
PV
GV
SV
MP
MS
DS
BL
SK
ZL
ZN
DV
BioTec-C 25
RP
15
5
Technical instructions BioTec-C

Steel hot water boilers BioTec-C, nominal heat output 25 to 45 kW, are designed for wood log
firing, for heating of small and middle sized premises. The wood gasification principle enables a
complete fuel burning. Logs up to 550 mm long can be inserted into the large combustion
chamber. The burning period of a single fill of logs is up to 4 hours, depend about nominal heat
output. The boiler can keep the glow even 8 hours, which means that in this period it is not
necessary to fire up the boiler in order to keep the heating process. Boiler operation is controlled
with inbuilt boiler control unit using the flue gas sensor and modulating underpressure fan on flue
gases outlet from boiler. The boiler must be connected to the central heating system with an
appropriate volume of the CAS water accumulation tanks.
1.1. CHARACTERSTICS OF THE BioTec-C BOILER
General, Characteristics
1.0. GENERAL
The BioTec-C boiler is produced in compliance with the EN 303-5:2012 norm, which enables the
required level of functioning and minimal environmental pollution, through the firing with wood
logs. The boiler is aimed for firing with wood logs. The system of flue gases conduction and their
additional burning out, enables its high efficiency, which makes this product extremely
economical. Widely sized fuel loading door enables firing with large pieces of wood logs and very
simple and easy cleaning and maintenance. One filling of logs lasts up to 4 hours, depend about
nominal heat output. There is also a possibility of prolonging the firing process to the entire day, if
the heating requirement is decreased. The boiler can keep the glow up to 8 hours, during which
period it is not necessary to repeat the start firing process. The flue gas passages are good
optimized. The boiler must be connected to the central heating system with return flow protection
and with CAS water accumulation tanks. Boiler operation is managed with inbuilt boiler control
unit using flue gas sensor and modulating underpressure fan on flue gases outlet from boiler.
Boiler controll unit can run return flow protection pump and 3-way mixing valve with actuator and
retun flow temp. sensor (between boiler and buffer tank), buffer tank managment and DHW water
heater tank pump. With boiler BioTec-C it is easy to handle, integrated control unit assures reliable
and simple boiler operation. With installed accumulation (buffer) tank excess of produced heat is
accumulated into the tank and can be consumed when needed. Because of accumulation tank,
firing can be planned in a reasonable time, and in the case of mild outside temperature, space
heating and DHW heating without firing boiler is also possible for several days. The boiler is
delivered together with thermal insulation, covered by a metal casing and it is pre-wired.
Concerning the specific need of sanitary hot water, the BioTec-C boiler can be connected to one of
water heaters produced by our company. We suggest the combination with wall hanged SKB Digi
or LKB Digi water heaters, as well as with floor standing TB water heaters or STB solar water
heaters, if the future connection to the solar system has been planned and also CAS-B or CAS-
BS, combination of accumulation buffer tank and stainless steel DHW tank, and solar heat
exchanger. The boiler is tested and certified according to the European standard EN 303-5:2012
and meets Class 5. It is manufactured in compliance with ISO 9001/2015 and ISO 14001/2004
standards.
Technical instructions BioTec-C
6

25
31
35
45
5/4''
5/4''
5/4"
5/4''
Alpha1 32-40
Alpha1 32-60
Alpha1 32-60
Alpha1 32-80
6/4''
6/4''
6/4''
6/4"
Recommendations for the VTC valve, circulation pump and water accumulator CAS - according to the
boiler output:
Heat output
range
(kW)
Connection
VTC 512
(outer thread)
Connection
VTC 531
(internal thread)
Circulation pump type Volume of CAS accumulation
tank for BioTec-C
wood gasification boilers
Minimum 50 litres / kW of boiler
Recommendations for the LTC units and the water accumulators CAS - according to the boiler output:
Minimum 50 litres / kW of boiler
25, 31, 35
45
5/4''
--
--
6/4''
Heat output
range
(kW)
Connection
LTC 261
(internal thread)
Connection
LTC 271
(internal thread)
Volume of CAS accumulation
tank for BioTec-C
wood gasification boilers
Wood gasification, delivery package, additional equipment
1.2. WOOD GASIFICATION COMBUSTION PROCESS
1.3. DELIVERY PACKAGE
1.4. ADDITIONAL EQUIPMENT
Combustion process is carried out in double combustion chamber in several phases. After filling the upper
chamber with logs, glow dry the logs, and at temperature 100÷300°C logs are beeing gasified. The gases
created in such process are mixed with the oxygen from air and burn out completely with high temperature.
Fuel: wood logs with moisture content up to 20% (max. 25%), minimum size must be bigger than a nozzle
in refractory stone of the upper chamber. This demand for moisture content is fulfilled with wood dried on
air at least 12 months.
Delivery package include:
- Boiler BioTec-C (covered with casing with thermal insulation) on wood pallet
- With inbuilt and pre-wired:
- display control unit
- flue gas sensor
- boiler sensor
- flue gas rpm modulating fan
- STB safety thermostat
- Additional sensors in basic delivery:
- accumulation tank sensor (2x)
- DHW tank sensor
- return flow sensor
- cleaning brush, two scrapers and holder for cleaning set, legs with the plastic slipper (x4)
Additional equipment is not included in basic delivery. Obligatory additional equipment must be
purchased seperately. Other additional equipment can be purchased optionally.
OBLIGATORY ADDITIONAL EQUIPMENT:
- accumulation tank for heating system (CAS (min. volume 50 lit/kW or according to local regulation))
- return flow protection:
option A: 3-way mixing valve with actuator and retun flow sensor (60°C) - recommended
option B: 3-way thermostatic valve (60°C) (like ESBE VTC 512, VTC 531, LTC 261, LTC 271)
Grundfos Wilo
Yonos PICO 30/1-4
Yonos PICO 30/1-6
Yonos PICO 30/1-6
Yonos PICO 30/1-8
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7
Technical instructions BioTec-C

Figure 1. Minimum distance from the boiler room walls
*valid for closest tank to the wall
min.
1000 mm
min. 500 mm
*min.
1000 mm
min.
1500 mm
min.
700 mm
ACCUMULATION TANK
For closed heating systems:
- Thermal safety valve
- Safety-airvent group (2,5 bar)
- Expansion vessel for closed heating systems (size according the volume of heating installation,
including buffer tank volume)
For open heating systems:
- Open expansion vessel (size according the volume of heating installation, including buffer tank
volume)
NOTE: this equipment is not in standard boiler delivery
Additional equipment, additional equipment positioning and assembly
2.0. BOILER / ADDITIONAL EQUIPMENT POSITIONING AND ASSEMBLY
The positioning of the boiler has to be carried out the authorized person. We suggest the
positioning on the solid concrete basis, which height is between 50-100 mm. The boiler room has
to be absolutely protected from freezing and properly ventilated. The boiler has to be positioned in
order to enable its connecting to the chimney (see point 3.) and heating installation as well as its
service during the functioning process, cleaning and maintenance (Figure 1). The connection of
the boiler to the central heating system is obligatory with the one or more CAS water
accumulation buffer tanks, depending of the boiler's power. It is recommended to connect
minimum 50 liters water accumulation to each 1 kW boiler power (i.e. for the 45 kW boiler
minimal water accumulation should be 2250 liters). The boiler should not be used without being
connected to the water accumulation tank. It must be connected to the CAS water accumulator
obligatory with return flow protection through an 3-way mixing valve with actuator and return
flow sensor (60°C) or 3-way thermic valve (like ESBE VTC 531 (60°C), LTC141(60°C) or
Laddomat 21 (63°C).
WARNING!
Flammable items must not be placed on the boiler and within the minimum distances
shown in Figure 1.
Technical instructions BioTec-C
8

1. The boiler is supplied on a wooden stand (pedestal) protected by a wooden box and PVC foil. The wood
box and the PVC foil must be removed before/when placing the boiler to the position of installation.
2. After removing the wooden box and the PVC foil, leave the boiler on a wooden stand (pedestal) affixed with
metal plates and screws (the possibility of manipulating (moving) the boiler, position of the hand forklift: on
side or front side).
3. Place the hand forklift under the boiler mandatory from the front side (25 kW - 1 fork, 34/35/45 - 2 forks),
unscrew the screws that hold the wooden stand (pedestal), remove them to separate the boiler and the
wooden stand (pedestal). Slightly lift the boiler with a hand forklift so that it can be possible to remove the
wooden stand (pedestal) (mandatory, the boiler 25 kW has to be supported (take care of the boiler) by the
other person all the time from the start to the end of the lifting (including the manipulation and moving
wooden parts)) and remove the existing legs (screws) and put the legs with the plastic slipper that came
with the boiler in the plastic bag.
4. Place the boiler to the position of installation and slightly lower it to the floor. Remove the hand forklift.
5. Level the boiler using the 4x plastic slipper that you have fitted to the boiler stand.
6. igure 2.a). Install base protection under the boiler (see f
2.1. INSTALLATION OF DELIVERED PARTS
Installation of delivered parts
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Technical instructions BioTec-C
1.
4.
4x
2.
3.
FORBIDDEN! ALLOWED!

Position of cleaning set - on the boiler
Position of cleaning set - on the wall
BioTec-C is delivered on wooden pallet. After the boiler is removed from wooden pallet, should be
positioned in the boiler room (see point 2.0.). Install base protection with stone wool under the boiler
as shown in figure 2.a.
In upper chamber of the boiler are delivered (figure 2.b):
1. Holder for cleaning set, 2 cleaning scrapers and cleaning brush
2. Temperature sensors (2x accumulation tank, 1x DHW, 1x return flow)
3. Ashtray
4. Legs with the plastic slipper (x4)
Holder for cleaning set can be positioned on lateral side of the boiler (A) or to the wall (B), near the
boiler and easy accessible. On this holder should be placed cleaning set (2 scrapers and brush).
Sensors should be connected according heating installation and connecting scheme.
Installation of delivered parts
Figure 2.a Base protection with stone wool
Install base protection under the boiler
Figure 2.b Delivered parts
B
A
Cleaning set
Sensors set
Ashtray
Legs with the plastic slipper
Technical instructions BioTec-C
10

Connection to the chimney
H - Useful chimney height
3.0. CONNECTION TO THE CHIMNEY
Properly dimensioned and built chimney is the precondition for a safe and reliable operation of the
boiler and economic heating. The chimney has to be good insulated, gas-proof and smooth. On
the lower part of the chimney, a cleaning door has to be built in. Brick layed chimney has to have 3
layers with an stone wool thermal insulation in the middle. The thickness of the insulation should
be 30 mm, if the chimney is situated inside the building, i.e. 50 mm if the chimney is situated
outside the building. Inside chimney diameter dimensions depend on its height and on the
boiler thermal output (Figure 5.). The temperature of the flue gases on chimney exit point
should be minimum 30°C higher then the temperature of their condensating point. The choice and
the construction of the chimney should be performed by an authorized person. Minimal distance
between boiler and the chimney is 500 mm. The flue gas tube has to have an inclination of 30-45°
to the chimney (Figure 3.). In order to unable entering of the condensate from the chimney into the
boiler, 10 mm of the flue gas tube length has to be inserted deaper inside the chimney. It is
obligatory to insulate the chimney connection tube with a mineral stone wool of 30-50 mm
thickness. All installation works must be made in accordance with valid national and European
standards.
Figure 3. - Possible connecting of the BioTec-C boiler to the chimney
Possible way of connecting to the chimney of the
BioTec-C boiler (recommended)
Possible way of connecting
to the chimney of the BioTec-C boiler
(Only BioTec-C 45 because of position of the fan
and flue gas connection)
min. 500 mm
10 mm
H
Opening for the cleaning
Thermal insulation
H
Opening for the cleaning
Thermal insulation
15
11
Technical instructions BioTec-C

Connection to the chimney, calibrating of the chimney
An example of the chimney selection:
- boiler output: 25 kW
- Fuel: wood logs
- required useful chimney height: H=8 m
- required inner chimney diameter: 18 cm
- boiler output: 31/35 kW
- Fuel: wood logs
- required useful chimney height: H=8 m
- required inner chimney diameter: 20 cm
- boiler output: 45 kW
- Fuel: wood logs
- required useful chimney height: H=8 m
- required inner chimney diameter: 22 cm
Figure 4. Incorrect connecting the boiler to the chimney - not possible cleaning of the fan
Figure 5. - Dimensioning of the chimney for BioTec-C boilers
Nominal thermal output of the boiler (kW)
At connecting a boiler to the chimney, flue gas tubes and elbows must not pass behind the fan
since in that case the cleaning and maintenance will not be possible. An example of incorrect
position of flue gas tubes and elbows in relation to the fan is presented at the Figure 4.
10
15
20
25
30
35
40
45
50
60
70
5 10 15
18
20
22
25
30
6 7 8 9
Inner diameter of the chimney (cm)
wood firing
Useful chimney height - from flue gas tube connection
to the top of chimney
Inner chimney diameter - interior chimney diameter.
Useful height of the chimney (m)
BioTec-C 25
Fan
Flue gas
elbow
Flue gas
tube
BioTec-C 31/35
Fan
Flue gas
elbow
Flue gas
tube
BioTec-C 45
Fan
Flue gas
elbow
Flue gas
tube
Technical instructions BioTec-C
12

5.0. BOILER THERMAL PROTECTION
According to European EN standards, boiler thermal protection must be installed in closed
heating system. Boiler is factory prepared for installation of thermal protection. Heat exchanger is
factory built into boiler, and thermal safety valve 7 should be installed according to Scheme 1. In
case of any damage of boiler installed in the closed heating system due to its overheating, and
boiler or system are not equipped with any thermal protection at all, or do not have properly
installed thermal protection, warranty is not valid.
IMPORTANT:
Thermal protection must be connected to the water supply installation of the premises supplied
from the public water supply line and not from hydrophor. Namely, in case of failure of power
supply, boiler could be overheated, and then hydrophor is not able to ensure required water
supply.
THERMAL PROTECTION:
Thermal protection for boiler BioTec-C consists of a heat exchanger which is factory built in
boiler, and thermal safety valve 7 (such as CALEFFI 543 513) (see Scheme 1).
Part 7 is installed into prepared connector (male thread 3/4") in the upper part of left lateral side
of the boiler casing.
INSTALLATION (see Scheme 1.)
- screw the thermal safety valve sensor 6 (outer thread1/2") into the sleeve joint 2
(inner thread1/2").
- fix the connection 4 (inner thread 3/4") of the thermal safety valve to the sanitary
cold water inlet and the connection 5 (inner thread 3/4") to the connection point of the heat
exchanger 1 (outer thread1/2") - the arrow shows the direction.
- fix the tube connected to the sewage outlet at the connecting point 3 (outer thread1/2").
Boiler room must be equipped with an opening for supply of fresh air which is dimensioned in
accordance with boiler thermal output (minimum opening area according to below shown
equation). Such opening must be protected with a net or grate. All installation works have to be
performed in accordance with valid national and European standards. Boiler must not operate in
flammable and explosive environment.
4.0. FRESH AIR OPENING
Q - boiler output in kW
2
A - opening area in cm
A = 6,02 × Q
Fresh air opening, boiler thermal protection
15
13
Technical instructions BioTec-C

6
4
5
7
1 - Heat exchanger connection (to thermal safety valve)
2 - Connection for the thermal safety valve sensor
3 - Heat exchanger connection (to the sewerage)
4 - Thermal safety valve connection (cold water inlet HV)
5 - Thermal exchanger connection (to the boiler)
6 - Thermal safety valve-sensor
7 - Thermal safety valve
8 - Dirt filter (recommended)
9 - Thermal protection heat exchanger (build into boiler body)
Thermal safety valve
1
2
3
3
2
1
bar
Safety air
vent group
Return flow
Main flow
Sewage
outlet
78
NOTE: thermal protection heat excahnger is located inside boiler body
Scheme 1. - Thermal protection in an closed heating system
9
9
Technical instructions BioTec-C
14

Connection to the central heating system
6.0. CONNECTION TO THE CENTRAL HEATING SYSTEM
All installation works must be made in accordance with valid national and European standards.
Boiler BioTec-C can be built to closed and open central heating system. In both cases boiler must
be fired with wood logs. Installation has to be made in according to technical standards, by a
professional who will be responsible for proper boiler operation. The main flow tube from the
boiler to the central heating system must not pass above the top back casing cover (PD),
otherwise the removal of the turbulators and cleaning of flue gas tubes is impossible (see Figure
6). Before connecting boiler to central heating system, the system has to be flushed to remove
impurities remaining after system installation. It prevents boiler overheating, noise within the
system, disturbances at a pump and mixing valve. Boiler should always be connected to central
heating system by connectors, never by welding. Figure 1. shows minimum distances required for
boiler cleaning and maintenance.
PD - Top back casing cover
PL - Main flow
Figure 6. Examples of main flow contructions
PD
PL bar
PD
bar
PL
PD
PL
bar
>1000 mm
PD
PL
bar
<1000 mm
15
15
Technical instructions BioTec-C

M
Scheme 2a.
Basic scheme for boiler instalation on closed central heating system with return flow protection with
3-way mixing valve with actuator and return flow sensor (recommended) or 3-way thermic valve
(group) (electrical connections and sensor are not drawn, for details
see general schemes)
bar
Scheme 2b.
Basic scheme for boiler instalation on open central heating system with return flow protection with
3-way mixing valve and return flow sensor or 3-way thermic valve
(electrical connecetions and sensors are not drawn, for details see general schemes)
above the
highest heating
body
2
5
6
Connection to the central heating system
1 - Boiler BioTec-C
2 - Accumulation tank CAS
3 - Boiler pump
4 - 3-way mixing valve with actuator (60°C)
5 - return flow sensor
6 - 3-way thermic valve (60°C)
5 - Expansion vessel for closed heating systems
(min. 10% of the total volume of installation)
6 - Open expansion vessel for open heating systems (OPC)
(min. 7% of total volume of installation)
63
43
5
2
OR
M
63
43
5
OR
OK
ESC
1
OK
ESC
1
RECOMMENDED
RECOMMENDED
Technical instructions BioTec-C
16

Connection to the closed and open central heating system
6.2. CONNECTION TO THE OPEN CENTRAL HEATING SYSTEM
If the boiler is aimed to be integrated into an open central heating system, one of possible way how
to connect the boiler to the system is shown on Scheme 2b. In case of BioTec-C boilers, the boiler
pump obligatory has to be connected to the boiler control unit, in order to make turning on and off
of the pump depending on the temperature of the water in the boiler, to avoid boiler condensation.
The functioning of boiler control unit is shown in Technical manual ''Digital boiler control unit
BioTec-C''.
Connection to an open central heating system requires the implementation of an open expansion
vessel (OPC) above the level of the highest heating body (radiator). If the expansion vessel is
situated inside the non heated room, it has to be insulated. The volume of the open expansion
vessel is min. 7% of the volume of entire heating installation. The boiler has to be connected with
one or more CAS water accumulation tanks, depending on its nominal power. It is recommended
to connect minimum 50 liters water accumulation to each 1 kW boiler nominal power (i.e. for the
45 kW boiler minimal water accumulation should be 2250 liters) and always check the local
regulation about the needed minimum volume. The boiler should not be used without being
connected to the water accumulation tank with needed min. volume. It must be connected to the
CAS water accumulator obligatory through an 3-way mixing valve with actuator and return flow
sensor or 3-way thermic valve like Esbe VTC 512 (60°C), VTC 531 (60°C), load unit LTC 261/271
(60°C), load unit Laddomat 21 (63°C).
6.1. CONNECTION TO THE CLOSED CENTRAL HEATING SYSTEM
In closed heating system (as in example shown in Scheme 2a) it is obligatory to build in certified
safety valve with opening pressure of 2,5 bar, minimum seat diameter of 15 mm, minimum inlet
connection of 1/2", minimum exit connection of 3/4" and a membrane expansion vessel. Safety
valve and expansion vessel must be built in accordance with professional rules and any valve
must not be located between safety valve and expansion vessel and boiler. The closed heating
system must have the installed expansion vessel of larger volume (vessel volume must be min.
10% of the heating installation volume). In all boiler types the heating pump must be connected to
boiler control unit so that the heating pump switching on and off would depend on water
temperature in the boiler. The functioning of boiler regulation is shown in Technical manual
''Digital boiler regulation BioTec-C''.
The boiler has to be connected with one or more CAS water accumulation tanks, depending of its
power. It is recommended to connect 50 liters water accumulation to each 1 kW boiler power (i.e.
for the 45 kW boiler minimal water accumulation should be 2250 liters). The functioning of boiler
control unit is shown in Technical manual ''Digital boiler control unit BioTec-C''. The boiler should
not be used without being connected to the water accumulation tank. It must be connected to the
CAS water accumulator obligatory through an 3-way mixing valve with actuator and return flow
sensor or 3-way thermic valve like Esbe VTC 512 (60°C), VTC 531 (60°C), load unit LTC 261/271
(60°C) or load unit Laddomat 21 (63°C).
15
17
Technical instructions BioTec-C

Scheme 3. - General scheme of closed central heating system with 2 or more accumulation tanks
6.3. GENERAL CONNECTION SCHEMES
General connectiong scheme
All general schemes hereafter will be shown with one accumulation tank, but they can be
performed with two or more accumulation tanks (buffer tanks).
Pay attention to electrical and sensors connections on general schemes!
1 - Boiler BioTec-C
2 - CAS accumulation tank
3 - Return flow protection:
3-way mixing valve with actuator and return flow sensor or
3-way thermic valve (60°C), VTC 531, LTC 261/271,
Laddomat 21
4 - Safety airvent unit
5 - Expansion vessel for closed systems
(min. 10% of the total volume of installation)
6 - Thermal safety valve
7 - Pump P1 (boiler - accumulation tank)
8 - Return flow sensor
9 - Accumulation tank sensor - upper
10 - Accumulation tank sensor - lower
22
3
7
9
10
2
M
bar
1
5
4
6OK
ESC
8
1
Technical instructions BioTec-C
18

2
1
M
3
6
7
8
2
4
6
7
8
General connectiong scheme
Scheme 4.1. - General scheme of closed central heating system with 1 accumulation tank
1 - Boiler BioTec-C
2 - CAS accumulation tank
3 - Return flow protection 3-way mixing valve with actuator (60°C)
4 - Return flow protection 3-way thermic valve (60°C)
(VTC 531, LTC 261/271, Laddomat 21)
5 - Expansion vessel for closed systems
(min. 10% of the total volume of installation
above the
highest heating
body
above the
highest heating
body
6 - Safety airvent unit
7 - Thermal safety valve
8 - Pump P1 (boiler pump)
9 - Accumulation tank sensor (upper)
10 - Accumulation tank sensor (lower)
11 - Return flow sensor
2
bar
M
3
6
8
9
10
2
bar
4
6
8
9
10
1 - Boiler BioTec-C
2 - CAS accumulation tank
3 - Return flow protection 3-way mixing valve with actuator (60°C)
4 - Return flow protection 3-way thermic valve (60°C)
(VTC 531, LTC 261/271, Laddomat 21)
5 - Expansion vessel for open systems
(min. 7% of the total volume of installation
6 - Pump P1 (boiler pump)
7 - Accumulation tank sensor (upper)
8 - Accumulation tank sensor (lower)
9 - Return flow sensor
Scheme 4.2. - General scheme of open central heating system with 1 accumulation tank
5 5
5
7OK
ESC
1
11
5
7
1
OK
ESC
OK
ESC
9
1
OK
ESC
1
1
15
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Technical instructions BioTec-C

Scheme 4.3. - General scheme of closed central heating system with 1 accumulation tank and
DHW tank
1 - Boiler BioTec-C
2 - CAS accumulation tank
3 - DHW tank
4 - Return flow protection 3-way mixing valve with actuator (60°C)
5 - Return flow protection 3-way thermic valve (60°C)
(VTC 531, LTC 261/271, Laddomat 21)
6 - Expansion vessel for closed systems
(min. 10% of the total volume of installation
7 - Safety airvent unit
8 - Thermal safety valve
9 - Pump P1 (boiler pump)
10 - Pump P2 (DHW pump)
11 - Accumulation tank sensor (upper)
12 - Accumulation tank sensor (lower)
13 - Return flow sensor
14 - DHW tank sensor
General connectiong scheme
2
bar
1
M
4
6
7
8
9
11
12 3
14
10
2
bar
5
7
9
11
12 3
14
10
OK
ESC
13
1
1
6
8OK
ESC
1
Technical instructions BioTec-C
20