Riello TAU 55 UNIT Manual

INSTALLATION AND
MAINTENANCE MANUAL
CONDENSING
BOILERS
TAU 55 - 75 - 110
UNIT

GENERAL
2
TAU UNIT condensing boilers conform to the following directives:
•
Gas Appliances Directive 2009/142/EC (until 20 April 2018) and Regulation (EU) 2016/426 (from 21 April 2018)
• Directive 92/42/EEC on efficiency requirements and Annex E and Pres. Republic Decree n. 412, 26 August
1993
(✫✫✫✫)
• Electromagnetic Compatibility Directive 2014/30/UE
• Ecodesign Directive 2009/125/CE for energy-related products
• Energy Labelling Directive 2010/30/EU
• Low Voltage Directive 2014/35/UE
• EN 677 Standard: Gas-fired central heating boilers; specific requirements for condensing boilers with a
nominal heat input not exceeding 70 kW
• Delegated Regulation (EU) N. 811/2013
• Delegated Regulation (EU) N. 813/2013.
CONFORMITY
RANGE
MODEL FUEL CODE
TAU 55 UNIT Methane - LPG 20011771
TAU 75 UNIT Methane - LPG 20011772
TAU 110 UNIT Methane - LPG 20011773
ACCESSORIES
DESCRIPTION CODE
First mixed zone electrical kit 20011764
Second mixed zone electrical kit 20012161
Third mixed zone electrical kit 20011194
CLIMA TOP kit for TAU UNIT 55-210 boilers 20012160
CLIMA COMFORT kit for TAU UNIT boilers 20012157
Cascade cabling kit 20012102
Clip-in communication card 4031840
0/10 Volt clip-in card 4031846
Storage cylinder temperature sensor 4031847
Pipe thermostat, NTC (10k Ohm) 20008753
N2 condensate neutralisation kit 4031810
HN2 condensate neutralisation kit (with drain pump) 4031811
LPG converting kit- 110 models 20026803

GENERAL
3
Dear heating engineer,
Congratulations on having chosen a r boiler. You have selected a modern, quality product
that is designed to give dependable, efficient and safe service and to provide comfort in the home
for many years to come. This manual provides information that is essential to the installation of the
appliance. Used in conjunction with your own knowledge and expertise it will enable you to install
the appliance quickly, easily, and correctly.
Once again, please accept our thanks and our congratulations on your choice of product
Riello S.p.A.

4
This manual, Code 20015335 Rev. 19 (12/17) is made
up of 72 pages.
The following symbols are used in this manual:
b = Identifies actions that require caution and
adequate preparation
a = Identifies actions that you MUST NOT do
CONTENTS
GENERAL
General Safety Information 5
Precautions 5
Product description 6
Safety devices 6
Identification 6
Data plate 7
Layout 7
Technical specifications 8
Water circuit 9
Wiring diagram 10
Positioning the temperature sensors 12
Pumps 12
Control panel 13
Programming levels 16
Information levels 18
INSTALLER
Unpacking the product 21
Opening 21
Dimensions and weight 22
Handling 22
Place of installation 23
Installation in older systems and systems requiring
modernisation 23
Water in heating circuits 24
Water connections 27
Draining the condensate 30
Condensate neutralisation unit 31
Gas connection 33
CH frost protection 34
Flue gas vent and comburent air intake 34
Electrical connections 35
Sensor connections 36
Outdoor sensor connections 37
Filling and draining the system 38
Preparing for first start-up 38
TECHNICAL ASSISTANCE SERVICE
Initial start-up 39
Checks during and after initial start-up 41
Temporary shutdown 42
Preparing for extended periods of disuse 42
Calibrating combustion parameters 43
Setting functioning parameters 45
Error codes 48
Complete list of parameters 59
Conversion from one gas type to another 64
Maintenance 67
Removing the burner 67
Positioning the electrodes 68
Cleaning the condensate drain and siphon 68
Troubleshooting 69
CONTENTS

GENERAL
5
The operation of any appliance that uses fuel, electrical power and water demands that a number of fundamental safety
precautions be respected:
a Do not allow children or infirm persons to operate the
boiler unsupervised
.
a Do not operate any electrical devices or equipment,
including switches or domestic appliances, etc., if you
can smell fuel or fumes. If you detect any suspicious
smells:
- Ventilate the room by opening all doors and win-
dows;
- Close the fuel shut-off cock;
- Report the fault immediately to your local r
Technical Assistance Service or a professionally
qualified heating engineer.
a Do not touch the boiler when barefoot or wet .
a Never clean or service the boiler without first disconnect-
ing it from the mains electricity supply by turning the main
power switch and the control panel switch OFF.
a Do not tamper with or adjust the safety or control devices
without prior authorisation and instructions from the boil-
er’s manufacturer.
a Do not plug or block the condensate drain outlet .
a Never pull, disconnect, or twist the electrical cables com-
ing from the boiler even if it is disconnected from the
mains electricity supply.
a Do no obstruct or restrict the vents in the room where the
appliance is installed. Adequate ventilation is essential for
correct combustion.
a Do not expose the boiler to the elements. Do not install the
boiler outdoors. It is not designed to work outdoors and is
not fitted with the necessary automatic anti-frost systems
to do so.
a Do not store containers of flammable substances in the
room where the boiler is installed.
a Do not dispose of packaging material in the environ-
ment, or leave it within the reach of children, since it can
become a potential hazard. Dispose of packaging mate-
rial in compliance with applicable legislation.
PRECAUTIONS
GENERAL SAFETY INFORMATION
b As soon as you open the packaging, check imme-
diately that the contents are all present and undam-
aged. Contact the rreseller from whom you pur-
chased the product if you notice any problems.
b This TAU UNIT boiler must be installed by a legally
qualified heating engineer. On completion of the
installation, the installer must issue the owner with a
declaration of conformity confirming that the instal-
lation has been completed to the highest standards
in compliance with the instructions provided by
rin this instruction manual, and that it conforms
to all applicable laws and standards.
b This TAU UNIT boiler must only be used for the pur-
pose specified by rand for which it is designed.
The manufacturer declines all responsibility, con-
tractual or other, for damage to property or injury to
persons or animals caused by improper installation,
adjustment, maintenance or use.
b If you notice any water leaking from the boiler, dis-
connect it immediately from the mains electricity
supply, shut off the water supply, and notify your
local rTechnical Assistance Centre or a quali-
fied heating engineer immediately.
b Periodically check that operating pressure in the
central heating circuit is over 1 bar but below the
maximum limit specified for the boiler. If water pres-
sure is consistently low, contact r's Technical
Assistance Service or a professionally qualified
heating engineer.
b If the boiler is not going to be used for an extended
period of time, proceed as follows to prepare it for
shut-down:
- Switch the appliance OFF at the control panel
- Turn the main power switch OFF
- Close the boiler's fuel cock and heating circuit
water cock
- Drain the central heating circuit and domestic hot
water circuit if there is any risk of freezing.
b This boiler must be serviced at least once a year.
b This instruction manual is an integral part of the
boiler. It must be kept safe and must ALWAYS
accompany the boiler, even if it is sold to another
owner or transferred to another user or to another
installation. If you damage or lose this manual, order
a replacement immediately from your local r
Technical Assistance Centre.

GENERAL
6
This TAU UNIT condensing boiler is designed to pro-
duce hot water for central heating systems. If used in
conjunction with a remote storage cylinder, it can also
produce domestic hot water. The innovative boiler body
uses the condensation of steam from the combustion
gases to recover up to 15% extra energy, with obvious
benefits in terms of running costs. The boiler body is
made from highly corrosion resistant stainless steel to
guarantee an extended working life and excellent reli-
ability. The boiler body conforms to the strictest Italian
and European standards governing the migration of
heavy metals to condensate. A premixed micro-flame
burner guarantees extremely low emissions.
PRODUCT DESCRIPTION
IDENTIFICATION
The boiler is identified by the following plates and labels:
- Data label
This lists the boiler's technical
specifications and performance.
-Serial number plate
This specifies the
serial number,
model, and furnace
power.
Paese di destinazione:
Tipo di apparecchio
Caldaia categoria
:
:
B23P
II2H3P
Pressioni di alimentazione gas:
Regolazione effettuata dal costruttore:
G20 - 20 mbar
ATTENZIONE
Leggere attentamente il libretto istruzioni
prima di installare e mettere in servizio
l'apparecchio.
Questo apparecchio può essere installato e
funzionare solo in locali permanentemente
ventilati, in conformità alle normative vigenti.
(Laterale DX)
068786_1_E4
G20 20 mbar
G31 37 mbar
This TAU UNIT condensing boiler is equipped with the following safety devices:
An automatic safety thermostat that trips at 100° and
shuts down the burner.
An electronic safety system that monitors flow rate
through the central heating system using two sensors,
one on the flow pipe and the other on the return pipe.
This safety system forces the boiler to perform a safety
shutdown if flow rate is insufficient or not detected.
Flue gas safety thermostat.
A flue gas thermostat in the bottom of the heat exchanger
that triggers an error condition if flue gas temperature
exceeds 75°C. A flue gas temperature sensor in the
bottom of the heat exchanger that triggers a transient
(temporary) error if flue gas temperature exceeds 85°C
and a permanent error if it exceeds 90°C.
A fan safety system that uses a Hall effect speed sensor
to continuously monitor fan speed.
b The activation of a safety device indicates a poten-
tially dangerous malfunction in the modulation sys-
tem. Contact r's Technical Assistance Service
immediately.
You may attempt to restart the boiler after a short delay
(see “Preparing for initial start-up”).
aNever start the boiler up even for a short period if
the safety devices are not functioning correctly or
have been tampered with.
b Safety devices must only be replaced by r's
Technical Assistance Service using original spare
parts. Refer to the spare parts catalogue supplied
with the boiler.
Always check that the boiler is functioning correctly after
any repairs.
The control system applies compensated control logic to
maximise energy recovery in all seasons. The combus-
tion gases are cooled to a temperature near that of the
central heating return before they leave the boiler body.
This makes it possible to use plastic flue pipes instead of
metal ones, with significant savings in overall installation
costs. Special accessories are available to increase the
number of central heating circuits served, to cascade a
number of TAU UNIT boilers and to connect single or
double return lines to suit the needs of the installation,
improving heat stratification in the water inside the body
and optimising performance.
SAFETY DEVICES
Gas label
This is applied at the rear
of the boiler and specifies
the type of gas used by
the boiler, and the coun-
try in which the boiler is
destined for use.
- G20 label
Cod.N°
Qn(max)
Pms barkW
RIELLO S.p.A.
Via Ing.Pilade Riello 7
Mod.
37045 Legnago (VR) - ITALY
T067697I0
PAESE DI DESTINAZIONE: - PAYS DE DESTINATION:
LAND VON BESTEMMING: - BESTIMMUNGSLAND:
BESTEMMELSESLAND:
T067697GE
CALDAIA REGOLATA PER: - CHAUDIERE REGLEE POUR: VERWARMINGSKETEL INGESTELD OP:
KESSEL GEREGELT FÜR: - KJEL INNSTILT FOR:
European Directive
92/42/EEC:
η=
η=
η=
η=
N°
230 V ~ 50Hz W
Pms= bar T = °C
Qn(min) =
Pn(min) =
NOx:
IP P.min.G20= mbar
Qn(max =
Pn(max) =
Cod.
kW
kW
kW
kW
kW
kW
kW
kW
RIELLO S.p.A.
Via Ing.Pilade Riello
737045 Legnago (VR) - ITALY
Categoria:
Categorie:
Kategorie:
Kategori:
Combustibile: Combustible:
Brandstof: Brennstoff:
Drivstoff:
T067697GE
Caldaia a condensazione - Chaudière à condensation
Brennwertkessel - Condenserende verwarmingsketel - Kondenskjel
G25 BE
C63,C63x verboden in België - C63,C63x défendu en Belgique
>
-
Max. fluegas loss: 7 %
/

GENERAL
7
1
2
3
4
5
15
6
7
8
9
10
11
12
14 13
LAYOUT
TAU 55 - 75 - 110 UNIT
1 - Control panel
2 - Boiler body
3 - Condensate drain siphon
4 - Front panel
5 - Gas pressure switch
6 - Gas fitting
7 - Automatic vent valve
8 - Sensor sockets
9 - Central heating flow
10 - High temperature return
11 - Low temperature return
12 - Condensate drain
13 - Cover panel
14 - Flue gas exhaust fitting
15 - Pressure switch (for combustion chamber)
DATA PLATE
Central heating circuit characteristics
Qn Rated heat input
Pn Rated useful heat output
IP Index of protection
P.min Minimum pressure
Pms Maximum operating pressure,
CH system
TTemperature
ηEfficiency
NOxNOxclass
PAESE DI DESTINAZIONE: - PAYS DE DESTINATION:
LAND VON BESTEMMING: - BESTIMMUNGSLAND:
BESTEMMELSESLAND:
T067697GE
CALDAIA REGOLATA PER: - CHAUDIERE REGLEE POUR: VERWARMINGSKETEL INGESTELD OP:
KESSEL GEREGELT FÜR: - KJEL INNSTILT FOR:
European Directive
92/42/EEC:
η=
η=
η=
η=
N°
230 V ~ 50Hz W
Pms= bar T = °C
Qn(min) =
Pn(min) =
NOx:
IP P.min.G20= mbar
Qn(max =
Pn(max) =
Cod.
kW
kW
kW
kW
kW
kW
kW
kW
RIELLO S.p.A.
Via Ing.Pilade Riello
737045 Legnago (VR) - ITALY
Categoria:
Categorie:
Kategorie:
Kategori:
Combustibile: Combustible:
Brandstof: Brennstoff:
Drivstoff:
T067697GE
Caldaia a condensazione - Chaudière à condensation
Brennwertkessel - Condenserende verwarmingsketel - Kondenskjel
G25 BE
C63,C63x verboden in België - C63,C63x défendu en Belgique
>
-
Max. fluegas loss: 7 %
/

GENERAL
8
TECHNICAL SPECIFICATIONS
MODELS UM TAU 55 UNIT TAU 75 UNIT TAU 110 UNIT
Device type condensing boiler for central heating
B23
Fuel
IT-CH: G20=20mbar G31=37mbar
FR: G20/G25 - 20/25 mbar G31=37mbar
BE: G20/G25 - 20/25 mbar
NO: G20=20mbar
Device category
IT-CH: II2H3P
FR: II2Esi3P
BE: I2E(S)
NO: I2H
IT-CH: II2H3P
FR: II2Esi3P
BE: I2E(R)
NO: I2H
IT-CH: II2H3P
FR: II2Esi3P
BE: I2E(R)
NO: I2H
Combustion chamber vertical vertical vertical
Maximum rated heat input at furnace referred to HVC (LCV) kW 61,1 (55) 83,3 (75) 122,2 (110)
Minimum rated heat input at furnace referred to HVC (LCV) kW 12,2 (11) 16,7 (15) 24,4 (22)
Useful (rated) heat output kW 54 74 107
Maximum rated heat output (80-60°C) P4 G20 kW 53,6 74,1 107,3
Maximum rated heat output (50-30°C) G20 kW 59,5 81,5 116,5
Maximum rated heat output (40-30°C) G20 kW 60,0 82,0 117,9
30% heat output with return at 30°C (P1) G20 kW 18,1 24,7 35,9
Minimum rated heat output (80-60°C) G20 kW 10,9 14,8 21,4
Efficiency class in central heating mode A - -
Seasonal energy efficiency in central
heating mode hs 94 - -
Efficiency at rated heat input in high
temperature mode (HCV) h4Useful Pn (60-80°C) % 87,7 89,0 87,8
Efficiency at 30% rated heat input in low
temperature mode (HCV) h1Useful 30% of Pn % 98,9 99,0 98,0
Perdite al camino a bruciatore spento % 0,1 0,1 0,1
Losses from stack with burner on % 2,3 1,0 2,2
Heat loss in standby mode Pstby W 54 74 107
Annual energy consumption QHE 165 - -
Noise level (sound power) LWA at P max dB(A) 56 57 59
LWA at P min dB(A) 45 46 47
Emissions NOx (referred to
HCV) mg/kWh 48 35 44
Emissions at max./min. heat input, G20
CO2 % 9-8,5 8,9-8,9 9,1-9,1
CO ppm 4-5 7-7 4-0
Δt flue
gas °C 52-37 57-33 49-35
Maximum rated heat input (LCV) kW 45,2 59,4 89,2
Minimum rated heat input (LCV) kW 10,1 12 19,7
Emissions at max./min. heat input, G25
CO2 % 9,2-8,6 9,25-8,7 9,2-9,2
CO ppm 5-5 7-7 4-1
Δt flue
gas °C 52-38 33-33 50-40
Pressure in combustion chamber mbar 1,0 1,0 1,8
Flue gas mass flow rate (*) Kg/s 0,025 0,034 0,05
Water-side pressure drop (Δt 10°C) mbar 15 28 50
Maximum working pressure bar 5
Minimum supply pressure bar 1
Maximum permitted temperature °C 100
Maximum operating temperature °C 82
Boiler water capacity l 91 99 130
Volume of expansion vessel (CH) l - - -

GENERAL
9
WATER CIRCUIT
(*) Values referred to atmospheric pressure at sea level..
MI
G
RI1
RI2
Sc
MI - CH flow
RI1 - High temperature CH return
RI2 - Low temperature CH return
G - Gas supply
Sc - Condensate drain
MODELS UM TAU 55 UNIT TAU 75 UNIT TAU 110 UNIT
Maximum condensation at 100% rated heat output (40-30°C) l/h 8,3 12,0 14,4
Power supply V-Hz 230-50
Electric degree of protection IP X0D
Consumption at full load Elmax W 100 100 280
Consumption at part load Elmin W 30 30 84
Consumption in standby mode PSB P sb W 15 15 15

GENERAL
10
WIRING DIAGRAM
L power 230V
X1-01-1
N power 230V
X1-01-2
PE
X1-01-3
Control L
X1-02-1
Control N
X1-02-2
Fan power L
X2-01-1
Fan power N
X2-01-2
pi 1 L
X2-02-1
pi 1 N
X2-02-2
Lockout L
X2-03-1
N
X2-03-2
L-Vmix
X2-04-1
Common
X2-04-2
L-PB
X2-04-3
ER
X2-05-1
Sic
X3-01-1
Sic
X3-01-2
VG 230VRC
X3-02-1
VG 230VRC
X3-02-2
T-at N
X3-03-1
T-at L
X3-03-2
0 M
X3-04-1
GND Fan controlX14-1
+UB Fan controlX14-2
HALL Fan controlX14-3
PWM Fan controlX14-4
+ 26VX11-1
Sic1 X11-2 Sic2 X11-3
X11-4
X11-5
VDCX11-6
IN X11-7
AN4 Flue gas temp. sensor X11-8
AN3 BW1X11-9
AN2 SR X11-10
AN1 SM X11-11
+5VX11-12
AN5 +5V SE X10-06-2
AN5 -I-SEX10-06-1
AN3 +5V SB X10-05-2
AN3 I SB X10-05-1
Pa
X10-04-2
Pa
X10-04-1
Sic-
X10-03-2
Sic-
X10-03-1
TA1 X10-02-2 TA1 X10-02-1
TA2-S QAA73X10-01-2
TA2-GND QAA73X10-01-1
AGU2.5 X50-5
AGU2.3 X30-14
OCI420 X40-5
X30-1/14 T1
T2 T3
T4
T5
T6 T7 T8 T9 T10
L1
N
PE
1
2
AT
PE
Fan-PWM
L1
N
PE
RIV
L1 1
L
2
N1 3
N
4
PE
5
FILTRO
6.3A
C1-L3
C1-N
C1-PE
C1-L1
C1-L2
M9 M8 M7 M6 M5 M4
M2 0
M2 1
M1 0M1 1
M
+
1TAC 2PE 3
DCV
PVM
4- 5
L1 N PE
M1 M2 M3
FI
FU
Connections to be made
by the installer
IG
PBPI
Sb
TF Pboiler
Pgas
Sm
SE
SCH2
SCH1
(*)
VE1
H2
TS
Treg
A
B
C
D
E
F
G
TR1
ER
EA
Sr Sf
L1L2PENL3
L1L2PENL3
PENL3
TA
230 Vac
VG1
230V~50Hz
C
A
B
D
E
F
G
open
Y1
close
Y2
BSB-4pBSB
NA/0-10V H1
CH1pump
Q2
QX1
QX1
St.cyl.pump
Q3
1st stage
L1
PE
PE
T1
T1 N
N
T2
T2
X30-10pX30
L1
L1
S3
S3
N
N
CH1 snsr
BX1BX1
ground M
Boiler snsr B2
DHW 1 snsr
B3
Outdoor snsr
B9
ground
BX2BX2
LPB-4p LPB
ground M
X50-5p X50 X60-6p X60
LPBDB
ground MB
L
L
PE
PE
S3
S3
4
4
SK2
SK2SK1 SK1
N
N
N
N
N
N
N
N
PE
PE
PE
PE
PE
PE
PE
PE
MM MM MM MM
CL+CL+ CL+CL+
CL-CL- CL-CL-
G+ G+
SCH3
SCH4
DB-LPB
MB-LPB
LMU
CLIP-IN
communication card
L 230V N 230V L P1 N P1 C val C comun. A val
NTC/10K
NTC 10K
SCH5
PI1
VM1
SI1
B1 M
Fan-PWM
TA Room thermostat (low voltage, 24V)
FU Fuse 6.3 A-T
IG Main switch
FI Mains filter
Treg Connection for temperature controller (accessory)
TF Flue gas thermostat, 75°C (+0/-10)
Pboiler Pressure switch (combustion chamber)
Pgas Gas pressure switch
SCH1 Main board
SCH2 Display and control card
ER Flame detection electrode
EA Ignition electrode
TS Safety thermostat (100°C +0/-6)
TR1 Ignition transformer
VG1 Gas valve
H2 Burner lockout indicator
VE1 Variable speed fan
PI CH pump (accessory)
PB Storage cylinder pump (accessory)
SE Outdoor temperature sensor (supplied)
Sm CH flow temperature sensor
Sr CH return temperature sensor
Sb Storage cylinder temperature sensor (accessory)
Sf Flue gas temperature sensor
(*) 230Vac output for alarm connection
BOILER CONTROL PANEL

GENERAL
11
L power 230V
X1-01-1
N power 230V
X1-01-2
PE
X1-01-3
Control L
X1-02-1
Control N
X1-02-2
Fan power L
X2-01-1
Fan power N
X2-01-2
pi 1 L
X2-02-1
pi 1 N
X2-02-2
Lockout L
X2-03-1
N
X2-03-2
L-Vmix
X2-04-1
Common
X2-04-2
L-PB
X2-04-3
ER
X2-05-1
Sic
X3-01-1
Sic
X3-01-2
VG 230VRC
X3-02-1
VG 230VRC
X3-02-2
T-at N
X3-03-1
T-at L
X3-03-2
0 M
X3-04-1
GND Fan controlX14-1
+UB Fan controlX14-2
HALL Fan controlX14-3
PWM Fan controlX14-4
+ 26VX11-1
Sic1 X11-2 Sic2 X11-3
X11-4
X11-5
VDCX11-6
IN X11-7
AN4 Flue gas temp. sensor X11-8
AN3 BW1X11-9
AN2 SR X11-10
AN1 SM X11-11
+5VX11-12
AN5 +5V SE X10-06-2
AN5 -I-SEX10-06-1
AN3 +5V SB X10-05-2
AN3 I SB X10-05-1
Pa
X10-04-2
Pa
X10-04-1
Sic-
X10-03-2
Sic-
X10-03-1
TA1 X10-02-2 TA1 X10-02-1
TA2-S QAA73X10-01-2
TA2-GND QAA73X10-01-1
AGU2.5 X50-5
AGU2.3 X30-14
OCI420 X40-5
X30-1/14 T1
T2 T3
T4
T5
T6 T7 T8 T9 T10
L1
N
PE
1
2
AT
PE
Fan-PWM
L1
N
PE
RIV
L1 1
L
2
N1 3
N
4
PE
5
FILTRO
6.3A
C1-L3
C1-N
C1-PE
C1-L1
C1-L2
M9 M8 M7 M6 M5 M4
M2 0
M2 1
M1 0M1 1
M
+
1TAC 2PE 3
DCV
PVM
4- 5
L1 N PE
M1 M2 M3
FI
FU
Connections to be made
by the installer
IG
PBPI
Sb
TF Pboiler
Pgas
Sm
SE
SCH2
SCH1
(*)
VE1
H2
TS
Treg
A
B
C
D
E
F
G
TR1
ER
EA
Sr Sf
L1L2PENL3
L1L2PENL3
PENL3
TA
230 Vac
VG1
230V~50Hz
C
A
B
D
E
F
G
open
Y1
close
Y2
BSB-4pBSB
NA/0-10V H1
CH1pump
Q2
QX1
QX1
St.cyl.pump
Q3
1st stage
L1
PE
PE
T1
T1 N
N
T2
T2
X30-10pX30
L1
L1
S3
S3
N
N
CH1 snsr
BX1BX1
ground M
Boiler snsr B2
DHW 1 snsr
B3
Outdoor snsr
B9
ground
BX2BX2
LPB-4p LPB
ground M
X50-5p X50 X60-6p X60
LPBDB
ground MB
L
L
PE
PE
S3
S3
4
4
SK2
SK2SK1 SK1
N
N
N
N
N
N
N
N
PE
PE
PE
PE
PE
PE
PE
PE
MM MM MM MM
CL+CL+ CL+CL+
CL-CL- CL-CL-
G+ G+
SCH3
SCH4
DB-LPB
MB-LPB
LMU
CLIP-IN
communication card
L 230V N 230V L P1 N P1 C val C comun. A val
NTC/10K
NTC 10K
SCH5
PI1
VM1
SI1
B1 M
Fan-PWM
Connection schematic for added accessories
SCH3 RVS control card (**)
SCH4 Room unit control card
SCH5 Mixed zone interface card (clip-in)
Pl1 Additional mixed zone pump
VM1 Mixer valve for additional zone
SI1 CH flow temperature sensor for additional mixed zone
(**) Refer to the instructions provided with your card for details on how to connect it to the RVS unit.

GENERAL
12
Pressure drop (mbar)
0
5
10
15
20
25
30
35
40
TAU 55 UNIT
0 45
FLOW-RATE (m /h)
321 678
TAU 75 UNIT
TAU 110 UNIT
POSITIONING THE TEMPERATURE SENSORS
b IMPORTANT:
LEAVE THE SENSORS IN THEIR ORIGINAL POSITIONS EVEN IF THE BOILER IS CONFIGURED FOR USE
IN A CASCADED SYSTEM.
b On initial start-up and at least every year, check that
all the pumps in the system rotate freely. Sludge and
lime scale can build up and cause seizure, especially
after long periods of disuse.
b Protect all electrical devices under the pump before
you unscrew the inspection cap just in case water
comes out.
a Never run the pump dry .
Water-side pressure drop
This TAU UNIT boiler comes without a pump. A pump must therefore be provided as part of the installation.
In order to choose a pump of the right size, bear in mind the boiler’s water-side pressure drop, as shown in the figure below
PUMPS
4
5
SENSORS INSERTED IN THEIR
SOCKETS IN THE BOILER:
- Flue gas temperature sensor (1)
-
Safety thermostat temperature sensor (2)
- CH flow temperature sensor (3)
- CH return temperature sensor (4)
- Flue gas thermostat (5)
1
2
3
Front view Rear view

GENERAL
13
1 2 4 7 11 12 13 15143 5 8 9 106
1 -Burner lockout indicator
2 -DHW mode selector (for use with remote storage cylinder: accessory)
3 -Central heating or room temperature setting key
4 -DHW temperature setting key (for use with remote storage cylinder: accessory)
5 -Reset key.
Restores normal functioning after a safety shutdown.
6 -Chimney sweep mode selection.
Press and hold keys 3 and 4 (for between 3 and 6 seconds) to enter chimney
sweep mode.
7-8 -Parameter selection keys
9-10 -Value decrement/increment keys
11 -Info key
12 -Display
13 -Functioning mode selection button.
A line appears under the symbols:
sAutomatic: the boiler functions according to the set program
oDaytime: the boiler operates at daytime (comfort) setpoint
lNight-time: the boiler operates at night-time (reduced) setpoint
bStand-by
14 -Housing for controller (accessory)
15 -Main switch
CONTROL PANEL AND SYMBOLS
CONTROL PANEL

GENERAL
14
A B H
D
C
FG E
A -Water pressure reading (not used)
B -Large numeric display.
Displays current value
C -Chimney sweep or Service Required symbol
D -Display symbols:
vDHW temperature or DHW mode active
rCH or room temperature setpoint, or CH mode active
cOutdoor temperature
oDaytime CH mode
lNight-time CH mode
fFlame detected
nError
E -Small numeric display
Displays time, parameters and error codes
F -Central heating modes:
sAutomatic: the boiler functions according to the set program
oDaytime: the boiler operates at daytime (comfort) setpoint
lNight-time: the boiler operates at night-time (reduced) setpoint
bStand-by
G -DHW mode: ON or OFF
H -Current time display
DISPLAY

GENERAL
15
F1 E1 H1
A1 FC1 D1B1
G1 I1
L1
A1 -Functioning mode.
Press the mode key Mto activate the various modes, as shown by the line
under the corresponding symbol
B1 -DHW mode.
Press the Vkey to activate and deactivate DHW mode
C1 -Daytime CH mode
D1 -Time of day
E1 -Current boiler temperature
F1 -Water pressure (not used)
G1 -Flame detected
H1 -Current time bar
I1 -CH mode active
L1 -DHW mode active
MAIN SCREEN

GENERAL
16
- The DHW priority function. This ensures that the boiler
can still serve the central heating circuit even when
domestic hot water is drawn off.
- The frost protection function:
This stops water freezing inside the boiler. If boiler
temperature falls below 5°C, the burner ignites and
runs at full power until temperature reaches 10°C.
The frost protection function is only active if an outdoor
temperature sensor is connected. If outside tempera-
ture drops below -5°C the pumps are switched on.
If outside temperature is between -4° and 1.5°C, the
pumps are switched on for 10 minutes at intervals of
6 hours. If outside temperature is above 1.5°C the
pumps are switched off.
- Overtemperature dispersal function. If the temperature
threshold thermostat trips (86°C) the boiler shuts down
and accumulated heat is dispersed by switching on
the central heating pump. If boiler temperature rises to
89°C, the fan is switched on too.
- The cascade control function. The addition of a con-
troller (accessory) allows you to connect a number
of boilers in cascade, sharing heat output between a
number of burners and improving overall system effi-
ciency.
- Boiler switching differential. This establishes a mini-
mum off time for the burner, to stop it igniting and shut-
ting down repeatedly. The boiler will only start up again
if the difference between the setpoint and the actual
boiler temperature exceeds a predetermined value.
Notes on functioning
The control panel on the TAU UNIT boiler controls the following functions:
PROGRAMMING LEVELS
There are three programming levels:
- End user
- Installer
- Manufacturer
You must follow a precise set of instructions to access any of these levels. The relevant instructions, complete with a list
of the keys to press, are provided in the tables below.
END USER LEVEL
This level provides the parameters needed by the end user. For example, it contains parameters for setting CH and DHW
functioning times and Summer/Winter mode switching temperature.
See the “Complete list of parameters” section for further details.
Key Explanation
1 D
UPress one of these keys to access the END USER programming level.
2 D
U Press one of these keys until you reach the parameter you require: the example here shows the parameter Pxx .
3 +
-Press these keys to change the current value.
To memorise the new value, you need to move on to another parameter.
4 M
V Press one of these keys to exit the end user programming level. Any new settings are not stored in memory.
5 IPress this key to exit the end user programming level. Any new settings are stored in memory.
Note 1: If no key is pressed for about 8 minutes, the display automatically returns to the main screen. Any new
settings made will not be saved.
Note 2: Any changes are saved if you switch to another programming level.

GENERAL
17
INSTALLER LEVEL
Parameters in this level must only be changed by personnel from r's Technical Assistance Service.
This level contains, among others, parameters for selecting the slope of the central heating 1 curve and setting the DHW
reduced temperature setpoint (if an optional remote storage cylinder is connected).
See the “Complete list of parameters” section for further details.
Key Explanation
1 D
UPress one of these keys to access the END USER programming level.
2 D
UPress and hold both these keys for at least 3 seconds
3 D
UPress one of these keys until you reach the parameter you require.
The example here shows the parameter Hxxx..
4 -
+Press these keys to change the current value..
To memorise the new value, you need to move on to another parameter..
5 M
V Press one of these keys to exit the installer programming level. Any new settings are not stored in memory.
6 IPress this key to exit the installer programming level. Any new settings are stored in memory.
Note 1: If no key is pressed for about 8 minutes, the display automatically returns to the main screen. Any new
settings made will not be saved.
Note 2: Any changes are saved if you switch to another programming level.
MANUFACTURER LEVEL
Parameters in this level must only be changed by personnel from r's Technical Assistance Service.
This level is reserved for the boiler manufacturer.
Using these two keys to represent the numbers
D
U
and these two keys as numbers
-
+
enter the access code : “1 2 4 3 4”.
See the “Complete list of parameters” section for further details.
Key Explanation
1 D UPress one of these keys to access the END USER programming level
2 D
UPress and hold both these keys for at least 6 seconds
3 D
U - + Enter the access code. Provided you have entered the correct code, you enter the MANUFACTURER
programming level. If you enter the wrong code, you return to the INSTALLER level.
1 2
3 4

GENERAL
18
Key Explanation
4 D
UPress one of these keys until you reach the parameter you require. The example here shows the
parameter Oxxx.
5 -
+Press these keys to change the current value.
To memorise the new value, you need to move on to another parameter.
6 M
VPress one of these keys to exit the manufacturer programming level.
Any changes will either be stored in memory or ignored depending on how the control board
parameters are configured.
7 I
Press this key to exit the manufacturer programming level. Any new settings are stored in memory.
Note 1: If no key is pressed for about 8 minutes, the display automatically returns to the main screen. Any new
settings made will not be saved
BASIC INFORMATION LEVEL
Press the Ikey to enter the basic information level. Press the Ikey again to scroll through the values listed below
Key Explanation
1 vDHW temperature
2 tWater pressure (NOT USED)
t
t
t
3 X. Functioning phase (see table 1)
4 cOutdoor temperature
5 Ex (Accessory) controller error codes (see the “Error codes” section)
6 rBoiler temperature
7 M
VPress one of these keys to return to the main screen
INFORMATION LEVELS

GENERAL
19
Functioning phases (table 1)
Nr. displayed Characteristic
00 Standby
01 Ignition prevented
02 Fan start
03 Pre-ventilation
04 Wait time
05 Pre-ignition time
06 Safety time, constant
07 Safety time, variable
10 Central heating mode
11 Domestic hot water mode
12 Simultaneous CH and DHW mode
20 Post-ventilation with last control used
21 Post-ventilation at pre-ventilation level
22 Home run (*)
99 Burner lockout (error code displayed)
(*) Home run = Boiler status after reset.
EXTENDED INFORMATION LEVEL 1: temperatures
Press the Ikey.
Press and hold both D
Ukeys for at least 3 seconds.
Press one of the +
- keys until you reach the required parameter.
Temperature
Nr. Characteristic
b 0 Control board error code
b 1 Boiler return temperature
b 2 Not used
b 3 Flue gas temperature
b 4 Outdoor temperature
b 5 Compound outdoor temperature
b 6 Attenuated outdoor temperature
b 7 Not used
b 8 Reserved
b 9 Reserved

GENERAL
20
EXTENDED INFORMATION LEVEL 2: process values
Press the Ikey.
Press and hold both D
Ukeys for at least 3 seconds.
Press the Ukey.
Press one of the +
-keys until you reach the parameter you require.
Process values
Nr. Characteristic
C 0 Reserved
C1 Ionisation current
C 2 Fan speed
C 3 Fan control current (PWM)
C 4 Relative boiler heat output
C 5 Pump setpoint
C 6 Differential control
C 7 Reserved
C 8 Reserved
C 9 Reserved
EXTENDED INFORMATION LEVEL 3: assistance
Press the Ikey.
Press and hold both D
Ukeys for at least 3 seconds.
Press the Ukey twice.
Press one of the +
-keys until you reach the parameter you require.
Assistance
Nr. Characteristic
d 0 Reserved
d 1 Two stage or modulating control setpoint (PID)
d 2 Current boiler setpoint
d 3 Room temperature setpoint
d 4 DHW setpoint
d 5 Maximum modulation in central heating mode
d 6 Maximum speed at maximum heating power
d 7 Reserved
d 8 Reserved
d 9 Reserved