Saunier duval ISOFAST CONDENS F 35 E User Manual

INSTRUCTIONS FOR USE, INSTALLATION AND SERVICING

FOR ISOFAST CONDENS F 35 E

3

4000135500-2 04/04

INSTRUCTIONS FOR USE

Lighting : make sure that:

• the boiler is connected

to the electrical supply,

• the gas service tap is open,

• Switch ON (I).
Switch off the boiler : Switch

to OFF (0) : the electrical
supply is off. Stop the gas
supply if the boiler is to be
out of use for a long time.

In case of fault, the
red warning light will flash
and a code appears
on the boiler display .

Code 21: Water pressure too
low: open the blue tap (t)
situated under the boiler until a
pressure of 1.5 bar is obtained.

Other codes: press the key of the
room thermostat and read the indications
given by the display.

Lighting/switch off the boiler

Fault indication

1-On/Off switch.
2-Room thermostat disabled when the

button light is ON

3-Sanitary function enabled when the

button light is ON

4-Heating function enabled when the

button light is ON

5-Hot water temperature adjuster.
6-Heating temperature adjuster.
7-Graphic display.
8-Green running light.
9-Red, flashing fault light.

10- Yellow running lamp for the burner.

1

➡

4

2

3

5

6

7

8

9

10

Operation without room thermostat

• Press the key (the key will light-up)

• Press the and/or buttons to
activate the heating and/or hot water
functions

• Use buttons and to determine the
heating and hot water temperatures.

• To revert to the operating mode with room
thermostat, again press the key (the
light will turn OFF;

5

6

9

7

t

21

OK

2

Important notice : The settings performed

on the boiler control panel are not
transmitted to the room thermostat.

Perform the temperature settings from
the wireless room thermostat supplied
together with the boiler, strictly adhering
to the instructions given in this manual,
pages 10 through 17.

Contents

INSTRUCTION FOR USE

Controls and Lighting page 2
Important informations 3 - 5
Guarantee informations 6 - 7
Controls informations 8 - 17

INSTALLATION
INSTRUCTIONS

General informations 18
Dimensions 19
Technical Data 20 - 23
Boiler coponents 24
Schematic layout of boiler 25
Boiler location 26 - 27
Flue location and
Ventilation 28 - 31
Heating System 32 - 33
Domestic
Hot Water System 33
Boiler Installation 34
Piping installation 35 - 38
Electrical Connection 39
Commissioning
on boiler 40 - 43
Commissioning
on room thermostat 44 - 51
Gas conversion 52 - 53

SERVICING
INSTRUCTION

Routine Cleaning
and Inspection 54 - 59
Wiring Diagram 60 - 61
Fault Finding 61 - 63
Replacement of Parts 64 - 72
Spare Parts 73

Important information

The instructions consist of
three parts, User,
Installation and Servicing
Instructions, which
includes the Guarantee
Registration Card. The
instructions are an integral
part of the appliance and
must, to comply with the
current issue of the Gas
Safety (Installation and Use)
Regulations, be handed
to the user on completion
of the installation.

General

This combination boiler is
able to provide room heating
as part of a central heating
system, and domestic hot
water direct from the cold
water supply without the
need for secondary storage.
The central heating water
temperature and domestic
hot water temperature can
both be adjusted on the
boiler.
Once the controls are set
the boiler operates
automatically.
A frost protection program is
also included.

Please read these
instructions and follow them
carefully for the safe and
economical use of your
boiler.

Gas Category

This boiler is for use only on
Natural gas (G20) or
propane (G31).

Gas Safety (Installation
and Use) Regulations

In your own interests and
that of safety, it is the Law
that ALL gas appliances are
installed by a competent
person in accordance with
the current issue of the
above regulations.

Gas Testing and
Certification

The boiler is tested and
certificated for safety and
performance.
It is, therefore, important
that no alteration is made to
the boiler unless approved,
in writing, by Saunier Duval.
Any alteration not approved
by Saunier Duval, could
invalidate the certification,
boiler warranty and may also
infringe the current issue of
the statutory requirements.

CE Mark

This boiler meets the
requirements of Statutory
Instrument, No. 3083 The
Boiler (Efficiency) Regulations,
and therefore is deemed to
meet the requirements of
Directive 92/42/EEC on the
efficiency requirements for
new hot water boilers fired
with liquid or gaseous fuels.
Type test for purposes of
Regulation 5 certified by :
Notified body 0086.
Product/production certified
by : Notified body 0086.

USERS

54

Important information

The CE mark on this
appliance shows

compliance with :

1. Directive 90/396/EEC on

the approximation of the
laws of the Member States
relating to appliances
burning gaseous fuels.

2. Directive 73/23/EEC on

the harmonisation of the
Laws of the Member States
relating to electrical
equipment designed for use
within certain voltage limits.

3. Directive 89/336/EEC on

the approximation of the
Laws of the Member States
relating to electromagnetic
compatibility.

Control of Substances
Hazardous to Health

Under Section 6 of The
Health and Safety at Work
Act 1974, we are required
to provide information on
substances hazardous to
health.
The adhesives and sealants
used in this appliance are
cured and give no known
hazard in this state.

Insulation Pads

These can cause irritation to
skin, eyes and the
respiratory tract.
If you have a history of skin
complaint you may be
susceptible to irritation. High
dust levels are usual only if
the material is broken.
Normal handling should not

cause discomfort, but follow
normal good hygiene and
wash your hands before
eating, drinking or going to
the lavatory.
If you do suffer irritation to
the eyes or severe irritation
to the skin seek medical
attention.

Spare Parts

REMEMBER, When
replacing a part on this
appliance, use only spare
parts that you can be
assured conform to the
safety and performance
specification that we require.
Do not use reconditioned or
copy parts that have not
been clearly authorised
by Saunier Duval.

Manual Handling
Guidance

During the appliance
installation and the
replacement of the
heat exchanger it will be
necessary to employ caution
and assistance whilst lifting
as the appliance or
component exceeds the
recommended weight for a
one man lift.
In certain situations it may
be required to use a
mechanical handling aid.
Take care to avoid trip
hazards, slippery or wet
surfaces.

Gas Leak or Fault

If a gas leak or fault exists or

is suspected, turn the boiler
mains electrical supply off
and turn off the gas supply
at the meter. Consult your
local gas company or your
local installation/ servicing
company.

Electrical Supply Failure

The boiler must be earthed.
The boiler will not work
without an electrical supply.
Normal operation of the
boiler should resume when
the electrical supply is
restored.
Reset any external controls,
to resume normal operation
of the central heating.
If the boiler does not resume
normal operation turn the
mains reset switch off and
on. If the boiler does not
resume normal operation
after this the overheat stat
may have operated. The
overheat stat would only
operate under abnormal
conditions and, under these
circumstances; it would be
advisable to consult your
installation / servicing
company.

Boilers Installed in a
Compartment or Cupboard

If the boiler is fitted into a
compartment or cupboard,
it does not require any
ventilation openings. Do not
use the compartment
or cupboard for storage.

Pluming from flue terminal

Like all condensing boilers
this appliance will produce a
plume of condensation from
the flue terminal in cool
weather. This is due to the
high efficiency and hence
low flue gas temperature of
the boiler. It is normal and
not a fault indication.

Replacement Parts

If replacement parts are
required contact
Saunier Duval service using
the telephone number on
the back cover of this
booklet.
Please quote the name of the
appliance this infomation will
be on the front of the
appliance.

Protection Against Freezing

The room thermostat
automatically ensures a
minimum installation
temperature of 6°C.
This protection is ensured
by the room thermostat as
long as it is active. This
means that the button
of the boiler must not be lit
and that the batteries of the
room thermostat must be in
good condition.

If you are out of home for a
few days, use the holidays
mode of your room
thermostat, and set the Start
and End dates, as well as
the desired temperature.

If the mains electricity and
gas are to be turned off for
any long periods during
severe weather, it is
recommended that the
whole system, including the
boiler, should be drained to
avoid the risk of freezing.

Contact your
installation/servicing
company as draining, refilling
and pressurising MUST be
carried out by a competent
person.

As a safety feature the boiler
will stop working if the
condensate drain becomes
blocked. During freezing
conditions this may be
due to the forming of ice in
the condense drain external
to the house. Release an ice
blockage by the use of

warm cloths on the pipe.
The boiler should then
restart. Contact your
installation/servicing
company if the fault
persists.

Draining and Filling

This boiler works in a
pressurised system, which
must only be drained,
refilled and pressurised by a
competent person.

Pressure Relief Safety
Valve

A pressure relief safety valve
and discharge pipe is fitted
to the boiler. This valve must
not be touched. Should
there be any discharge from
the pipe, isolate the boiler
electrical supply and
call your installer or
Saunier Duval service using
the telephone number on
the back cover of this
booklet.

Access to the user menu :

+

HOLIDAYS START DATE

OK

MENU

END DATE

CANCEL

OK

+

To ensure the continued
efficient and safe operation
of the appliance it is
recommended that it is
checked and serviced as
necessary at regular
intervals. The frequency of
servicing will depend upon
the particular installation
conditions and usage, but in
general once a year should
be enough. Refer to Section
«Routine Cleaning and
Inspection».

If this appliance is installed
in a rented property there is
a duty of care imposed on
the owner of the property by

the current issue of the Gas
Safety (Installation and Use)
Regulations, section 35.
Servicing/maintenance
should be carried out by a
competent person in
accordance with the rules in
force in the countries of
destination.

To obtain service,
please call your installer or
Saunier Duval service using
the telephone number on
the back cover of this
booklet.

Please be advised that the
‘Benchmark’ logbook

should be completed by the
installation engineer on
completion of
commissioning and
servicing.
All CORGI Registered
Installers carry a CORGI ID
card, and have a registration
number. Both should be
recorded in your boiler
Logbook. You can check
your installer is CORGI
registered by calling CORGI
direct on: 01256 372300.

Cleaning

The boiler casing can be
cleaned with a damp cloth
followed by a dry cloth to
polish.
Do not use abrasive or
solvent cleaners.

Boiler casing

CAUTION. Do not remove
or adjust the casing in any
way, as incorrect fitting may
result in faulty operation. If in
doubt, consult your
installation/service company.

USERS

76

Servicing,
all you need to know

Many thanks for choising
Saunier Duval market
leaders in boiler
manufacture,

Your appliance is
guaranteed for a period of
24 months from the date
of installation or 30
months from the date of
manufacture whichever is

the shorter and covers
manufacturing defects only.

We, Saunier Duval,
undertake to repair or
replace parts free of charge
which are recognised by us
to be of faulty manufacture ­if necessary after return to
our factory for examination ­on condition that :
a) The appliance was
installed by a qualifled gas
installer in accordance with
installation instructions, and
all the relevant codes of
practice, standards and
legislation in force.
b) The appliance has been
used for normal domestic
purposes and in accordance
with the manufacturer's
operating and maintenance

instructions.
c) The appliance has not
been serviced, maintained,
repaired dismantled or
tampered with during the
guarantee period, by anyone
other than an engineer
approved by Saunier Duval.
d) The appliance is still in
the possession of the
original user, and proof of
purchase in the form of a
receipt or invoice is shown
to the service engineer on
request.
The repair or replacement of
parts during the guarantee
period does not have the
effect of extending the
period.

This guarantee does not
cover :

a) Any defects or damage
resulting from incorrect or
poor installation, inadequate
servicing, or maladjustment
of the gas or water used.
b) Any defects in the system
to which the appliance is
connected.
c) Any deterioration or
maladjustment following
changes in the nature or
pressure of the gas or the
water used, or a change in
the characteristics of the
electrical supply voltage.

Notification of any fault
should be made to the
appliance installer.
No repairs should be
undertaken upon the

Welcome users

appliance, intending it to be
covered by the product
guarantee without prior
authorisation from
Saunier Duval.

IMPORTANT : The
appliance serial number
must be quoted on all
correspondence/contact
made with Saunier Duval.

This guarantee is in
addition to your statutory
and other legal rights, which
will not be excluded or
diminished by the return
of the guarantee registration
card.

USERS

8 9

SYSTEM PRESSURE
TOO LOW
FILL IN AT 1,5 BAR

Ambient

temperature display

Time period for the

COMFORT temperature

Hot water
mode indicator

Heating mode

indicator

Time display

Time period for the
ECO temperature

Low battery
indicator

1-Display.
2- Fault indicator.
3-Return to previous menu
4-Confirm OK.
5-Access to the menus.
6 - Menu scrolling
7-Changing the mode
8-Wall bracket
9-Mains power plug

1

2

3

4

5
6

7

8

9

Fault description

Heating demand
indicator

Indicators of the
current temperature levels
for “COMFORT
or ECO”
(Day/Night).

(Attention: this value may

vary when you hold the

thermostat in your hand).

Your Isofast boiler is
factory set to operate within
a customary installation.

Nevertheless, as many
installations may
incorporate specific
features, feel free to contact
your installer who will be
able – by adapting the
parameters of the boiler
(maximum temperature
and/or maximum power of
the heating system) - to
warrant you the best
operating performance of
your installation.

These settings being made,
you still have the possibility
of selecting the ambient
temperature to suit your
own requirements not only
when you are at home, but
also during nightime or
when you are out

All these settings are
achieved from the room
thermostat supplied
together with your boiler: if
you accurately determine
the temperatures that best
suit to your needs, you will
make significant savings in
terms of gas consumption.

Control
as a source of savings

Essential adjustments to
the wireless room
thermostat :
A – Setting the time
B – Setting the date

The thermostat’s
weekly programme
functions enable you :
C – To activate or
deactivate the heating
function.

D – To have a standard
weekly programme by

activating the programme
pre-set at the factory.

E – To bypass the current
programme, temporarily,
to increase or lower the
temperature at any time
during the day.

F – To set up a custom
programme for each day of
the week, with 2
temperature levels, for
example:

• COMFORT for the periods
you are present and.

• ECO at night or when you
are away.

G – To have the same
temperature 24 hours a day
by deactivating the
programme.

H – To leave on holiday,
determining the desired
temperature according to the
date you leave and when
you return.

I – To select the temperature
of your domestic hot water
from 38°C to 60°C.
However, keeping the
temperature below 50°C,
reduces gas consumption
and provides good
protection against scalds.

J – To prevent undesired
alterations to your settings
by locking the thermostat’s
buttons.

K – To be informed of any
operating faults in the

boiler and be instructed in
the procedure to follow.

USERS

1110

Control
as a source of savings

A B

Progress of the operations :

at any time takes you back to the previous step

1 - Accessing the user menu

• Press to call up the next menu:

2 - Setting the time

• Use the buttons to select the "Set time" menu:

3 - Setting the date

• Use the buttons to select the "Set date" menu:

• Press to select the "ON/OFF heating "
menu:

1 - Activate the heating

MENU

SET TIME

SET DATE

C

MENU

ON/OFF HEATING

Settings for the time and the dateand

OK

OK

Please note that pressing button

SET COMFORT T¡

SET ECO T¡
PROGRAMME
SET HOT WATER T¡
ON/OFF HEATING
HOLIDAYS
SET TIME
SET DATE

17:23

TUE 14/JUA/ 03

+

+

OK

OK

Activating/deactivating the heating function

PROGRAMME

+

OK OK

OFF

SET HOT WATER T¡
ON/OFF HEATING
...

ON

C

OK

D

Progress of the operations:

1 - Activating the weekly programme

PROG

• Press , the room thermostat shows this display:

• Pressing reverses
ON and OFF mode every time

• When the ON mode appears, wait 5 seconds for the display to return to normal position
and automatically validate the selection.

2 -Accessing the initial programme

• Press to select the
"Programme" menu :

PROGRAMME

• Exit from the menu by pressing , which initiates the standard weekly programme
pre-set at the factory :

Monday to Friday

• Pressing one of the scroll buttons calls up the menu for setting the ambient temperature :

PROG

MENU

ECO ECOCOMFORT COMFORT

11 PM >> 6 AM>> 8 AM >> 4 PM >> 11 PM

E

Temporarily bypassing the weekly programme

Activating the initial programme

Please note that pressing button
at any time takes you back to the previous step.

or

PROGRAMME ON

OK

+

OK

+

PROGRAMME OFF

INITIAL PROGRAMME
MONDAY

SET COMFORT T¡
SET ECO T¡
PROGRAMME
...

C

Weekends

ECO temperature 16°C COMFORT temperature 19°C

ECO COMFORT

11 PM >> 7 AM >> 11 PM

C

OK

2 - Deactivate the heating

ON/OFF HEATING

OK OK

ON

OFF

SET ROOM T¡

22¡C

This setting is automatically cancelled when the programme changes to Eco or Confort temperature level.

SET ROOM T¡

20¡C

Confirm by pressing

OK

OK

USERS

1312

PROG

OK

MODIFY
COPY TO

MONDAY
TUESDAY

MONDAY

TUESDAY

OK OK OK

• Press to confirm the parameters you have set for the day.

• Follow the same procedure for every day of the week or use the duplication function,
as explained below.

19.5

MODIFY
TIME-SLOTS :
T¡ CHOICE : PROG

19.5 16.5

Press to switch from
COMFORT to ECO temperature

This symbol indicates the
mode authorising deletion
of black squares to set up
operating periods at the
stated ECO temperature
using the buttons / .

E.g. :

In the case of the
illustration opposite, each
press of the button
adds a blank from 6 AM
onwards, corresponding to
an extra 30 minutes
heating at 16.5°C.

E.g. :

In the case of the
illustration opposite, each
press of the button
adds a square from 11
PM onwards,
corresponding to an extra
30 minutes heating at

19.5°C.

This symbol indicates the
mode authorising additional
operating periods at the
stated COMFORT
temperature (black
squares)
using the buttons / .

The squares indicate

the time periods when the boiler will
provide the COMFORT temperature
level
(e.g.: 19.5°C between 4 PM and 11
PM and 6 AM and 8 AM)

The blanks indicate

the time periods when the boiler will
provide the ECO temperature level.
(e.g.: 16.5°C between 8 AM and 4
PM and 11 PM and 6 AM)

Duplicating a programme

• To save time, you can copy the parameters you have set onto another day via the menu :

/

MODIFY
TIME-SLOTS :
T¡ CHOICE : PROG

/

MODIFY
TIME-SLOTS :
T¡ CHOICE : PROG

/

23:00 6:00

Control
as a source of savings

OK OK

SET COMFORT T¡

SET COMFORT T¡

SET ECO T¡
PROGRAMME
...

19.0¡C

19.5¡C

18.5¡C

20.0¡C

OK

PROGRAMME

MODIFY
COPY TO

MONDAY

TUESDAY
WEDNESDAY
THURSDAY
FRIDAY
SATURDAY
SUNDAY
INITIAL PROGRAMME

OK OK

/...

/...

(to set the desired temperature during the day)

(to set the desired temperature
during the night or while you are away)

OK OK

SET ECO T¡

16.0¡C

16.5¡C

16.0¡C

17.0¡C

/...

/...

(to allocate time periods for the
Comfort and Eco temperatures)

PROG

PROG

• When the ON mode appears, wait 5 seconds for the display to return to normal position
and automatically validate the selection.

PROGRAMME OFF

PROGRAMME ON

or

C

• Press to call up the next menu:

• Press , the room thermostat shows this display:

• Pressing
reverses ON and OFF mode every time.

Progress of the operations :

MENU

Setting the custom weekly programme

1 - Activating the weekly programme

2 - Access to the user menu

3 - Setting the Comfort temperature

4 - Setting the Eco temperature

5 - Programme

Please note that pressing button
at any time takes you back to the previous step.

F

USERS

1514

SET ECO T¡
PROGRAMME
SET HOT WATER T¡
...

OK OK

SET HOT WATER T¡

50¡C

51¡C
49¡C

52¡C

/....

/....

(to set the hot water to
the desired temperature)

C

• Press to call up the next menu :

Progress of the operations :

MENU

Setting the hot water temperature

1 - Access to the user menu

2 - Setting the hot water temperature

Please note that pressing button
at any time takes you back to the previous step.

+

I

Locking/unlocking the thermostat’s buttons

J

• Holding down the and buttons simultaneously for 3 seconds locks the room
thermostat’s buttons.

• Follow the same procedure to unlock the buttons.

Press for 3 seconds

C

OK

OK OK

SET ROOM T¡

SET ROOM T¡
...

19.0¡C

19.5¡C

18.5¡C

20.0¡C

/...

/...

(to set the constant
temperature desired)

PROG

C

• Press to call up the next menu :

• Pressing activates or deactivates the programme mode each time :

• Retain the

PROGRAMME OFF position. After 5 seconds, the display returns to its normal position

and automatically validates this selection.

Progress of the operations :

MENU

Setting the heating temperatures outside Programme mode

1 - Deactivating the weekly programme

2 - Access to the user menu

3 - Setting the ambient temperature

Please note that pressing button
at any time takes you back to the previous step.

PROGRAMME ON PROGRAMME OFF

PROG PROG

G

Control
as a source of savings

SET HOT WATER T¡
ON/OFF HEATING
HOLIDAYS
...

HOLIDAYS

• Press to call up the next menu :

• Determine the temperatures you wish according to your departure and return dates.

MENU

Holiday programme

1 - Access to the user menu

2 - Activating the Holiday programme

+

H

+

OK

OK

START DATE
END DATE
SET ROOM T¡
CANCEL

USERS

1716

Glossary
for the user menu

Control
as a source of savings

Setting the ambient temperature when the programme has
not been activated (Programme inactive).

Setting the Confort temperature for the periods set in
“Programme” menu.

Setting the reduced temperature for the periods set in the
“Programme” menu.

Allocating operating periods for Confort and Eco
temperature for each day of the week. In the morning, for

example, you are recommended to start heating
approximately 1 hour before you get up.

Displaying the external temperature when an external
sensor is installed.

Setting the hot water temperature.
Starting / stopping heating

On = Heating + hot water
Off = Hot water only
Outdoor T° = displayed when an external sensor is

connected. When “Driven by ext. T°” is
selected, the boiler automatically cuts off the
heating when the temperature is higher than
18°C (factory setting).

Displayed if your installer has selected "consigne
”manual“ in the “heating control” menu under the
“installer” menu

Setting the ambient temperature for while you are
away.

Setting the time.
Setting the date.

Set room T°

Set comfort T°

Set eco T°

Programme

Outdoor T°

Set hot water T°
ON/OFF heating

Set radiator T°
or
Floor heating T°

Holidays

Set time
Set date

K

• If a fault occurs, the red lights on the boiler and on the room thermostat flash

and a pictogram is displayed on the thermostat : , , , or

• Press the button on the thermostat:

Fault level 1

• The thermostat shows the procedure to follow:

• At the same time, the boiler’s screen shows
the code for the fault:

OK

Fault indicators

SYSTEM PRESSURE
TOO LOW
FILL IN AT 1.5 BAR

21

Fault level 2

• The thermostat asks you to call your After-Sales service
engineer, informing him of the fault code flashing on the boiler
to assist in his diagnosis.

• At the same time, the boiler’s screen
shows the code for the fault:

FLOW RATE FAULT
CALL AFTERSALES
TEL [phone]

23

INSTALLERS

1918

Dimensions

The boiler is delivered in
one package :

the boiler itself, the wireless
thermostat, the fixing
bracket, the template and
pipe connections .

The different packages
relating to the flue system
will be ordered depending
on the actual configuration
of the installation

418

890

510

232

Isofast F 35E
Net weight (kg) 52
Gross weight (kg) 60

The “as delivered” package consists of :

- 1 wireless thermostat

- 1 fixing bracket

- 3 x 1.5 V alkaline battery cells type LR6

- 1 access cover to the battery cells

ATTENTION: DO NOT FORGET TO RECOVER
THE ROOM THERMOSTAT placed in a

polystyrene case in the bottom of the package.

General Information

IMPORTANT NOTICE

The boiler and pipes are
supplied in one pack, the
flue is supplied seperately.
This boiler is factory set for
use only on G20 natural
gas.

Where no British Standards
exists, materials and
equipment should be fit for
their purpose and of suitable
quality and workmanship.
Refer to Manual Handling
Operations, 1992
regulations.

The installation of this boiler
must be carried out by a
competent person in
accordance the rules in
force in the countries of
destination.

Manufacturer’s instructions
must not be taken as
overriding statutory
requirements.

Sheet Metal Parts

WARNING: When installing
the appliance, care should
be taken to avoid any
possibility of personal injury
when handling sheet metal
parts.

Statutory Requirements

The installation of the boiler
MUST be carried out by a
competent person in
accordance with the relevant

requirements of the current
issue of : Manufacturer’s
instructions, supplied.

The Gas Safety (Installation
and Use) Regulations, The
Building Regulations, The
Building Standards
(Scotland) Regulations
(applicable in Scotland),
local Water Company
Bylaws, The Health and
Safety at Work Act, Control
of Substances Hazardous
to Health, The Electricity at
Work Regulations and any
applicable local regulations.
Detailed recommendations
are contained in the current
issue of the following British
Standards and Codes of
Practice, BS4814, BS5440
Part 1 and 2, BS5449,
BS5546, BS6700, BS6798,
BS6891 and BS7074 Part 1
and 2, BS7478, BS7593,
BS7671.

We also suggest that you
have to hand a copy of the
British Gas publication,
“Guidance Notes for the
Installation of Domestic
Condensing Boilers”.

Manufacturer’s notes must
not be taken as overriding
statutory obligations.

Certification

This boiler certificated to the
current issue of EN 483 for

performance and safety.
It is important that no
alteration is made to the
boiler, without permission, in
writing, from Saunier Duval.

Any alteration that is not
approved by Saunier Duval.,
could invalidate the warranty
and could also infringe the
current issue of the
Statutory Requirements.

Electrical Supply

All system components shall
be of an approved type and
all wiring to current I.E.E.
wiring regulations.
External wiring must be
correctly earthed, polarised
and in accordance with the
relevant standards.

In GB this is BS 6891.
In IE this is the current
edition of I.S.813 "Domestic
Gas Installations".
The boiler must be
connected to a permanent
230V ac, 50Hz supply.
Connection of the whole
electrical system of the
boiler, including any heating
controls, to the electrical
supply must be through one
common isolator and must
be fused 3 Amp maximum.

Wiring to the boiler must be
PVC 85°C insulated cable,
not less than 0.75mm2
(24/0.20mm).

INSTALLERS

2120

Natural Gas (G 20) F 35 E

Ø burner injector (mm) 5,65
inlet pressure (mbar) 20
Sanitary flow rate at maximum input (m

3

/h) 3,62

Heating flow rate at maximum input (m

3

/h) 3,02

Flow rate at minimum input (m

3

/h) 0,85

Electricity F 35 E

Electrical supply (V) 230
Electrical rating (A) 0,9
Maximum absorbed power (W) 206
IP classification IPX4D
Class 1

Technical Data
Isofast

Heating F 35 E

Heating output at 80°C/60°C (P) adjustable (kW) from 7,6 to 28

(BTU/H) from 25,930 to 95,536

Heating input min. (Q) (kW)/(BTU/H) 8 / 27,296
Heating input max. (Q) (kW)/(BTU/H) 28,6 / 97,583
SEDBUK efficiency (%) ?
Heating output at 50°C/30°C adjustable (kW) from 8,6 to 30,6
Maximum heating temperature (°C) 80
Minimum heating temperature (°C) 22
Expansion vessel charge pressure (bar) 0,5
Maximum system capacity at 75°C (l) 215
Safety valve, maximum service pressure (PMS) (bar) 3,0

Hot water F 35 E

Heating output (P) adjustable from… (kW)/(BTU/H) 34,2 / 116,690

to… (kW)/(BTU/H) 7,6 / 25,931

Maximum hot water temperature (°C) 60
Threshold flow rate (l/min.) 1
Specific flow rate (D) (for 30°C temp rise) (l/min.) 16,3
Storage capacity (l) 4
Expansion valve setting (bar) 10
Minimum operating pressure (bar) 0,7
Maximum operating pressure (P

MW) (bar) 10

Combustion F 35 E

Product outlet diameter (mm) 60
Fresh air inlet diameter (mm) 100
Fresh air flow rate (1013 mbar - 0°C) (m

3

/h) 43

Product outlet flow rate (g/s) 15,3
Product outlet temperature (°C) 68
Values of product outlet CO (ppm o mg/kWh) 100 or 176

CO2 (%) 9,2

NOx (ppm o mg/kWh) 21,1 or 37,3

Gas Supply

The gas installation must be
in accordance with the
relevant standards.
In GB this is BS6891.
In IE this is the current
edition of I.S.813 "Domestic
Gas Installations".

The supply from the
governed meter must be of
adequate size to provide a
steady inlet working
pressure of 20mbar (8in wg)
at the boiler.

On completion, test the gas
installation for soundness
using the pressure drop
method and suitable leak
detection fluid, purge in
accordance with the above
standard.

Technical Data

All dimensions are given in
millimetres (except as
noted).

The data label is positioned
on the inner door.

The Seasonal Efficiency
Domestic Boilers UK
(SEDBUK) is Band 'A'.

The value is used in the UK
Government's Standard
Assessment Procedure
(SAP) for energy rating of
dwellings. The test data
from which it has been
calculated has been certified
by B.S.I.

F 35 E

Gas category II2H3P

INSTALLERS

2322

By-pass fully shut
Open 1/2 turn

By-pass fully shut
Open 1/4 turn
Open 1/2 turn
Open 2 turns

1
2

NB : Factory seeting : Speed II

III

II

I

Speed III

Bypass

The Isofast boiler has a
built-in bypass. This must
be adjusted according
to the requirements of the
system, refer to the flow
rate pressure curve.
The boiler is supplied with
the built-in bypass open
a half a turn. It is
adjusted by turning the
bypass screw (a).
Turn the screw clockwise
to close the bypass.
When using thermostatic
radiator valves (TRV’s)
on all of the radiators, it is
essential that a separate,
adjustable bypass of 15 mm
minimum diameter is fitted
between the flow and return

of the heating circuit.Any
bypass must be fitted before
system controls.

a

By-pass fully shut
Open 1/4 turn

Open 1/2 turn

70
60
50

40
30

20
10

500 14001000

2

3

9

7

8

6

1

4

5

Curve output/pressure

Available pressure (kPa)

between heating supply and return lines

Flow rate through heating system (l/h)

Technical Data

Speed II

Speed I

3
4

5
6

7

8
9