Cranborne THI 5-25c User guide

HAMWORTHY HEATING LTD CRANBORNE THI 5-25c 500001116/B
i
Cranborne THI 5-25c
Wall Hung Gas Fired Condensing Boiler
Room Sealed or Open Flue
INSTALLATION, COMMISSIONING AND SERVICING
INSTRUCTIONS
IMPORTANT NOTE: THESE INSTRUCTIONS MUST BE READ AND UNDERSTOOD
BEFORE INSTALLING, COMMISSIONING, OPERATING OR SERVICING THIS
APPLIANCE.
THE CRANBORNE THI 5-25c BOILER IS INTENDED FOR USE AS A DOMESTIC /
LIGHT COMMERCIAL APPLIANCE FOR HEATING AND DOMESTIC HOT WATER
INSTALLATIONS.
THIS BOILER IS FOR USE ON GROUP H NATURAL GAS (2ND FAMILY) I2H. PLEASE
ENSURE RELEVANT INFORMATION REQUIRED WITHIN DOCUMENT IS FOUND
RELATING TO SPECIFIC GAS TO BE FIRED BEFORE FIRING BOILER.
THIS BOILER COMPLIES WITH ALL RELEVANT EUROPEAN DIRECTIVES
EC IDENTIFICATION No. CE-0085AQ0543
PUBLICATION NO. 500001116
ISSUE 'B'
AUGUST 2003

- 2 -
CONTENTS
I-PRESENTATION ................................................................................................................................... 5
1-DESCRIPTION ...................................................................................................................................... 5
II - TECHNICAL SPECIFICATIONS ........................................................................................................... 6
1-CHARACTERISTICS............................................................................................................................. 6
2-PIPE CONNECTION DIAMETERS........................................................................................................ 7
3-DIMENSIONS ........................................................................................................................................ 8
3.1-THI 5-25 C .................................................................................................................................... 8
4-LIST OF COMPONENTS..................................................................................................................... 10
4.1-THI 5-25 C............................................................................................................................... 10
4.6 - Control panel ........................................................................................................................... 15
5-MODULATING PUMP CHARACTERISTICS....................................................................................... 16
6-PRESSURE DROP IN THE BOILER (HEATING CIRCUIT)................................................................ 17
7-EXPANSION VESSEL CHARACTERISTICS...................................................................................... 17
8-THERMAL EFFICIENCY ..................................................................................................................... 18
III - OPERATION ........................................................................................................................................ 19
1-GENERAL OPERATING PRINCIPLE.................................................................................................. 19
2-OPERATION OF THE LMU MANAGEMENT UNIT............................................................................. 20
2.1 - Normal operating conditions ....................................................................................................20
2.2 - Operating diagram ................................................................................................................... 20
2.3 - Principle of air/gas servo-control system ................................................................................. 22
2.4 - Air pressure variation procedure ............................................................................................. 22
2.5 - Emission of pollutants .............................................................................................................. 22
3-FUNCTIONS......................................................................... ............................................................... 23
3.1 - Anti-freeze function .................................................................................................................. 23
3.2 - Anti-legionnella function .......................................................................................................... 23
3.3 - Pump run-on after the end of heating ...................................................................................... 23
3.4 - Pump kick or selector valve kick .............................................................................................. 23
3.5 - Boiler overheat protection ........................................................................................................ 23
3.6 - Monitoring of flue gas temperature .......................................................................................... 24
3.7 - Boiler return temperature control ............................................................................................. 24
3.8 - Monitoring of hydraulic pressure ............................................................................................. 24
3.9 - Anti-short burner cycle protection function .............................................................................. 24
3.10 - Cleaning function ..................................................................................................................... 24
3.11 - Regulator shutdown function ................................................................................................... 24
3.12 - LMU programmable key .......................................................................................................... 25
3.13 - Automatic summer/winter switching (only activated with outside sensor) ............................... 25
4-DIFFERENT VERSIONS OF THE THI ................................................................................................ 26
4.1 - THI basic model (without outside sensor, without room sensor) ............................................. 26
4.2 - THI with outside sensor only ...................................................................................................26
4.3 - THI with outside and room sensors ......................................................................................... 29

- 3 -
CONTENT
IV - INSTALLATION ................................................................................................................................... 30
1-GENERAL............................................................................................................................................ 30
2-VENTILATION ..................................................................................................................................... 31
2.1 - THI models with conventional flue connection ........................................................................ 31
2.2 - THI models with balanced flue connection .............................................................................. 31
3-COMBUSTION PRODUCT FLUEING ................................................................................................. 32
3.1 - Conventional flue outlets (B23 model) ..................................................................................... 32
3.2 - Balanced flue outlet ................................................................................................................. 33
4-SUPPORT BRACKET.......................................................................................................................... 40
5-HYDRAULIC CONNECTION ............................................................................................................... 41
5.1-Recommendations................................................................................................................... 41
5.2 - Accessories to connect, install or adjust .................................................................................. 41
5.3 - Under-floor heating recommendations .................................................................................... 42
5.4 - Heat exchanger flow rate ......................................................................................................... 42
5.5-Hydraulic connectionformodel THI 5-25 C............................................................................. 43
5.6 - Hydraulic connection for models THI C+ DHW production system of type BS ........................ 43
6-GAS CONNECTION ............................................................................................................................ 46
7-ELECTRICAL CONNECTION.............................................................................................................. 46
7.1 - Mains connection ..................................................................................................................... 46
7.2 - Connection of the sensors to the LMU management unit ....................................................... 46
7.3 - Under-floor heating safety ....................................................................................................... 46
7.4 - Wiring diagram ........................................................................................................................ 47
V-SETTINGS OF THE INSTALLATION TYPES ..................................................................................... 48
1-SINGLE CIRCUIT ................................................................................................................................ 48
2-DOUBLE CIRCUIT............................................................................................................................... 49
2.1 - Without room sensor ............................................................................................................... 50
2.2 - With room sensor .................................................................................................................... 50
3-ACCESS THE SETTINGS VIA THE QAA 73 ROOM SENSOR ......................................................... 50
3.1 - Access the lines 51 to 98 ......................................................................................................... 50
3.2 - Access the lines 501 to 755 ..................................................................................................... 51
VI - COMMISSIONING ............................................................................................................................... 52
1-PROTECTION OF THE INSTALLATION............................................................................................. 52
1.1 - Bionibal .................................................................................................................................... 52
1.2 - Bionibagel ................................................................................................................................ 52
2-FILLING THE INSTALLATION WITH WATER .................................................................................... 53
3-PRESSURE SENSOR......................................................................................................................... 53
4-GAS SUPPLY ...................................................................................................................................... 53
6-SETTING THE MAXIMUM POWER IN HEATING MODE................................................................... 54
7-VERIFICATIONS PRIOR TO COMMISSIONING................................................................................ 54
8-USER INFORMATION......................................................................................................................... 54

- 4 -
CONTENT
9-COMMISSIONING............................................................................................................................... 55
10 - FLAME SETTING ................................................................................................................................ 56
11 - COMBUSTION PRODUCT CHECKING.............................................................................................. 56
VII - GAS CONVERSION ............................................................................................................................ 57
1-SERVICE PRESSURE CONTROL...................................................................................................... 57
3-GAS/CO2/CO/NOX FLOW CONTROL................................................................................................ 58
3.1 - Surveillance procedure ............................................................................................................ 58
3.2 - Setting table ............................................................................................................................. 59
VIII - MAINTENANCE .................................................................................................................................. 60
1-SERVICING THE FAN AND THE BURNER........................................................................................ 60
2-SERVICING THE HEAT EXCHANGER OF THE BOILER SHELL...................................................... 61
4-CHECKING ACCESSORIES............................................................................................................... 61
5-EXPANSION VESSEL PRE-INFLATION PRESSURE CHECK .......................................................... 61
6-COMBUSTION PRODUCT CONDUITS.............................................................................................. 62
7-DRAINING ........................................................................................................................................... 62
8-SENSOR RESISTANCES ................................................................................................................... 62
IX - OPERATING FAULTS ........................................................................................................................ 63
X-OPTIONS ............................................................................................................................................. 65
1-REAR WALL SPACER ........................................................................................................................ 65
3-SET-UP TAKING ROOM TEMPERATURE INTO ACCOUNT (REG 73) ............................................ 66
4-LPB COMMUNICATION CLIP-IN KIT (REG 130) ............................................................................... 66
5-2ND HEATING CIRCUIT CLIP-IN KIT................................................................................................. 66
6-DOUBLE CIRCUIT KIT (REG 125)...................................................................................................... 67
7-PROGRAMMABLE RELAY CLIP-IN KIT (REG 127)........................................................................... 67
8-ZHTI 46 CONTROL UNIT (REG 129).................................................................................................. 67
9-ZHTI 47 CONTROL UNIT (REG 128).................................................................................................. 68
11 - SELECTOR VALVE KIT FOR CONNECTING THI..C/BS ................................................................... 68
XII - NOMENCLATURE .............................................................................................................................. 71

- 5 -
I - PRESENTATION
1 - DESCRIPTION
Standard description: wall mounted condensation
boiler for hot water heating, sealed combustion cir-
cuit, pre-mixing burner with air-gas supply, and
linear power modulation connecting combustion
product types B23, C13, C33, following EN 483 (04/
00)
The THI boiler is pre-set in the factory for natural
gas H (G20).
This boiler comprises all the necessary accessories
for the correct working of a water based central hea-
ting circuit specifically:
- one boiler comprising:
• a high performance double walled condensa-
tion exchanger,
- a pre-mixing burner, with stainless steel refracto-
ry grate,
- a variable speed 230 Volt fan controlled by the re-
gulator,
- a 230 Volt two way gas valve controlled by the air
pressure,
- electronic regulation which ensures power modu-
lation depending on the demands for heating or
DHW (LMU control unit),
- an outside sensor,
- an expansion vessel,
- a modulating pump PWM signal,
- a 3 bar safety-valve,
- a rear wall spacer,
OPTIONAL:
- Horizontal flue kit (C13) allowing the boiler to be
connected to a straight horizontal flue.
- Accessories for horizontal connection of the boi-
ler (C13) - (extensions, elbows etc.).
- Flue adapter (C33) allowing the boiler to be con-
nected to a vertical flue.
- Accessories for vertical connection of the boiler
(C33) - (terminal, extensions, elbows etc.).
- Adjustment as a function of the room temperature
(REG 73).
- 2nd heating circuit kit allowing the connection of
a secondary heating circuit (REG 125).
- 2nd heating circuit clip-in allowing the connection
of a secondary heating circuit.
- Clip-in LPB communication kit used for cascade
or multi-circuit installations (REG 130).
- Clip-in programmable relay kit allowing a secon-
dary pump to work in parallel (REG 127).
- Control unit ZHTi 46 (REG 129) controlling an ad-
ditional heating circuit.
- Control unit ZHTi 47 (REG 128) allowing cascade
management for two boilers.
- Selector valve kit for connecting THI..C/BS.

- 6 -
II - TECHNICAL SPECIFICATIONS
1 - CHARACTERISTICS
Model
THI
5-25 C
Certification CE0085AQ0543
Category/Countryof destination: GB I2H
heat output 30/50 °C
60/80 °C kW kW 5.4/25.8 4.8/23.9
Heat input kW 5.0/24.5
Efficiency Nett 30/50 °C
60/80 °C % %108.0/105.3 97.5/96.0
Efficiency Gross 30/50 °C
60/80 °C % %97.2/94.5 87.8/86.5
Efficiency according to92/42 CEE directive (30%)load %108.5
Useable gases (NG:Natural gas)NG H
Combustion product temperature maxi °C 80
Over-heating safety of combustion products °C 85
Flow rate of combustion products mini/maxi kg/h 9.0/44.1
Permitted back pressure (C13)maxi Pa 100
Air flow required for combustion m3/h 30
NOx
mg/kWh
<60
CO
mg/kWh
<50
Heating service pressure mini/maxi bar 1/3
Heating circuit water temperature maxi °C 80
Water overheating safety thermostat °C 100
Boiler water capacitylitre 2.5
Primary water flow 60/80 °C m3/h 1.03
DP water (at nominal flow) mbar 130
Total capacity of expansion vessel litre 8
Useful capacity (with 5m static height)
litre 5
Thermal losses (DT30 K) W79
Acoustic output at minimum heat output 5,1 kW dBA 31,2

- 7 -
TECHNICAL SPECIFICATIONS
2 - PIPE CONNECTION DIAMETERS
Absorbed electrical power in heating mode :
Control alone Wmin. load: 23
max load: 37
Modulating pump mini W30
maxi W67
Stand By Position W9.2
Power supply/frequency 230 V (+ 10%. - 15%)/50 Hz
Protection factor
models B23
model C13/C33
IP 24
IP 44
Weight packaged kg 63
Models
THI
5-25 C
Models
THI
5-25 C
ÆCombustion products B23 mm 125
ÆCombustion products C13
C33
mm
mm 75/110 80/125
ÆGas inlet inch 1
ÆHeating flow/return inch 1
ÆCondensation outlet mm 25
ÆSafety valve outlet inch 3/4
ÆDHW production system connection (option § 11 -
page 68) (* 3/4 with coupling) inch 1*

- 8 -
TECHNICAL SPECIFICATIONS
3 - DIMENSIONS
3.1 - THI5-25 C
540
760
495
120 82,5
a
100
55,6 55,5
61,5 184,5 42
361
THI-04-0
102
20,6
b
cd f
e
hg
19
56
Fig. 1
Bottom view
Rear view
Legend:
a: Combustion products outlet
b: Gas inlet
c: Heating flow
d: Heating return
f:
Connection DHW production system (option)
(THI C)
g: Condensate drain
h: Safety valve drain

- 10 -
TECHNICAL SPECIFICATIONS
4 - LIST OF COMPONENTS
4.1 - THI 5-25 C
104
6
7
15
11
16
2
8
18
12
13
2022
1
3
9
17
19
21
24
25
THI-02-0
5
14
23
1) Gas inlet
2) Gas unit (solenoids and regulator) 230 V
3) Gas burner
4) Combustion products outlet
5) Flue gas sensor
6) Heating flow
7) Heating outlet and safety sensor
8) Heating return manifold
9) Boiler return sensor
10)Ignition transformer 230 V
11) Fan 230 V
12) Boiler shell
13) Sight-glass
14) Microprocessor control panel
15)3 speed pump 230 V
16) Air bleed
17) Pressure sensor
18) Filter and drain tap
19) Safety valve 3 bar
20) Safety valve outlet
21) Siphon trap
22) Condensate drain
23) Combustion check window
24) Connection for domestic hot water production sys-
tem (option)
25) Expansion vessel
Fig. 5

- 15 -
TECHNICAL SPECIFICATIONS
4.6 - Control panel
THI Without room sensor or outside sensor
The heating (2) and hot water (3) temperatures set-
ting are manually set on the boiler control panel.
- The FUNCTION key (1) gives access to 2 opera-
ting modes:
• Auto mode operation (4): no access
• Winter mode operation: LED (5) on
• Summer mode operation: LED (5) off
THI Without room sensor and with outside sensor
Possibility of correcting the heating temperature (2)
computed automatically using the outside tempera-
ture and manual setting of the hot water temperatu-
re (3) on the boiler control panel. (The room
temperature setting can be changed by + or - 3°C
maximum according to the setting).
- The FUNCTION key (1) gives access to 3 opera-
ting modes:
• Auto mode function:
auto winter = Leds (4) and (5) on
auto summer = Led (4) on + Led (5) off
• Winter mode operation: LED (5) on
• Summer mode operation: LEDs (4) and (5) off
THI With room sensor and outside sensor
Fitting the QAA73 room sensor cancels the func-
tions of the heating temperature setting (2) and hot
water setting (3) on the boiler control panel. All the
temperatures required, together with the heating
programmes, are set on the QAA 73 (refer to the
sensor instructions).
j
bar
auto
Function
Info
O
I
°C
Reset
THI-01-0
2
3
4
1
6
8
7
10
9
1112
13
14
5
Fig. 10
1) The "Function" key gives access to 3 operating
modes by simply pressing the key:
auto mode: LED (4) on
winter mode: LED (5) on
summer mode: LED (4) and (5) off
2) Regulation of the heating temperature (setting
read on the display (13)) *
3) Regulation of the DHW temperature (setting
read on the display (13)) *
6) Maintenance key: reserved for servicemen or
maitenance (see overleaf)
7) "Info" key gives access to 5 types of information
on the display (13) by simply pressing the key:
Boiler outlet temperature: LED (9) on
Sensor temperature: LED (9) flashing
Boiler water pressure: LED (8) on
Operating phase: LEDs (8/9) off
Diagnostics: LEDs (8/9) off/
Display (13) flashing
10) Boiler reset button (After each reset, wait for
about 30 seconds before the restart = reset)
11) Alarm: Red LED on
12) Flame indicator: Green LED on
13) Digital display: Alternatively displays the setting
selected by the "Info" key and the current default
code
14) ON/OFF switch (depending on the models) **
*The function of the heating temperature (2) and DHW temperature (3)
potentiometers differs according the 3 examples below.
**The On/Off switch (after initial lighting) should be maintained in the "ON"
position in order to preserve all the automatic functions of the boiler (an-
ti-freeze, anti-legionella functions, etc).

- 16 -
TECHNICAL SPECIFICATIONS
5 - MODULATING PUMP CHARACTERISTICS
Advantages :
- Modulation allows a reduction in the electrical
consumption of the pump by adapting its flow to
the needs of the installation.
- Varying the flow and controlling the return tempe-
rature enables the boiler efficiency to be optimi-
zed.
- This modulating pump also reduces the noise
created by the installation (circulation noise).
The modulating pump option is only
possible with a single heating circuit.
The modulation function can be deac-
tivated via the KonfigRg7 parameter.
It is possible to limit the modulation range via the pa-
rameters “NqmodNenn” (Max range) and
“NqmodMin” (min. range) (fig. 12).
Action on the “min” allows the equilibrium of the ins-
tallation to be adapted.
Note:
- A perfectly balanced installation makes for better
use of the pump capacities.
!
Fig. 11
Pump modulating
Head (m)
P1 (W)
Q (m3/h)
Q (m3/h)
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
0
0 10203040 5060708090
NqmodNenn
(= 18)
Allure calculée
pour NqmodMin
(= 6)
QmodDrehzStufen
(= 30 )
QmodMin
(= 3 %)
NqmodMin (= 40)
QmodMax
(= 82 %)
100 %
Plage de modulation
de la pompe
7494d38/0102
Allure [-]
Degré de modulation (PWM) [%]
Fig. 12
QmodMin
(=2%) QmodMax
(=84%)
Modulation degree (PWM) [%]
Rate [-]
Rate calculated
for NqmodMin
(=6)
Pump modulation
range

- 17 -
TECHNICAL SPECIFICATIONS
6 - PRESSURE DROP IN THE BOILER (HEATING CIRCUIT)
7 - EXPANSION VESSEL CHARACTERISTICS
THI boilers are pre-equipped with an expansion ves-
sel for an installation water capacity of approxima-
tely 100 liters.
The expansion vessel absorbs the increase in the
water volume in the installation produced by the in-
crease in temperature. The pre-inflation of the ves-
sel sends the internal membrane to the side of the
connection and the water dilation pushes on this
membrane. Optimum efficiency is obtained when
the inflation pressure is equal to the water pressure.
Note:
- The minimum water pressure necessary for the
correct working of the installation is defined by
the difference in levels between the boiler and the
highest point in the installation (e.g. 8 m = 0.8
bar).
Fig. 13
0
0,5
1
1,5
2
2,5
0 500 1000 1500 2000
Flow (dm 3/h)
Pressuredrop (mWG)
H
Water inlet Dilated water
volume
Inflating
valve
Pressure rises
as the air is
compressed
Max vessel
volume
Membrane
AM4-06-3
Fig. 14

- 18 -
TECHNICAL SPECIFICATIONS
8 - THERMAL EFFICIENCY
10
0,90
0,92
0,94
0,96
0,98
1,00
1,02
1,04
1,06
1,08
1,10
525-09-3
20 30 40 50 60 70
Efficiency on NCV
Return temperature
max. rate
min. rate
Fig. 15

- 19 -
III - OPERATION
1 - GENERAL OPERATING PRINCIPLE
The THI boiler is a very high efficiency condensation
boiler owing to the burner and heat exchanger that
benefit from our longstanding experience.
The over-sized fin tube exchanger and its combus-
tion chamber cooled by water in the upper section,
combines the functions of heat exchanger and con-
denser.
Second generation digital control continuously opti-
mizes the operating rate by using information sent to
the microprocessor by the sensors fitted on the boi-
ler:
- boiler flow sensor,
- boiler return sensor,
- outside temperature sensor,
- flue gas temperature sensor,
- room sensor,
- pressure sensor,
- fan speed control (pneumatic air/gas control),
- circulating pump speed control,
- communication bus with external regulators.
Each of the sensors is allocated to an algorithm that
optimizes the operation and generates information
or fault codes that can be read from the display of
the control panel or QAA73 room sensor.

- 20 -
OPERATION
2 - OPERATION OF THE LMU MANAGEMENT UNIT
2.1 - Normal operating conditions
To access the operating phases of the LMU (display
level A4), press the info key (7) three times. The dif-
ferent phases will then be displayed (13).
Note:
- The phase display will stop automatically after 8
minutes,
- Otherwise, press the info key a 2 times more.
2.2 - Operating diagram
bar Info
°C
Reset
INFO-0
713
Fig. 16
Programming order for normal operating conditions
Display Meaning Display Meaning
Stand-by (no heating request) Ignition - safety time
Start-up blocked Heating mode operation
Fan speed rise time Hot water mode operation
Pre-ventilation time Heating + DHW operation (disabled for
THI)
Waiting time Post-ventilation with last operation
command
Pre-ignition time Return to initial setting
Fault position (display of current fault
code)
022 1 2 3 654 10 H
11 DHW
12 H+DHW 20 2 4 7 21 99
HMI
display:
Phase
Home return
TLO
TNB
Standby
ti
PH_TNB
tv TBRE
Operation
TW1 TW2 tvz tsa1 tsa2 tn
tsa
TNN tsa1 tsa2
tsa
THL2 tn
PH_TLO PH_TNN
PH_
STANDBY
PH_
STARTVER
PH_
THL1_1 PH_TV PH_TBRE PH_TW1 PH_TW2 PH_TVZ
PH_
TSA2_1 PH_TI
PH_
MODU-
LATION
PH_
THL2_1 PH_TN_1
PH_
TSA1_1
PH_
TSA2_2
PH_
TSA1_2
PH_
THL2_2 PH_TN_2
PH_
STOER
THL1
PH_
THL1_2
THL1 (TW1)
PH_TW1
Flame
Head
demand
STANDBY
Z Z
Logic on
Logic off
On deviation
transition to home run
Deviation leads to lockout
On deviation transition to
specified or following phase
Permitted range
Prohibited range
-> Home run
Prohibited range
-> Lockout
Ideal signal
Transition criterion
Control signal
Triggering forced prepurging
Z
7494f01D/0801
THI-65-3
NoG_Null
BV
Ignition
LP (4)
NoG_Max
N_VL
N_TL
N_Vor
N_ZL
-N_TL_Delta
-N_ZL_Delta
+N_ZL_Delta
-N_Vor_Delta
+N_VL_Delta
Depend on
parameter
setting
LP (3)
LP (2)
Z
Z
Z Z
PH_
PH_
THL2
PH_
THL2
Z
PH_
THL2
Z
PH_
THL2
PH_
THL2
PH_
THL2
PH_
THL2
PH_
THL2
PH_
TSA1_2
Z
Z
Z Z
Z ZZ Z Z Z
Z
Z
Depend on
parameter
setting
Depend on
parameter
setting
Depend on
parameter
setting
Depend on
parameter
setting
Depend on
parameter
setting
Fig. 17

- 21 -
OPERATION
Explanation of the operating phases
Display Phase Description
Shut down
PH_STANDBY (unlimited) The boiler is on standby and waiting for a heating request.
PH_STARTVER Start-up is blocked. The corresponding diagnostic code is emitted (shunt
X10-03).
Start-up: heating request
PH_THL1_1 (THL1) Fan speed rise time:
- This time ends as soon as the fan motor speed reaches the program
for pre-ventilation
PH_TV (tv) Pre-ventilation time
PH_TBRE + PH_TW1 Tapering time
- This time ends as soon as the ignition load programmed for pre-venti-
lation is reached
PH_TVZ (tvz) Pre-ignition time:
- Appearance of the ignition arc prior to opening the gas valve, which oc-
curs at the start of phase 6
or
PH_TSA1_1 + PH_TSA2_1 (tsa) Safety time
- A flame signal should be present before the safety time has elapsed. If
this does not occur, another ignition attempt is made.
or
or
PH_TI + PH_MODULATION: Burner operation
10: heating operation
11: domestic hot water operation
12: heating and domestic hot water operation (disabled for THI)
• PH_TI...............................: Flame stabilisation interval.
•PH_MODULATION...........: In this phase, the LMU (regulator) send its results.
Return to standby: The switch from the operating position to the Standby position is split into “shut-down”
and “return to initial setting”
Shut-down: This occurs when the heating request disappears
or
PH_THL2_1 + PH_TN1 Post-ventilation time
- The fan remains on during the post-ventilation time
Return to initial setting: Compulsory switch from the shut-down position to standby. This phase is also
used to bring the boiler to standby position after exceptional events such as a RESET.
PH_TNB + PH_TLO + PH_ TNN: Return to initial setting

- 22 -
OPERATION
2.3 - Principle of air/gas servo-control system
The gas valve fitted on each boiler is controlled by
the air pressure supplied by the fan, thus guaran-
teeing a correct air-gas ratio over the whole modu-
lation range (constant CO2). This ratio remains
constant despite any pressure drop in the combus-
tion products outlet or the air intake. The air-gas link
is pneumatic.
2.4 - Air pressure variation procedure
Linear pressure modulation is carried out by a 230 V
variable-speed fan controlled by the LMU which cal-
culates the speed needed at any given time to pro-
duce the required pressure.
2.5 - Emission of pollutants
This air/gas control combined with high efficiency
pre-mixing burner enables CO and nitrogen oxide
(NOx) emissions to be obtained that lie within the
values laid down by the most demanding of quality
standards.
Fig. 18
0
1
2
3
4
5
6
7
8
9
0246810
PL mbar
PO mba r GN
THI5-25
Ai r -Gaz T HRi
PL : Air pressure of air/gas servo-system
PO : Gas valve output system
Air/Gas servo-system

- 23 -
OPERATION
3-FUNCTIONS
- Boiler anti-freeze protection: When the boiler
temperature is below 5°C, the burner and the
heating circuit pump are switched on. When the
temperature increases and exceeds 15°C, the
burner stops and the pump continues to circulate
for 10 minutes.
- Anti-freeze protection for the installation: This
function uses the real outside temperature. It
adopts a different behaviour depending on the
temperature. If no measured outside temperature
is available, the function is blocked.
Different reactions can occur depending on the
outdoor temperature measured:
• If the outdoor temperature is less than or equal
to -5°C, the pumps operate continuously,
• If the temperature lies between -4 and 1.5°C,
the pumps operate for 10 minutes every 6
hours.
• If the outdoor temperature is over 1.5°C, the
pumps shut-down (no heating request).
Any domestic hot water request is given priority.
- Building anti-freeze protection:
The anti-freeze function of the building is a control
function (available with the QAA73 room sensor)
used to maintain the room temperature at a mini-
mum value, thus preventing the risk of freezing in
the building.
To provide a substantial degree of protection
against the development of pathogenic bacteria in
the domestic hot water tank during prolonged shut-
downs, the domestic hot water must be heated once
a week to a temperature above 60°C.
The anti-legionnella function is used for this purpo-
se. It heats the hot water storage tank once a week,
on Monday, after the first load, to a 65°C "anti-le-
gionnella" temperature.
When the heating mode ends, the heating circuit
pump remains on for a certain period (depending on
the settings used : QAA 73 setting : 544).
In hot water storage systems, when domestic hot
water heating ends, the heating circuit pump re-
mains on until the boiler temperature drops below
70°C. During this pump run-on period, the selector
valve remains in the “domestic hot water feed” posi-
tion.
If the heating circuit pump has not operated or if the
selector valve has not been activated for more than
about 24 hours, these elements are activated during
operating stops for approximately 5 seconds.
The boiler flow sensor in combination with the hea-
ting return sensor provide the overheat safety func-
tion.
There are two safety levels:
- if the first temperature value is exceeded, this is
signalled by a fault code on the display screen,
•THI 5-25 : 92°C ,
- if the second temperature value is exceeded
(100°C), it is signalled by an alarm code on the
display. The boiler switches to safety mode. The
boiler must be reset to be restarted.
If the temperature is exceeded, the heat present
must be evacuated through the fan and circulation
pump.
The two elements (fan and circulation pump) remain
on until the boiler shell temperature drops.
In the control algorithm, supervision of the tempera-
ture difference DT between the flow and return re-
sults in the shutdown of the burner if DT is above
56°C.
3.1 - Anti-freeze function
3.2 - Anti-legionnella function
3.3 - Pump run-on after the end of heating
3.4 - Pump kick or selector valve kick
3.5 - Boiler overheat protection

- 24 -
OPERATION
The monitoring of flue gas temperature is not
classed as a function related to safety, but is a prio-
rity factor in the control of the boiler.
- The boiler operates at minimum power if the flue
gas temperature exceeds 85°C,
- The boiler is on "Stand-by" if the flue gas tempe-
rature reaches 88°C.
The boiler can only be restarted automatically after
15 minutes if there is no longer a fault.
The information from the return sensor is used in the
event of a very low flow (large DT) (reduction in bur-
ner power or shut-down of the burner).
It is also used in control algorithm of the modulating
pump (optimization of the boiler thermal efficiency).
It is also enabled for cascade connection.
This is a priority function with respect to the control
of the boiler.
- the power of the boiler is limited if the pressure is
above 4 bar,
- the boiler reduces power to 20% if the pressure in
between 0.2 and 0.4 bars (fault code is dis-
played),
- the boiler sets of an alarm and the pump stops if
the pressure is lower than 0.2 bars (alarm code is
displayed).
The boiler must be reset to clear the fault position if
the minimum value has been exceeded.
To prevent the boiler from cutting out suddenly, the
power failure differential is adjusted according to the
real temperature curve of the boiler.
To enable this function, press the clean key (6) until
the red LED (11) lights up then release it. The LED
(11) then starts flashing once per period. The signal-
ling coded “SF” is displayed on the screen (13).
Heating takes place at maximum heat output until
arriving at the maximum temperature TKSmax.
To stop the cleaning function, press on the clean
key (6) for 3 seconds then release it.
The regulator shut-down function enables the fan
motor speed to be set manually via a domestic hot
water temperature potentiometer (3), and therefore
the heat output of the boiler.
- Press the clean key (6) for longer than 8 seconds,
• The red LED (11) flashes twice per period.
• The codes appear on the display
(13) and flash twice. This code corresponds to
the percentage of the boiler heating rate.
The safety function and the “all or nothing” regulator
are operating
To disable the regulator shutdown function, press
the clean key (6) for 3 seconds then release it.
3.6 - Monitoring of flue gas temperature
3.7 - Boiler return temperature control
3.8 - Monitoring of hydraulic pressure
3.9 - Anti-short burner cycle protection
function
3.10 - Cleaning function
3.11 - Regulator shutdown function
j
bar Info
°C
Reset
6
11
13
RAMO-SF
Fig. 19
j
bar Info
°C
Reset
6
11
13
RAMO-AR
j
bar Info
°C
Reset
6
11
13
RAMO-AR
Fig. 20

- 25 -
OPERATION
The following functions can be allocated to the pro-
grammable key via the setting
KonfigEingang (QAA 73 setting : 614 ):
- 0: The programmable key function is not used.
- 1: Default, modem function enabled, if the contact
(X10-04) is closed; disabled if the contact is
open.
- 2: Modem function disabled, if the contact (X10-
04) is open; enabled if the contact is closed.
- 3: Hot air curtain function enabled, if the contact
(X10-04) is closed.
Hot air curtain function (swimming pool):
This function enables the boiler setting to be raised
to its maximum value.
It can be enabled in summer and winter modes.
- Modulation of the burner output is maintained.
- Domestic hot water priority is maintained.
- This function is enabled when the contact is
closed.
- There is no effect on the control of a modulating
pump.
Modem function:
The modem function allows the boiler to be placed
on "standby" or to be switched off via the telephone.
All protection functions (e.g. anti-freeze function,
pump kick) remain active.
On the other hand, when this function is activated,
some of the other functions are not ensured:
- The antifreeze function of the installation is not
guaranteed.
- The anti-legionella function of the unit is no longer
used.
The automatic summer/winter switching function
enables summer mode to be switched to winter
mode (and vice versa) throughout the year without
the need for any intervention.
The heating is shut down (when switching from win-
ter mode to summer mode) when the average outsi-
de temperature measured over the preceding 24
hours is over the +1°C setting, namely 20°C.
The heating is also started up again (when switching
from summer mode to winter mode) automatically
when the average outside temperature measured
over the preceding 24 hours is below the -1°C set-
ting, namely 18°C.
-Note:
The switchover setting is set to 19°C and can only
be changed by using the QAA 73 room sensor.
The automatic mode must obviously be activated
on the boiler as well as on the QAA 73 room sen-
sor for the automatic summer/winter switching to
be available.
This function is activated by default in the QAA 73
basic configuration.
3.12 - LMU programmable key 3.13 - Automatic summer/winter switching
(only activated with outside sensor)